aquaculture

Viral haemorrhagic septicaemia (VHS) was initially noted as a disease of cultured European rainbow trout (Oncorhynchus mykiss). The disease has been noted amongst marine species, notably farmed turbot (Germany, Scotland and Ireland), but until relatively recently (approximately Spring 2005), appears to have been restricted to Europe. Dr. Robert S. Bakal, of the U.S. Fish & Wildlife Service’s Division of the National Fish Hatchery System, reports from a conference on VHS held in August 2006,

…leading expert on VHS in the United States, Jim Winton of the US Geological Survey, indicated that the VHS virus exists in four strains, with a single, unique sub-strain occurring in the Great Lakes. The VHS virus has been known in Europe, Japan, and the coasts of the U.S. for many years; how it came to occur in the Great Lakes is not known. Winton speculates that it may have originated in ballast water from ocean-going ships sailing into the Great Lakes, or that it may have hitchhiked in shipments of hatchery-raised fish.

According to the New York State Department of Environmental Conservation (NYSDEC),

Viral hemorrhagic septicemia (VHS) virus is a serious pathogen of fresh and saltwater fish that is causing an emerging disease in the Great Lakes region of the United States and Canada. VHS virus is a rhabdovirus (rod shaped virus) that affects fish of all size and age ranges. It does not pose any threat to human health. VHS can cause hemorrhaging of fish tissue, including internal organs, and can cause the death of infected fish. Once a fish is infected with VHS, there is no known cure. Not all infected fish develop the disease, but they can carry and spread the disease to other fish. VHS has been blamed for fish kills in Lake Huron, Lake St. Clair (MI), Lake Erie, Lake Ontario, the St. Lawrence River and Conesus Lake (Western NY). The World Organization of Animal Health has categorized VHS as a transmissible disease with the potential for profound socio-economic consequences. Because of this, they list VHS as a disease that should be reported to the international community as an exceptional epidemiological (study of diseases in large populations) occurrence.

The NYSDEC has released revised Emergency Regulations Adopted to Prevent Spread of VHS.

Animal and Plant Health Inspection Service (APHIS) note the following species are susceptable: Atlantic cod Gadus morhua, Black crappie Pomoxis nigromaculatus, Bluegill Lepomis macrochirus, Bluntnose minnow Pimephales notatus, Brown bullhead Ictalurus nebulosus, Brown trout Salmo trutta, Burbot Lota lota, Channel catfish Ictalurus punctatus, Chinook salmon Oncorhynchus tshawytscha, Coho salmon Oncorhynchus kisutch, Chum salmon Oncorhynchus keta, Emerald shiner Notropis atherinoides, Freshwater drum Aplodinotus grunniens, Gizzard shad Dorosoma cepedianum, Grayling Thymallus thymallus, Haddock Gadus aeglefinus, Herring Clupea spp, Japanese flounder Paralichthys olivaceus, Largemouth bass Micropterus salmoides, Muskellunge Esox masquinongy, Pacific cod Gadus macrocephalus, Pike Esox lucius, Pink salmon Onchorhynchus gorbuscha, Pumpkinseed Lepomis gibbosus, Rainbow trout Oncorhynchus mykiss, Redhorse sucker Moxostoma spp, Rock bass Ambloplites rupestris, Rockling Onos mustelus, Round goby Neogobius melanostomus, Smallmouth bass Micropterus dolomieu, Sprat Sprattus spp, Turbot Scophthalmus maximus, Walleye Sander vitreus, White bass Morone chrysops, White perch Morone americana, Whitefish Coregonus spp, Yellow perch Perca flavescens.

APHIS has also released the Amended Federal Order Viral Hemorrhagic Septicemia (VHS) dated May 4, 2007. The purpose of this Federal Order is to prevent the spread of viral hemorrhagic septicemia (VHS) into aquaculture facilities. Also refer to the APHIS July 2006 Emerging Disease Notice – Viral Hemorrhagic Septicemia in the Great Lakes for further analysis.

Research reports published from the Scottish Fisheries Research Services may serve to provide management options:
Viral Haemorrhagic Septicaemia (VHS) – from the abstract:

Viral haemorrhagic septicaemia (VHS) was diagnosed inrainbow trout (Oncorhynchus mykiss) at a farm in Englandon 26 May 2006. VHS is a notifiable disease in the UK and a List II disease under European Directive 91/67/EEC. Investigations into the source and potential spread of the disease are being carried out by Centre for Environment, Fisheries and Aquaculture Science (Cefas) in England and Wales, and by Fisheries Research Services (FRS) in Scotland. VHS has occurred once before in the UK, in 1994, affecting a single turbot farm. The disease was successfully eradicated on that occasion. VHS has no implications for human health.

