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Penyakit EMS ( Early Mortality Syndrome ) pada budidaya udang

DISEASE ADVISORY

Early Mortality Syndrome (EMS)/Acute Hepatopancreatic Necrosis Syndrome (AHPNS):
An emerging threat in the Asian shrimp industry
Eduardo M. Leaño and C.V. Mohan
NACA, Bangkok, Thailand

The Asia-Pacific region, being the top producer of aquaculture products in the world, is continuously
beset by emerging aquatic animal disease problems causing high mortalities and economic losses among small farmers as well as commercial producers. Over the last couple of decades, several diseases (e.g.luminous vibriosis, white spot syndrome, yellowhead disease, Taura syndrome) have caused significantdevastation in the shrimp aquaculture of the region, causing the collapse of some industries (e.g. Penaeusmonodon). Recently, a new/emerging disease known as early mortality syndrome (EMS) in shrimp (alsotermed acute hepatopancreatic necrosis syndrome or AHPNS) has been reported to cause significant lossesamong shrimp farmers in China (2009), Vietnam (2010) and Malaysia (2011). It was also reported to affectshrimp in the eastern Gulf of Thailand (Flegel, 2012).

The disease affects both P. monodon and P. vannamei and is characterized by mass mortalities
(reaching up to 100% in some cases) during the first 20-30 days of culture (post-stocking in grow-out
ponds). Clinical signs observed include slow growth, corkscrew swimming, loose shells, as well as pale
coloration. Affected shrimp also consistently show an abnormal hepatopancreas (shrunken, small, swollenor discouloured). The primary pathogen (considering the disease is infectious) has not been identified,while the presence of some microbes including Vibrio, microsporidians and nematode has been observedin some samples. Lightner et al. (2012) described the pathological and etiological details of this disease.

Histological examination showed that the effects of EMS in both P. monodon and P. vannamei appear to belimited to the hepatopancreas (HP) and show the following pathology:
1) Lack of mitotic activity in generative E cells of the HP;
2) Dysfunction of central hepatopancreatic B, F and R cells;
3) Prominent karyomegaly and massive sloughing of central HP tubule epithelial cells;
4) Terminal stages including massive intertubular hemocytic aggregation followed by secondary
bacterial infections.

Similar histopathological results were obtained by Prachumwat et al. (2012) on Thai samples of P.
vannamei collected from Chantaburi and Rayong provinces in late 2011 and early 2012 (Figure 1). The
progressive dysfunction of the HP results from lesions that reflect degeneration and dysfunction of the
tubule epithelial cells that progress from proximal to distal ends of HP tubules. This degenerative
pathology of HP is highly suggestive of a toxic etiology, but anecdotal information suggests that disease
spread patterns may be consistent with an infectious agent.

In China, the occurrence of EMS in 2009 was initially ignored by most farmers. But in 2011,
outbreaks became more serious especially in farms with culture history of more than 5 years and those
closer to the sea using very saline water of 20 (Panakorn, 2012). Shrimp farming in Hainan, Guangdong,
Fujian and Guangxi suffered during the first half of 2011 with almost 80% losses

In Vietnam, the disease has been observed since 2010 but the most widespread devastation due to
EMS has only been reported since March 2011 in the Mekong Delta (South Vietnam). It affects the main
shrimp production areas of Tien Gang, Ben Tre, Kien Giang, Soc Trang, Bac Lieu and Ca Mau provinces with a total shrimp pond area of around 98,000 hectares. In June 2011, unprecedented losses in P. monodon were reported in 11,000 ha of shrimp farms in Bac Lieu, 6,200 ha in Tra Vinh (total of 330 million shrimphave died causing a loss of over VND12 billion), and 20,000 ha in Soc Trang (causing VND1.5 trillion in losses) (Mooney, 2012).

In Malaysia, EMS was first reported in mid-2010 in the east coast of peninsular states of Pahang and
Johor. The outbreaks of EMS resulted in the significant drop in P. vannamei production, from 70,000 mt in
2010 to 40,000 mt in 2011. Production for 2012 (up to May) is only 30,000 mt and worse is expected to
come as unconfirmed reports on EMS outbreaks in the states of Sabah and Sarawak came in April 2012.
So far no potential causative pathogen has been found and possible etiologies include toxins (biotic
or abiotic), bacteria and viruses (NACA-FAO 2011). Nonetheless, the spread of the disease and its
devastating effect in the shrimp industry of the countries affected so far, will require proper contingency
planning in other countries in the region, especially in P. vannamei culture which is commonly cultivated at present in many Southeast Asian countries. Added to this is the standing threat of infections myonecrosis (IMN) on P. vannamei culture, which is now somehow contained within Indonesia. Rumors of disease outbreaks caused by IMNV from other countries in Asia have so far been false (Senapin et al., 2011).

With Vietnam suffering the greatest loss due to EMS outbreak, the Food and Agriculture Organization of the United Nations (FAO) undertook an emergency mission in 2011 to assess the disease situation in the
country, in collaboration with national as well as international shrimp health experts. As a follow-up on
this emergency mission, FAO also developed a national TCP on emergency assistance to control the spreadof this shrimp disease. Implementation of the national TCP in Vietnam has commenced in April 2012.

Identifying the primary cause of the disease is necessary, but while this information is still not yet
available, increased disease awareness and preparedness should be implemented by every shrimpproducing country in the region. Considering the great economic loss that EMS will cause in the region’s shrimp industry, ways of  preventing the spread and/or occurrence of this disease should be formulated by

concerned experts, officials and other regulatory bodies. Farmers, on the other hand, should also properly
cooperate with the concerned agencies by promptly reporting any suspected mortalities among cultured
shrimp that appear to be similar to the clinical description of EMS/AHPNS. It is important that histological
examination be carried out to confirm that suspected occurrences fit the AHPNS case definition devised by Dr. Lightner.

The purpose of this short communication is to inform all NACA members of the emerging threat
and request respective Competent Authorities (CA) and concerned stakeholders to increase surveillance
and reporting efforts. Only through surveillance, early response, contingency planning and disease
preparedness, can countries minimize the impact of the impending threat. NACA Secretariat will approach
the CA of the four member governments currently affected by EMS to put up a multi-disciplinary team of
experts to understand more about the disease and develop contingency measures to prevent its further
spread in the region.

NACA will greatly appreciate receiving any relevant information pertaining to EMS/AHPNS from all
member countries in the region. Information can be sent by e-mail to the authors at eduardo@enaca.org
and mohan@enaca.org.

References:
Flegel, T.W. 2012. Historic emergence, impact and current status of shrimp pathogens in Asia. Journal of Invertebrate
Pathology 110:166-173.
Lightner, DV, Redman, RM, Pantoja, CR, Noble, BI, Tran, L. 2012. Early mortality syndrome affects shrimp in Asia. Global
Aquaculture Advocate, January/February 2012:40.
Mooney, A. 2012. An emerging shrimp disease in Vietnam, microsporidiosis or liver disease? Available at:

http://aquatichealth.net/issue/38607.

NACA-FAO 2011. Quarterly Aquatic Animal Disease report (Asia and Pacific Region), 2011/2, April-June 2011. NACA, Bangkok,
Thailand.
Panakorn, S. 2012. Opinion article: more on early mortality syndrome in shrimp. Aqua Culture Asia Pacific, Volume 8 No. 1: 8-
10.
Anuparp Prachumwat, A., Thitamadee, S., Sriurairatana, S., Chuchird, N., Limsuwan, C. Jantratit, W., Chaiyapechara, S., Flegel,
T.W. 2012. Shotgun sequencing of bacteria from AHPNS, a new shrimp disease threat for Thailand. Poster, National
Institute for Aquaculture Biotechnology, Mahidol University, Bangkok, Thailand (Poster available for free download at
http://www.enaca.org)
Senapin, S., Phiwsaiya, K., Gangnonngiw, W., Flegel, T.W. 2011. False rumours of disease outbreaks caused by infectious
myonecrosis virus (IMNV) in the whiteleg shrimp in Asia. Journal of Negative Results in BioMedicine. 10: 10

Hasil Final Report of the Emergency Regional Consultation on Early Mortality Syndrome / Acute HepatopancrEAS BANGKOK 9-10 AGUSTUS 2012  klik disini

JIKA INGIN MENDENGARKAR AUDIO HASIL DISKUSI EMS klik disini

BUDIDAYA KEPITING BAKAU (MUDCRAB)

DAFTAR HATCHERY/PEMBENIHAN YANG SUDAH TEREGISTRASI

DAFTAR HATCHERY TEREGISTRASI

No Nama Kelompok Usaha/Perusahaan Comodity Location Certificate Number Production/ year Certificate Date
Grade Issued Date
1 Anugrah Winduadi Pratama (AWP I) Windu Pl Way Urang, Kalianda, Lampung Selatan 2003002 - 01-10-2003
2 PT. Central Panganpertiwi Pabuaran Lele Pabuaran, Subang, Jawa Barat 05.007A-P00.00B.00C-P00 60.000.000 27-01-2005
3 Nila 05.008A-P00.00B.00C-P00 6.800.000 27-01-2005
4 Mas 05.009A-P00.00B.00C-P00 18.700.000 27-01-2005
5 Kelompok Tani Sri Utama Gurame Karang Lewas, Banyumas, Jawa Tengah 06.012A- P1.00B-P00.00C-P00 22.000.000 01-03-2006
6 Kelompok Tani Setia Maju Gurame Kedung Banteng,  Banyumas, Jawa Tengah 06.011A- P1.00B-P00.00C-P00 5.000.000 01-03-2006
7 UPR Mina Tanjung Gurame Rakit, Banjarnegara, Jawa Tengah 06.013A- P1.00B-P00.00C-P00 2.300.000 01-03-2006
8 PPU Probolinggo Udang Galah Probolinggo, Jawa Timur 06.014A- P1.00B-P00.00C-P00 2.000.000 01-03-2006
0025.0109.A1.B0-FormCPIB11 Good 22-01-2009
9 PT Tirta Mutiara Makmur Vaname Pl Banyuglugur, Situbondo, Jawa Timur 07.18A-P1.00B-P00.00C-P00 126.000.000 01-02-2006
0021.0109.A1.B0-FrmCPIB11 125.000.000 Excellent 22-01-2009
10 PT Nalendra Sinta Mina Usaha Nila Cijambe, Subang, Jawa Barat 06.016A- P1.00B-P00.00C-P00 14.400 01-03-2006
11 PT Sejati Minat Tahta Gurame Singaparna, Tasikmalaya, Jawa Barat 06.015A-P00.00B-P00.00C-P00 800.000 01-03-2006
12 HSRT Puspasari Udang Galah Ciamis, Jawa Barat 07.19A-P1.00B-P00.00C-P00 750.000
13 BPBPAT Cijengkol Patin Sukamandi, Subang, Jawa Barat 06.017A-P00.00B-P00.C-P00 10.300.000 29-12-2006
0048.0710.A1.B1-FormCPIB11 8.000.000 Excellent 07-07-2010
14 Lele 0013.1108.A1.B0-FormCPIB11 8.000.000 Fair 12-11-2008
15 Nila 0015.1108.A1.B0-FormCPIB11 10.300.000 Fair 12-11-2008
16 PT. Kuala Putri Permai Vaname Pl Pantai Cermin, Sumatera Utara 0001.0707. A1.B0-FormCPIB11 250.000.000 Fair 24-07-2007
17 PT. Anugrah Tambak Perkasindo Vaname Pl Perbaungan, Sumatera Utara 0002.0707. A1.B0-FormCPIB11 216.000.000 Fair 24-07-2007
18 PT. Biru Laut Khatulistiwa Vaname Pl Merak Belantung, Kalianda, Lampung Selatan 0003.0707.A1.B0-FormCPIB11 1.440.000.000 Good 24-07-2007
19 PT. Komindo Trading Utama, Vaname Pl Pandeglang, Banten 0004.0707.A1.B0-FormCPIB11 3.000.000.000 Good 24-07-2007
20 PT. Komindo Trading Utama, (Delta) Vaname Pl Banyuglugur, Situbondo, Jawa Timur 0005.0707. A1.B0-FormCPIB11 200.000.000 Good 24-07-2007
0049.0710. A1.B1-FormCPIB11 Excellent 07-07-2010
21 PT. Central Pertiwi Bahari, Vaname Pl Pecaron, Kendit, Situbondo, Jawa Timur 0006.0707. A1.B0-FormCPIB11 250.000.000 Good 24-07-2007
0051.0710. A1.B1-FormCPIB11 554.496.070 Excellent 07-07-2010
22 PT. Central Pertiwi Bahari, Vaname Pl Kragan, Rembang,  Jawa Tengah 0012.0707. A1.B0-Form CPIB11 1.000.000.000 Good 24-07-2007
0052.0710. A1.B0-Form CPIB11 Excellent 07-07-2010
23 PT. Suri Tani Pamuka Vaname Pl Gerokgak, Buleleng, Bali 0007.0707. A1.B0-FormCPIB11 70.000.000 Excellent 24-07-2007
24 PT. Esa Putlii Prakarsa Utama Vaname Pl Mallusetasi, Barru, Sulawesi Selatan 0008.0707. A1.B0-FormCPIB11 100.000.000 Fair 24-07-2007
25 PT. Ndaru Laut Vaname Pl Kalipuro, Banyuwangi, Jawa Timur 0010.0707. A1.B0-FormCPIB11 36.000.000 Good 24-07-2007
26 PT. Unimexco Jaya Sakti Vaname Pl Mappakasunggu, Takalar, Selatan Sulawesi 0009.0707. A1.B0-FormCPIB11 90.000.000 Fair 24-07-2007
27 PT. Surya Indah Teguh Abadi Vaname Pl Jenu, Tuban, Jawa Timur 0011.0707. A1.B0-FormCPIB11 300.000.000 Fair 24-07-2007
28 BPBIAT  Wanayasa Nila Purwakarta, Jawa Barat 0014.1108.A1.B0-FormCPIB11 23.000.000 Fair 12-11-2008
0050.0710.A1.B1-FormCPIB11 13.061.000 Excellent 07-07-2010
29 SK Food Windu Pl Bungatan, Situbondo, Jawa Timur 0016.1108.A1.B0-FormCPIB11 15.000.000 Excellent 12-11-2008
30 Kelompok Samudra Jaya Vaname Palang, Tuban, Jawa Timur 0017.0109.A1.B0-FormCPIB11 Fair 22-01-2009
31 Kelompok Pantura Benur Vaname Palang, Tuban, Jawa Timur 0018.0109.A1.B0-FormCPIB11 Fair 22-01-2009
32 Kelompok Windu Alam Perkasa Vaname Jenu, Tuban, Jawa Timur 0019.0109.A1.B0-FormCPIB11 Fair 22-01-2009
33 PT. Artha Laut Jaya Vaname Banyuglugur, Situbondo, Jawa Timur 0020.0109.A1.B0-FormCPIB11 20.000.000 Fair 22-01-2009
34 PT. Bago Tambak Windu Vaname Bungatan, Situbondo, Jawa Timur 0022.0109.A1.B0-FormCPIB11 12.000.000 Fair 22-01-2009
35 UPI Kerapu BBAP SITUBONDO Kerapu Pecaron, Kendit, Situbondo, Jawa Timur 0023.0109.A1.B0-FormCPIB11 100.000 Good 22-01-2009
36 BCUV BBAP SITUBONDO Vaname Pecaron, Kendit, Situbondo, Jawa Timur 0024.0109.A1.B0-FormCPIB11 100.000.000 Good 22-01-2009
37 UPI Mas BBI PUNTEN Carp Sidomulyo, Kota Batu, Jawa Timur 0026.0109.A1.B0-FormCPIB11 5.000.000 Good 22-01-2009
38 Ponpes JAWAAHIRUL HIKMAH Lobster Air Tawar Besuki, Tulungagung, Jawa Timur 0027.0109.A1.B0-FormCPIB11 480.000 Good 22-01-2009
39 BBIS Sei Tibun Patin Padang Mutung, Kampar, Riau 0028.0909.A1.B0-FormCPIB11 1.000.000 Fair 09-09-2009
40 Ohara Sakti Indo Pratiwi Patin Padang Mutung, Kampar, Riau 0029.0909.A1.B0-FormCPIB11 18.000.000 Fair 09-09-2009
41 UPR Graha Pratama Fish Patin Koto Masjid, Kampar, Riau 0030.0909.A1.B0-FormCPIB11 4.500.000 Fair 09-09-2009
42 Dolphin Farm Patin Kec. Lima Puluh, Pekanbaru, Riau 0031.0909.A1.B0-FormCPIB11 3.400.000 Fair 09-09-2009
43 UPR Stanum Hatchery Patin Bangkinang, Kampar,Riau 0032.0909.A1.B0-FormCPIB11 3.600.000 Fair 09-09-2009
44 PT. Komindo Trading Utama Nauplii Center Lombok Udang Vaname Kayangan, Lombok Utara, NTB 0033.0210.A1.B0-FormCPIB11 4.000.000.000 Excellent 03-02-2010
45 CV. Mika Distrindo Patin Kota Metro Lampung 0034.0210.A1.B0-FormCPIB11 3.0000.000 Excellent 12-02-2010
46 PB. Berkah Windu 2 Windu Raja Basa, Lampung Selatan 0035.0210.A1.B0-FormCPIB11 60.000.000 Fair 12.02.2010
47 UD. Mina Rahayu Windu Merak Belantung, Kalianda, Lampung Selatan 0036.0210.A1.B0-FormCPIB11 80.000.000 Fair 12.02.2010
48 PB. Jasa Tirta Samudera Udang Windu Raja Basa, Lampung Selatan 0037.0710.A1.B0-FormCPIB11 34.000.000 Good 07.07.2010
49 Divisi Perbenihan BBPBL Lampung Kerapu Tikus Pd Cermin, Pesawaran, Lampung 0038.0710.A1.B0-FormCPIB11 3.000.000 Excellent 07.07.2010
50 Instalasi Pembenihan Udang (IPU) Gelung Udang Vaname Pecaron Panarukan, Situbondo, Jawa Timur 0039.0710.A1.B0-FormCPIB11 90.000.000 Excellent 07.07.2010
51 UPPUW Situbondo Kerapu Macan Pasir Putih, Situbondo, Jawa Timur 0040.0710.A1.B0-FormCPIB11 250.000 Good 07.07.2010
52 Udang Vaname 0041.0710.A1.B0-FormCPIB11 3.500.000 Good 07.07.2010
53 UPI Lele Sangkuriang BBPBAT Sukabumi Lele Sangkuriang Selabintana, Sukabumi, Jawa Barat 0042.0710.A1.B0-FormCPIB11 1.000.000 Excellent 07.07.2010
54 Sub Unit Pembenihan Udang Galah

