Crawfish/By Robert Shetterly © Blue Ocean Institute
Crawfish/By Robert Shetterly © Blue Ocean Institute

Crawfish (farmed, U.S.)

Red Swamp Crawfish (Procambarus clarkii); White River Crawfish (Procambarus zonangulus)

Sometimes known as crawdads, crayfish or mudbugs.

These species are farm-raised.

Summary

U.S. farmers grow Red Swamp and White Swamp Crawfish in man-made ponds, often with rice or soybean crops. More than 90% of all U.S. crawfish production occurs in Louisiana, where these species are native. Crawfish producers do not use feed to raise crawfish; instead they subsist on detritus and small animals in their ponds' food webs.

Criterion Points
Inherent Operational Risks 2.50
Feed 3.75
Pollution 2.25
Risk to Other Species 2.25
Ecological Effects 3.75
Final Score (average of criteria) 2.90
Color
Final Score Color
2.60 - 4.00
2.20 - 2.59
1.80 - 2.19
1.40 - 1.79
0.00 - 1.39

Last updated April 19, 2006.

Inherent Operational Risks

Core Points (only one selection allowed)

General System Design:

An aquaculture system's design is a good overall proxy measure for the likely effect of the operation on the environment. For example, open systems (e.g., net pens and net cages) are more likely to have pollution, disease, and escape issues than closed systems (e.g., recirculating tanks). With shellfish, which don’t require supplemental food input, the more important question is whether they are harvested on or off of the bottom.

1.00
This species is raised in a high risk system (e.g., net pens; net cages).
2.00
This species is raised in a moderate risk system (e.g., most ponds; raceways; bottom culture of mollusks).

In the U.S., farmers raise crawfish in man-made ponds constructed by flooding agricultural lands (Caffey et al.1996; McClain and Romaire 2004). Pollution is a concern, because farmers drain their ponds several times a year (LSU 1999). But other potential issues associated with this type of moderate-risk aquaculture system–disease transmission to wild populations and negative effects of escaped crawfish–are not a concern. Disease rarely affects farmed crawfish, and farm escapees are not known to transmit it to wild populations in the U.S. (McClain, pers. comm., 2006; AquaNIC 2006). The effects of escaped farmed crawfish on wild populations are also minimal for two reasons: 1) the vast majority of U.S. crawfish production occurs within the native ranges of the most widely farmed species, Red Swamp and White River Crawfish, and 2) wild and farmed crawfish populations are not genetically different (McClain and Romaire 2004; Boyd, pers. comm., 2006; Lutz, pers. comm., 2006).

3.00
This species is raised in a low risk system (e.g., re-circulating closed system; suspended culture of mollusks; zero-discharge ponds).

Points of Adjustment (multiple selections allowed)

-0.25
Species is raised at a high stocking density; OR there is a high density of sites in the geographic region, with evidence of environmental impact.
-0.25
Operations do not incorporate best-available, cost-effective technology to reduce environmental impact.
-0.25
There are no effective zoning or permitting practices for siting of facilities.
-0.25
Government programs encourage expansion of high-impact systems.
+0.25
Species is raised at a low stocking density OR there is a low density of sites in the geographic region, which results in minimal impact to the natural ecosystem.

Stocking densities of crawfish vary. Compared to other aquaculture operations, though, crawfish in farm ponds are at low stocking densities. Overcrowding is not an issue: higher densities of crawfish result only in smaller crawfish at harvest (Lutz, pers. comm., 2006; McClain, pers. comm., 2006; Shirley 2005).

Louisiana crawfish farms generate 90% of the crawfish produced annually in the U.S. (Caffey et al. 1996; Romaire et al. 2004; LSU 2005a). In Louisiana, there are 1200 farms that use 118,000 acres of flooded agricultural land to produce crawfish (LSU 2005a). However, these farms constitute less than half of a percent of the land area of Louisiana (Parr 2002).

+0.25
Operations incorporate innovative culture methods that limit environmental impacts (e.g., polyculture).

