All Catfish sold in the United States is produced domestically. Fish similar to Catfish that are raised in Vietnam -- Tra (Pangasius hypopthalmus), Basa (Pangasius bocourti), and Swai (Pangasius micronemus) -- cannot be sold under the market name "Catfish" in the U.S. Also, in 2003 the U.S. International Trade Commission ruled that imports of these species from Vietnam were injuring the domestic Catfish industry so they created an Antidumping rule, under which imports of these species are subject to tariffs (CFA 2003).

Aquaculture facilities raise Catfish in earthen ponds, which are usually 10-20 acres in size and 3-6 feet deep (Robinson and Avery 2000). Effluent from catfish farms contains nitrogen, phosphorus, and organic matter, but at low concentrations compared to other aquaculture systems, due to removal of these wastes by internal processes such as sedimentation and phytoplankton uptake (Tucker, pers. comm., 2004). Catfish farmers partially drain food fish ponds about every 6 years and fully drain ponds every 8 (Boyd, pers. comm., 2005) to 20 years (AU and USDA 2004). However, they drain most fry and fingerling ponds each year, as well as food fish ponds that are not seinable (AU and USDA 2004). The ponds can overflow during heavy rainfall due to rain falling directly into the pond or due to runoff on the watershed (AU and USDA 2004). Also, escapes do happen, despite the strong economic incentive for farmers to prevent them.

We determined that catfish farms have a moderate effect on the environment and awarded 2.00 points here.

There are approximately 174,000 acres of land used for production for Catfish (USDA 2005). Production of Channel Catfish in the U.S. is centered in the southeast, mostly in the Mississippi River flood plain. Almost all Channel Catfish aquaculture facilities (95%) are located in Alabama, Arkansas, Louisiana, and Mississippi, with Mississippi accounting for more than 70% of the total production (Robinson and Avery 2000). Production in Mississippi is concentrated in the Yazoo-Mississippi River floodplain (Tucker, pers. comm., 2004).

Stocking density in ponds is at a moderate level. In the ponds of marketable fish, Catfish are generally stocked at 4,500 to 7,000 fish per acre (Tucker, pers. comm., 2004). Production is limited largely by the ability of the water to provide fish with enough oxygen: ponds typically have to be mechanically aerated to maintain appropriate oxygen levels and are still subject to low oxygen periods (Boyd et al. 2000).

We chose not to subtract or add for this factor. While a large proportion of Catfish farming, the U.S.’s largest aquaculture sector, is concentrated in one floodplain, the farms constitute only 1% of the total land use in the floodplain (Tucker, pers. comm., 2004).

In Alabama, Best Management Practices encourage farmers construct seinable ponds that do not have to be emptied for harvest and that drain near the surface. They also recommend the use settling basins, wetlands, or other ponds to treat the final 20 to 25% of discharged effluent or that farmers retain the final effluent in the pond and release it slowly after suspended solids have had the chance settle to the bottom of the pond after 2 to 3 days. Doing so greatly reduces the concentration of total suspended solids, nitrogen, and phosphorus released (AU and USDA 2004), but this practice does not seem to be widespread. The catfish industry has experimented with constructed wetlands, but does not view them as feasible, because they require considerable land (Seok et al. 1995).

Zoning laws vary on state, regional, and often local basis. In Mississippi, where the majority of operations are located, regulations dealing with the location of Catfish farms deal primarily with well-water permitting and the wetland provisions of the Clean Water Act (Warren, pers. comm., 2004).

The natural diet of Channel Catfish includes both plant and animal material. Adults feed on insects, snails, crawfish, green algae, aquatic plants, seeds, and small fish (Wellborn 1998). Studies from the National Warmwater Aquaculture Center at the University of Mississippi show that Catfish can be raised on soybean meal-based diets with low levels of fishmeal, or with no fishmeal (Li et al. 2003). Although some all-vegetable protein diets are used, Catfish feed typically contains 2 to 6% fishmeal or other animal protein (Robinson, pers. comm., 2004), as well as plant meals, grains, vitamins, and minerals (UA and USDA 2004).