BBPBAT Sukabumi

Udang Galah Cisolok, Sukabumi, Jawa Barat 0043.0710.A1.B0-FormCPIB11 1.000.000 Good 07.07.2010
55 PT. Fega Marikultura Kakap Putih Kepulauan Seribu, DKI Jakarta 0044.0710.A1.B0-FormCPIB11 1.000.000 Excellent 07.07.2010
56 PT. Maju Tambak Sumur Udang Vaname Way Urang Kalianda, Lampung Selatan 0045.0710.A1.B0-FormCPIB11 300.000.000 Excellent 07.07.2010
57 BBPBAP Jepara Kerapu Cik Lanang, Bulu Jepara, Jawa Tengah 0046.0710.A1.B0-FormCPIB11 10.000-15.000 Good 07.07.2010
58 Udang Windu 0047.0710.A1.B0-FormCPIB11 7.500.000 Good 07.07.2010

Breeding for disease resistance of Penaeid shrimps

James Cock a, Thomas Gitterle a, Marcela Salazar a, Morten Rye b,

Aq ua c ul t ur e 2 8 6 (2 00 9 ) 1 –11

Aquaculture

 1. Introduction

 the nativespeciesP. mon odon and the introduced species of P. vannamei. Furthermore, P. stylirostris, which represented close to 20% of the neo- Diseases and pestsare major constraintson the supply of high quality tropicalcultivated shrimp production, is now rarely cultivated dueto its plant and animal products underintensive production systems. Growers susceptibility to various viruses (Lightner, 2005b). and researchers have developed a whole series of crop and animal Most of the concepts behind disease control in animal species have husbandry systems geared to minimizing the harmful effects of been developed for warmblooded terrestrial species. However, there are pathogens and pests. Recently Keen et al. (2001) observed the major differences in their environment and that of marine anima ls, commonality in microbial virulence mechanisms and the occurrence indicating that transfer of technology from one to the other should be of similar innate resistance systems in animals and plants with an carried out with caution. Warmblooded terrestrial landanimalsmaintain ancient and intertwined history. Similarly, Toyodaet al. (2002) comment a relatively constant body temperature, whereas shrimps like many other on the remarkable similarityof innate responses to pathogens in plants, aquatic organisms are ectothermal andtheir bodytemperature uctuates insects and mammals. In the particular case of shrimps, cultivation is with that of the water in which they live. Similarly, the composition of the relatively new and there is limited knowledge on response to pathogens. medium in which land animals live, the air, varies little with such vital Hence, where there are major gaps in knowledge specifictoshrimpsor aspects as oxygen and carbon dioxide content relatively constant on a crustaceans, we use experience obtained in both plants and animals as global basis. On the other hand, shrimps face tremendous variability in analogous guidelines. In thefirst section of thearticle wediscuss disease the environment in which they live with dramatic changes often and disease control, particularly geneticallycontrolled host resistance, in occurring abruptly. Stress, which is closely related to the manifestation cultivated shrimp and other species in general terms, and then use this of diseases (Biggs, 1985),isofteninducedbychangesinsuchparameters information to provide guidelines on the circumstances when breeding as temperature, oxygen, salinity and ammonium. Farmers on a dayto day for disease resistance is an appropriate control measure and how basis attempt to control diseases by managing the environment and breeding programmes can be structured. reducing the variability in the aquatic environment. Vaccination is a common disease control measure in warm blooded 2. Diseases in intensive shrimp production systems animals, protecting hundreds of millions of animals from disease and death (NOAH, 2002). Vaccines stimulate the body to produce its own Shrimps have only recently been cultivated by man, and it is only defence against infection. The defensive system “remembers” the been in the last twenty to thirty years that the cultivated populations, identity of invading organisms and combats them when a vaccinated animal is confronted with a specific disease organism. This protects the of some species that are easily reproduced in captivity, have been isolated from wild populations. Consequently, most populations of individual animal and, because this animal will not develop the disease cultivated shrimp haveonly had a relatively short period to evolve and and will not become infective, it will also help protect the population adapt to intensive cultivated production systems. from the disease due to ‘herd immunity’ (NOAH, 2002). It is generally Diseases that remain at a low level of incidence in natural accepted that Crustaceans do not possess the capacity to acquire populations may reach epidemic levels in intensive cultivation systems. resistance and hence vaccination is not possible, although this Intensive management systems in livestock production encourage the assumption is questioned by Witteveldt (2006). unpredictable appearance of new diseases and changes in the characteristics of established diseases (Biggs, 1985). Modern intensive 2.1. Disease avoidance shrimp systems provide almost ideal conditions for the propagation of diseases. In the tropics shrimp are often cultivated year round with no On a global scalesimpleavoidanceof diseases and pestshas been one break in the production cycle. Animals are confined in ponds, tanks or of the most effective means of minimizing damage of cultivated or raceways at high densities, water exchange is limited and moribund cultured species. Crop productivity is normally greater outside the animals are not culled from the system. This latter is of particular centre of origin due to less diseases and pest pressure (Jennings and importance as cannibalism is common, disseminating pathogens Cock,1977). In plants the classic exampleof avoidance outsidethecentre effectively. Furthermore some diseases of shrimps are common to of origin isthesuccess of rubber plantations in South East Asiaand Africa various crustaceans (Wang et al., 2004, 2005; Nunan et al., 2004; Lo due to the absence of South American Leaf Blight, which decimates et al., 1996; Lightner, 2005b) and it is difficult to isolate commercia l intensively cultivated populations in the Amazon basin (Davis, 1996). In production from other crustacean species, such as crabs, or copepods, animal populations there are also large differences in disease incidence that may be alternate hosts of shrimp diseases. All these conditions depending on their geographical locations with introduced species favour epidemics and the appearance of apparently new diseases in facing fewer parasites (Torchin et al., 2003). The success of introduced intensive shrimp production systems. On the Pacific coast of Centraland invasive species is often directly attributable to the lack of pathogens in South America, where a native species, Penaeus vannamei,ismost the new environment. In domesticated animal populations simple widely cultivated, Taura Syndrome Virus (TSV) devastated the industry avoidance of diseases and pests has long been oneof the most important in the early nineties (Brock, 1997). Later White Spot Syndrome Virus means of disease control, with eradication of Newcastle disease in (WSSV) appeared in Asia and rapidly devastated the shrimp industry in poultry and rinderpest and foot and mouth disease in cattle being well many parts of the world. Both of these diseases were previously known cases (Biggs, 1985). unreported. Similarly in Asia White Spot and Yellow Head epidemics Disease avoidance or eradication is only possible in certain have reduced production of various Penaeid shrimp species, including circumstances. Exclusion of diseases has been attempted with some 3 J . C oc k et al . / A qu ac u ltu r e 28 6 (20 09 ) 1 – 1 1 success in shrimp cultivation (McIntosh,1999; Moss, 1999), with various system that protects them from foreign organisms. It is generally programmes emphasising the use of Specific Pathogen Free stock in accepted that they do not have the ability to acquire immunity and breedingprogrammes to minimize spread of diseases (Moss, 1999; Moss hence there is no possibility of developing vaccines for shrimps which et al., 2003; Lightner, 2005a; Hennig et al., 2005). However, it is not easy willprovide longterm immunity to a specific disease. However, recently to avoid or eradicate diseases with an open air aquatic grow-out Witteveldt (2006) indicated that vaccination of shrimp against WSSV environment that is normally close to the sea. McCallum et al. (2004) might be possible which would open the way to the design of new have pointed out that, although the same basic principles apply to the strategies to control WSSV and other invertebrate pathogens. Never- epidemiology of both terrestrial and marine species, there are major theless, this result is questioned by many immunologists. In addition qualitative differences and these affect the management practices for there may be possibilities to stimulate the immune system and a series their control. The life cycles differconsiderably and the rate of spread of of non-specific responses against invading organisms. epidemics appears to bemuch greater in marine environments and they Geneticallycontrolled behavioural characteristics may also provide tend to bemoredevastating (McCallum et al., 2004). With the exception resistance to disease: for example genetically controlled hygienic of some diseases, such as Yellow Head Virus (YHV) and Monodon behaviour in bees prevents chalk brood disease (Milne, 1983). With Bacillus Virus (MBV), most of the shrimp viruses have spread rapidly cannibalism playing such an important role in infection in intensive from the sites where they were first recognised (Lightner 1996, 2005b; shrimp culture, it is possible that genetic control of cannibalistic Flegel et al., 2004). The recent epidemic of White Spot Syndrome behaviour may be involved in providing a measure of resistance to indicates how rapidly an epidemic may spread in marine species: First infection (Gitterle et al., 2005). detected in Taiwan in 1992 (Chou et al., 1995), WSSV rapidly spread to With diseases that are difficult to eradicate, control measures have most Asian countries (Inouye et al., 1994; Zhan et al., 1998; Flegel and been developed based on stimulation or enhancement of the natural Alday-Sanz, 1998; Wongteerasupaya et al., 1995) and by 1996 most defencemechanisms of the host organism, including selection for host shrimp farming regions in South East Asia were affected (Flegel and resistance or tolerance to diseases and modification of the environ- Alday-Sanz, 1998). In thewestern hemisphere the first outbreak of WSSV ment so that the disease is not favoured. In plants conscious selective appeared in farmed P. vannamei and P. stylirostris in South Carolina breeding for host resistance or tolerance to diseases dates back to (USA) in 1997 and it was associated with 95% cumulative losses approximately the middle of the twentieth century, whereas (Lightner, 1999). By early 1999, WSSV had spread to farmed P. vann amei conscious selective breeding schemes for livestock disease resistance in Central America (Jory and Dixon, 1999) reachingtheColombian Pacific is more recent and in the case of Penaeid shrimps selective breeding coast in May of that year. The diseases devastated most of the major for resistance was initiated in the 1990s. shrimp producing areas of the world. Attempts to eradicate or exclude the disease were mostly unsuccessful. White Spot Syndrome Virus 3. Disease resistance appeared to have been successfully excluded from a few shrimp producing regions, particularly the Atlantic coast of South America; Genetically based host resistance is an attractive proposition from however it has recently been reported in thecooler temperatureregions the point of view of the grower of improved stock. The grower, apart of southern Brazil (Anon, 2005). It now appears that conditions on the from paying for the resistant genetic stock, does not have to make Atlantic coast of South America were in general not conducive to the further major outlays, although management practices that allow the development of full scaleWhite Spot due to thehigh water temperatures resistance to be expressed may be required. A further advantage of (Vidal et al., 2001). The lack of White Spot Virus epidemics in this area host resistance is the minimal negative impact on the environment as appears to be related to the virus’s inability to replicate at the higher neither antibiotics nor chemical treatments are normally needed to temperature rather than a temperature mediated response by the enhance control. On the other hand development of genetically based shrimp (Reyes et al., 2007). Some areasin South and South East Asiamay host resistance is often costly and may be impossible to achieve in the have escaped or have low incidence of WSSV due to higher water absence of useful levels of resistance. Furthermore, each characteristic temperatures. Shrimp farmers have in some cases reduced water that is added to a selective breeding program inevitably leads to exchange and appear to have achieved some level of control of WSSV slower progress in other desirable characteristics in the breeding goal. with this practice, which probably both increases water temperatures Added to this, disease resistance may be negatively associated with and also reduces the chances of pathogens entering the ponds. other desirable characteristics. These associations may be genetically Furthermore, in Thailand the use of Specific Pathogen Free (SPF) stocks linked to genes that are close to each other on the same chromosome, and bio-security measures have reduced WSSV incidence dramatically or there may be a metabolic, physiological or ecological cost of the (anonymous reviewer, pers. comm.). On the other hand, on the Pacific resistance. Selective breeding for resistance is an attractive option for Coast of the neo-tropics WSSV SPFs and other bio-security measures managing diseases, but it is not a panacea for control of all diseases. In have not markedly reduced disease incidence. Thus, although it is order to justify the high cost of developing genetically disease generally difficult to avoid diseases in cultivated shrimps through resistant populations this approach is only advisable when: (a) the elimination of the causal agent or the use of Specific Pathogen Free disease causes severe damage; (b) there are no other existing simple stocks, it may be possible in certain circumstances to use these cost effective control measures; and (c) there is demonstrable genetic approaches to reduce incidence: in the particular case of WSSV the variation in resistance and this is not coupled with an excessive level avoidance of disease epidemics in the neo-tropics is largely based on of negative associations with other desirable characteristics. finding conditions not suitable for the development of the organism, rather than through elimination of the causal agent itself. 3.1. Evolution of genetic disease resistance 2.2. Host response and resistance to diseases Selection for disease resistance under natural conditions depends on both the advantages that ensue from being able to combat Shrimps have evolved under conditions that are favourable for infections and also the costs of maintaining defences in the absenceof infection and have developed a series of defence mechanisms that infection (Kraaijeveld and Godfray, 1997; Coustau et al., 2000). There protect them from infectious diseases in their native habitat. Disease are a small number of genetic improvement programmes with the resistance in many animals is mediated by both innate and acquired species that were first bred in captivity (P. stylirostris and P. vannamei) resistance. Innate immunity is rapid, non-specific and acts as a first line that have passed through many generations (Goyard et al., 2002; of defence, whileacquired resistance involvesantigen specific responses Wyban et al., 1992). However, the Penaeid shrimp populations used in (Bishop et al., 2002). Shrimps, ascrustaceans, possess an innateimmune most breeding programs are only, at the most, a few generations 4 J . Co ck et a l. / A qu ac u l tur e 2 86 (2 00 9) 1– 1 1 removed from the native populations from which they were natural selection in the field with larger genetic variation and extremely developed and hence levels of disease resistance will tend to re ect high mortalities (well over 99%) are likely to uncover single gene the balance between the advantages and costs under natural resistance which will normally be dominant. conditions, unless selection pressure for disease resistance under Initially in plants horizontal resistance or polygenic resistance was cultivated conditions has been strong. considered to be durable, and vertical (gene for gene or single gene) The genetic control of disease resistance in shrimps is not well resistance was subject to breakdown as thealteration of one genein the understood and little research has been dedicated to the theme until pathogens was sufficient to overcome the one gene conferring very recently. As noted previously, shrimps appear to have no acquired resistance in the vertical gene-for-gene resistance. As Zadoks (2002) immune response, and in this sense they are perhaps somewhere points out, most of the concepts related to vertical and horizontal between plants and mammals in their response, and certainly with resistance have been modified: single gene resistance can be durable some interesting comparisons with invertebrates in general. Unfortu- and polygenic resistance can be eroded or worn down. The most widely nately the information on genetic control of disease resistance in cited examples of durable resistance against bacterial and fungal invertebrates is also limited. Consequently we draw inferences on pathogens in plants are quantitative traits (Leach, 2001). Nevertheless, various aspects of genetic control of disease resistance in other species, there are a few cases where single gene partial resistance has been particularly plants and mammals in which there is a vast stock of durable in plants and it appears that this occurs when the cost to the knowledge. Selective breeding for disease resistance in plants has a pathogen of overcoming the resistance is high (Leach, 2001; Hulbert longer trajectory than in mammals. The early work on host plant et al., 2001). Nevertheless the tendency in plant breeding has moved resistance divided resistance broadly into two categories (see for from breeding for vertical resistance to breeding for horizontal example Van der Planck, 1963, 1968; Zadoks, 2002). In simple terms resistance or pyramiding of single genes as a means of making break- vertical resistant provided effective immunity, normally through down of resistance less likely(seefor example Pink, 2002; Pederson and hypersensitivity, somewhat similar to apoptosis in animals, and was Leath, 1988). controlled by single genes. Horizontal resistance did not provide total Disease resistance in most animals that have been studied is immunity but slowed the spread of the disease and was controlled by controlled quantitatively by many genes and in breeding programmes many genes. it is generally assumed that disease resistance is a quantitative trait Recently, whilst reviewing invertebrateimmunology, Rolff and Siva- under the control of many genes (see for example Detilleux, 2001). Jothy (2003) indicate that when selection pressure is strong, resistance Nevertheless there are recorded cases of single gene resistance in may be monogenic and when selection pressure is lower polygenic. animals and humans (Hill, 2001) and breeders should not ignore the Similarly, Coustau et al. (2000) indicate that when there is a new possibility of using them to confer resistance. At the same time we note environment inwhich the current phenotypesarenot viable, theoretical that most animal breeding programmes and studies of the genetics of considerations suggest that single major mutations are likely to be resistance have been developed with species in which screening of involved in adaptation to the new environment. Although Orrand Coyne millions of animals for disease resistance is simply not possible. The (1992) suggest that responses to pathogens are more likely to be mind simply boggles at inoculation and subsequent screening of several polygenic with small effects, Orr (1998) indicates that long term million cows to see if just one possesses a single gene for resistance to evolution often involves the fixation of mutations of large effect. We mastitis. On theother hand plant breeders regularly inoculate hundreds suggest that in shrimps entering a new environment under intensive of thousands of plants to identify and select resistant materials. cultivated systems and with the extremely high selection pressure in the Furthermore, in the case of the development of pesticide resistance in case of diseases such as WSSV, which kill 98% or more of the population insects and acaroids millions of individuals were subjected to the in severe epidemics (Lightner, 1996; Vidal et al., 2001), monogenic equivalent of screening for the very few resistant genotypes every time resistance or resistance under the control of a small number of genes farmers applied insecticides to their commercial plantations. In the case may arise. Certainly resistance to antibiotics in bacteria (Mazel and of shrimps a single hatchery can easily produceseveral million nauplii in Davies, 1999) and to insecticides in insect populations (Roush and a day and could expose millions of larvae or subsequent stages to a McKenzie, 1987), where selection pressure is extremely high, is disease within few days or at the most weeks and select any survivors. frequently conferred by single genes. This seems obvious when one Hence, wesuggest that usefulsingle generesistancewhich is likelyoccur considers that in the case of catastrophic circumstances, in which all for pathogens that cause severe mortalities, but that they may exist in susceptible organisms die, there is little chance for the slow accumula- very low frequencies, could well be identified in shrimps and may tion of polygenic resistance: it is only the mutant or recombinant that provide opportunities for rapidly obtaining resistant populations. In confers the ability to survive that proliferates. these cases, in the process of selection for resistance there may be a Although pesticide resistance in insects may not be precisely the severe genetic bottleneck, and special breeding methodologies will be same as resistanceto diseases caused by biologicalorganisms, theremay required to introgress the resistant genes into commercial populations. be some interesting parallels in the evolution and genetics of resistance. Fjalestad et al. (1993) suggest that in the fish farming environment, When chemical pesticides were first developed, insect populations in resistance to a given pathogen will normally develop slowly. However, the field were frequently faced with, from their point of view, a resistance to serious pathogens may develop through natural selection catastrophic situation in which only resistant animals could survive. The in aquaculture populations where the animals have continuously been frequency of resistant genes was extremely low, but nevertheless exposed to the pathogen foronly a few generations, as in the case of TSV resistant individuals and populations eventually emerged. In the field, in P. vann amei (Gitterle, 1999), and with the QX disease in the Sydney where applications were sufficiently intense to cause massive mortal- rock oyster Saccostrea glomerata (Nell and Hand, 2003). In shrimp, ities, single gene resistance normally developed (Roush and McKenzie, which has only recently been bred in captivity, most of the genes that 1987). In studies of the development of resistance in laboratory control resistance will probably have come from the original native populations, where the initial populations were much smaller and populations, although theirfrequency mayhavebeen radicallyaltered as dosage was often reduced so as to increasethe frequency of survivors to populations encountered vastly different conditions. 