In Louisiana, farmers raise more than 75% of the state crawfish crop in conjunction with agricultural crops, mostly rice and soybeans (Caffey et al. 1996; Hunner 2000).

+0.25
There are effective zoning or permitting practices for siting and operation of facilities (e.g., mandatory consideration of hydrographic characteristics; requirements for site rotation).

Individual states have permitting programs for farm siting, building wetlands, removing and releasing water, and raising crawfish (LSU 2005b; AquaNIC 2006). However, there is little indication that crawfish farm siting is closely regulated, so we chose to not add here.

+0.25
Government programs preferentially encourage the expansion of low-impact systems over high impact systems.
2.50
Points for Inherent Operational Risks

Feed

Core Points (only one selection allowed)

Ecological Footprint of Feed:

"Trash" fish, frequently used in developing countries, is an industry term used to refer to whole fish or fish parts fed to farmed fish without being processed into fish meal and fish oil.

Twenty percent was selected as a cut-off because carnivorous species (e.g., salmon; eel; tuna; cobia; etc.) generally consume greater than twenty percent fish products (fishmeal, fish oil, or trash fish), while omnivorous or herbivorous species (e.g., catfish; tilapia; carps; etc.) consume less than twenty percent fish products.

1.00
Typical aquaculture feed includes high levels of fishmeal, fish oil, or "trash" fish (i.e., >20% of the feed; e.g., salmonid feeds).
2.00
Typical aquaculture feed includes moderate levels of fishmeal, fish oil, or "trash" fish (i.e., <20% of the feed; e.g., tilapia and catfish feeds).
3.00
No feed is used (e.g., mollusks and seaweeds) or typical aquaculture feed includes no fishmeal, fish oil, or "trash" fish (e.g., paddlefish; filter-feeding carps).

Farming crawfish does not require feed. Farmers raise crawfish in ponds created on flooded agricultural fields. Decomposing vegetation in these ponds forms the basis of the food webs that support crawfish, which consume a variety of the plants, animals, and decomposing matter in the ponds. The small animals that feed on the decomposing vegetation provide the majority of nutrition for the crawfish (LSU Ag 1999, 2005a; Shirley 2005; Lutz, pers. comm., 2006).

Farmers use wild-caught fish, such as Gizzard Shad and Menhaden, to bait traps during crawfish harvesting (LSU 1999). We chose to not subtract for baitfish usage, however, because the amount used is likely minimal compared to the amount of fish products used by other aquaculture operations.

Points of Adjustment (multiple selections allowed)

-0.25
When fish products are used, the major sources score low on the Wild-Caught Fisheries Ranking System.
-0.25
Feed contains greater than 10% of fish products and public or private sectors are not working to reduce fish content in feed.
-0.25
Feed conversion ratio (FCR) is high (i.e., >2.0; e.g., eel).
-0.25
Government policy promotes research, development and commercialization of carnivorous or other highly fishmeal-dependent species.
+0.25
When fish products are used, the major sources score high on the Wild-Caught Fisheries Ranking System; OR the source is innovative and ecologically sound (e.g., fisheries byproducts); OR no feed is used.

No feed is used to raise crawfish.

+0.25
Feed contains less than 10% of fish products OR public and private sectors are working to reduce the fish content in feed; OR no feed is used.

No feed is used to raise crawfish.

+0.25
Feed conversion ratio (FCR) is low (i.e., <1.3; e.g., salmon); OR no feed is used.

No feed is used to raise crawfish.

+0.25
Government policy promotes research, development and commercialization of herbivorous species or other species not highly dependent on fishmeal.
3.75
Points for Feed

Pollution

Core Points (only one selection allowed)

Typical effluent treatment procedures:

1.00
Effluent is not treated before discharge (e.g., salmon net pens).
2.00
Effluent is partially treated before discharge (e.g., infrequently discharged effluent from catfish ponds).