Catfish are capable of converting feed at a ratio of 1.5 or better, but throughout the industry the feed conversion ratio is about 2.4 to 2.5 (Li, pers. comm., 2004).

This is not a biological conversion, however, and does not incorporate consideration of fish lost to disease and predators and that some fish are harvested using a multi-batch system, which complicates FCR calculations. Instead it is a rough estimate based on the amount of feed sold each year and the amount of fish produced. Though realized FCRs may be higher than 1.5 in many farms due to overfeeding (Boyd and Tucker 1995), results from carefully controlled studies under commercial conditions indicate that they are less than 2.0 (Tucker, pers. comm., 2004). Therefore, we chose to not subtract points here.

Feed for Catfish typically contains 2 to 6% fishmeal or other animal protein. This level of fishmeal represents an improvement from previous years when Catfish feeds contained closer to 8% fishmeal (Li, pers. comm., 2004). Efforts are underway to eliminate all animal protein from Catfish feeds (Robinson, pers. comm., 2004). If feeds are made without animal-derived proteins, they must be supplemented with the amino acid lysine, which plant proteins lack. Widespread use of lysine in Catfish feed is not economically feasible at this time, but research is ongoing (Tucker, pers. comm., 2004).

Research on developing more sustainable Catfish feeds is ongoing at Mississippi State University’s Thad Conchran National Warmwater Aquaculture Center and Auburn University, as well as at other universities, the United States Department of Agriculture, and in the private sector.

Catfish farmers do not treat discharged effluent but instead rely on natural processes (e.g. algal and bacterial metabolism) to reduce excess nutrients and organic matter in pond waters. Algae and bacteria in ponds use most (90%; Tucker, pers. comm., 2004) of the excess nitrogen, phosphorus, and organic matter. The majority of these nutrients end up in pond sediments or the atmosphere, and the nutrient load in effluent discharged from Catfish farms is relatively small compared with the nutrient load in other aquaculture operations’ effluents (Goldburg and Triplett 1997).

Farmers also avoid discharging large volumes of polluted effluent by draining their food fish ponds infrequently, as little as every 20 years, when they drain the water to repair pond levees. However, they drain most fry and fingerling ponds each year, as well as food fish ponds that are not seinable. Some farms drain effluent or the final 20-25% of the effluent into settling basins, other ponds, or wetlands, to reduce its relatively high concentrations of suspended matter and excess nutrients, but this practice is not widespread. Effluent is also released when ponds overflow during heavy rainfall due to rain falling directly into the pond or due to runoff on the watershed (AU and USDA 2004).

Some farms drain their food fish ponds yearly, but this technique, “clean harvesting,” is practiced less frequently. This method is more costly and involves removing all fish from the pond at the same time and draining the untreated pond water afterwards (Robinson and Avery 2000).

In June 2004, the U.S. Environmental Protection Agency (EPA) signed a Final Rule that established wastewater controls and performance standards for 245 aquaculture facilities in the United States. The regulations aim to reduce discharge of pollutants such as Total Suspended Solids, as well as non-conventional pollutants including nutrients, drugs, chemicals, and toxic pollutants such as metals and PCBs. These new controls stem from a 1989 lawsuit in which the Natural Resources Defense Council and other environmental groups sued the EPA for failing to comply with the Clean Water Act. The rule related to aquaculture was the last of a series of rules issued under this lawsuit (EPA 2004).

Unfortunately, these regulations did not include discharge caps, permit requirements, or enforcement measures for closed pond systems, including those used for raising Catfish, and only apply to facilities that primarily raise trout, salmon, Hybrid Striped Bass, and Tilapia. The EPA does not consider pond aquaculture systems to be a substantial source of water pollution (Goldburg, pers. comm., 2005; EPA 2004).

