Aquaculture Operations - Production and General Information
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Information and links to assist aquaculture producers.
- Federal Aquaculture Programs and Information
- Aquaculture Contacts
- Aquaculture Links
- Catfish Production
- Cercopagis pengoi
- Harmful Algal Blooms
- Influence of Climate Change on Fisheries and Aquatic Systems
- Threat from Invasive Species
Regional Aquaculture Centers
- USDA Aquaculture Program
- National Sea Grant Office
- Sea Grant Program Contacts
- Northeast Marine Fisheries Service, Northeast Fisheries Science Center
- U.S. Fish and Wildlife Service
- North Central (IL, IN, IA, KS, MI, MN, MO, NE, ND, OH, SD, WI)
- North Eastern (CT, DC, DE, ME, MD, MA, NH, NJ, NY, PA, RI, VT, WV)
- Southern (AL, AR, FL, GA, KY, LA, MS, NC, OK, PR, VA, SC, TN, TX, VI)
- Tropical and Subtropical (American Samoa, Commonwealth of the N. Mariana Islands, Guam, HI, Republic of the Marshall Islands, Federation States of Micronesia, Palau)
- Western (AK, AZ, CA, CO, ID, MT, NV, NM, OR, UT, WA, WY)
Cercopagis pengoiCercopagis pengoi is the latest exotic crustacean to invade the Great Lakes. Cercopagis is similar to another recent invader in the Great Lakes, Bythotrephes cederstroemi. Both species occur in brackish and freshwater environments.
More information from EPA
Fact Sheet: Cercopagis pengoi
Harmful Algal BloomsHarmful Algal Blooms (HABs) is a relatively term used to describe a proliferation, or "bloom," of single-celled marine algae called phytoplankton. Once more commonly referred to as "red tides," these blooms occur when the algae photosynthesize and multiply. While there are thousands of phytoplankton species in existence, only a few dozen are known to be toxic. However, because phytoplankton serve as the base of the marine food web, the impact of these blooms can be devastating for consumers throughout the food web and for other marine flora or fauna in the affected ecosystem. Even blooms of non-toxic species can spell disaster for marine animals since the massive quantities of phytoplankton deplete the oxygen in the shallow waters where most phytoplankton blooms occur.
Recently, the world's coastal waters have experienced an increase in the number and type of HAB events. This is especially true in the U.S., where almost every coastal state is now threatened, in some cases by more than one species.
Scientists are unsure of the causes for this trend. Possibilities range from natural causes (species dispersal) to human-related causes (nutrient enrichment, shifts in global climate, or transport of algal species by ship ballast water).
The species of marine phytoplankton that cause HABs-and their effects-vary dramatically. While some are toxic only when concentrations reach high densities, others can be toxic at very low densities (only a few cells per liter). Whereas some blooms discolor the water (thus the terms "red tide" and "brown tide"), others are undetectable by even highly sensitive satellite imagery techniques designed to pick up color differences.
While the bloom characteristics of HABs are highly variable, the effects of HABs generally fall into two major categories, public health and ecosystem effects and economic impacts.
Public Health and Ecosystem Effects:
- Filter feeding shellfish (clams, mussels, oysters, scallops) may accumulate algal toxins by feeding on the toxic phytoplankton, sometimes at levels potentially lethal to humans or other consumers and may decrease light penetration.
- Potential fish, shellfish, and bird kills, occasionally invertebrate and marine mammal kills.
- Discoloration of water can be aesthetically unpleasant.
- Toxins or other compounds released by the microalgae can kill marine fauna directly or result in low oxygen conditions as the bloom biomass decays (especially dangerous for aquaculture sites where fauna cannot easily escape).
- Blooms of seaweeds can be harmful to seagrass and coral reef ecosystems and the food webs that are dependent on those system.
- Shellfish bed closures or quarantines, wild or farmed fish mortalities, loss of income due to closures and mortalities, and consumer fear of purchasing seafood are the most direct and costly economic impacts, but indirect impacts, such as fear of investing in aquaculture businesses, are also costly.