Crawfish farmers do not treat the water they release from their ponds during harvest (AU and USDA 2004). However, they generally follow state-suggested best management practices (BMPs), which increase the quality and decrease the volume of wastewater drained from their ponds (Lutz, pers. comm., 2006; McClain, pers. comm., 2006). Most crawfish farms are far removed from receiving waters (i.e., the streams, etc. into which wastewater is disposed), so farmers channel pond effluent through vegetated ditches that lead to the receiving waters (McClain, pers. comm., 2006; Pitre, pers. comm., 2006; Romaire, pers. comm., 2006). This system allows solid particles and some nutrients to settle out from the effluent before it reaches streams or other bodies of water (McClain, pers. comm., 2006; Romaire, pers. comm., 2006).

Currently, little is known about the effects of crawfish pond effluent on nearby aquatic ecosystems (Johnson et al. 2004; LSU 2005a). Research conducted during the 1990s demonstrated that water drained from crawfish ponds in the spring and summer is of poorer quality (i.e., contains higher concentrations of nutrients and suspended solids) than water drained during the fall and winter (Tucker 1998; Parr 2002). However, further information on the quality and environmental impact of crawfish farm effluent is lacking (McClain, pers. comm., 2006).

The U.S. Environmental Protection Agency (EPA) sets aquaculture effluent guidelines through the National Pollution Discharge Elimination System (NPDES) program (SRAC 1999). However, when the EPA created the program, it determined that crawfish ponds did not need to be regulated (McClain, pers. comm., 2006). Individual states have permitting programs for farm siting, building wetlands, removing and releasing water, and raising crawfish (LSU 2005b; AquaNIC 2006). These programs, however, do not require that effluent be treated before discharge.

Although no feed is used to farm crawfish (LSU 1999; McClain and Romaire 2004; Lutz, pers. comm., 2006), the periodic draining of effluent from crawfish farms and the lack of effluent discharge regulations are a concern. Therefore we chose to award a medium score of 2.00 points here.

3.00
Effluent is substantially treated before discharge (e.g., recirculating shrimp systems; settling ponds; reconstructed wetlands); OR treatment is not necessary because supplemental feed is not used (e.g., molluscs or seaweeds).

Points of Adjustment (multiple selections allowed)

-0.25
Operations have demonstrated negative impacts on water quality or sediment/benthic characteristics (e.g., elevated nutrient levels; algal blooms; altered benthic communities).

Scientists have conducted little research on the effects of effluent discharged from crawfish farms on the surrounding ecosystem, although current studies are underway (McClain, pers. comm., 2006; Romaire, pers. comm., 2006). We chose to not subtract here as we await the studies’ results.

-0.25
Pollutants (e.g., pesticides; parasiticides; antibiotics; plastic; nets; dead fish) are frequently discharged into the environment or otherwise not appropriately discarded.
-0.25
Effluent regulations do not exist, are lax, or are poorly enforced, which allows for degradation of the aquatic environment.

Louisiana State University’s Agriculture Center and Auburn University have researched and established a list of best management practices (BMPs) for crawfish operations (LSU 1999; AU and USDA 2004). These BMPs include strategies for water conservation (including utilization of rainfall, minimization of pond water exchange, and reuse of drained water for irrigation), improvement of pond water and effluent quality (including pond aeration and ways to promote the settling of solids before drainage) and wetlands construction (LSU 1999; Lutz, pers. comm., 2006).

Most crawfish farmers follow these suggested BMPs, because they are often associated with economic advantages (Romaire, pers. comm., 2006). However, the use of BMPs on crawfish farms is not mandated (Tucker 1998; SRAC 1999). Since neither federal nor state agencies regulate crawfish operations with strong enforcement or regular monitoring, we chose to subtract for this factor.

-0.25
Available technologies and practices to reduce or recycle waste (e.g., feed sensors; low-pollution feeds) are not used.
+0.25
Operations generally improve water quality or sediment/benthic characteristics (e.g., oyster farms).
+0.25
Chemicals (e.g., pesticides; parasiticides; antibiotics) are rarely or never used.