10–20%, polygenic resistance was the norm (Roush and McKenzie, 1987). In most animal breeding programmes the genetic variation to be This strongly suggests that in a selection programme, the selection exploited is assumed to be that which exists in the base populations protocol itself maywell affect thetype of resistancethat is encountered: when the organisms are domesticated. Nevertheless, over several selection procedures with a limited range of genetic variation and generations with continuous selection pressure on populations of dosages or inoculum pressure that ensure more survivors are likely to prolific species, mutations probably play an important role: this view lead to uncovering and selection for polygenic resistance, whereas is supported by the Iowa corn experiments (Dudley and Lambert, 2004) 5 J . C oc k et al . / A qu ac u ltu r e 28 6 (20 09 ) 1 – 1 1 and much of the work on fruit ies (Harshman and Hoffmann, 2000). In were unimportant in the wild may occur in wild populations, but the the case of shrimps, with extremely large populations and a relatively frequency of resistance may be extremely low. In the case of some new short reproductive cycle, mutations may play a significant role in diseases, previous selection for resistance to another disease may providing genetic variation which can be utilized. In the case of insect confer a level of resistance. This would suggest that in shrimps, even if resistance to pesticides the estimates vary widely from one favourable new diseases attack them in their new intensive cultivation habitats, disease resistance may well exist. This would appear to be especially gene in 102 to one in 101 3 individuals (Mazel and Davies, 1999). The likely in shrimps as the resistance response is not specifictoa favourable mutation rate estimated for E. coli was 4 × 10- 9 per generation (Imhof and Schlotterer, 2001; Foster, 2004). Current particular causal agent. At the same time in these cases the frequency estimates suggest a surprisingly constant mutation rate for a wide of resistant genes is likely to be extremely low. From a breeding point of view the HIV and Hoja Blanca cases are intriguing: If one were to range of organisms of approximately 10- 5 mutations per locus per generation with less than 2% of these being favourable (Frankham et al., search for HIV resistance sources in native Africans, the population 2002; Drake, 1991). The percentage of favourable mutations is probable where the disease first infected human beings, the chances of finding less when they have a large effect than when they have a smaller effect it would be extremely low. Similarly, in Hoja Blanca the resistance (Imhof and Schlotterer, 2001). However, the proportion of favourable or camefrom Japonica rice which was not even grown in the neo-tropics. advantageous mutations would seem to be high in the case of immune- What is certain is that in such cases it is necessary to screen large system genes (Hurst and Smith, 1999). We suggest aconservative figure numbers of individuals from a wide range of populations. Gemmill and Read (1998) suggest that there is a major possibility of 1% of favourable mutationsthat, coupled with amutation rate of 10- 5 , that resistance correlates negatively with other important fitness gives an estimateof 10- 7 favourablemutations perlocus per generation. If we then assume that resistance to a particular diseaseis controlled by components. Consequently, resistance genes could be subject to genes on ten loci, or could occur due to a mutation on any one of ten loci, antagonistic selective forces, which conspire to impose an equilibrium then there willbe onefavourable mutation for every million individuals. frequency somewhere short of complete fixation. There has been much debate about the cost of genetic resistance, but until recently there has In a pond of 10ha (105 m2) stocked at 50 animals m- 2 there are 5million animals, which translates into five favourable mutations. In the case of been little evidence to substantiate this notion (Coustau et al., 2000; favourable mutations that could possibly provide single gene resistance Brown, 2003). Heil and Baldwin (2002) suggested, for plants, that there there are, to our knowledge, no published estimates of the probabilities arevarious possible tradeoffs between fitness and resistance. These can of encountering such genes in large populations. Nevertheless, the very be adapted to the situation in animals, with trade offs being due to rough estimates of favourable mutation rates suggest that they may (a) allocation of fitness limiting resources to resistance traits (b) consti- occur with sufficiently high frequency in shrimp cultivation for them to tutive costs of inducible resistance related to detection pathways and be asignificant sourceof genetic variation fordisease resistanceorother reserves for response (c) auto-toxicity costs in which resistance con- traits. Certainly the opportunity should not be ignored in species where ferring traits are directly toxic or detrimental to the host (d) ecological it is a relatively simple matter to screen millions of animals. costs related to the interaction between the host and the environment: In native or commercial populations, in order for there to be a For example less aggressive cannibalistic feeders might avoid infection selection advantage for disease resistance genes, the disease must be by not consuming moribund infected animals of the same species, but present in the populations. However, little is known about the incidence would also be less fit in situations were feed is limiting and (e) incom- and severityof diseases of Penaeid shrimps in the wild. It is quite possible patibility of resistance to one disease with another. In addition theremay that diseases that are of little orno importancein thenative populations be close genetic linkages between the genes that control disease in theirnativehabitats only become epidemic in theintensive conditions resistance and genes that negatively effect fitness. Heil and Baldwin of cultivated shrimp. Three of the major diseases of shrimp, Taura (2002) indicatethat thereis increasing evidence in plants for tradeoffsin Syndrome Virus (TSV), Yellow Head Virus (YHV) and White Spot fitness related to resistancein the absence of disease pressure. Tian et al. Syndrome Virus (WSSV) were not reported in native populations before (2003) in an elegant piece of work showed a large cost of resistance to the massive epidemics in cultivated shrimp and hence little was known bacterial infection in the quintessential laboratory plant, Arabadopsis about the likelihood of encountering genetic resistance. In the case of (Brown, 2003). Similarly, Kraaijeveld and Godfray (1997) showed a WSSVgenetic analysis indicates that it is arepresentative of a previously strong trade off between the capacity for melanoid encapsulation of unknown virus group now provisionally designated as a whispovirus parasitoids in Drosophila fruit ies and their competitiveness. Gemmill (VanHultenetal.,2000). Nevertheless in both TSV and WSSV genetic and Read (1998) give furtherexamples of tradeoffs for moths with virus differences in resistance have been detected (Gitterle, 1999; White et al., resistanceand mosquitoes for resistance to protozoan parasites. Coustau 2002; Zarain-Herzberg and Ascencio-Valle, 2001). et al. (2000) note that in the case of animal resistance to parasites, In the case of species that apparently have not previously been although the precise physiological mechanisms involved in resistance infected by a particular organism it is not unusual to find resistance. are poorly documented, most of the evolutionary literature is based on Indica rice, originally from Asia, is attacked by the Hoja Blancavirus in the central assumption of a costly investment in defence functions, the Americas, but after screening thousands of varieties, simply leading to a trade off between resistance and other fitness related traits. inherited, dominant resistance was found at a very low frequency in Along the same lines, based on his experience, Detilleux (2001), when germplasm originating in Asia in Japonica type rice (Ou and Jennings, reviewing genetic improvement of livestock, concluded that increased 1969). Similarly, humans have only recently been exposed to HIV and selection pressure to improve commercially important traits is often yet genetic resistance has already been identified related to poly- accompanied by an increase in disease problems, suggesting a trade off morphism on the CCR5 allele. The resistant allele’s prevalence varies between disease tolerance and other desirable characteristics. In the by ethnicity, being as high as 4–15% in Caucasians, and virtually absent case of crustaceans our work in P. vannamei shows a negative genetic in native Africans and East Asians (O’Brien and Moore, 2000). This correlation between resistance to White Spot Syndrome Virus and resistance differs from that of simians that do not develop AIDS growth (Gitterle et al., 2005) and we have repeatedly observed poor (Stebbing et al., 2004) and hence does not seem to have been reproductive fitness of putatively resistant individuals. maintained at a low level after a previous pandemic. Current thinking Recently plant breeders have been moving to more subtle suggests that the CCR5 allele might have conferred selective advan- approaches that include enhancing Induced Systemic Resistance and tage in Caucasian populations under conditions where smallpox was Systemic Acquired Resistance (SAR) in which the plant defences are prevalent (Galvani and Slatkin, 2003). preconditioned by prior infection or treatment that results in resistance These two examples, one from the plant kingdom and the other (or tolerance) against subsequent challenge by a pathogen or parasite from animals, indicate that resistance to new diseases or diseases that (Vallad and Goodman, 2004). The conditioned response which only 6 J . Co ck et a l. / A qu ac u l tur e 2 86 (2 00 9) 1– 1 1 occurs in the presence of infection may be obtained with a lower cost populations may decline at the low levels of disease incidence in the than permanently maintaining a resistance mechanism. resistant populations. 4. Breeding for resistance to diseases 4.1. Success and failure As we have suggested earlier, the high cost of developing In practice disease resistance breeding programs are built genetically disease resistant populations makes this approach suitable empirically and two examples illustrate how a breeding program for when the potential damage is severe, there are no other cost effective disease resistance can be established when knowledge is extremely control measures and there is evidence of genetic variation for the limited and consequently uncertainty is great. Furthermore, one desired trait which is not strongly negatively correlated with other example, breeding for WSSV resistance, indicates some of the pitfalls desirable traits. and dangers of working with very little base line information on the Selection for disease resistance is directly related to its effect on genetic variation for resistance. growth and survival: the objective is not disease resistance per se but rather the impact that disease resistance will have on the desired 4.1.1. Taura Syndrome Virus resistance performance characteristics of theselected stock. Diseases can directly In the mid 1990s theshrimp industry in Ecuador and Colombia was effect both growth and survival. Diseases such as TSV and WSSV cause decimated by TSV. At that time most ponds were stocked with larva severe damage through mortality, although animals that survive may caught in their native habitats or from broodstock captured in the have reduced growth rates. Other diseases such as NHP and vibrio, wild. Pond survivals declined dramatically (Fig. 1) and nobody knew may cause high mortality under some conditions, whilst in others why. There was no doubt of theeconomic importance of thelosses: if a their main effect may beto reduce growth. Up to the present, the main solution was not found to the problem the shrimp industry would focus in selection for disease resistance in shrimps has been to simply disappear. Attempts to control the epidemic by modifying improve survival in the face of epidemics of diseases such as TSV, management practices were largely unsuccessful. In spite of almost which may cause mortalities of 70% or greater and WSSV with total ignorance on the cause of the problem at that time it was noted mortalities close to 100%. We suggest that this emphasis on survival that 20–30% of animals survived and various leaders, technicians and will continue, firstly due to the importance of this trait per se and researchers (including one of us) of the sector surmised that the secondly due to methodological difficulties in screening and selecting survivors could simply be escapes or, on the other hand, they could be for tolerance that allows infected animals to grow well. Furthermore, genetically resistant animals. With little to lose and much to gain, one if selection for growth is carried out under commercial conditions, and of the major producers in Colombia, C.I. Oceanos S.A. initiated a chronic diseases that effect growth rate are endemic, selection for program to select the survivors from infected ponds and use them as growth will effectively be for growth and survival (˜ yield) in the parents for the next generation in a simple, extremely low cost mass presence of the disease. It is noteworthy that this approach is selection scheme. Although the sector was aware of the potential extremely difficult to implement in programmes based on Specific problems of inbreeding, the scheme was deemed acceptable as it Pathogen Free breeding stocks. would rapidly indicate whether there was useful genetic variance for In certain populations a sufficiently high level of disease resistance resistance. Within two to three generations commercial pond survival may be reached to reduce the disease to the level of no longer being rates had once again reached their previous levels indicating the problematic. This has already happened in some shrimp populations success of this simple process (Fig. 1). In later years the industry selected for Taura resistance. However, a watching brief must be kept changed from a mass selection procedure to a combined family and on such diseases as the causal agent may co-evolve with the resistant within-family selection scheme, which incorporated resistant animals stock and become a problem, or the level of resistance in the into the population and monitored levels of Taura to ensure that, with Fig . 1 . Su rv i val o f s h ri m p i n c o m m erc i a l po n d s i n th e Atl an ti c Co as t of Co l om b i a ( re d sq u ar es r efer to s to c ki n g d en s it y). T SV fi rs t ap pe ar ed i n 19 95 . (Fo r i n ter p ret ati o n o f th e re fere n c es to c o l o ur i n t h is fi g ur e l eg en d , th e r ea de r i s re fer red to th e w eb v er si o n of t hi s ar ti c l e. ) 7 J . C oc k et al . / A qu ac u ltu r e 28 6 (20 09 ) 1 – 1 1 the low incidence of the disease under commercial conditions, survival was treated as abinary trait and subjected to a cross-sectional resistance was not lost. linear model with one record per individual. The binary survival data The Taura case indicates several important aspects of deciding for individual animals were recorded when the overall survival rate in whether to include a particular disease resistance trait into a selective the challenge test was approximately 50%, which is the failure rate breeding program and how it can be incorporated. In the case of Taura expected to maximize the accuracy of the linear model. We suggest there was no doubt about the economic importance of the disease, and that looking at the 50% survival in quite small populations, rather than furthermore therewas no known means of controlling or managing the looking for the rare animal that could survive until maturity, will likely disease: when the breeding programme commenced the causal agent uncover polygenic rather than single gene resistance. Thirdly there is had not even been identified. At the same time the simple field negative genetic correlation between growth and resistance and we observation of the presence of survivors under commercial conditions strongly suspect that there is a strong negative association with suggested that useful genetic variance for resistance to whatever was resistance and reproductive performance. Up to the present we have causing the disease might exist. Thus, with the undoubted economic noted that it is difficult to get survivors from challenge tests to potential advantages of resistant populations coupled with the compel- reproduce, however, othershave apparentlybeen ableto obtain progeny ling, but not rigorous evidence for genetic variance in resistance, the from survivors. Nevertheless, in both themass selection programme run decision was taken to set up an extremely simple program to see by a commercial shrimp farm and the family selection program there is whether the supposed genetic variance in resistance could be usefully conclusive evidencethat resistance levels can be improved by both mass deployed. The selection process successfully identified truly resistant selection and family selection and that resistance is lost if selection is individuals; demonstrated that there was indeed useful genetic variance based largely on growth which is negatively correlated with WSSV for resistance; and developed protocols for selection that identified (CENIACUA unpublished data). Nevertheless, the levels of resistance commercially useful resistance. The whole industry moved towards achieved so far are not sufficient to revive the shrimp industry in areas closed cycle mass selection for survival in the presence of TSV and where WSSV is endemic and severe. growth. A hidden factor that probably contributed to the success of the The White Spot case highlights the importance of having a broad Taura resistant selection program was the fact that the populations in genetic base so as to identify sources of resistance: the frequency of the sector were based on wild populations that probably had a broad resistance genes appears to be very low and there may be sources of genetic base, thus increasing the probability of encountering resistance. resistancethat are not included in theinitial populations. In addition it Nowadays we know that the heritability for resistance to TSV is rather highlights the difficulties encountered when there is a negative high for a viral disease, with published estimates in the range 0.20–0.30 correlation between two or more desired traits. We suspect that due (Fjalestad et al., 1997; Argue et al., 2002; CENIACUA unpublished data). to a negative relationship between both growth and reproductive Argue et al. (2002) also found a negative relationship between growth capacity and WSSV resistance some of the most resistant material has and TSV resistance aftera singleround of selection and Mosset al. (2005) been lost from the gene pools used for breeding for resistance. reported a weak but statistically significant negative correlation (r= Furthermore WSSV shows the necessity of selection procedures that -0.15) between mean familyharvest weight and mean familysurvivalin can identifyresistance that will manifest itself at thecommercial level. aTSV challenge test. In other populations selected for resistance to TSV, the growth rate of animals that survived infection was equal to that of 4.2. Selection procedures animals from uninfected tanks when the effects of mortality on population density and its effect on growth were taken into account Selection procedures are needed that ensure that selected stock will (CENIACUA unpublished data). Similarly, in long term studies resistance perform well commercially: this normally means the ability to survive to Tauradoes not appearto be strongly negatively correlated with other an epidemic. Presently selection for disease resistance in designed desirable traits such as general pond survival, growth and reproductive breeding schemes is normally carried out based on survival recorded in fitness (CENIACUA and AKVAFORSK unpublished data). controlled challenge tests. Moss et al. (2005) point out the difficulties of This latter is of particular importance in mass selection, as any developing challenge tests that provide useful information for develop- reduction of selection pressure for disease resistance, if it were ing populations resistant to specific pathogens under commercial negatively correlated with growth, would then lead to increased conditions. Their design should be such that they (i) emulate a natural susceptibility in the population as a whole. Furthermore, although outbreak in theponds and (ii) evaluateallthedefence mechanismof the there islittleconcrete data, thereis considerablecircumstantial evidence shrimps. In order to emulatea natural pond outbreak in achallenge test, that inbreeding depression was minimal in the populations used. it is necessary to identifythenaturalinfection pathways ofthedisease so as to establish an infection protocol that closely mimics them. Selection 4.1.2. Searching for resistance to White Spot Syndrome Virus procedures depend on the natureof the diseaseand thereis no standard The Taura case contrasts with that of breeding for WSSV resistance protocolthat can berecommended for shrimp diseases in general. Anew and indicates some of the potential pitfalls of breeding for resistance protocol is required for each disease. The experience with Taura, in with limited knowledge about the genetic structure of the target several breeding programmes, indicates that effective protocols can be resistance trait. Similar reasoning was used to attempt to rapidly developed and used within on going breeding programmes. Techniques obtain resistant materials using mass selection on commercial farms such as marker assisted selection are postulated as useful; nevertheless and also to incorporateresistance in nuclear stocks of afamilyselection they can only be deployed when protocols have been established to breeding program. However, in this case successful deployment of detect resistant individuals or populations, and closely linked markers commercially viable stock has been an elusive goal. Once again there identified. In the particular case of resistance that increases survival of was no doubt about the economic importance of control. The first sign animals in thepresenceof adisease in an extremely prolific species such of difficulties was the extremely low frequency of survivors, with as shrimps, with a relatively short growth cycle, looking for marker mortalities as high as 98% in the field and in challenge tests. This genes may provide little advantage. It is after all very simple to infect suggested an extremely low frequencyof resistance genes in the initial large numbers of animals and simple select the survivors. populations. Second, was the difficulty of developing a reliable means Breeders tend to look for selection protocols which are simple and of testing for resistance. In commercial mass selection, the selection that maximize heritability and genetic variance. Whilst breeding for pressure depended on the water temperature, which varied from year survival in the face of WSSV, the time to 50% survival in animals to year and in the family selection the controlled challengetests did not inoculated with WSSV, was chosen for reasons given before. The levels appear to select truly resistant materials (Gitterle et al., 2005). of resistance in selected populations, as measured by both 50% Following the classical method for analyzing challenge test data, survival and final survival, were both increased but survival of 8 J . Co ck et a l. / A qu ac u