- Lost marine recreational opportunities including tourism, fishing, shellfishing, swimming and sunbathing resulting from blooms, including dead fish or shellfish washing up on beaches, discolored water, noxious odors, and human respiratory problems caused by toxins released into the air.
- Cost of maintaining monitoring and testing programs designed to detect algal toxins and costs associated with cleaning up fish or shellfish kills when they do occur.
- Medical costs and lost productivity of workers poisoned by HAB toxins is a significant and recurring annual impact.
Overall, preliminary estimates of the overall impact of HAB outbreaks on the U.S. economy, taking the above factors into account, are over $40 million per year, or nearly $1 billion over a decade.
More information from EPA
Mississippi River Basin and Gulf of Mexico Hypoxia Task Force
PfiesteriaPfiesteria piscicida is a toxic dinoflagellate that has been associated with fish lesions and fish kills in coastal waters from Delaware to North Carolina. Pfiesteria is not a virus, fungus, or bacterium. It is not contagious or infectious, and cannot be "caught" like a cold or flu. There is no evidence that Pfiesteria-related illnesses are associated with the consumption of finfish, shellfish, or crustaceans such as crabs, lobsters, and shrimp. Any human health problems associated with the microbe stem from its release of toxins into river and estuarine waters. State and federal agencies are working closely with local governments and academic institutions to address the problems posed by Pfiesteria. Federal agencies involved in the effort include the EPA, the National Oceanic and Atmospheric Administration, the Centers for Disease Control and Prevention, the National Institute of Environmental Health Sciences, the Food and Drug Administration, the U.S. Geological Survey, and the USDA. Together with state departments of health and natural resources, these agencies are working to:
- Manage the risk of human health effects by monitoring and rapid response through river closures and public health advisories
- Direct funding and technical expertise to Pfiesteria-related research and monitoring
- Make current and accurate information widely available to the public
- Understand and address the causes of Pfiesteria outbreaks, especially the possible role of excess nutrients
More Information from Federal Agencies
USDA - Water Quality Information Center: Water Quality - Pfiesteria piscicida
CDC - Harmful Algal Blooms: Pfiesteria psicicida
Sea Grant - Pfiesteria and Harmful Algal Blooms in the Mid-Atlantic
Influence of Climate Change on Fisheries and Aquatic SystemsAlthough there is considerable uncertainty about the physical changes and response of the various freshwater and marine species, it is possible to suggest how certain species may respond to projected climate changes over the next 50-100 years. The uncertainties highlight the importance of research to separate the impacts of changing climate from natural population fluctuations and fishing effects. Many commercial finfish populations already are under pressure (e.g., overexploited), and global change may be of minor concern compared with the impacts of ongoing and future commercial fishing and human use or impacts on the coastal zone. Further, changes in the variability of climate may have more serious consequences on the abundance and distribution of fisheries than changes in mean conditions alone (Katz and Brown, 1992), and changes in future climate variability are poorly understood at this time.
Fish, including shellfish, respond directly to climate fluctuations, as well as to changes in their biological environment (predators, prey, species interactions, disease) and fishing pressures. Although this multiforcing sometimes makes it difficult to establish unequivocal linkages between changes in the physical environment and the responses of fish or shellfish stocks, some effects are clear (see reviews by Cushing and Dickson, 1976; Bakun et al., 1982; Cushing, 1982; Sheppard et al., 1984; Sissenwine, 1984; and Sharp, 1987). These effects include changes in the growth and reproduction of individual fish, as well as the distribution and abundance of fish populations. In terms of abundance, the influence occurs principally through effects on recruitment (how many young survive long enough to potentially enter the fishery) but in some cases may be related to direct mortality of adult fish.
Fish carrying capacity in aquatic ecosystems is a function of the biology of a particular species and its interrelationship with its environment and associated species. Specific factors that regulate the carrying capacity are poorly known for virtually all species, but some general statements can be made with some confidence. Fish are affected by their environment through four main processes (Sheppard et al., 1984):
- Direct physiological effects, including metabolic processes influenced by temperature, salinity, and oxygen levels. Fish often seek optimal temperature or salinity regimes or avoid suboptimal conditions. Thus, ocean and freshwater changes as a result of projected climate changes can lead to distributional changes. In suboptimal conditions, performance is reduced, leading to starvation or increased predation.