Disease is not a problem in crawfish production, so farmers do not apply antibiotics to their ponds. Crawfish farming operations rarely use other chemicals, because they can kill crawfish (Johnson et al. 2004; Shirley 2005; McClain, pers. comm., 2006).

+0.25
Robust water quality regulations exist (e.g., permits required; discharge caps; strong enforcement), and regular monitoring occurs.
+0.25
Innovative methods and practices to reduce or recycle wastes are used (e.g., integrated systems; effluent and solid wastes used as terrestrial fertilizer); OR innovative methods and practices are not needed because raising this species does not create waste.

Crawfish farmers drain water from their ponds and release it into local waters without first treating it. However, more and more farmers are using best management practices (BMPs), which include strategies to reduce the environmental impact of effluent. For example, the BMPs call for the release of pond water from the surface of crawfish ponds instead of from the bottom. Doing this reduces the amount of suspended solids in the effluent, because these solids tend to aggregate at the bottom (Parr 2002).

Farmers also discharge pond wastewater into vegetated ditches that slowly channel the wastewater into public waters, allowing time for suspended solids and nutrients to settle out. Besides installing a filtration system, this effluent discharge technique is the most environmentally sound (Parr 2002). Other suggestions include planting native plants near pond drains to serve as natural effluent filters (LSU 1999). Some farmers use settling ponds to hold discharged water before releasing it into streams and rivers. However, this is not necessarily a common practice (Johnson et al. 2004).

A concern of crawfish farms is the depletion of dissolved oxygen in the ponds (Caffey et al. 1996; Johnson et al. 2004). Farmers counteract this problem by aerating the pond water (Caffey et al. 1996). Aeration decreases the number of times farmers must drain and refill the ponds and likely improves the quality of the pond water when it is discharged (Caffey et al. 1996; Parr 2002).

2.25
Points for Pollution

Risk to Other Species

Core Points (only one selection allowed)

Frequency and Impact of Escapes:

1.00
Farmed species regularly or intermittently escape into the wild AND escapes are non-native to the area or otherwise pose a risk to native populations or ecosystems (e.g., most non-native fish raised in outdoor facilities).
2.00
Escape frequency is not known OR farmed species is native to the area where it is raised and poses minimal risk to native populations or ecosystems (e.g., channel catfish in the US; most native mollusks).

Escape does occur and is expected due to the nature of open-pond crawfish farms, but nearly all U.S. crawfish farms are located in areas where Red Swamp and White River Crawfish are native (Caffey et al. 1996; LSU 1999, 2005a; Johnson et al. 2004; McClain and Romaire 2004. There is no indication that escaped farm-raised crawfish negatively impact wild populations of Red Swamp and White River Crawfish or their ecosystems.

Farm-raised crawfish (in particular, Red Swamp Crawfish) have escaped and established populations outside of their native range in the U.S., as well as in South America, Asia, Africa, and Europe (NBIS 2005). In Europe, the negative impacts of these introductions have been well documented (Lodge et al. 2000; Duval-Smith 2004; NBIS 2005). However, this ranking is based only on U.S. production, the vast majority of which is located in the native ranges of Red Swamp and White River Crawfish. Therefore, we chose to award the medium score of 2.00 points here.

3.00
Farmed species never (or virtually never) escape to the wild (e.g., species is raised in bio-secure facilities).

Points of Adjustment (multiple selections allowed)

-0.25
This farmed species has been known to survive in the surrounding ecosystem if it escapes; OR would likely survive given its physiological requirements.

Farm-raised crawfish generally survive upon escape from ponds in the U.S. (Caffey et al. 1996; LSU 1999; Johnson et al. 2004). Many crawfish species are well adapted to surviving outside of their native range; and, Red Swamp Crawfish, in particular, can tolerate long dry periods and other environmental changes (Duval-Smith 2004; NBIS 2005).