Water quality regulations for Catfish farms do exist at the state level. However, we chose to subtract here, because regulation of Catfish-farm effluent disposal is not strong or closely monitored.

Less than 1/2 of 1% of Catfish feed is medicated. Bayluscide, a molluscide, controls the digenetic trematode, Bolbophorus sp., which can be passed onto Catfish by American White Pelicans (Terhune et al. 2003). However, the Catfish Farmers of America states that Bayluscide is almost never used due to its high cost and a regulation that requires that ponds must be empty of fish to use the chemical (Warren, pers. comm., 2004).

Catfish farmers also use sodium chloride to prevent nitrite toxicity in fish and copper sulfate to control algal blooms that cause off-flavor in fish (Silapajarn et al. 2004).

Typically the potential for the highest instantaneous delivery of pollutants to the environment occurs when ponds are drained to collect fish. Otherwise, effluent quality varies seasonally and tends to be poorest in the summer when the rate of fish feeding is highest. During this time, organic matter, nitrogen and phosphorous accumulate in pond waters. Processes that reduce particulate material, such as sedimentation, reduce the concentrations of suspended solids and total phosphorus in pond water. By raising fish of different ages together, and collecting only the largest ones using seine nets, producers can wait up to 10 years before draining ponds (Warren, pers. comm., 2004).

In Alabama, Best Management Practices (BMPs) encourage farmers to construct seinable ponds that drain near the surface. They also recommend when draining ponds that farmers pump the bottom 20 to 25% of water, which contains the highest amount of suspended matter, into settling basins and reconstructed wetlands. Doing this allows time for excess nutrients and small clay particles to settle out of the effluent before final discharge. However, these recommendations are not requirements, and the BMPs state that farmers should only use this treatment technique where space is available and construction costs are manageable (AU and USDA 2004).

Although Catfish farming innately produces less waste than other types of aquaculture, Catfish farmers rarely use best possible treatment methods, such as draining effluent near the surface of the pond and pumping it into empty ponds, settling basins, or wetlands, to reduce the environmental impacts of the effluent (AU and USDA 2004). Therefore we chose to neither add nor subtract points here.

Originally Channel Catfish were distributed only in the Gulf States and in the Mississippi valley north to the prairie provinces of Canada and Mexico. Their range did not extend west of the Rocky Mountains or to the Atlantic coastal plain. However, the species has since been introduced throughout the United States and globally (Wellborn 1988). Nonetheless, the vast majority of Channel Catfish aquaculture operations in the U.S. occur within their native range, and farm-raised Catfish rarely escape from ponds. Pond drainage systems typically use screens to prevent Catfish from escaping and unwanted fish (e.g., Sunfish) from entering ponds (Warren, pers. comm., 2004).

Since this species is indigenous to the area where the majority of production occurs, escaped fish are likely to survive in the surrounding ecosystem.

Researchers have found evidence that escaped domestic Catfish do not compromise the genetic integrity of wild Catfish. A study of 8 locations near Catfish farms in Alabama concluded that there is no greater similarity of wild Catfish to domestic Catfish captured near Catfish farms than to wild Catfish captured far from the farms. This study, although still under review and limited in its coverage, finds evidence that no major escapes have happened in Alabama (Liu, pers. comm., 2005). It would be unlikely for any interbreeding of farmed and wild Catfish to significantly alter the wild population’s genetics (Goldburg, pers. comm., 2005).

There is no documentation of disease being spread through escaped Catfish. The digenetic trematode, Bolbophorus sp., can occur in commercially raised Catfish. Bolbophorus sp., which lives in the gastrointestinal tract of the American White Pelican, is passed on to Catfish when the pelican defecates into Catfish ponds. The eggs of the Bolbophorus infest an intermediate host, the Ram’s Horn Snail, are later released into the pond water, and then infest Catfish. To complete the life cycle of this trematode, pelicans feeding on Catfish at Catfish farms eat infected fish and become infected or re-infected with the parasite (Terhune et al. 2003).