- Diseases-Certain environmental conditions are more conducive to diseases than others (e.g., warm waters can trigger disease outbreaks and cold temperatures can limit them).
- Food-The environment affects feeding rates and competition, and abundance, quality, size, timing, spatial distribution, and concentration of food.
- Predators-The environment affects predation through influences on the abundance and distribution of predators.
Fish are influenced not only by temperature and salinity conditions but
also by mixing and transport processes (e.g., mixing can affect primary
production by promoting nutrient replenishment of the surface layers;
it also can influence the encounter rate between larvae and prey organisms).
Ichthyoplankton (fish eggs and larvae) can be dispersed by the currents,
which may carry them into or away from areas of good food production,
or into or out of optimal temperature or salinity conditions and perhaps,
ultimately determine whether they are lost to the original population.
Climate is only one of several factors that regulate fish abundance. Managers attempt to model abundance trends in relation to fishing effects in order to sustain fisheries. In theory, a successful model could account for global warming impacts along with other impacts without understanding them. For many species of fish, the natural mortality rate is an inverse function of age: Longer-living fish will be affected by natural changes differently than shorter-living fish. If the atmosphere-freshwater-ocean regime is stable for a particular time, it is possible to estimate the age-specific mortality rates for a species of interest. However, at least some parts of the atmosphere- freshwater-ocean system are prone to oscillations on a decadal scale, which may not be cyclical. These natural changes occur globally; thus, they will have impacts on the freshwater and marine ecosystems that support North American fish populations. Under natural conditions, it may be expected that the different life histories of these fish will result in different times of adjustment to a new set of environmental conditions.
Any effects of climate change on fisheries are expected to be most pronounced in sectors that already are characterized by full utilization, large overcapacities of harvesting and processing, and sharp conflicts among users and competing uses of aquatic ecosystems. Climate change impacts, including changes in natural climate variability on seasonal to interannual time scales, are likely to exacerbate existing stresses on fish stocks. The effectiveness of actions to reduce the decline of fisheries depends on our ability to distinguish among these stresses and other causes of change and on our ability to effectively deal with those over which we have control or for which we have adaptation options. This ability is insufficient at present; although the effects of environmental variability are increasingly recognized, the contribution of climate change to such variability is not yet clear.
Recreational fishing is a highly valued activity that could incur losses in some regions as a result of climate-induced changes in fisheries. In the U.S., 45 million anglers participate in recreational fishing annually; they contribute to the economy through spending on fishing and related activities. The net economic effect of changes in recreational fishing opportunities as a result of climate-induced changes in fisheries is dependent on whether projected gains in cool- and warm-water fisheries offset losses in cold-water fisheries. Work by Stefan et al. (1993) suggests mixed results for the U. S., ranging from annual losses of $85-320 million to benefits of about $80 million under a number of GCM projections. A sensitivity analysis (U.S. EPA, 1995) was conducted to test the assumption of costless transitions across these fisheries. This analysis assumed that best-use cold-water fishery losses caused by thermal changes were effectively lost recreational services. Under this assumption, all scenarios resulted in damages, with losses of $619-1,129 million annually.
More information from other organizations
The Regional Impacts of Climate Change, Chapter 8 - North America
Threat from Invasive SpeciesInvasive species are alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health. Invasive species are one of the largest threats to our terrestrial, coastal and freshwater ecosystems, as well as being a major global concern. Invasive species can affect aquatic ecosystems directly or by affecting the land in ways that harm aquatic ecosystems. Invasive species represent the second leading cause of species extinction and loss of biodiversity in aquatic environments worldwide. They also result in considerable economic effects through direct economic losses and management/control costs, while dramatically altering ecosystems supporting commercial and recreational activities. Effects on aquatic ecosystems result in decreased native populations, modified water tables, changes in run-off dynamics and fire frequency, among other alterations. These ecological changes in turn impact many recreational and commercial activities dependent on aquatic ecosystems. Common sources of aquatic invasive species introduction include ballast water, aquaculture escapes, and accidental and/or intentional introductions, among others.
More information from EPA