-0.25
This farmed species is known or is likely to compete with wild species for food or habitat if it escapes; OR this species is known or is likely to compromise the genetic integrity of the wild species (e.g., through spawning disruption, genetic introgression or establishment of feral stocks) if it escapes.
-0.25
This farmed species is known or is likely to amplify and transmit disease or parasites to wild populations (e.g., infectious salmon anemia or sea lice infestations) if it escapes.
-0.25
Regulatory authorities are not adequately addressing the risks of escape or spread of disease associated with farming this species.

In the U.S., more than 90% of crawfish production occurs within the native ranges of Red Swamp and White River Crawfish, the species most commonly farmed (McClain and Romaire 2004; Romaire et al. 2004; LSU 2005a; AquaNIC 2006). However, there are a limited number of crawfish farms in the U.S. that are located outside of the ranges of Red Swamp and White River Crawfish (NBIS 2005). For example, farmers grow Red Swamp Crawfish in North Carolina, where there are no regulations in place to prevent the spread of the non-native species. The North Carolina Department of Agriculture and Consumer Services only requires that farmers attain an aquaculture license to raise crawfish (NCDA&CS 2006). On the other hand, some U.S. states prohibit the transport of non-indigenous crawfish species across their borders and instead encourage the farming of native species (Brown and Gunderson 1997).

Due to the varying degrees of regulation and the fact that the vast majority of U.S. production occurs within the native ranges of Red Swamp and White River Crawfish, we chose not to subtract for this factor.

+0.25
This farmed species has not been known to survive in the surrounding ecosystem if it escapes; OR would not likely survive given its physiological requirements; OR farmed species is a native mollusc.
+0.25
Operations employ management protocols and techniques to limit the ecological impacts of escaped farmed fish (e.g., triploidy; sterilization); OR it’s unlikely that escaped individuals will either compete with wild species for resources, or compromise the genetic integrity of wild species.

Where Red Swamp Crawfish are not native and have escaped from farms, they have often out-competed native crawfish, causing declines in their populations (Lodge et al. 2000; NBIS 2005). However, this ranking is focused on U.S. crawfish production, almost all of which occurs within the native ranges of Red Swamp and White River Crawfish.

Genetic studies have shown that no difference exists between farmed and wild populations of crawfish in the south-central U.S. (Lutz, pers. comm., 2006). Therefore, the interbreeding of farm-raised crawfish with wild crawfish will not likely jeopardize wild populations in the U.S.

+0.25
Operations employ effective disease and parasite management protocols (e.g., fallowing of pens; retaining water when disease outbreak occurs); OR incidence of disease or risk of retransmitting disease is low.

Disease in U.S. farm-raised crawfish ponds is rare; therefore, the risk of transmitting disease to wild populations is extremely low (Johnson et al. 2004).

+0.25
Regulatory authorities are addressing the risks of escape and spread of disease associated with farming this species.
2.25
Points for Risk to Other Species

Ecological Effects

Core Points (only one selection allowed)

Ecological sensitivity of site used for operations:

1.00
Operations are generally located in areas of high ecological sensitivity (e.g., coastal wetlands; mangroves).
2.00
Operations are generally located in areas of moderate ecological sensitivity (e.g., coastal and nearshore waters; rocky intertidal or subtidal zones; river or stream shorelines).
3.00
Operations are generally located in areas of low ecological sensitivity (e.g., land that is less susceptible to degradation such as land formerly used for agriculture or land previously developed).

U.S. farmers raise crawfish in flooded agricultural fields (LSU 1999).