l tur e 2 86 (2 00 9) 1– 1 1 resistant stock has still not reached the levels required for commercial diseases. Unfortunately, several of the mass selection programmes that use of the stock. have been carried out by commercial operations producing their own In the particular case of breeding for survival, recently developed stock have not been welldocumented. Mass selection in the absenceof a longitudinal models (e.g. proportional hazards and survival score particulardisease maylead to low levels of resistance and devastation by models) that utilize information from the full course of the challenge that particular diseasewhen it is introduced. On the other hand there is test have provided greater selection accuracy than conventional cross- some evidence that inbreeding with mass selection for such traits as sectional models (Gitterle et al., 2006; Ødegård et al., 2006, 2007). These growth and pond survival may not always lead to serious problems in longitudinal models facilitate analysis of time-until-death and survival breeding programmes. This view is supported datafrom theP. vannamei within sub-periods, but, for maximum accuracy, require the challenge programme at the Oceanic Institute from which Moss et al. (2007) test to proceed until all animals are dead or mortality levels off. conclude that under favourable conditions inbreeding effects are Fjalestad (2005) pointed out that disease resistance is a candidate statistically significant but small for growth, and are minimal for for theuse of indirect selection protocols in fish due to the difficulty of grow-out survival, in the absence of viralpathogens. Whilst the negative measuring traits such as survival on individuals. It opens the way for effects of inbreeding on survival and growth are small under favourable combined between and within-familyselection. Furthermore, indirect conditions they increase when animals grow in poor environments selection is particularly appropriate when the desired character is (Doyle et al., 2006; Moss et al., 2007). Furthermore, through selection difficult to measure precisely (Fjalestad 2005). However, for indirect substantial gains for growth can likely be achieved at low to moderate selection for survival to compete with direct selection the correlation levels of inbreeding (Moss et al., 2007). De Donato et al. (2005) followed between the correlated trait and survival must be high. This suggests 11 generations of mass selected lines in Venezuela and reported that when breeding for increased survival it is important to ensure increased resistance to endemic diseases such as IHHNV and no signs that the selection protocols, whatever the breeding methodology, of deterioration on thefitness-related traits. In the caseof shrimpsunder truly identify the desired trait and provide the opportunity to reach commercial conditionsa 20% mortalityin the grow-out period and a50% levels of resistance that are commercially useful. mortality in the phase from spawning to stocking ponds are considered normal and accepted. This translates into a survival rate of only 40% 4.3. Breeding methodologies which would be unacceptablein manyspecies. We surmise that there is little build up of deleterious genes in shrimp populations mass selected The advantages and disadvantages of different breeding meth- for pond survival and growth under commercial conditions; those odologies can be found in the standard texts on animal breeding. In animals that carry deleterious genes will be eliminated naturally as this section the advantages and disadvantages of different breeding animals that carry them neither survive nor grow well. This type of self methodologies are discussed solely with respect to the specific case of elimination of poor types is readily achie ved in highly prolificspecies disease resistance. Mass selection, family selection and combined grown under commercial conditions where a moderate loss of unfit family and within-family selection can all be effectively used in animals is the norm. On the other hand inbreeding moderately to selective breeding for disease resistance depending on the circum- severely affects survival in the presence of TSV and WSSV (Moss et al., stances. Family based designs are particularly effective for those traits 2007). Similarly the Venezuelan populations described by De Donato where heritability is low and hence the information on the individual et al. (2005) when confronted with TSV, after manycycles of selection in breeding candidate’s own record provides little information on its the absence of the virus, proved to behighlysusceptible. Thus control of additive genetic capacity. It seems likely that family selection will also inbreeding is particularly important when improving such traits such as be particularly appropriate for resistance under polygenic control disease resistance, nevertheless, it is probably prudent for breeding where the heritability is likely to be intermediate or low. On the other programs to manageinbreeding irrespectiveof the traits underselection hand, if disease resistance is under the control of few genes or is (Moss et al., 2007). monogenic, and also of extremely low frequency simple mass The experiences with TSV highlight some of dangers of loss of selection may be effective but also implies a risk of greatly reduced heterozygosity due to inbreeding in the absenceof aparticular pathogen. overall genetic variability in the population. Special breeding metho- Themass selected Venezuelan populations (De Donato et al., 2005)were dologies such as backcrossing may be expedient so as to introgress free of TSV for many generations, but when TSV appeared the levels of resistancewere extremely low. Similarly, the SPF Konapopulations from resistance into populations with other desirable characteristics and to maintain genetic variability. the Oceanic Institute from Hawaii, that were not selected for TSV Family selection has several advantages over mass and individual resistance proved to be extremely susceptible to TSV (Srisuvan et al., selection when developing disease resistant populations. For many 2006). Breeding programmes that maintain their breeding nuclei as reasons it may be advantageous to maintain the nuclear breeding Specific Pathogen Free populations run the risk of producing animals stock free of diseases and several programmes are based on Specific that are extremely susceptible to those specific pathogens unless Pathogen Free breeding nuclei. Amongst the most important is to selection for resistance is incorporated into the breeding scheme: this provide good quality stock that is not loaded with diseases for becomes complex when there are several pathogens on the list. dissemination to commercial producers. With mass selection the only Mass selection is not as effective as family selection when possible manner of obtaining information to select future breeders is simultaneously selecting for traits that are negatively correlated, a by challenging them and this almost inevitably means exposing them case which appears to be quite common for disease resistance. On the to the disease followed by complex procedures to eliminate the other hand, family selection for improved resistance is currently based disease. In some cases it may be possible to select for resistance to on sib-testing without exposing the breeding candidates to the toxins produced by pathogens or use Marker Assisted Selection and pathogen, which only utilizes the 50% of the additive genetic variance hence no exposure to the live pathogen is necessary. On the other accounted for by the between-family component. It is evident that hand, with family selection, close relatives (usually full- and half-sibs) development of appropriatetesting and biosecuritymeasures that make of the breeding candidates can be challenged with disease organisms it possible to safely introduce animals surviving the challenge test (or and the information generated from these tests used to rank the non- gametes from survivors) willsubstantially increase the efficacy of family exposed breeding candidates. based selection schemes targeting resistance to diseases. There is no A further problem with mass selection when dealing with extremely individual selection if challenge tests are carried out on separate virulent diseases such as WSSV is the rapid narrowing of the genetic populations that are not included in the breeding nucleus. In contrast, variation in the population, which will restrict future genetic improve- mass selection is particularly effectivewhen the desired trait determines ment and may make populations extremely vulnerable to other whether an individual survives, when no resistance has yet been 9 J . C oc k et al . / A qu ac u ltu r e 28 6 (20 09 ) 1 – 1 1 detected or when frequencies of the desired trait are extremely low and extremely virulent and kill their host before having the opportunity to large numbers of animals from different genetic backgrounds need to be infect a new host, as is the case for example with Ebola virus, are often screened. We suggest that in thesesituations mass selection can be used not able to maintain themselves (Ebert, 1998)). Selection pressure in to screen massive numbers of individuals, literally millions, and to select these cases is initially for less virulence in the pathogen, as has been those rare individuals that are able to survive a severe disease epidemic shown to occur in myxomatosis although over the long term a series of and go on to produce. In these cases it is necessary to ensure that the strains of differing virulence coexist (Aparicio et al., 2004). Conversely challenge test used re ects commercialconditions and that theselection when host resistance levels are increased in a population the pathogen pressure is maintained: if there is a cost to the resistance then will tend to evolve mechanisms that overcome that resistance. Recently populations are likely to revert rapidly if the selection pressure is various strains of TSV have been recognized with varying levels of relaxed. With the extremely heavy selection pressure applied in such virulence (Srisuvan et al., 2006). Fortunately it appears that shrimp cases the disease resistant animals finally encountered may lack many populations resistant to one particular strain are also resistant to other other desirable traits for commercial production. strains (Moss et al., 2005; Srisuvan et al., 2006), that is to say thereis not In plants it is quite common to detect diseaseresistancein extremely astrain by resistant genotypeinteraction. In Colombia there are notable poor plant types. In order to remedy this situation plant breeders differences in the sequences in the CP2 section of TSV samples taken in introgress disease resistance from unimproved or wild species into 1998 and in 2006/7, indicating evolution of the virus strains (CENIACUA improved populations using backcrossing techniques. We suggest that unpublished data). It is not yet clear as to whether this evolution is this approach may be appropriate for shrimps. In those cases where related to increased virulence in the face of shrimp populations bred for there is not a ready source of commercially useful resistance in the resistance to TSV. Nevertheless, breeders should take into account both current commercial or nuclear breeding stock populations, it may be the co-evolution of host resistance and pathogen virulence and the possible to produce millions of larvae or juveniles and screen these for possible lack of selection pressurefor diseases by constantlymonitoring survival using mass selection. If resistant types are discovered, and we levels of resistance, even for diseases that have ceased to be a problem. have no way of knowing beforehand the probability, then the resistant Furthermore, it may bepossibleto guard against loss of resistance by the animal or animals can then be used to introgress resistance into the host or evolution of more virulent pathogens by a well designed commercial populations. Various techniques such as backcrossing may dissemination programme in which mass selection forendemic diseases be used to introgress the desired genes and eliminate the undesirable is included as part of the process for multiplication of broodstock. genetic load associated with them in the initial resistant genotype. The search for the rare individual that survives in the case of 4.4. Base populations and population size catastrophic diseases is dangerous as there is no guarantee of the durabilityof theresistance. Forseveral decadesplant breeders havebeen Selective breeding programmes are only appropriate when genetic using pyramiding of genes to lower the probability of break down of variation exists for the traits to be selected. A number of breeding resistance(Pink, 2002; Pederson and Leath,1988). In this process several programs in fish may havefailed dueto low genetic variation in the base single genes that provide resistance are“pyramided”into the population population (Teichert-Coddington and Smitherman, 1988; Huang and so that all individuals carry more than one gene-for-gene resistance Liao, 1990). Miles and Pandey (2004) indicate that plant improvement gene. This reduces the probability of breakdown enormously. For program tend to make more rapid progress after the introduction of more diverse germplasm. Similarly, in cassava the success of modern example if the probability of breakdown is one in 10- 8 of the pathogen overcoming either of two resistances in a given individual in a given breeding efforts has been attributed to the great genetic variability which the modern programmes acquired from the outset (Kawano and period of time it willbe reduced to one in 10- 16 if two genes are present. In order to pyramid genes it is necessary to identify the sources of Cock, 2005). On the other hand, in the long term divergent selection for resistance in resistant individuals. Until recently this was extremely oil and protein content of maize in Illinois starting from an extremely difficult to achieve: nowadays with molecular markers it may be narrow genetic base, Dudley and Lambert (2004) state tha t “10 0 possible to identify different sources of single gene resistance on generations of selection have not eliminated genetic variability and an different loci and to determine which resistant genes an individual upper limit has not been reached.” In several long term selection trials possesses. Hence, use of single gene resistance should preferably be for body weight in mice with effective population sizes of less than 100 based on more than one source of single gene resistance pyramided some, but not all, populations have reached a plateau (Hill and Bunger, into the population with marker assisted selection to ensure that 2004). In reviews of long term selection in laboratory and domestic selected resistant phenotypes are also pyramided genotypes. animals much of the initial gains areattributed to thegenetic variancein Breeding for resistance is a continuous dynamic process: the genetic the initial base population, and later response to mutations in the composition of both pathogen and host are continually changing (Ebert, population (Hill and Bunger, 2004; Weber, 2004). 19 98 ). Carius et al. (2001) found significant genetic variation among In manyanimal improvement programmes the breeding design pays clones of the freshwater crustacean Daphnia magna for susceptibility to careful attention to maintaining genetic variation, but less attention is its parasite Pasteuria ramosa and significant genetic variation among paid to ensuring maximum diversity in theinitial foundation stock. Part isolates of the bacterial parasite P. ramosa for infectivity to it host of the reason is undoubtedly related to the fact that most domesticated D. magna. Loss of resistance in a population can be the result of changes specieshave been selected for alongperiod of timefor specific traits and in the host and the genetic make up of the pathogen. After host the introduction of more genetic diversity to a foundation population resistance has been developed above a certain level in a population, would undoubtedly introduce many undesirable traits. Breeders simply disease incidence may be reduced to extremely low levels. Under these cannot use native stocks to enhancetheiralready improved stocks as the conditions selection pressure is reduced for resistance, and if there is a native populations are so far behind in performance that they are not fitness cost associated with the resistance this will be lost. We suggest competitive (Hill and Bunger, 2004) and could, at least in the short term that in shrimp populations, with prolific breeders, the drift towards induce negative genetic gain in the desired traits. In the case of Penaeid susceptibility is potentially rapid. This viewpoint is supported by our shrimps this is not currently a major problem as the existing improved observations of a combined family and within family selection populations are mostly only a few generations from the wild popula- programme for resistance to TSV in which populations not subjected tions. However, as populations are improved it willrapidly become more to continuous selection pressure for resistance appeared to lose difficult to incorporate genetic diversity and still maintain the genetic resistance (CENIACUA unpublished data). gains in desired traits. Furthermore, in many countries importation of Pathogen populations are continually evolving and adapting to the wild populations or specific populations is restricted due to biosecurity host environment which is itself changing. Pathogens which are measures. In addition the introduction of new germplasm into breeding 10 J . Co ck et a l. / A qu ac u l tur e 2 86 (2 00 9) 1– 1 1 programme with Specific Pathogen Free nuclei is onerous and time Eb er t, D. , 1 99 8 . E xp er i m en tal ev ol u ti o n of p ar as i tes . S c i en c e 2 82 , 14 32 – 14 35 . Fj al es ta d, K. T. , 20 0 5. In : G j ed re m, T . (E d. ), S el ec ti o n M et h od s . I n S el ec ti o n a nd B re ed in g consuming. Thus the relatively new shrimp breeding programs should Pr og ra ms i n Aqu ac u l tu r e. Sp ri n ge r, N et he rl an d s , p p . 159 – 171. make every effort to obtain genetically diverse populations before the Fj al es ta d, K.T. , Gj e dr em , T ., G j er de , B ., 19 93 . G en eti c i m p ro vem e nt o f d is e as e re si s ta nc e populations have diverged substantially fromthe wild populations from i n fi s h : an o ver vi ew . Aq ua c ul t ur e 111, 65 – 74. Fj al es ta d, K. T. , Gj ed r em , T., C ar r, W .H ., S wee n ey, J .N ., 19 9 7. Fi na l R ep o rt: T h e S h ri m p which they were recently derived. Br ee di n g Pr og ra m, Se le c ti ve Br ee di n g of P ena eus va nn am ei . T h e Oc e an i c I n st i tu te, Unfortunately, studies on how the basepopulation should be formed Wai m an al o , H I , U SA. (i.e. the numberof individuals to besampled from one orseveral founder Fl ege l , T.W ., Al d ay -S an z, V., 19 9 8. T h e c ri s i s i n A si an s h ri m p aq u ac u l tu re : c u r re n t s t atu s an d f ut ur e n ee ds . J . Ap p l . I c h th yo l . 1 4, 26 9 –2 73 . strains, their mixing, and the intensity of selection to be applied during Fl egel , T. W., N i el se n, L., T h amav it , V., Ko n gti m , S., Pas h araw ip as , T. , 20 0 4. Pre sen c e o f the initial generations) their effects on the magnitude and va riability of mu l ti pl e vi ru se s i n n on -d i s eas ed, c ul ti vat ed sh ri m p at h ar ves t. Aq u acu l tu re 24 0, 55 –6 8. the long term selection response and inbreeding are few (Holtsmark Fos te r, P.L ., 2 00 4 . Ad apt i ve m ut ati o n i n Es c her i c hi a c ol i. J . B ac te ri o l . 18 6 (15 ), 4 8 46 – 48 5 2. et al., 2006). Fra nk h am , R ., B al l ou , J . D., B r i sc o e, D .A. , 2 00 2 . I nt ro d uc t i on t o C on s er vat io n G en et i cs . Ca m br i dg e Un i v ers i ty Pr es s , U K. 6 17 p p . In the case of shrimp breeding for diseaseresistanceit would appear Gal v an i, A. P., Sl at ki n , M ., 20 0 3 . E val u at in g p l agu e an d sm a ll p o x a s hi s to ri c a l se l ec ti ve that in order todetect genetic resistance in existing populations a wide a pr es s u re s fo r t h e C CR 5 – de l ta 3 2 H I V- re s is t an c e al l el e. Pr o c . N atl . A c ad . Sc i . U. S . A. range of origins of base populations should be explored and screened. 10 0, 1 52 76 –1 52 7 9. Gem m i l l , A.W ., R ead , A. F., 199 8 . Co u n ti n g th e c os t of di s ea se r es i s tan c e. T ren d s E c ol . Furthermore, large populations (millions of animals) should be Ev ol . 13 , 8 – 9. produced and screened to detect mutants or recombinants that confer Gi tt erl e , T., 199 9 . Ev al u ac i ón de l a re si s ten c i a d e d i fer en t es p ob l ac i o ne s d el c a ma ró n resistanceto catastrophic diseases. Anydesirable traits obtained in these m ari n o L it op ena eus va nn am ei (B oo n e 19 31 ) a l Vi ru s d el Sí n d ro m e d el Tau r a (T SV) baj o c o n d ic i o n es c o n tr ol ad as . Th e si s . Un i ve rs i d ad J o rg e T ad eo Lo zan o , B o go ta, massive screening efforts should then be incorporated into the base Co l om b i a, 7 4 p p . population and maintained irrespective of the breeding scheme being Gi tt erl e , T ., Sa lt e, R ., Gj e rd e, B ., C o c k, J ., J o h an s en , H. , Sal aza r, M ., Lo zan o , C . , Ry e, M ., used. 20 0 5. Gen et i c ( c o)v ar ia ti on i n r es i s tan c e to w hi t e sp o t sy n dr o me v i ru s ( WS SV) an d h arv es t w ei gh t i n Pen aeu s (L i top ena eus ) va nn am ei . Aq u ac u l tu re 2 4 6, 1 39 –1 49 . Gi tte rl e, T., Ød eg ård , J ., Gj er de , B ., R ye , M ., Sa lte , R . , 2 0 06 . Gen et ic pa ram ete rs an d ac c u rac y 5. Conclusions of s el ec ti o n fo r r es is ta nc e to Wh i te S po t Sy nd r om e Vi ru s (WS SV) i n P ena eus (L ito pen aeu s) van na me i u s i ng d i ffer en t s ta ti st ic al m od el s . Aqu ac u lt ur e 251, 210 –21 8. Goy ard , E ., Pat ro is , J ., Pe i gn on , J ., Van aa, V. , Du fou r, R ., Vi al l on , J ., B ed ie r, E. , 20 0 2. Sel ec t io n Selective breeding provides a useful means of controlling shrimp for b ette r g ro wth of P ena eu s s tyli ro str i s i n Ta hi ti a nd New C al ed on i a. Aqu ac u l tur e 2 0 4, diseases when these currently cause severe losses, other control 46 1– 46 8. measures are difficult, useful genetic variation in resistance exists and Ha rs h m an , L .G ., Ho ffm an n , A .A. , 2 0 0 0. Lab o rat or y s e le c ti on exp er i m en ts u s in g Dr os o- ph i la : wh at do th ey re al ly tel l u s ? Tr ee 1 5, 32 – 36 . resistance is not negatively and stronglyassociated with other desirable He i l, M . , B al dw i n , I .T. , 20 0 2. F it n es s c o st s o f i n d uc e d r es i st an c e: em er gi n g ex pe ri m en t al traits. Genetic variation in resistance may be encountered either in the su p p or t fo r a s l i p p ery c on c ep t. Tr en d s P l an t S c i. 7, 6 1– 6 7. initial base populations or may spontaneously arise due to mutations or He n ni g , O. L., A rc e, S .M . , Mo s s , S.M . , Pa nt oj a, C . R ., Li g ht n er, D .V. , 20 0 5 . Dev el o pm e nt o f a new recombinants. Effective protocols are required to detect resistance; sp e c ifi c p at ho g en fre e p op u l ati o n o f th e Ch i n es e e sh y p r awn , Fenn ero pen aeu s c hi n ens i s P ar t I I . Se c on d . Q ua r. A qu ac . 2 5 0, 57 9 –5 8 5. due to the prolificacy of shrimps large populations can be screened so as Hi l l , A. V.S ., 2 0 01. T h e gen o m i c s an d g en et ic s of h u ma n i n fec t io u s d i s eas e s u sc e pt i bi l i ty. to identify sources of resistancethat occur at low frequencies. The most An n u. R ev. G en o m. Hu m . G en et . 2 , 3 73 –4 0 0 . appropriate breedingmethodology dependson thenature of the disease Hi l l , W .G ., B u n ger , L. , 2 00 4 . 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Breeding Clownfish (Budidaya Ikan Badut)
David Bloch

