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Aquaculture Operations - Research and Technology Transfer

Aquaculture Operations
Highlights

Research presentations and technological information useful to aquaculture operations.


Shrimp Virus Report

New, virulent viruses have been documented in foreign shrimp aquaculture, and evidence suggests that these viruses could cause widespread disease in shrimp raised in aquaculture and in wild shrimp in the Gulf of Mexico and southeastern Atlantic coastal regions. To assess the risks associated with these emerging viral pathogens, the Joint Subcommittee on Aquaculture (JSA), which is under the auspices of the President's Office of Science and Technology Policy, formed the interagency Shrimp Virus Work Group.

EPA is making available a qualitative ecological risk assessment describing the potential risks of nonindigenous pathogenic shrimp viruses on wild shrimp populations in U.S. coastal waters. Expert conclusions and recommendations contained in the report are currently undergoing an independent scientific review. Publication of this draft final report is another in a series of related activities initiated out of increasing public concerns over the potential introduction and spread of nonindigenous pathogenic shrimp viruses to the wild shrimp fishery and shrimp aquaculture industry in the U.S. Although these viruses pose no threat to human health, outbreaks on U.S. shrimp farms, the appearance of diseased shrimp in U.S. commerce, and new information on the susceptibility of shrimp and other crustaceans to these viruses, prompted the JSA to take action.

The report concludes that viruses could survive in pathways leading to coastal environments, and that there is potential for viruses to affect native shrimp in localized areas, such as an estuary or bay. However, it notes that local populations of shrimp would recover rapidly as a result of reintroduction of shrimp or increases in reproduction. Although there was high uncertainty, the report concludes that the risks from viral introductions to the entire population of native shrimp in U.S. coastal waters is relatively low. While qualitative evaluations such as these are valuable, the report concludes that they are associated with a great deal of uncertainty. Therefore, given the limited information currently available, the report states that it is not feasible to conduct a more comprehensive, quantitative assessment of the risks associated with nonindigenous pathogenic shrimp viruses at this time. The report notes that there is a need to conduct further systematic research efforts to reduce uncertainty and it identifies a number of priority research areas.

More information from EPA
Shrimp Virus Report

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Cages in Fish Culture

The use of cages in open waters has emerged recently as a fish culture technology that meets the needs of the industry for large-volume water supplies at temperatures appropriate to the needs of coldwater species. Because the cages' structure makes them vulnerable to storm damage, many concerns have been expressed about the impact of escaped fish on natural biodiversity and on the integrity of the wild gene pools. Further, unlike the relatively sterile groundwaters used for most fish hatcheries, the cages' natural environments expose the fish to natural pathogens that must be routinely treated with therapeutants and prophylactics-which in turn are harmful to other elements of the natural biota.

But the most worrisome potential effect of cage aquaculture on wild fish production is the nutrient enrichment of the surrounding waters via feces and surplus food. Unlike wastes produced by onshore feedlots and hatcheries (and cities), these wastes cannot be harvested from the effluents. The conversion efficiency of fish food to fish is roughly 50 percent. Thus for every ton of fish produced, there will be about a ton of waste.  If the caged fish are fed on netted lake fish, there may be an effect on natural populations. If the caged fish are fed on prepared food, the waste produced represents a new nutrient load to the system. The phosphorus output from a salmonid cage facility producing 100 tons of fish in the most efficient way is the equivalent of the raw sewage effluent from a community of 850 people. Since the industry will seek out relatively sheltered sites, the list of concerns includes losses of aesthetic and recreational values, contamination of bottom sediments, and the potential for rising drinking-water costs.

Background Information from EPA
Nearshore Waters of the Great Lakes: Aquaculture (PDF) (179 pp, 2.8MB) - scroll to chapter 9.2, Aquaculture

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National Harmful Algal Bloom Research and Monitoring Strategy: An Initial Focus on Pfiesteria, Fish Lesions, Fish Kills, and Public Health

"In response to fish lesions, kills, Pfiesteria-like organisms, and possible threats to public health in the Mid-Atlantic region, the White House asked federal agencies to develop and coordinate a long-term national strategy for federally supported research and monitoring on problems associated with harmful algal blooms (HABs), particularly Pfiesteria and Pfiesteria-like species." November 1997.

There is growing concern that the crisis in the mid-Atlantic is another of the increasing number of harmful bloom events that have become a problem in U.S. coastal waters. In previous work, scientists critically reviewed the problem and developed a national plan to monitor, assess, control, and mitigate impacts from HABs. This current strategy builds upon an existing Federal plan outlined in the report, "Marine Biotoxins and Harmful Algae: A National Plan"(Anderson et al. 1993), and eight focused objectives that are identified below.

To protect human health and the environment, immediate support is needed to:

To ensure that responsible agencies can respond rapidly and if necessary, implement effective management and mitigation measures, capabilities need to be in place to:

To support management and mitigation efforts, research must also begin immediately to:

Efforts coordinated under this strategy will complement and augment state programs, and be implemented through a mix of in-house research and monitoring and research grants to universities and the states.

More Information from EPA
Challenges Facing Our Estuaries

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EPA Gulf Ecology Division Research

EPA's Gulf Ecology Division (GED) is responsible for research on the physical, chemical, and biological dynamics of coastal wetlands and estuaries, to determine ecological condition, evaluate rates and causes of declining systems, and predict future conditions under various alternative water quality scenarios. The research program will: (1) Monitor and assess the ecological condition of coastal wetlands, bays, estuaries, and coral reefs of the Gulf of Mexico and evaluate the causes of changes: (2) Develop biological/ecological indicators to (i) classify the ecological status of coastal wetlands, bays and estuaries, (ii) detect significant change in ecological status related to chemical contaminants, biotechnology products, disease, nutrients, energy development, and global warming, and (iii) identify cause(s) of ecological change, using both reactive (diagnostic and epidemiologic) and predictive approaches, and (3) Compare ecological structure and function among microcosms, mesocosms, and field sites to predict relationships between chemical/stressor exposure and changes in biodiversity and ecological function. The Division also provides research and science support to the Gulf of Mexico Program and the Regions and states.

More information from EPA
Gulf Ecology Division Research

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