Points of Adjustment (multiple selections allowed)

-0.25
Farming this species causes substantial damage to surrounding habitat, ecosystem or other resources (e.g., groundwater depletion; stream diversion; saltwater intrusion; soil salinization; loss of habitat for juvenile fish; loss of flood control; dredging hard bottoms; etc.).
-0.25
Harmful or lethal predator deterrents are used (e.g., bird/seal shootings; acoustic deterrent devices); OR operation otherwise harms wildlife (e.g., dolphin/seal entanglement; disrupting migration routes; bird/animal shooting).
-0.25
If seed is collected from wild sources, the intensity of collection is high enough to result in depletion of brood stock, wild juveniles, or associated non-target organisms (e.g., collection of postlarvae shrimp).
-0.25
Government policy encourages aquaculture operations to locate or expand in areas of high ecological sensitivity.
+0.25
Operations enhance habitat structure or function (e.g., constructed wetlands).

Farmers raise crawfish in flooded agricultural lands that act as constructed wetlands habitat for wildlife (Hunner 2000; Lutz, pers. comm., 2006). Increases observed in several waterfowl populations in Louisiana have been attributed to crawfish operations providing additional wetland habitat (Hunner 2000).

There is no evidence that crawfish farms cause substantial damage to the surrounding habitat or deplete groundwater (Hunner 2000; Lutz, pers. comm., 2006). Farmers use water from both surface (e.g., streams) and subsurface sources to flood their fields (LSU 1999). Reliance on groundwater is declining due to the high fuel costs associated with pumping groundwater (Shirley and Lutz 2005; Lutz, pers. comm., 2006).

In order to help crawfish farmers offset the increasing costs of energy, Louisiana state agencies and Louisiana State University, compiled a manual of Best Management Practices to follow (BMPs; LSU 1999; Lutz, pers. comm., 2006). These BMPs recommend economically and environmentally sound water use practices, like flooding crawfish ponds to a shallower depth and retaining rainwater to use for pond flooding (Lutz, pers. comm., 2006). Although laws do not mandate that farmers use BMPs, most farmers opt to follow them due to the economic gain they provide by reducing their energy costs (Lutz, pers. comm., 2006).

Because there is no evidence that crawfish operations cause substantial damage to the surrounding habitat or deplete groundwater, we chose to add here.

+0.25
Predator deterrents are not used OR predator deterrents are used but are not harmful or lethal (e.g., predator exclusion nets), AND operation does not otherwise harm wildlife.

There is no indication that crawfish farming operations harm wildlife. It is illegal for farmers to kill most of the animals that enter their crawfish ponds (Lutz, pers. comm., 2006).

+0.25
Seed comes predominantly from hatcheries or on-farm sites (e.g., seed for trout); OR if seed is collected from the wild, it does not deplete brood stock, wild juveniles, or associated non-target organisms (e.g., collection of oyster or mussel spat).

During harvest, farmers do not remove all the crawfish from their ponds. The remaining crawfish reproduce and naturally re-stock the ponds (LSU 1999). Farmers stock new ponds with crawfish from other ponds (AU and USDA 2004), although, in Louisiana, wild-caught crawfish from the local fishery are also sometimes used (D’Abramo et al. 2004). There is no indication that use of wild-caught crawfish to seed ponds in Louisiana depletes wild crawfish populations.

+0.25
Government policy encourages the growth of aquaculture operations in areas of low ecological sensitivity; OR protects sensitive habitats from aquaculture operations (e.g., prohibitions on cutting mangroves).
3.75
Points for Ecological Effects

References

Aquaculture Network Information Center (AquaNIC). 2006. Crawfish Production. Available at: http://aquanic.org/publicat/state/ga/crawfish.htm

Auburn University and USDA-Natural Resources Conservation Service (AU and USDA). 2004. Alabama Aquaculture Best Management Practice (BMP): Managing Crawfish Ponds. Available at: http://efotg.nrcs.usda.gov/references/public/AL/G21ManagingCrawfishPonds.pdf

Boyd, C. 2006. Personal Communication. Auburn University.

Brown, P. and J. Gunderson. 1997. Culture Potential of Selected Crayfishes in the North Central Region. Iowa State University Publication.

Caffey, R.H., R.P. Romaire, and J.W. Avault, Jr. 1996. Sustainable Aquaculture: Crawfish Farming. Freshwater Crayfish 11: 587-598.