Introduction

Clownfish are one of the easiest tropical marine aquarium fish to breed. Unlike many of the other tropical marine fish, clownfish regularly spawn in a marine aquarium. Furthermore clownfish have relatively large eggs and larvae which makes rearing them a somewhat easier task as the larvae are able to eat easily cultured foods

The purpose of this article is to convey the information that I have found and learned over the last few months while I have been raising clownfish. This information is a compilation of both my ideas and the ideas from other articles written about clownfish. A complete reference list of clownfish related articles will be compiled at the end of the article.

There are a few very important steps to breeding clownfish. These include setting up the tank, choosing the broodstock, feeding, spawning, and raising the larvae. These points will all be discussed in detail below.

Setting up the Tank

A clownfish spawning tank should be as large as possible, and preferably not smaller than 100 liters. If the purpose of the tank is to solely breed clownfish than it would be wise to avoid putting any other fish in the tank. Small non-aggressive fish can be added, however, once the fish start spawning anything that comes toward them is viewed as a threat and is chased away.

As a rule the more natural a tank is the more at home the fish will feel, and the more likely they will be to spawn. This is not to say that a tank with a flowerpot and a thin layer of coral sand won’t produce results, it is just that the more relaxed and stress-free the fish feel, the sooner they will spawn and the healthier the eggs will be.

An ideal tank would be a 3x2x2 feet tank filled with live rock, a layer of coral sand at the bottom, a nice anenome, bright lighting, and good filtration preferably consisting of an efficient protein skimmer. As the bioload of the tank would just be the clownfish, the live rock and protein skimmer would handle the ammonia and organics from the fish. A trickle filter could be used providing regular water changes are performed to keep the nitrates low enough for the anenome to do well.

In nature the clownfish spawning is linked to the lunar cycle. It is generally not paractical to artificially stimulate the lunar cycle in the aquarium. It is important however, that the lights are connected to a timer so that the fish receive a regular daylight lighting cycle. This regular day/night cycle is all that is needed.

An anenome is generally not required to breed clownfish, however, it certainly makes the task much easier in the long run. In fact clownfish have been known to spawn on clay pots, clam shells, and even the aquarium glass in the absence of an anenome. An added benefit of having an anenome is that it may release compounds that help protect the eggs, even chemically, as with the apparent immunity that clownfish have with the anenome.

The key to your clownfish home is that it be STRESS FREE! That means good water quality, no aggressive tank mates, and an anenome.

Choosing the Broodstock

There are three basic ways to obtaining a pair of clownfish. These include: 1) to buy a naturally mated pair captured from the wild, 2) to buy a small group of at least four fish, and 3) to buy two fish of greatly differing size.

Obtaining a naturally mated pair of clownfish is always the best option. This is because the pair of fish will be a naturally mated pair from the time you put them into the aquarium and will not have to go through the territorial and aggressive struggles that happen in an aquarium when fish are first introduced. Also the fish will not view each other as aggressive rivals as they are in a pair. The best news however, is that by introducing a mated pair into the aquarium, spawning will commence much sooner than by the other two methods.

Buying a small group of clownfish, preferably from different sources, is the next best option. This is because it gives the clowns a chance to form a hierarchal structure in the tank with the two most dominant fish naturally pairing off. It also lowers the chance of the other clownfish becoming overly stressed due to aggression from the dominant fish, as the aggression is spread out over a number of individuals. This option will produce a pair but it will take longer for them to start spawning than if they were a mated pair as soon as they were added to their aquarium.

Putting two fish of differing size in together is an extreme way of obtaining a pair of fish. The reason for this is that often the larger fish will be very aggressive towards its own kind and, if there is only one other clownfish, than that aggression can cause the smaller fish to become very stressed, and more prone to disease. This problem will persist until the larger, more dominant female fish accepts the smaller male. This task may take anywhere from a few days to several weeks.
Feeding

Once the tank is set up and the fish have been introduced to the tank it’s time to start feeding them. Believe it or not feeding is probably the most important aspect of whether you will have success with breeding clownfish. If your broodstock do not attain the correct amounts and types of nutrients than they will not be able to develop good quality eggs. If the eggs are of bad quality, then no matter how hard you try, you will not have much success in raising the larvae.

The key to nutrition in clownfish is a mixed diet of fresh raw seafood and vegetable matter. A good diet for clownfish includes mussels, prawns, squid and green vegetables. These can be mixed together into a mash anf frozen, or can be just fed separately. The amounts of food to feed the clownfish depends on their size, however, it is always best to feed small amounts at regular intervals. Remember, clownfish will take large bits of food to their anenome so it’s a good idea to feed them small bits!

Spawning

Once the clownfish have settled into their new home, anywhere from one to twelve months, spawning will commence. The first indication of possible spawning is when the male clownfish swims up and down in front of the female. The male will dance in a head-up fashion and will thrust towards the female. This is known as the clownfish waggle. This behavior is a pretty lose indicator but generally means that spawningwill happen soon. The next indication is when the male, and often the female, will start to clean a portion of rock near the base of the anenome. This is a good indication that spawning will commence within a day or two. The last indicator of spawning behavior is the appearance of both the male and female clownfishs’ genital tubes.

Spawning starts when the female swims over the cleared patch of rock and deposits a small line of eggs with her ovopositor. The males follows shortly after and fertilizes them. The process of laying eggs takes anywhere from 2 to 3 hours. The eggs look like little capsules about 2 to 3 mm long and 1 mm wide. If the adults have been fed well the eggs should be a bright orange color. During this time the clownfish, notably Amphiprion clarkii, may lay up to 600 eggs. More often than not however, the number of eggs start out small, around 200, and increases with each spawn and as the female increases in size. Once the fish have started spawning they’re likely to repeat it at intervals of around 12 to 18 days.

The eggs usually take from 6 to 15 days to hatch depending on the temperature. One day before hatching the larvae develop a silvery color around their eyes. This is the time when you must make a decision: Either you leave the eggs in the tank to hatch, and you remove the larvae, or, one day prior to hatching you remove the live rock upon which the eggs were laid.

If the eggs are to be removed on the rock then it is important that the eggs be kept underwater at all times. The water in which the eggs are kept must have also been taken from the spawning tank as small differences in water quality may damage the eggs. Once the eggs are in the larval rearing tank then they must be provided with sufficient water current to properly oxygenate them. . The easiest way to do this is via an airstone that produces coarse bubbles. All then that is required is to remove the rock after hatching.

If the eggs are to be left in the main aquarium then some planning will have to be made. To make things easier, the lights can be turned off as the larvae hatch within 2 hours of darkness. Once the lights have switched off all circulation to and within the tank must be ceased. This will ensure that the larvae are not sucked up and damaged by pumps and water currents. After the pumps have been turned off and the tank is still it’s time to wait! The eggs will hatch in waves, and as the larvae hatch they will swim to the surface. Once at least a quarter of the eggs have hatched it’s time to use the torch (flashlight). The torch is shone in the water from above, and used to concentrate the larvae into a small group. Once this is done the larvae can either be siphoned into the larval rearing tank with airline tubing, or dipped out with small plastic cups/containers. This is done repetitively until all larvae are caught.

Larval Rearing Tank

Clownfish larvae can be reared in many different sorts of containers and tanks. Old 2 foot aquariums can be used, however, I have found that circular tanks give much better results.This is because square/rectangular tanks have corners, and with no strong currents to thoroughly mix the water, dead spots develop in the corners. This occurence in the end will cause the death of many clownfish larvae. With round tanks there is no such problem, as there are no corners, and it is very easy to get water to circulate in a circular fashion.

An ideal larval rearing tank is a round plastic or fiberglass tank with a water holding capacity of between 50 and 150 liters. These tanks can be set up as: 1) having a filter and recirculating water, or 2) stand alone, and just using airstones and water changes.

The ideal setup for clownfish larvae is to have a central standpipe in the round tank, and to place a mesh screen of between 100 and 300 microns around it. The different mesh sizes are used for the different sized live feeds such as rotifers and artemia. Water overflows into a sump where there is some sort of both biological and mechanical filtration. A low volume pumpthen pumps the water back into the tank at very slow rate, just enough to cause the water to circulate slowly and keep the larvae moving. An airstone may be required in the center of the tank along the side of the screen to ensure that it does not block up. This system closely matches the natural environment where they are found drifting in the surface waters.

The second option is to have a round tank with only surface aeration provided. This setup is much easier to prepare but water quality can become a problem unless regular water changes are performed to reduce ammonia levels. A further problem develops in that it is much harder to flush excess live foods out of the tank.

The larval rearing tank should receive the same lighting cycle as the main tank. It preferably should have its own light and timer. is that the larvae are visual predators and require light to hunt for their live food prey.

Conclusion

Hopefully the above information gives you, the hobbyist, a concrete start to breeding clownfish. It can be a very challenging, yet exciting venture, particularly when you are rewarded with post-larval juveniles. It is then when you can sit back and murmur “success”.

David Bloch

Budidaya Ikan mas (Cyprinus carpio)

BUDIDAYA IKAN MAS
Oktober 22, 2007 oleh sutanmuda

1. SEJARAH SINGKAT

Ikan mas merupakan jenis ikan konsumsi air tawar, berbadan memanjang

pipih kesamping dan lunak. Ikan mas sudah dipelihara sejak tahun 475

sebelum masehi di Cina. Di Indonesia ikan mas mulai dipelihara sekitar tahun

1920. Ikan mas yang terdapat di Indonesia merupakan merupakan ikan mas

yang dibawa dari Cina, Eropa, Taiwan dan Jepang. Ikan mas Punten dan

Majalaya merupakan hasil seleksi di Indonesia. Sampai saat ini sudah terdapat

10 ikan mas yang dapat diidentifikasi berdasarkan karakteristik morfologisnya.

2. SENTRA PERIKANAN

Budidaya ikan mas telah berkembang pesat di kolam biasa, di sawah, waduk,

sungai air deras, bahkan ada yang dipelihara dalam keramba di perairan

umum. Adapun sentra produksi ikan mas adalah: Ciamis, Sukabumi,

Tasikmalaya, Bogor, Garut, Bandung, Cianjur, Purwakarta

3. JENIS

Dalam ilmu taksonomi hewan, klasifikasi ikan mas adalah sebagai berikut:

Kelas : Osteichthyes

Anak kelas : Actinopterygii

Bangsa : Cypriniformes

Suku : Cyprinidae

Marga : Cyprinus

Jenis : Cyprinus carpio L.

Saat ini ikan mas mempunyai banyak ras atau stain. Perbedaan sifat dan ciri

dari ras disebabkan oleh adanya interaksi antara genotipe dan lingkungan

kolam, musim dan cara pemeliharaan yang terlihat dari penampilan bentuk fisik,

bentuk tubuh dan warnanya. Adapun ciri-ciri dari beberapa strain ikan mas

adalah sebagai berikut:

1) Ikan mas punten: sisik berwarna hijau gelap; potongan badan paling pendek;

bagian punggung tinggi melebar; mata agak menonjol; gerakannya gesit;

perbandingan antara panjang badan dan tinggi badan antara 2,3:1.

2) Ikan mas majalaya: sisik berwarna hijau keabu-abuan dengan tepi sisik lebih

gelap; punggung tinggi; badannya relatif pendek; gerakannya lamban, bila

diberi makanan suka berenang di permukaan air; perbandingan panjang

badan dengan tinggi badan antara 3,2:1.

3) Ikan mas si nyonya: sisik berwarna kuning muda; badan relatif panjang; mata

pada ikan muda tidak menonjol, sedangkan ikan dewasa bermata sipit;

gerakannya lamban, lebih suka berada di permukaan air; perbandingan

panjang badan dengan tinggi badan antara 3,6:1.

4) Ikan mas taiwan: sisik berwarna hijau kekuning-kuningan; badan relatif

panjang; penampang punggung membulat; mata agak menonjol; gerakan

lebih gesit dan aktif; perbandingan panjang badan dengan tinggi badan

antara 3,5:1.

5) Ikan mas koi: bentuk badan bulat panjang dan bersisisk penuh; warna sisik

bermacam-macam seperti putih, kuning, merah menyala, atau kombinasi dari

warna-warna tersebut. Beberapa ras koi adalah long tail Indonesian carp,

long tail platinm nishikigoi, platinum nishikigoi, long tail shusui nishikigoi,

shusi nishikigoi, kohaku hishikigoi, lonh tail hishikigoi, taishusanshoku

nshikigoi dan long tail taishusanshoku nishikigoi.

Dari sekian banyak strain ikan mas, di Jawa Barat ikan mas punten kurang

berkembang karena diduga orang Jawa Barat lebih menyukai ikan mas yang

berbadan relatif panjang. Ikan mas majalaya termasuk jenis unggul yang

banyak dibudidayakan.

4. MANFAAT

1) Sebagai sumber penyediaan protein hewani.

2) Sebagai ikan hias.

5. PERSYARATAN LOKASI

1) Tanah yang baik untuk kolam pemeliharaan adalah jenis tanah liat/lempung,

tidak berporos. Jenis tanah tersebut dapat menahan massa air yang besar

dan tidak bocor sehingga dapat dibuat pematang/dinding kolam.

2) Kemiringan tanah yang baik untuk pembuatan kolam berkisar antara 3-5%

untuk memudahkan pengairan kolam secara gravitasi.

3) Ikan mas dapat tumbuh normal, jika lokasi pemeliharaan berada pada

ketinggian antara 150-1000 m dpl.

4) Kualitas air untuk pemeliharaan ikan mas harus bersih, tidak terlalu keruh

dan tidak tercemar bahan-bahan kimia beracun, dan minyak/limbah pabrik.

5) Ikan mas dapat berkembang pesat di kolam, sawah, kakaban, dan sungai air

deras. Kolam dengan sistem pengairannya yang mengalir sangat baik bagi

pertumbuhan dan perkembangan fisik ikan mas. Debit air untuk kolam air

tenang 8-15 liter/detik/ha, sedangkan untuk pembesaran di kolam air deras

debitnya 100 liter/menit/m3.

6) Keasaman air (pH) yang baik adalah antara 7-8.

7) Suhu air yang baik berkisar antara 20-25 derajat C.

6. PEDOMAN TEKNIS BUDIDAYA

6.1. Penyiapan Sarana dan Peralatan

1) Kolam

Lokasi kolam dicari yang dekat dengan sumber air dan bebas banjir. Kolam

dibangun di lahan yang landai dengan kemiringan 2–5% sehingga

memudahkan pengairan kolam secara gravitasi.

a. Kolam pemeliharaan induk

Luas kolam tergantung jumlah induk dan intensitas pengelolaannya.