Risks to Wild Freshwater Fisheries from Viral Haemorrhagic Septicaemia (VHS) – from the abstract:

There is a risk of transfer of VHSV from farmed to wild freshwater fish species and vice versa. There is evidence that a reservoir of infection may be created in wild freshwater fish species. This may pose a risk of re-infection of farms (eg rainbow trout). There are no reports of VHSV infection leading to significant disease outbreaks in wild freshwater fish stocks. Based on evidence from outbreaks in farms and experimental evidence, free living rainbow trout, brown trout, whitefish, grayling and pike may be at risk of disease. Available evidence suggests a high infection pressure would be required to initiate a disease outbreak in wild fish (eg shedding of virus from an infected farm).

Disinfection guide version IV: practical steps to prevent the introduction and minimise transmission of diseases of fish – from the abstract:

Emerging diseases have had a significant impact on development of the Scottish aquaculture industry, highlighting the importance of preventing their introduction and minimising their transmission. The risk of disease spread is reduced by the implementation of good sanitary practices by fish farmers, and fisheries and the application of effluent disinfection systems in the processing industry. To maintain healthy fish stocks and minimise the introduction and spread of disease, the aquaculture industry should ensure best practice on farm sites, during transportation of live or dead fish and equipment, at the processing plant and during subsequent effluent and waste disposal. For an assessment of the risks associated with specific tasks, reference should be made to the Final Report of the Joint Government/ Industry Working Group on Infectious Salmon Anaemia (ISA) available from the Fisheries Research Services (FRS) web site, at www.frs-scotland.gov.uk. The protocols described in this guide are based upon current scientific knowledge and practical experience and will continue to be developed as the needs of industry change. This guide is intended for distribution to relevant industry personnel.

Charles F. Cotton has published a 2002 MSc thesis entitled Optimizing Growth for Aquaculture of Juvenile Black Sea Bass Centropristis Striata L. : Effects Of Temperature, Salinity, Commercial Diet and Feeding Ration. The abstract notes:

A new market has emerged for live black sea bass, Centropristis striata L., in fish markets of the northeast United States and Canada. Efforts to culture black sea bass have been hampered by the lack of information regarding optimal grow-out conditions. This research was designed to determine optimal commercial diet, feeding ration, temperature, and salinity for growth of hatchery-reared, juvenile black sea bass. Optimal diet was Zeigler Salmon Starter (compared to Nelson and Son’s Silver Cup Salmon Crumbles, Trout Crumbles, and Rangen Trout and Salmon Starter). Optimal daily feeding ration was 5% (compared to 2.5% and 7.5%). Optimal water temperature was 25º C (compared to 15º C, 20º C, and 30º C), and optimal salinity was 20 ppt or 30 ppt (compared to 10 ppt). Additionally, growth rates, feed conversion ratio, and mortality were calculated in each experiment. This information will be a valuable guide for culturing juvenile black sea bass.

The Marine Resources Research Institute notes that the first reported spawning of black sea bass occurred in 1884 with fish captured off South Carolina and shortly afterwards, ripe fish captured off Massachusetts were spawned. Since then there has been increasing information developed on the culture of this typical reef dwelling species. It is unclear if the 1884 date is correct. There is no doubt about the value of the species, and the, as yet undeveloped, potential for aquaculture.

Randal L. Walker and Deborah A. Moroney from the Shellfish Aquaculture Laboratory, Marine Extension Service, University of Georgia, USA; have published their findings entitled Growth of juvenile black sea bass, Centropristis striata, fed either a commercial salmon or trout diet. They observe:

An opportunity exists to expand Georgia’s commercial fishery by developing aquaculture techniques for the black sea bass, Centropristis striata. Black sea bass fillets sell for $1.25 to $1.50 per 0.45 kg wholesale. However, live, 0.9 to 1.13 kg fish are sold on the sushi market at a wholesale price of $3.50 to $8.00 per 0.45 kg. Little biological information exists concerning the culture of this potential aquaculture species. Six 600-L tanks on a flow-through system were stocked with 12 juvenile fish each (ranging in total length from 153 to 235 mm). Fish were pot-trapped from an offshore population. Tanks (3 for each diet) were randomly assigned a diet of either a commercial trout or salmon chow. Fish were fed a two percent daily ration (grams dry weight of food to grams wet weight of fish). Rations were adjusted biweekly to account for fish weight increases per treatment. Fish fed the salmon chow were significantly heavier after 10 weeks (P = 0.0209) and after 14 weeks (P = 0.0003) than fish fed the trout chow. Fish fed trout chow increased from 196 grams to 304 grams (55% increase) in 14 weeks, while fish fed the salmon chow increased from 163 grams to 386 grams (137% increase). Based upon fish growth and cost of feed, salmon chow is the preferred diet over trout chow for rearing black sea bass.