Control options include: 1. keeping birds away from farms (White Pelicans are protected, and USDA/APHIS/Wildlife Services determines what methods are acceptable); 2. reducing snail populations with chemical treatments (e.g., treating pond margins with hydrated lime, copper sulfate, and/or using the molluscide, Bayluscide); 3. using biological controls (e.g., Black Carp prey on snails, but their use is limited because they are non-indigenous; using aquatic weed controls (e.g., Grass Carp and aquatic herbicides reduce vegetation; Terhune et al. 2003).

Because fish-to-fish transmission of digenic trematodes is not possible and Catfish farms are not directly responsible for transmitting this disease, we added points here.

Catfish operations all occur on land, most often on converted agricultural land.

Since DDT was banned in the U.S., populations of Double-crested Cormorants (DCCOs) have rebounded to high levels of abundance, and their breeding range has expanded. The boom in Catfish farming has aided DCCOs’ proliferation, as the cormorants now have large quantities of prey available to them in large, shallow Catfish ponds near their over-wintering grounds. Over-wintering survival of DCCOs in the Southeastern U.S. has increased for adults and sub-adults, due to the abundance of food at aquaculture ponds. Though there is still disagreement about the extent of the economic damage to aquaculture and though the damage is often local and intense in nature, DCCOs have become an economic liability to Catfish farmers, who shoot them and other piscivorous birds feeding at their Catfish ponds (Glahn et al. 2002).

Although DCCOs are protected from unauthorized “take” under the Migratory Bird Treaty Act of 1918, shooting DCCOs that are preying on (or about to prey on) fish at aquaculture facilities is currently authorized without a permit under an Aquaculture Depredation Order. In addition to this order, the U.S. Fish and Wildlife Service issued a Public Resource Depredation Order in 2003, which allows Wildlife Services, state agencies, and federally recognized tribes to kill adult DCCOs and oil eggs at roost sites in the winter and shoot DCCOs at their breeding grounds in the Great Lakes area in the summer (USFWS 2003).

The National Wildlife Research Center (USDA/APHIS, Wildlife Services) has researched alternative methods to prevent DCCOs from preying on fish in aquaculture ponds, including scaring devices, lasers, and robo-alligators. Unfortunately, none of these has proved to provide a lasting solution. In addition, it would be too costly to place exclosure nets over the ponds to keep birds out, and the nets would likely blow over in inclement weather. Had the Catfish aquaculture industry been able to predict that DCCOs would be a major problem, they could have made their ponds deeper and developed alternative ways to feeding fish at the surface of the water, which makes them easy prey to piscivorous birds (Paul, pers. comm., 2005).

The U.S. Fish and Wildlife Service has collected only poor data on how many birds are killed legally each year at aquaculture facilities. It conducted a voluntary survey of a limited group of Catfish farms two years ago, which achieved only a minimal response rate. Illegal take is also occurring, and the service has little idea to what extent (Paul, pers. comm., 2005). The Service estimates that in recent years (1998 to 2001), 46,664 DCCOs have been taken each year, representing an annual take of 2.1% of the continental population. With the Public Resource Order, the Service estimates that the annual take will rise to 159,635 DCCOs, or 8.0% of the continental population (USFWS 2003). These numbers are likely to be very low, and others estimate that the number of DCCOs killed each year will be closer to 204,500 birds (Paul, pers. comm., 2005).

Catfish ponds host large numbers of ducks and geese during their annual migrations and dozens of non-nuisance shore birds year-round. However, piscivorous birds also find the farms attractive, and the shooting of birds at Catfish farms prevents us from awarding points here.

Catfish spawn in farm ponds. Fertilized eggs are collected and taken to the hatchery, where they are hatched. Then the larvae are moved to nursery ponds and, later, to grow-out ponds (Robinson and Avery 2000).