Sebagai contoh untuk 100 kg induk memerlukan kolam seluas 500 meter

persegi bila hanya mengandalkan pakan alami dan dedak. Sedangkan bila

diberi pakan pelet, maka untuk 100 kg induk memerlukan luas 150-200

meter persegi saja. Bentuk kolam sebaiknya persegi panjang dengan

dinding bisa ditembok atau kolam tanah dengan dilapisi anyaman bambu

bagian dalamnya. Pintu pemasukan air bisa dengan paralon dan dipasang

sarinya, sedangkan untuk pengeluaran air sebaiknya berbentuk monik.

b. Kolam pemijahan

Tempat pemijahan dapat berupa kolam tanah atau bak tembok.

Ukuran/luas kolam pemijahan tergantung jumlah induk yang dipijahkan

dengan bentuk kolam empat persegi panjang. Sebagai patokan bahwa

untuk 1 ekor induk dengan berat 3 kg memerlukan luas kolam sekitar 18

m2 dengan 18 buah ijuk/kakaban. Dasar kolam dibuat miring kearah

pembuangan, untuk menjamin agar dasar kolam dapat dikeringkan. Pintu

pemasukan bisa dengan pralon dan pengeluarannya bisa juga memakai

pralon (kalau ukuran kolam kecil) atau pintu monik. Bentuk kolam

penetasan pada dasarnya sama dengan kolam pemijahan dan seringkali

juga untuk penetasan menggunakan kolam pemijahan. Pada kolam

penetasan diusahakan agar air yang masuk dapat menyebar ke daerah

yang ada telurnya.

c. Kolam pendederan

Bentuk kolam pendederan yang baik adalah segi empat. Untuk kegiatan

pendederan ini biasanya ada beberapa kolam yaitu pendederan pertama

dengan luas 25-500 m2 dan pendederan lanjutan 500-1000 m2 per petak.

Pemasukan air bisa dengan pralon dan pengeluaran/ pembuangan

dengan pintu berbentuk monik. Dasar kolam dibuatkan kemalir (saluran

dasar) dan di dekat pintu pengeluaran dibuat kubangan. Fungsi kemalir

adalah tempat berkumpulnya benih saat panen dan kubangan untuk

memudahkan penangkapan benih. dasar kolam dibuat miring ke arah

pembuangan. Petak tambahan air yang mempunyai kekeruhan tinggi (air

sungai) maka perlu dibuat bak pengendapan dan bak penyaringan.

2) Peralatan

Alat-alat yang biasa digunakan dalam usaha pembenihan ikan mas

diantaranya adalah: jala, waring (anco), hapa (kotak dari jaring/kelambu

untuk menampung sementara induk maupun benih), seser, ember-ember,

baskom berbagai ukuran, timbangan skala kecil (gram) dan besar (kg),

cangkul, arit, pisau serta piring secchi (secchi disc) untuk mengukur kadar

kekeruhan.

Sedangkan peralatan lain yang digunakan untuk memanen/menangkap ikan

mas antara lain adalah warring/scoopnet yang halus, ayakan

panglembangan diameter 100 cm, ayakan penandean diameter 5 cm, tempat

menyimpan ikan, keramba kemplung, keramba kupyak, fish bus (untuk

mengangkut ikan jarak dekat), kekaban (untuk tempat penempelan telur

yang bersifat melekat), hapa dari kain tricote (untuk penetasan telur secara

terkontrol) atau kadang-kadang untuk penangkapan benih, ayakan

penyabetan dari alumunium/bambu, oblok/delok (untuk pengangkut benih),

sirib (untuk menangkap benih ukuran 10 cm keatas), anco/hanco (untuk

menangkap ikan), lambit dari jaring nilon (untuk menangkap ikan konsumsi),

scoopnet (untuk menangkap benih ikan yang berumur satu minggu keatas),

seser (gunanya= scoopnet, tetapi ukurannya lebih besar), jaring berbentuk

segiempat (untuk menangkap induk ikan atau ikan konsumsi).

3) Persiapan Media

Yang dimaksud dengan persiapan adalah melakukan penyiapan media untuk

pemeliharaan ikan, terutama mengenai pengeringan, pemupukan dlsb.

Dalam menyiapkan media pemeliharaan ini, yang perlu dilakukan adalah

pengeringan kolam selama beberapa hari, lalu dilakukan pengapuran untuk

memberantas hama dan ikan-ikan liar sebanyak 25-200 gram/meter persegi,

diberi pemupukan berupa pupuk buatan, yaitu urea dan TSP masing-masing

dengan dosis 50-700 gram/meter persegi, bisa juga ditambahkan pupuk

buatan yang berupa urea dan TSP masing-masing dengan dosis 15 gram

dan 10 gram/meter persegi.

6.2. Pembibitan

1) Pemilihan Bibit dan Induk

Usaha pembenihan ikan mas dapat dilakukan dengan berbagai cara yaitu

secara tradisional, semi intensif dan secara intensif. Dengan semakin

meningkatnya teknologi budidaya ikan, khususnya teknologi pembenihan

maka telah dilaksanakan penggunaan induk-induk yang berkualitas baik.

Keberhasilan usaha pembenihan tidak lagi banyak bergantung pada kondisi

alam namun manusia telah banyak menemukan kemajuan diantaranya

pemijahan dengan hipofisisasi, peningkatan derajat pembuahan telur dengan

teknik pembunuhan buatan, penetasan telur secara terkontrol, pengendalian

kuantitas dan kualitas air, teknik kultur makanan alami dan pemurnian

kualitas induk ikan. Untuk peningkatan produksi benih perlu dilakukan

penyeleksian terhadap induk ikan mas.

Adapun ciri-ciri induk jantan dan induk betina unggul yang sudah matang

untuk dipijah adalah sebagai berikut:

a. Betina: umur antara 1,5-2 tahun dengan berat berkisar 2 kg/ekor; Jantan:

umur minimum 8 bulan dengan berat berkisar 0,5 kg/ekor.

b. Bentuk tubuh secar akeseluruhan mulai dari mulut sampai ujung sirip ekor

mulus, sehat, sirip tidak cacat.

c. Tutup insan normal tidak tebal dan bila dibuka tidak terdapat bercak putih;

panjang kepala minimal 1/3 dari panjang badan; lensa mata tampak

jernih.

d. Sisik tersusun rapih, cerah tidak kusam.

e. Pangkal ekor kuat dan normal dengan panjang panmgkal ekor harus lebih

panjang dibandingkan lebar/tebal ekor.

Sedangkan ciri-ciri untuk membedakan induk jantan dan induk betina adalah

sebagai berikut:

a) Betina

- Badan bagian perut besar, buncit dan lembek.

- Gerakan lambat, pada malam hari biasanya loncat-loncat.

- Jika perut distriping mengeluarkan cairan berwarna kuning.

b) Jantan

- Badan tampak langsing.

- Gerakan lincah dan gesit.

- Jika perut distriping mengeluarkan cairan sperma berwarna putih.

2) Sistim Pembenihan/Pemijahan

Saat ini dikenal dua macam sistim pemijahan pada budidaya ikan mas, yaitu:

a. Sistim pemijahan tradisional

Dikenal beberapa cara melakukan pemijahan secara tradisional, yaitu:

- Cara sunda: (1) luas kolam pemijahan 25-30 meter persegi, dasar

kolam sedikit berlumpur, kolam dikeringkan lalu diisi air pada pagi hari,

induk dimasukan pada sore hari; (2) disediakan injuk untuk menepelkan

telur; (3) setelah proses pemijahan selesai, ijuk dipindah ke kolam

penetasan.

- Cara cimindi: (1) luas kolam pemijahan 25-30 meter persegi, dasar

kolam sedikit berlumpur, kolam dikeringkan lalu diisi air pada pagi hari,

induk dimasukan pada sore hari; kolam pemijahan merupakan kolam

penetasan; (2) disediakan injuk untuk menepelkan telur, ijuk dijepit

bambu dan diletakkan dipojok kolam dan dibatasi pematang antara dari

tanah; (3) setelah proses pemijahan selesai induk dipindahkan ke

kolam lain; (4) tujuh hari setelah pemijahan ijuk ini dibuka kemudian

sekitar 2-3 minggu setelah itu dapat dipanen benih-benih ikan.

- Cara rancapaku: (1) luas kolam pemijahan 25-30 meter persegi, dasar

kolam sedikit berlumpur, kolam dikeringkan lalu diisi air pada pagi hari,

induk dimasukan pada sore hari; kolam pemijahan merupakan kolam

penetasan, batas pematang antara terbuat dari batu; (2) disediakan

rumput kering untuk menepelkan telur, rumput disebar merata di

seluruh permukaan air kolam dan dibatasi pematang antara dari tanah;

(3) setelah proses pemijahan selesai induk tetap di kolam pemijahan.;

(4) setelah benih ikan kuat maka akan berpindah tempat melalui sela

bebatuan, setelah 3 minggu maka benih dapat dipanen.

- Cara sumatera: (1) luas kolam pemijahan 5 meter persegi, dasar kolam

sedikit berlumpur, kolam dikeringkan lalu diisi air pada pagi hari, induk

dimasukan pada sore hari; kolam pemijahan merupakan kolam

penetasan; (2) disediakan injuk untuk menepelkan telur, ijuk ditebar di

permukaan air; (3) setelah proses pemijahan selesai induk dipindahkan

ke kolam lain; (4) setelah benih berumur 5 hari lalu pindahkan ke kolam

pendederan.

- Cara dubish: (1) luas kolam pemijahan 25-50 meter persegi, dibuat parit

keliling dengan lebar 60 cm dalam 35 cm, kolam dikeringkan lalu diisi

air pada pagi hari, induk dimasukan pada sore hari; kolam pemijahan

merupakan kolam penetasan; (2) sebagai media penempel telur

digunakan tanaman hidup seperti Cynodon dactylon setinggi 40 cm; (3)

setelah proses pemijahan selesai induk dipindahkan ke kolam lain; (4)

setelah benih berumur 5 hari lalu pindahkan ke kolam pendederan.

- Cara hofer: (1) sama seperti cara dubish hanya tidak ada parit dan

tanaman Cynodon dactylon dipasang di depan pintu pemasukan air.

b. Sistim kawin suntik

Pada sisitim ini induk baik jantan maupun betina yang matang bertelur

dirangsang untuk memijah setelah penyuntikan ekstrak kelenjar hyphofise

ke dalam tubuh ikan. Kelenjar hyphofise diperoleh dari kepala ikan donor

(berada dilekukan tulang tengkorak di bawah otak besar). Setelah

suntikan dilakukan dua kali, dalam tempo 6 jam induk akan terangsang

TTG BUDIDAYA PERIKANAN

melakukan pemijahan. Sistim ini memerlukan biaya yang tinggi, sarana

yang lengkap dan perawatan yang intensif.

3) Pembenihan/Pemijahan

Hal yang perlu diperhatikan dalam melakukan pemijahan ikan mas:

a. Dasar kolam tidak berlumpur, tidak bercadas.

b. Air tidak terlalu keruh; kadar oksigen dalam air cukup; debit air cukup; dan

suhu berkisar 25 derajat C.

c. Diperlukan bahan penempel telur seperti ijuk atau tanaman air.

d. Jumlah induk yang disebar tergantung dari luas kolam, sebagai patokan

seekor induk berat 1 kg memerlukan kolam seluas 5 meter persegi.

e. Pemberian makanan dengan kandungan protein 25%. Untuk pellet

diberikan secara teratur 2 kali sehari (pagi dan sore hari) dengan takaran

2-4% dari jumlah berat induk ikan.

4) Pemeliharaan Bibit/Pendederan

Pendederan atau pemeliharaan anak ikan mas dilakukan setelah telur-telur

hasil pemijahan menetas. Kegiatan ini dilakukan pada kolam pendederan

(luas 200-500 meter persegi) yang sudah siap menerima anak ikan dimana

kolam tersebut dikeringkan terlebih dahulu serta dibersihkan dari ikan-ikan

liar. Kolam diberi kapur dan dipupuk sesuai ketentuan. Begitu pula dengan

pemberian pakan untuk bibit diseuaikan dengan ketentuan.

Pendederan ikan mas dilakukan dalam beberapa tahap, yaitu:

a. Tahap I: umur benih yang disebar sekitar 5-7 hari(ukuran1-1,5 cm); jumlah

benih yang disebar=100-200 ekor/meter persegi; lama pemeliharaan 1

bulan; ukuran benih menjadi 2-3 cm.

b. Tahap II: umur benih setelah tahap I selesai; jumlah benih yang

disebar=50-75 ekor/meter persegi; lama pemeliharaan 1 bulan; ukuran

benih menjadi 3-5 cm.

c. Tahap III: umur benih setelah tahap II selesai; jumlah benih yang

disebar=25-50 ekor/meter persegi; lama pemeliharaan 1 bulan; ukuran

benih menjadi 5-8 cm; perlu penambahan makanan berupa dedak halus

3-5% dari jumlah bobot benih.

d. Tahap IV: umur benih setelah tahap III selesai; jumlah benih yang

disebar=3-5 ekor/meter persegi; lama pemeliharaan 1 bulan; ukuran benih

menjadi 8-12 cm; perlu penambahan makanan berupa dedak halus 3-5%

dari jumlah bobot benih.

5) Perlakuan dan Perawatan Bibit

Apabila benih belum mencapai ukuran 100 gram, maka benih diberi pakan

pelet 2 mm sebanyak 3 kali bobot total benih yang diberikan 4 kali sehari

selama 3 minggu.

TTG BUDIDAYA PERIKANAN

6.3. Pemeliharaan Pembesaran

Pemeliharaan pembesaran dapat dilakukan secara polikultur maupun

monokultur.

a) Polikultur

1. ikan mas 50%, ikan tawes 20%, dan mujair 30%, atau

2. ikan mas 50%, ikan gurame 20% dan ikan mujair 30%.

b) Monokultur

Pemeliharaan sistem ini merupakan pemeliharaan terbaik dibandingkan

dengan polikultur dan pada sistem ini dilakukan pemisahan antara induk

jantan dan betina.

1) Pemupukan

Pemupukan dengan kotoran kandang (ayam) sebanyak 250-500 gram/m2,

TSP 10 gram/m2, Urea 10 gram/m2, kapur 25-100 gram/m2. Setelah itu kolam

diisi air 39-40 cm. Biarkan 5-7 hari. Dua hari setelah pengisian air, kolam

disemprot dengan insektisida organophosphat seperti Sumithion 60 EC,

Basudin 60 EC dengan dosis 2-4 ppm. Tujuannya untuk memberantas

serangga dan udang-udangan yang memangsa rotifera. Setelah 7 hari

kemudian, air ditinggikan sekitar 60 cm. Padat penebaran ikan tergantung

pemeliharaannya. Jika hanya mengandalkan pakan alami dan dedak, maka

padat penebaran adalah 100-200 ekor/m2, sedangkan bila diberi pakan

pellet, maka penebaran adalah 300-400 ekor/m2 (benih lepas hapa).

Penebaran dilakukan pada pagi/sore hari saat suhu rendah.

2) Pemberian Pakan

Dalam pembenihan secara intensif biasanya diutamakan pemberian pakan

buatan. Pakan yang berkualitas baik mengandung zat-zat makanan yang

cukup, yaitu protein yang mengandung asam amino esensial, karbohidrat,

lemak, vitamin dan mineral. Perawatan larva dalam hapa sekitar 4-5 hari.

Setelah larva tidak menempel pada kakaban (3-4 hari kemudian) kakaban

diangkat dan dibersihkan. Pemberian pakan untuk larva, 1 butir kuning telur

rebus untuk 100.000 ekor/hari. Caranya kuning telur dibuat suspensi (1/4 liter

air untuk 1 butir), kuning telur diremas dalam kain kemudian diberikan pada

benih, perawatan 5-7 hari.

3) Pemeliharaan Kolam/Tambak

Dalam hal pemeliharaan ikan mas yang tidak boleh terabaikan adalah

menjaga kondisi perairan agar kualitas air cukup stabil dan bersih serta tidak

tercemari/teracuni oleh zat beracun.

7. HAMA DAN PENYAKIT

7.1. Hama

1) Bebeasan (Notonecta)

Berbahaya bagi benih karena sengatannya. Pengendalian: menuangkan

minyak tanah ke permukaan air 500 cc/100 meter persegi.

2) Ucrit (Larva cybister)

Menjepit badan ikan dengan taringnya hingga robek. Pengendalian: sulit

diberantas; hindari bahan organik menumpuk di sekitar kolam.

3) Kodok

Makan telur telur ikan. Pengendalian: sering membuang telur yang

mengapung; menagkap dan membuang hidup-hidup.

4) Ular

Menyerang benih dan ikan kecil. Pengendalian: lakukan penangkapan;

pemagaran kolam.

5) Lingsang

Memakan ikan pada malam hari. Pengendalian:pasang jebakan berumpun.

6) Burung

Memakan benih yang berwarna menyala seperti merah, kuning.

Pengendalian: diberi penghalang bambu agar supaya sulit menerkam; diberi

rumbai-rumbai atau tali penghalang.

7) Ikan gabus

Memangsa ikan kecil. Pengendalian:pintu masukan air diberi saringan atau

dibuat bak filter.

Belut dan kepiting

Pengendalian: lakukan penangkapan.

7.2. Penyakit

1) Bintik merah (White spot)

Gejala: pada bagian tubuh (kepala, insang, sirip) tampak bintik-bintik putih,

pada infeksi berat terlihat jelas lapisan putih, menggosok-gosokkan

badannya pada benda yang ada disekitarnya dan berenang sangat lemah

serta sering muncul di permukaan air. Pengendalian: direndam dalam

larutan Methylene blue 1% (1 gram dalam 100 cc air) larutan ini diambil 2-4

cc dicampur 4 liter air selama 24 jam dan Direndam dalam garam dapur

NaCl selama 10 menit, dosis 1-3 gram/100 cc air.

TTG BUDIDAYA PERIKANAN

2) Bengkak insang dan badan ( Myxosporesis)

Gejala: tutup insang selalu terbuka oleh bintik kemerahan, bagian punggung

terjadi pendarahan. Pengendalian; pengeringan kolam secara total, ditabur

kapur tohon 200 gram/m2, biarkan selama 1-2 minggu.

3) Cacing insang, sirip, kulit (Dactypogyrus dan girodactylogyrus)

Gejala: ikan tampak kurus, sisik kusam, sirip ekor kadang-kadang rontok,

ikan menggosok-gosokkan badannya pada benda keras disekitarnya, terjadi

pendarahan dan menebal pada insang. Pengendalian: (1) direndan dalam

larutan formalin 250 gram/m3 selama 15 menit dan direndam dalam

Methylene blue 3 gram/m3 selama 24 jam; (2) hindari penebaran ikan yang

berlebihan.