Again, from the Shellfish Aquaculture Laboratory, Marine Extension Service, University of Georgia, USA; Richard W. Kupfer, Dorset H. Hurley and Randal L. Walker have published their findings entitled A Comparison of Six Diets on the Growth of Black Sea Bass, Centropristis striata, in an Aquacultural Environment. The abstract notes:

Two studies of juvenile black sea bass, Centropristis striata, were conducted to address questions concerning the biological feasibility of aquaculture of C. striata. Juvenile C. striata and rock sea bass, C. philadelphica, were trapped inshore, while sub-adult C. striata were trapped in nearshore waters of coastal Georgia, south of Savannah. Catch composition of inshore trapping was dominated by Centropristis philadelphica (80%). Few C. striata were caught. A comparative growth study of juvenile C. philadelphica and C. striata fed a 3% daily ration (gram dry weight feed/gram wet weight of fish) was performed over 27 days. Overall juvenile C. striata mean increase in growth was 42% ± 5.3% (SE), with 10% mortality; whereas, C. philadelphica mean growth was 14% ± 4.7%, with 65% mortality.

Sub-adult C. striata (164 g mean weight ± 1.74) were subjected to six ration treatments for 18 weeks. Three replicate 500-L tanks were used per treatment, and each tank was stocked with 15 fish. Ration treatments consisted of a high-protein trout feed, a lower-protein trout feed, and an equal mixture of both delivered daily in rations of 2% and 3% dry weight feed/wet weight fish. All rations were adjusted biweekly based upon mean fish wet weight per treatment. At week 16, ANOVA revealed no significant differences (p=0.4096) in mean fish weight among treatments with a pooled treatment mean fish weight increase of 48%. Based on cost effectiveness, the lower-protein 2% ration was judged the optimum choice among the diets tested. This study reinforces the biological feasibility of rearing trapped C. striata on a commercial diet of 2% dry weight feed/wet weight fish.

Further, from the Shellfish Aquaculture Laboratory, Marine Extension Service, University of Georgia, USA; Alan Power, Tiffany Lee, Todd Recicar, Mary Sweeney-Reeves, and Randal L. Walker have published their findings entitled The Growth and survival of juvenile black sea bass, Centropristis striata, on an artificial (Salmon chow) versus a natural (grass shrimp) diet. The abstract notes:

This study examined growth and survival rates of juvenile black sea bass Centropristis striata (Linnaeus, 1758), that were fed two distinct dietary treatments, – one, a commercially available salmon chow and the other a diet consisting of natural live grass shrimp (Palaemonetes pugio, Holthuis, 1949). The diets were fed at a 2.5% ration (grams dry weight of food/ grams wet weight of fish). Fish were reared in replicated (N=3 per dietary treatment) 65-liter flow-through tanks for six weeks between May 7 and June 25, 2001. The fish provided with live shrimp had a mean survival of 69 ± 5.9% and increased in size from an initial mean wet weight of 20.7 grams to 30.4 grams – a growth rate of 0.194 grams per day. A higher mean survival of 80 ± 6.7% and a slightly lower growth rate of 0.184 grams per day (mean wet weight increase from 20.4 grams to 29.6 grams) were recorded for fish fed the salmon pellet diet. However, there were no statistically significant differences detected in either growth (p=0.7849) or percent survival (p=0.4999) between dietary treatments. Based on these results, we recommend using the commercially available salmon chow because of its convenience and supplementing it occasionally with grass shrimp to provide essential amino acids common in natural diets.

According to the Marine Resources Research Institute (South Carolina Department of Natural Resources), the red drum (Sciaenops ocellatus) is a long lived marine finfish (> 50 years of age) which has an estuarine dependant early life history (ages 0-4). Throughout the southeast USA, this species (known locally as spottail bass) is one of the top three fish preferred by saltwater anglers.

Lawrence W. McEachron, C.E. McCarty, and Robert R. Vega have reported on the Successful Enhancement of the Texas Red Drum (Sciaenops ocellatus) Population. From the abstract:

Red drum (Sciaenops ocellatus) is an estuarine-dependent sciaenid that inhabits estuaries, bays, and coastal regions from New York to Mexico. In Texas, the red drum population began a dramatic decline in the 1970s, prompting the Texas Parks and Wildlife Department (TPWD) to set up a three-pronged recovery plan. Management approaches were: 1) Initiate an independent monitoring program to assess relative abundance; 2) Implement restrictive regulations to reduce fishing pressure, including license restrictions, size, bag, and possession limits, a commercial quota, restrictions on netting, and a ban on commercial sale of red drum; and 3) Develop and start a marine enhancement program based on the release of hatchery-reared fingerlings and assessment of subsequent survival.