D’Abramo, L.R., C.L. Ohs, T.R. Hanson, and J.L. Montanez. 2004. Semi-Intensive Production of Red Swamp Crawfish in Earthen Ponds without Planted Forage. Southern Regional Aquaculture Center Fact Sheet. Available at: http://srac.tamu.edu/2401fs.pdf

Duval-Smith, A. 2004. Rampant Louisiana Crayfish Threaten Future of French Frogs. The Independent, U.K. 12 November 2004.

Hunner, J.V. 2000. Societal Services Provided by Crawfish Impoundments. Environmental State of the State-V 2000 Conference Proceedings. Available at: http://agecon.lsu.edu/ESOS-V%20Proceedings/

Johnson, S.L., B. Grumbles, G. Grubbs, M. Smith, M. Rubin, I. Goodwin, and M. Jordan. 2004. Technical Development Document for the Final Effluent Limitations Guidelines and New Source Performance Standards for the Concentrated Aquatic Animal Production Point Source Category. Environmental Protection Agency.

Lodge, D.M., C.A. Taylor, D.M. Holdich, and J. Skurdal. 2000. Reducing Impacts of Exotic Crayfish Introductions: New Policies Needed. Fisheries 25: 21-23.

Louisiana State University Agricultural Center (LSU). 2005a. Research Sustains Crawfish Industry. Available at: http://www.lsuagcenter.com/en/crops_livestock/aquaculture/crawfish/

LSU. 2005b. Management of Recreational and Farm Ponds in Louisiana. Available at: http://www.lsuagcenter.com/en/communications/publications/Publications+Catalog/Environment/Aquaculture++Fisheries/

LSU. 1999. Crawfish Production Manual. Available at: http://www.agctr.lsu.edu/en/crops_livestock/aquaculture/crawfish/

Lutz, G. 2006. Personal Communication. Louisiana State University Agricultural Center.

McClain, W.R. 2006. Personal Communication. Louisiana State University Agricultural Center.

McClain, W.R. and R.P. Romaire. 2004. Crawfish Culture: A Louisiana Aquaculture Success Story. World Aquaculture 35: 31-35, 60-61.

National Biological Information Infrastructure and Invasive Species Specialist Group (NBIS). 2005. Procambarus clarkii. Global Invasive Species Database. Available at: www.issg.org

North Carolina Department of Agriculture and Consumer Services (NCDA&CS). 2006. Aquaculture License. Available at: http://www.ncagr.com/aquacult/license.html

Parr, L.D. 2002. Water Discharge Models, Seasonal Effluent Mass Loading, and Best Management Practices for Crawfish Ponds. Master’s Thesis, Louisiana State University. Available at: http://etd.lsu.edu/docs/available/etd-1119102-163547/

Pitre, J. 2006. Personal Communication. Natural Resources Conservation Service.

Romaire, R.P. 2006. Personal Communication. Louisiana State University Agricultural Center.

Romaire, R.P., W.R. McClain, and C.G. Lutz. 2004. Crawfish Production: Harvesting. Southern Region Aquaculture Center Fact Sheet.

Shirley, M. 2005. Crawfish Connection News for March 17, 2005. Louisiana Cooperative Extension Service. Available at: http://www.lsuagcenter.com/en/our_offices/parishes/Vermilion/Features/Newsletters/Crawfish_Connection/

Shirley, M. and G. Lutz. 2005. Crawfish Connection News for September 8, 2005. Louisiana Cooperative Extension Service. Available at: http://www.lsuagcenter.com/en/our_offices/parishes/Vermilion/Features/Newsletters/Crawfish_Connection/

Southern Regional Aquaculture Center (SRAC). 1999. Characterization and Management of Effluents from Aquaculture Ponds in the Southeastern United States. Publication No. 470.

Tucker, C.S. 1998. Characterization of Finfish and Shellfish Aquaculture Effluents. Final Project Report on the SRAC Regional Research Project. Stoneville, Mississippi.

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