4) Kutu ikan (argulosis)

Gejala: benih dan induk menjadi kurus, karena dihisap darahnya. Bagian

kulit, sirip dan insang terlihat jelas adanya bercak merah (hemorrtage).

Pengendalian: (1) ikan yang terinfeksi direndan dalam garam dapur 20

gram/liter air selama 15 menit dan direndam larutan PK 10 ppm (10 ml/m3)

selama 30 menit; (2) dengan pengeringan kolam hingga retak-retak.

5) Jamur (Saprolegniasis)

Menyerang bagian kepala, tutup insang, sirip dan bagian yang lainnya.

Gejala: tubuh yang diserang tampak seperti kapas. Telur yang terserang

jamur, terlihat benang halus seperti kapas. Pengendalian: direndam dalam

larutan Malactile green oxalat (MGO) dosis 3 gram/m3 selama 30 menit; telur

yang terserang direndam dengan MGO 2-3 gram/m3 selama 1 jam.

6) Gatal (Trichodiniasis)

Menyerang benih ikan. Gejala: gerakan lamban; suka menggosok-gosokan

badan pada sisi kolam/aquarium. Pengendalian: rendam selam 15 menit

dalam larutan formalin 150-200 ppm.

7) Bakteri psedomonas flurescens

Penyakit yang sangat ganas. Gejala: pendarahan dan bobok pada kulit; sirip

ekor terkikis. Pengendalian: pemberian pakan yang dicampur

oxytetracycline 25-30 mg/kg ikan atau sulafamerazine 200mg/kg ikan selama

7 hari berturut-turut.

Bakteri aeromonas punctata

Penyakit yang sangat ganas. Gejala: warna badan suram, tidak cerah; kulit

kesat dan melepuh; cara bernafas mengap-mengap; kantong empedu

gembung; pendarahan dalam organ hati dan ginjal. Pengendalian:

penyuntikan chloramphenicol 10-15 mg/kg ikan atau streptomycin 80-100

mg/kg ikan; pakan dicampur terramicine 50 mg/kg ikan selama 7 hari

berturut-turut.

Secara umum hal-hal yang dilakukan untuk dapat mencegah timbulnya

penyakit dan hama pada budidaya ikan mas:

1) Pengeringan dasar kolam secara teratur setiap selesai panen.

2) Pemeliharaan ikan yang benar-benar bebas penyakit.

3) Hindari penebaran ikan secara berlebihan melebihi kapasitas.

4) Sistem pemasukan air yang ideal adalah paralel, tiap kolam diberi satu

pintu pemasukan air.

5) Pemberian pakan cukup, baik kualitas maupun kuantitasnya.

6) Penanganan saat panen atau pemindahan benih hendaknya dilakukan

secara hati-hati dan benar.

7) Binatang seperti burung, siput, ikan seribu (lebistus reticulatus peters)

sebagai pembawa penyakit jangan dibiarkan masuk ke areal perkolaman.

8. PANEN

8.1. Pemanenan Benih

Sebelum dilakukan pemanenan benih ikan, terlebih dahulu dipersiapkan alatalat

tangkap dan sarana perlengkapannya. Beberapa alat tangkap dan sarana

yang disiapkan diantaranya keramba, ember biasa, ember lebar, seser halus

sebagai alat tangkap benih, jaring atau hapa sebagai penyimpanan benih

sementara, saringan yang digunakan untuk mengeluarkan air dari kolam agar

benih ikan tidak terbawa arus, dan bak-bak penampungan yang berisi air bersih

untuk penyimpanan benih hasil panen.

Panen benih ikan dimulai pagi-pagi, yaitu antara jam 04.00–05.00 pagi dan

sebaiknya berakhir tidak lebih dari jam 09.00 pagi. Hal ini dimaksudkan untuk

menghindari terik matahari yang dapat mengganggu benih ikan kesehatan

tersebut. Pemanenan dilakukan mula-mula dengan menyurutkan air kolam

pendederan sekitar pkul 04.00 atau 05.00 pagi secara perlahan-lahan agar ikan

tidak stres akibat tekanan air yang berubah secara mendadak. Setelah air surut

benih mulai ditangkap dengan seser halus atau jaring dan ditampung dalam

ember atau keramba.

Benih dapat dipanen setelah dipelihara selama 21 hari. Panenan yang dapat

diperoleh dapat mencapai 70-80% dengan ukuran benih antara 8-12 cm.

8.2. Cara Perhitungan Benih

Untuk mengetahui benih ikan hasil panenan yang disimpan dalam bak

penyimpanan maka sebelum dijual, terlebih dahulu dihitung jumlahnya. Cara

menghitung benih umumnya dengan memakai takaran, yaitu dengan

menggunakan sendok untuk larva dan kebul, cawan untuk menghitung putihan,

dan dihitung per ekor untuk benih ukuran glondongan. Penghitungan benih

biasanya dengan cara:

a) Penghitungan dengan sendok.

b) Penghitungan dengan mangkok.

8.3. Pembersihan

Pada umumnya, dasar kolam pendederan sudah dirancang miring dan ada

saluran di tengah kolam, selain itu pada dasar kolam tersebut ada bagian yang

lebih dalam dengan ukuran 1-2 meter persegi sehingga ketika air menyurut,

maka benih ikan akan mengumpul di bagian kolam yang dalam tersebut. Benih

ikan lalu ditangkap sampai habis dan tidak ada yang ketinggalan dalam kolam.

Benih ikan tersebut semuanya disimpan dalam bak-bak penampungan yang

telah disiapkan.

8.4. Pemanenan Hasil Pembesaran

Untuk menangkap/memanen ikan hasil pembesaran umumnya dilakukan panen

total. Umur ikan mas yang dipanen berkisar antara 3-4 bulan dengan berat

berkisar antara 400-600 gram/ekor. Panen total dilakukan dengan cara

mengeringkan kolam, hingga ketinggian air tinggal 10-20 cm. Petak

pemanenan/petak penangkapan dibuat seluas 2 meter persegi di depan pintu

pengeluaran (monnik), sehingga memudahkan dalam penangkapan ikan.

Pemanenan dilakukan pagi hari saat keadaan tidak panas dengan

menggunakan waring atau scoopnet yang halus. Lakukan pemanenan

secepatnya dan hati-hati untuk menghindari lukanya ikan.

9. PASCAPANEN

Penanganan pascapanen ikan mas dapat dilakukan dengan cara penanganan

ikan hidup maupun ikan segar.

1) Penanganan ikan hidup

Adakalanya ikan konsumsi ini akan lebih mahal harganya bila dijual dalam

keadaan hidup. Hal yang perlu diperhatikan agar ikan tersebut sampai ke

konsumen dalam keadaan hidup, segar dan sehat antara lain:

a. Dalam pengangkutan gunakan air yang bersuhu rendah sekitar 20 derajat

C.

b. Waktu pengangkutan hendaknya pada pagi hari atau sore hari.

c. Jumlah kepadatan ikan dalam alat pengangkutan tidak terlalu padat.

2) Penanganan ikan segar

Ikan segar mas merupakan produk yang cepat turun kualitasnya. Hal yang

perlu diperhatikan untuk mempertahankan kesegaran antara lain:

a. Penangkapan harus dilakukan hati-hati agar ikan-ikan tidak luka.

b. Sebelum dikemas, ikan harus dicuci agar bersih dan lendir.

c. Wadah pengangkut harus bersih dan tertutup. Untuk pengangkutan jarak

dekat (2 jam perjalanan), dapat digunakan keranjang yang dilapisi dengan

daun pisang/plastik. Untuk pengangkutan jarak jauh digunakan kotak dan

seng atau fiberglass. Kapasitas kotak maksimum 50 kg dengan tinggi

kotak maksimum 50 cm.

d. Ikan diletakkan di dalam wadah yang diberi es dengan suhu 6-7 derajat C.

Gunakan es berupa potongan kecil-kecil (es curai) dengan perbandingan

jumlah es dan ikan=1:1. Dasar kotak dilapisi es setebal 4-5 cm. Kemudian

ikan disusun di atas lapisan es ini setebal 5-10 cm, lalu disusul lapisan es

lagi dan seterusnya. Antara ikan dengan dinding kotak diberi es, demikian

juga antara ikan dengan penutup kotak.

3) Sedangkan hal-hal yang perlu diperhatikan dalam pananganan benih adalah

sebagai berikut:

a. Benih ikan harus dipilih yang sehat yaitu bebas dari penyakit, parasit dan

tidak cacat. Setelah itu, benih ikan baru dimasukkan ke dalam kantong

plastik (sistem tertutup) atau keramba (sistem terbuka).

b. Air yang dipakai media pengangkutan harus bersih, sehat, bebas hama

dan penyakit serta bahan organik lainya. Sebagai contoh dapat digunakan

air sumur yang telah diaerasi semalam.

c. Sebelum diangkut benih ikan harus diberok dahulu selama beberapa hari.

Gunakan tempat pemberokan berupa bak yang berisi air bersih dan

dengan aerasi yang baik. Bak pemberokan dapat dibuat dengan ukuran 1

m x 1 m atau 2 m x 0,5 m. Dengan ukuran tersebut, bak pemberokan

dapat menampung benih ikan mas sejumlah 5000–6000 ekor dengan

ukuran 3-5 cm. Jumlah benih dalam pemberokan harus disesuaikan

dengan ukuran benihnya.

d. Berdasarkan lama/jarak pengiriman, sistem pengangkutan benih terbagi

menjadi dua bagian, yaitu:

- Sistem terbuka

Dilakukan untuk mengangkut benih dalam jarak dekat atau tidak

memerlukan waktu yang lama. Alat pengangkut berupa keramba.

Setiap keramba dapat diisi air bersih 15 liter dan dapat untuk

mengangkut sekitar 5000 ekor benih ukuran 3-5 cm.

- Sistem tertutup

Dilakukan untuk pengangkutan benih jarak jauh yang memerlukan

waktu lebih dari 4-5 jam, menggunakan kantong plastik. Volume media

pengangkutan terdiri dari air bersih 5 liter yang diberi buffer

Na2(hpo)4.H2O sebanyak 9 gram. Cara pengemasan benih ikan yang

diangkut dengan kantong plastik: (1) masukkan air bersih ke dalam

kantong plastik kemudian benih; (3) hilangkan udara dengan menekan

kantong plastik ke permukaan air; (3) alirkan oksigen dari tabung

dialirkan ke kantong plastik sebanyak 2/3 volume keseluruhan rongga

(air:oksigen=1:2); (4) kantong plastik lalu diikat. (5) kantong plastik

dimasukkan ke dalam dos dengan posisi membujur atau ditidurkan.

Dos yang berukuran panjang 0,50 m, lebar 0,35 m, dan tinggi 0,50 m

dapat diisi 2 buah kantong plastik.

Beberapa hal yang perlu diperhatikan setelah benih sampai di tempat tujuan

adalah sebagai berikut:

- Siapkan larutan tetrasiklin 25 ppm dalam waskom (1 kapsul tertasiklin

dalam 10 liter air bersih).

- Buka kantong plastik, tambahkan air bersih yang berasal dari kolam

setempat sedikit demi sedikit agar perubahan suhu air dalam kantong

plastik terjadi perlahan-lahan.

- Pindahkan benih ikan ke waskom yang berisi larutan tetrasiklin selama 1-

2 menit.

- Masukan benih ikan ke dalam bak pemberokan. Dalam bak pemberokan

benih ikan diberi pakan secukupnya. Selain itu, dilakukan pengobatan

dengan tetrasiklin 25 ppm selama 3 hari berturut-turut. Selain tetrsikli

dapat juga digunakan obat lain seperti KMNO4 sebanyak 20 ppm atau

formalin sebanyak 4% selama 3-5 menit.

- Setelah 1 minggu dikarantina, tebar benih ikan di kolam budidaya.

10. ANALISIS EKONOMI BUDIDAYA

10.1.Analisis Usaha Budidaya

Analisis budidaya ikan mas koki dengan luas lahan 70 m2 (kapasitas 1000 ekor)

selama 7 bulan pada tahun 1999 di daerah Jawa Barat.

1) Biaya produksi

a. Sewa dan pembuatan kolam Rp. 1.500.000,-

b. Benih ikan 1.000 ekor, @ Rp.100,- Rp. 100.000,-

c. Pakan

- Cacing rambut 150 kg @ Rp. 1.500,- Rp. 225.000,-

- Pelet udang 10 kg @ Rp. 9.500,- Rp. 95.000,-

- Tepung jagung 50 kg @ Rp. 1.500,- Rp. 75.000,-

- Ganti air 7 bulan x 4 x2 @ Rp. 5.000,- Rp. 140.000,-

- Tenaga kerja 28 minggu @ Rp.10.000,- Rp. 280.000,-

- Obat-oabatan Rp. 10.000,-

d. Peralatan Rp. 50.000,-

e. Lain-lain Rp. 150.000,-

Jumlah biaya produksi Rp. 2.625.000,-

2) Pendapatan

a. Panen I (2 bulan) 400 ekor @ Rp.1.000,- Rp. 400.000,-

b. Panen II (4 bulan) 250 ekor @ Rp. 3.000,- Rp. 750.000,-

c. Panen III ( 2 bulan) 250 ekor @ Rp. 10.000,- Rp. 2.500.000,-

Jumlah pendapatan Rp. 3.650.000,-

TTG BUDIDAYA PERIKANAN

3) Keuntungan dalam 7 bulan Rp. 1.025.000,-

a. Keuntungan per bulan Rp. 146.425,-

4) Parameter kelayakan usaha

B/C ratio 1,39

10.2.Gambaran Peluang Agribisnis

Dengan adanya luas perairan umum di Indonesia yang terdiri dari sungai, rawa,

danau alam dan buatan seluas hampir mendekati 13 juta ha merupakan potensi

alam yang sangat baik bagi pengembangan usaha perikanan di Indonesia.

Disamping itu banyak potensi pendukung lainnya yang dilaksanakan oleh

pemerintah dan swasta dalam hal permodalan, program penelitian dalam hal

pembenihan, penanganan penyakit dan hama dan penanganan pasca panen,

penanganan budidaya serta adanya kemudahan dalam hal periizinan import.

Walaupun permintaan di tingkal pasaran lokal akan ikan mas dan ikan air tawar

lainnya selalu mengalami pasang surut, namun dilihat dari jumlah hasil

penjualan secara rata-rata selalu mengalami kenaikan dari tahun ke tahun.

Apabila pasaran lokal ikan mas mengalami kelesuan, maka akan sangat

berpengaruh terhadap harga jual baik di tingkat petani maupun di tingkat grosir

di pasar ikan. Selain itu penjualan benih ikan mas boleh dikatakan hampir tak

ada masalah, prospeknya cukup baik. Selain adanya potensi pendukung dan

faktor permintaan komoditi perikanan untuk pasaran lokal, maka sektor

perikanan merupakan salah satu peluang usaha bisnis yang cerah.

11. DAFTAR PUSTAKA

1) DAMANA, Rahman. 1990. Pembenihan Ikan Mas Secara Intensif dalam

Sinar Tani. 2 ,Juni 1990 hal. 2

2) GUNAWAN. Mengenal Cara Pemijahan Ikan Mas dalam Sinar Tani. 27

Agustus 1988 hal. 5

3) RUKMANA, Rahmat. 1991. Budidaya Ikan Mas, Untungnya Bagai Menabung

Emas dalam Sinar Tani. 13 Februari 1991 hal. 5

4) RUKMANA, Rahmat. 1992. Prospek Usaha Ikan Mas Menggiurkan Dan

Menguntungkan dalam Suara Karya. 18 Februari 1992 hal. 7

5) SANTOSO, Budi. 1993. Petunjuk praktis : Budidaya ikan mas. Yogyakarta :

Kanisius.

6) SUMANTADINATA, Komar. 1981. Pengembangbiakan ikan-ikan peliharaan

di Indonesia. Jakarta : Sastra Hudaya.

7) SUSENO, Djoko. 1999. Pengelolaan usaha pembenihan ikan mas, cet. :7.

Jakarta : Penebar Swadaya.

12. KONTAK HUBUNGAN

Proyek Pengembangan Ekonomi Masyarakat Pedesaan – BAPPENAS;

Jl.Sunda Kelapa No. 7 Jakarta, Tel. 021 390 9829 , Fax. 021 390 9829

Jakarta, Maret 2000

Sumber : Proyek Pengembangan Ekonomi Masyarakat Pedesaan, Bappenas

Editor : Kemal Prihatman

http://sutanmuda.wordpress.com/2007/10/22/budidaya-ikan-mas/#comment-158

PENGARUH DONOR DAN DOSIS KELENJAR HIPOFISA TERHADAP OVULASI DAN DAYA TETAS TELURIKAN BETOK (Anabas testudineus Bloch)

 

 

 

 

Muhammad, Hamzah Sunusi, dan Irfan Ambas )

Fakultas Ilmu Kelautan dan Perikanan Unhas, Makassar

 

 

 

There were eighteen females (76± 4 g) and thirty-six males (35 ± 5 g) injected by Anabas testudineus and Cyprinus carpio male pituitary extract with three level dosages 5, 10, and 15mg kg-1 of fish body weight to find out the effect of donor and dosage of pituitary extract on ovulation and hatchability of climbing perch egg. Nested design with two factors and three replications used in this research. The data were analyzed by analysis of variance (anova),Honestly Significant Difference (HSD), and regression. The result of this research has find out the range of latency time from 09,17 to 12,17 hours, fecundity from 9497 to 16668 eggs 100-1 g, fertilization rate from 90,00 to 98,80 %, incubation time from 20,10 to 21,45 hours, and hatching rate from 87,78 to 97,47 %. The result of anova indicate that pituitary gland extract donors have not effect (P > 0,05) on latency time, fertilization rate, incubation time, and hatching rate, but has effect (P < 0,05) on fecundity. The dosages of pituitary gland extract have not different (P > 0,05) on the incubation time, but have significantly different ( P <0,01) on latency time, fecundity, fertilization rate, and hatching ate. HSD test showed that climbing perch pituitary extract at the level of 10 mg kg-1 body weight is the best treatment.Regression analysis showed that the optimal dosage of climbing perch and common carp pituitary extract on hatching rate are 11,50 mg kg-1 and 12,47 mg kg, respectively.Keywords: ovulation and hatchability

Pembenihan Nila Merah (Oreochromis sp) dalam Bak Semen

[ kembali ]
12/10/04 – Informasi: Teknologi
Pembenihan Nila Merah (Oreochromis sp) dalam Bak Semen

Pembenihan Nila Merah dalam Bak Semen

Pematangan Gonad Induk

Induk nila merah dimatangkan gonadnya dalam bak semen berukuran (10 x 5 x 1 m3 dengan ketinggian air 0,8 m dan kepadatan 2 – 3 ekor/m3. Bak dilengkapi dengan aerasi dari blower sebanyak 10 titik per bak dengan kadar oksigen minimal mencapai 5 ppm. Bak diberi atap dengan tujuan untuk mengurangi sinar matahari yang masuk sehingga dapat menekan laju tumbuh plankton.