Recently, the red drum population in Texas coastal water rebounded because of several factors that had a positive effect on the recovery. TPWDs long-term management plan utilizing hatcheries and stocking to supplement natural spawning played a role in reversing the decline of the red drum population. The strategy used by the TPWD can serve as a blueprint for other marine enhancement programs.

The FAO have reported on Aquaculture Development of Red Drum (Sciaenops Ocellatus) in Martinique and the French West Indies. Note – the report is contained with other aquaculture reports on the page. From the summary:

The aquaculture of red drum (Sciaenops ocellatus) has been the subject of research and development work in Martinique since 1985. It was during the initial eight-year period that research findings showed the suitability of the species for domestication and mariculture.

However, whilst biological and technical knowledge is a compulsory prerequisite, it is not the only requirement for development. Operations throughout the production chain need to be synchronised, right through to product selling and company profitability. This explains the lengthy development process.

Since 2000, research reorganisation at IFREMER, the separation of larval rearing from growing-out, and the political and financial support of Martinique Region, have given a fresh impetus to our work, and development is now really taking off.

However, Martinique should not be the only island to benefit from this example; other Caribbean countries must also be given the opportunity to put the small-scale aquaculture model into practice.

According to a report published by SEAFDEC/AQD, Philippines, milkfish (Chanos chanos) farming is a centuries-old industry in Indonesia, the Philippines, and Taiwan.

Research into the culture of milkfish has not been limited to the Philippines. Research into the feasibility of milkfish culture in Fiji has been undertaken. Esteban Dela Cruz has published a report 1997, through the FAO, entitled, Potential of milkfish farming development in Fiji. From the summary:

Milkfish has been a successful food industry in Asian countries like Philippines, Taiwan, and Indonesia. The Government of Fiji had wanted to develop a similar industry, and so enlisted the help of the Food and Agriculture Organisation of the United Nations. The South Pacific Aquaculture Development Project (Phase II) devised this survey to ascertain the extent of the milkfish stocks in Fiji waters, and further to investigate the possibility of milkfish farming in Fiji. Such farms have already been established in Nauru, Kiribati and Tuvalu, and it was thought that milkfish farms would be not only a good source of protein for human diets and an alternative to depleting fish from the sea (and thus a way to ameliorate an environmental pressure), but also a source of income for villages and farmers as tuna bait as well.

There are many sites suitable to develop milkfish farms in Fiji, such as unused rice paddies, salt or prawn farms, or swamps and marshlands. Farmers need to acquire skills in preparing the ponds for stocking by draining, drying, leveling, and liming or poisoning for unwanted animals (where necessary). Also, dykes and water gates must be constructed and farmers must learn to feed the ponds to grow benthic algae (brackishwater ponds), and plankton (freshwater ponds). The design of the farms must take into account that milkfish swim against the current, so the catching ponds will be placed to concentrate fish from the grow-out ponds for easy harvesting.

The Fiji Islands Trade and Investment Bureau has published a report (2001) entitled Milkfish Farming Project Profile. This report outlines the investment potential of a milkfish project, including government incentives, and some forecast costs. Their summary of the market:

Market Milkfish is currently used as an intermediate good – an input – in the form of live baits for catching fish. Given the fact that milkfish baits supplements the longline tuna industry, which earns around F$40 million in export income, is indicative of the fact that there is a considerable market locally.

Prospective investors should do their own due diligence, and use the figures purely as indicators rather than current market realities.

Milkfish has been cultured throughout Asia for many years. In the Philippines there has been a steady and substantial demand for milkfish or bangus as is known locally. According to the Philippine Department of Agriculture, milkfish ‘has been doing well in the international market with Philippine export of frozen or chilled bangus reaching over 526 metric tons or some P8.5 million annually.’ The Philippine Department of Agriculture has published an overview of the semi-intensive culture of milkfish.

Kee-Chai Chong, Ian R. Smith, and Maura S. Lizarondo have published, through the United Nations University (1982), a substantial paper entitled Economics of the Philippine Milkfish Resource System.

From the preface:

Considerable research has been conducted on milkfish in the Philippines. However, the available publications are scattered, and no attempt has been made in recent years to consolidate this information so that a concise appraisal can be made of the entire milkfish resource system, from fry gathering through dealers and nursery, rearing pond, and fishpen operators to marketing. The dual purpose of this paper is to provide such an overview of the Philippines milkfish resource system and to evaluate its efficiency.