Pergantian air dilakukan sebanyak 20% tiap dua hari. Pemeliharaan induk untuk pematangan gonad dilakukan secara terpisah antara jantan dan betina. Pakan yang diberikan berupapellet komersial untuk induk dengan kadar protein minimal 30% sebanyak 3% dari total biomassa dengan frekuensi pemberian pakan 3 kali sehari yaitu pagi, siang, dan sore.

Seleksi Induk

Pengambilan induk yang matang gonad dilakukan setelah pemeliharaan selam 15 hari dengan cara menyeleksi. Induk betina diseleksi berdasarkan bentuk perutnya, yakni bagian perut kelihatan buncit, lembut bila diraba dan beratnya minimal 400 g/ekor. Sedangkan induk jantan diseleksi berdasarkan ukuran berat dan kondisi induk.

Pemijahan

Pemijahan ikan nila dilakukan secara alami dengan mencampurkan induk jantan dan betina hasil seleksi ke dalam bak semen (ukuran 10 x 5 x 1 m3), bak yang digunakan adalah bak yang tidak diberi atap dengan tujuan untuk mempercepat pertumbuhan plankton sebagai sumber pakan alami bagi larva setelah menetas. Perbandingan induk jantan dan betina dalam pemijahan adalah 1 : 3. Bak pemijahan juga dilengkapi dengan aerasi sebanyak 10 titik. Lama pemijahan 15 hari dan panen larva dilakukan setelah hari ke 15. Selama pemijahan induk diberi pakan pellet induk sebanyak 1% dari biomassa dengan frekuensi pemberian 3 kali sehari.

Panen Larva

Pemanenan larva dilakukan dengan cara mengurangi air bak hingga ketinggian 20 cm. Induk ditangkap terlebih dahulu dengan jaring induk (mesh size >0,5 inchi) dan dipisahkan antara jantan dan betina untuk dimatangkan gonadnya kembali. Larva nila merah yang baru menetas mempunyai panjang 2 mm dengan berat rata-rata 0,02 mg/ekor. Penangkapan larva dilakukan dengan jaring larva (mesh size < 1 mm) sampai habis dan dihitung untuk mencari jumlah total larva yang dihasilkan dan selanjutnya dimasukkan dalam bak pendederan.

Pendederan

Pendederan larva dilakukan dalam bak semen dengan ukuran (6 x 2 x 1 m3) dengan ketinggian air 0,8 cm. Lama pemeliharaan 30 hari dan diberikan pakan pellet komersial dengan kadar protein minimal 28% dengan cara menambah ukuran pellet setiap tahapan ukuran larva. Pakan tepung untuk pemeliharaan larva pada minggu pertama, pakan crumble 1 (butiran) untuk minggu ke 2 dan crumble 3 untuk minggu ke 3 dan 4. Jadi pemberian pakan dilakukan dengan variasi 100% dari total biomassa pada minggu pertama, 75% pada minggu ke 2 dan 30% pada minggu ke 3 dan 4, frekuensi pemberian pakan sebanyak 4 kali sehari.

Panen Benih

Sebelum dilakukan pemanenan, benih tidak diberikann pakan selama satu hari. Pemanenan dilakukan dengan cara menjaring benih dalam bak dan selanjutnya panen total dengan cara mengeringkan bak.

Benih hasil panen diseleksi berdasarkan ukuran pasaran yaitu 1 – 3 cm, 3 – 5 cm dan 5-8 cm. Untuk mengurangi stress seleksi benih dilakukan menggunakan alat bantu berupa ember atau keranjang berlubang (grader). Lubang dengan diamtere 4 mm untuk benih 3 – 5 cm dan 8 mm untuk ukuran 5 – 8 cm.

Hasil seleksi ditampung dalam wadah terpisah berdasarkan ukuran dan siap untuk didistribusikan.

Biaya Tetap
Biaya Konstruksi
1 buah bak pemijahan volume 50 ton
Rp. 12.000.000
3 buah bak pematangan gonad 25 ton
Rp. 21.000.000
6 buah bak pendederan volume 12 ton
Rp. 30.000.000
Induk 100 kg
Rp. 1.500.000
Total biaya konstruksi
Rp. 64.500.000
Biaya penyusutan 10%
Rp. 6.450.000
Total
Rp. 70.950.000
Peralatan
1 unit blower 90 watt
Rp. 300.000
1 unit instalasi udara
Rp. 270.000
1 unit jaring induk
Rp. 100.000
1 unit jaring larva
Rp. 75.000
1 unit peralatan lapangan
Rp. 597.000
Total biaya peralatan
Rp. 1. 342.000
Biaya penyusutan 10%
Rp. 134.200
Total
Rp. 1.476.200
Biaya Operasional 1 siklus
Pakan induk 40 kg
Rp. 140.000
Pakan benih 20 kg
Rp. 70.000
Tenga kerja 3 orang
Rp. 600.000
Biaya listrik 1 bulan
Rp. 100.000
Peralatan pengemas benih
Rp. 200.000
Total
Rp. 1.110.000

Pendapatan

1 siklus (1 bulan)

Asumsi :

  1.  
    1. SR 80%
    2. 10 % ukr < 3- 5 cm ; 70% ukr 3 – 5 cm; 20% ukr 5 – 8 cm

Hasil :

  1.  
    1. 80% x 30.000 ekor = 24.000 ekor
    2. 70% x 24.000 ekor = 16.800 ekor
    3. 20% x 24.000 ekor = 4.800 ekor

Nilai jual :

  1.  
    1. 16.800 ekor @ Rp. 60,- = Rp. 1.008.000,-
    2. 4.800 ekor @Rp. 100,- = Rp. 480.000,-

Total nilai jual per tahun (12 siklus) : Rp. 1.488.000 x 12 = Rp. 17.856.000,-

Informasi lebih lanjut hubungi :

Balai Budidaya Air Tawar Jambi

Desa Sungai Gelam Kecamatan Kumpeh Ulu Kabupaten Muaro Jambi 36361 Indonesia PO. BOX 78 Jambi 36000 telp. (0741) 54472 ; email : bbatj@indo.net.id

 

 



Hak Cipta 2003, Departemen Kelautan dan Perikanan Republik Indonesia

Pembenihan Ikan Baung

19/10/04 – Informasi: Teknologi
Pembenihan Ikan Baung

Pembenihan Ikan Baung (Mystus Nemurus)

Pemeliharaan Induk

Pemeliharaan induk dilakukan di kolam induk yang berukuran 600 m2 dengan kedalaman air rata-rata 1 m dengan padat tebar 15 ekor /m2. Selama pemeliharaan induk diberikan pakan berprotein minimal 28% sebanyak 2% dari total Biomass/hari dengan frekuensi pemberian pakan dua kali sehari yaitu pada pagi hari dan sore hari.

Seleksi Induk

Pengecekan tingkat kematangan gonad induk betina yang siap pijah dapat dicirikan perut yang membesar dan lembek bentuk badan yang agak melebar dan pendek. Pada sekitar lubang genital agak kemerahan dan telur berwarna kecoklatan. Ukuran diameter telur ikan baung yang siap dipijahkan dan mampu berkembang dengan baik berkisar 1,5 sampai 1,8 mm dengan rata-rata 1,6 mm. Telur yang bagus dapat dilihat intinya sudah menepi dan tidak terjadi penggumpalan jika diberi larutan sera.

Sedangkan untuk induk jantan yang siap dicirikan dengan ujung genital papilla (penis) berwarna merah yang panjangnya sampai ke pangkal sirip anal. Cairan sperma ikan baung ini berwarna bening.

Pemijahan dilakukan secara buatan dengan penyuntikan hormon. Jenis hormon yang digunakan adalah ovaprim denga dosis 0,5 cc/kg induk betina dan 0,3 cc/kg untuk induk jantan.

Induk ditampung dalam wadah fiber/waskom/aquarium yang berfungsi sebagai tempat inkubasi induk. Induk ditimbang beratnya untuk menentukan jumlah hormon yang akan digunakan. Penyuntikan induk betina dilakukan 2 kali dengan interval waktu penyuntikan 6 jam, untuk penyuntikan I digunakan 1/3 dari dosis dan 2/3 sisanya untuk penyuntikan ke II. Sedangkan untuk induk jantan dilakukan sekali penyuntikan yaitu waktu penyuntikan kedua pada induk betina. Penyuntikan dilaksanakan secara intra muskular di bagian kiri/kanan belakang sirip punggung. Posisi jarum suntik terhadap tubuh induk membentuk sudut 30o – 40o sejajar dengan panjang tubuh.

Waktu ovulasi berkisar antara 6 – 8 jam setelah penyuntikan ke II (kisaran suhu 29o – 31o ditandai dengan keluarnya telur bila dilakukan pengurutan pada bagian perut.

Pembuahan

Pengambilan sperma dilakukan dengan pengurutan ke arah lubang genital dan dengan spuit yang sudah diisi dengan larutan NaCl 0,9% dengan perbandingan 4 cc NaCl dengan 1 cc sperma. Pembuahan buatan dilakukan dengan cara mencampurkan telur dengan sperma kemudian diaduk dengan bulu ayam searah jarum jam selama kurang lebih 2 – 3 menit secara perlahan sampai tercampur rata, lalu diberi air bersih. Selanjutnya telur ditetaskan di dalam aquarium.

Penetasan Telur

Penetasan dilakukan pada substrat buatan yang diletakkan menggantung di aquarium. Hal ini dikarenakan telur ikan baung memiliki daya rekat yang tinggi sehingga telur tersebut menempel kuat pada substrat. Setelah telur menetas larva akan jatuh ke dasar aquarium dan larva baung bersifat bergerombol dan lebih suka berada di dasar aquarium. Sedangkan telur yang tak menetas tetap menempel pada substrat.

Pemeliharaan Larva

Panen larva dilakukan setelah larva berumur 6 – 8 jam setelah menetas dengan cara disifon dengan selang plastik dan ditampung dalam waskom atau dengan menggunakan serok halus dan dihitung kepadatannya. Selanjutnya baru dilakukan penebaran di media pemeliharaan larva. Padat penebaran yang digunakan dalam pemeliharaan larva ikan baung ini 20 ekor/liter.

Larva yang baru menetas berukuran 0,5 cm dengan berat 0,7 mg. Selama pemeliharaan larva, pakan yang diberikan adalah nauplii Artemia sp dan cacing rambut diberikan setelah larva berumur 8 hari. Frekuensi pemberian pakan dilakukan 5 kali per hari yaitu pada pukul 07.00, 11.00, 15.00, 19.00, dan 23.00 WIB. Agar kualitas air tetap baik dilakukan penyifonan kotoran yang mengendap di dasar aquarium. Penyifonan dilakukan 1 x per hari pada pagi hari sebelum pemberian pakan.

Pendederan

Sebelum dilakukan penebaran benih, terlebih dahulu dilakukan persiapan kolam pendederan yang meliputi pengeringan kolam, perbaikan pematang, pengolahan tanah dasar kolam dan pembuatan caren (kemalir). Dalam kegiatan persiapan kolam juga dilakukan pemupukan, pengapuran, pengisian air dan inokulasi moina sp. dengan kepadatan 10 juta individu/500 m2

Pengolahan dasar kolam dilakukan dengan cara pembalikan tanah dasar kolam, diratakan dengan pembuatan kemalir dengan kemiringan 0,5 – 1% ke arah pintu pengeluaran. Setelah pengolahan tanah, dilakukan pemupukan dengan pupuk kandang (kotoran ayam petelur) dengan dosis 60 gr/m2. Penjemuran kolam dilakukan selama 3 hari lalu diisi air secara bertahap sampai ketinggian air 90 cm.

Inokulasi Moina sp dilakukan sehari setelah pengisian air. Kolam didiamkan selama 3 – 4 hari agar ekosistem kolam dapat mencapai keseimbangan dan Moina sp berkembang biak. Sebelum benih ditebar di kolam dilakukan pengukuran kualitas air yang meliputi suhu, oksigen dan pH.

Penebaran banih dilakukan pada hari ke-8 dari awal persiapan kolam (3 hari setelah penebaran Moina sp). Penebaran benih dilakukan pagi atau sore hari untuk menghindari stress. Benih yang ditebar berukuran rata-rata 2,4 cm dengan padat tebar 20 ekor/m2 Pemeliharaan benih dilakukan selama 4 minggu. Setelah penebaran, benih diberi makan berupa pakan komersial (pellet) yang dihancurkan dengan kadar protein 28 – 30% sebanyak 25 – 100% total biomassa/hari. Total pemberian pakan tersebut adalah sebagai berikut :

  • Minggu I : 100%,
  • Minggu II : 80%
  • Minggu III : 70%
  • Minggu IV : 30%

Frekuensi pemberian pakan 3 x sehari pagi, siang dan sore .

Pemanenan

Pemanenan dilakukan dengan menjaring ikan dalam kolam menggunakan jaring, selanjutnya ditampung dalam hapa penampungan dan diberok selama 1 hari. Sebelum dilakukan pendistribusian benih pada pembudidaya ikan, benih terlebih dulu diseleksi sesuai ukuran.

Benih dikemas dalam kantong plastik ukuran 60 x 90 cm. Kepadatan per kantong tergantung pada ukuran benih dan waktu tempuh.

* BBAT Jambi

 



Hak Cipta 2003, Departemen Kelautan dan Perikanan Republik Indonesia

Pembenihan Kakap Putih

[ kembali ]
16/06/04 – Informasi: Teknologi
Pembenihan Kakap Putih

Pembenihan Kakap Putih (Lates calcarifer Bloch) dengan Manipulasi Rangsang Hormonal

Keberhasilan dalam penerapan teknologi pembenihan kakap putih di Loka Budidaya Laut Batam diharapkan mampu mengatasi masalah keterbatasan benih yang selama ini menjadi kendala utama dalam pengembangan budidayanya. Potensi lahan budidaya yang cukup memberikan peluang, dengan penawaran harga yang cukup menarik merupakan daya dukung tersendiri bagi terselenggaranya kegiatan budidaya dalam rangka diversifikasi usaha.

Aspek Biologi
Kakap Putih bersifat Euryhaline dan Katadromus hidup di perairan tropik dan subtropik Indopasifik Barat. Ikan jantan yang telah mencapai bobot 2-2,5 kg dapat berubah kelamin menjadi betina (Protandry Hermaprodite).

Teknologi Pembenihan
1. Pengadaan dan Pemeliharaan Induk

Calon Induk dapat diperoleh dari hasil tangkapan di alam maupun hasil penangkaran. Untuk mempercepat pematangan kelamin, calon induk dipelihara di laut dengan menggunakan jaring apung, kepadatan 1 ekor per 1-2 menter per kubik air.

Pakan berupa ikan rucah segar diberikan 1 kali sehari dengan jadwal waktu yang tetap. Dosis pakan 5% dari total berat badan per hari, kemudian diturunkan menjadi 1-3% pada saat musim pijah tiba.

Pengontrolan kondisi fisik sarana pemeliharaan dilakukan rutin setiap hari, penggantian jaring sebulan sekali untuk mencagah lolosnya ikan, mengurangi Fauling Organisme dan menciptakn suasana yang nyaman serta alami.

2. Seleksi Induk

Kriteria induk yang baik untuk dipijahkan :

  • Induk sehat berwarna kelabu cerah
  • Gerakan aktif
  • Sirip dan sisip lengkap serta tidak cacat
  • Mata berwarna jernih
  • Umur minimal 3 tahun dengan berat badan 2-5 kg/ekor
  • Ukuran diusahakan seimbang

Pemeriksaan tingkat pematangan gonad dapat dilakukan dengan cara stripping atau kanulasi terhadap ikan yang telah dipingsankan dengan Ethylineglicol monophenil ether 200 ppm. Oocyst yang siap dipijahkan berdiameter 0,4-0,5 mm.

3. Pemijahan

Dilakukan dengan cara menginduksi hormon LH – RH a pada induk jantan dan betina pilihan secara intramuscular dibawah sirip punggung. Penyuntikan dilakukan satu kali (pukul 10.00 pagi) dengan dosis 0,05 mg per kg berat total ikan.

Sex ratio pemijahan 1:1, secara normal ikan akan memijah pada malam hari (± 32 jam setelah penyuntikan hormon).

4. Pemanenan dan Penetasan Telur

Telur yang baru saja dipanen diseleksi, kemudian dipindahkan ke dalam bak penetasan dengan kepadatan telur 50-100 butir/liter air. Masa inkubasi ± 18 jam, dan larva yang baru menetas memiliki panjang total 1,60 ± 0,04 mm.

5. Pemeliharaan Larva dan Benih

Bak pemeliharaan larva dilengkapi dengan pipa pemasukan dan pembuangan air, serta unit aerasi untuk mensuplai oksigen. Secara ringkas jadwal kegiatan operasional pemebrian pakan, penggantian air media dan penjarangan padat tebar benih hingga umur 30 hari dapat dilihat pada lampiran berikut.

Efesiensi Pemeliharaan
Setiap kilo bobot induk dapat menghasilkan telur sekitar 0,6-0,76 juta butir. Saat kondisi normal tingkat penetasan mencapai 85%. Tingkat kelulushidupan larva pada umur 15 hari (70-80%) dan pada umur 30 hari (30-50%).

Dalam satu tahun bisa dilakukan 8 kali pemijahan, dimana setiap kali produksi membutuhkan waktu kurang lebih 40 hari, dengan produksi benih 5000 ekor/m3, umur 30 hari.

Sumber : Loka Budidaya Laut Batam

[ Jadwal Kegiatan Operasional Pemeliharaan Larva dan ]



Hak Cipta 2003, Departemen Kelautan dan Perikanan Republik Indonesia