Source: LOUISIANA STATE UNIVERSITY submitted to
IMPROVING PRODUCTION EFFICIENCY IN PROCAMBARID CRAWFISH AQUACULTURE
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
EXTENDED
Funding Source
Reporting Frequency
Annual
Accession No.
0213341
Grant No.
(N/A)
Project No.
LAB93891
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Jan 1, 2008
Project End Date
Dec 31, 2013
Grant Year
(N/A)
Project Director
Romaire, R. P.
Recipient Organization
LOUISIANA STATE UNIVERSITY
(N/A)
BATON ROUGE,LA 70893
Performing Department
AQUACULTURE RESEARCH STATION
Non Technical Summary
The red swamp crawfish and the white river crawfish are a valuable seafood resource in Louisiana, representing the only large-scale, commercially successful crustacean aquaculture enterprise in North America, with over 130,000 acres, 1,200 farmers, and an estimated economic impact in Louisiana that exceeds $250 million. The extensive method of crawfish cultivation, although profitable for many producers, presents a challenge because yield and quality (size) is not consistent from year to year. A significant contributor to production variability appears to be reproduction. Field evidence indicates some crawfish crop failures may be associated with crawfish exposure to poor water quality or accidental introductions of ecotoxicants. Crawfish harvested early in the production season receive the highest prices because of the low availability of crawfish at that time. For many producers, early season production of crawfish is critical to profitability. Flooding ponds prior to the currently recommended flooding date of early October may have potential to increase the supply of crawfish during low production months. Bait and labor are among the highest expenses in crawfish aquaculture, and more than any other management factor, they can most easily be managed by the producer to maximize harvest and minimize cost. This project addresses several priority research areas of crawfish aquaculture identified by LSU AgCenter aquaculture researchers, extension specialists and crawfish producers. These areas include assessment of the effects of climatic and physicochemical stressors on reproduction, survival, growth, and production; evaluation of the potential to produce early season and out-of-season crawfish when prices are highest; and refinement of harvesting practices that increase efficiency by reducing labor and bait cost. The anticipated impact of this project is that improved management guidelines and management alternatives for commercial freshwater crawfish aquaculture producers in Louisiana will be developed and extended to the crawfish farming community in outreach programs to improve their production efficiency and increase profitability of their farming operations.
Animal Health Component
80%
Research Effort Categories
Basic
10%
Applied
80%
Developmental
10%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
3013720119015%
3073720115020%
3073720119050%
3143720115015%
Goals / Objectives
The goal of this project to provide improved management guidelines and management alternatives to commercial freshwater crawfish aquaculture producers in Louisiana in order to improve production efficiency and increase profitability of their farming operations. The objectives of this project include assessment of the effects of climatic and physicochemical stressors on reproduction, survival, growth and production of crawfish; evaluation of the potential to produce early season and out-of-season crawfish when supply is low and prices are highest; and to refine crawfish harvesting strategies to reduce production cost, with emphasis on determining crawfish movement patterns to traps as influenced by bait type and water temperature. Expected deliverables from this project include improved management procedures for crawfish producers that will be conveyed via technical scientific journal articles to the scientific community, and extension publications and newsletters on crawfish aquaculture best management practices that minimize production cost and increase profitability while minimizing any negative effects on the environment. New findings from this project will be dissemination at crawfish producer meetings and workshops, and via web-based delivery systems from the Louisiana State University AgCenter public website.
Project Methods
The effects of stress on reproduction will be simulated by exposing mature females to stressing factors including chronic hypoxia and food deprivation. Mature females will be placed in artificial burrows and survival, time to spawning, spawning percentage, and egg hatch determined. Pond soils will be analyzed for texture and permeability, and chemical composition of soil and water will be analyzed for mineral content. Historical data on precipitation, air temperature, and soil moisture will be analyzed with principal-components analysis to determine factor scores, which will be regressed on crawfish reproductive indices to determine the relationship between environmental factors and crawfish reproduction. Juvenile red swamp and white river crawfish will be exposed to four oxygen concentrations (10, 20, 50 and 90% of oxygen saturation) at each of two water temperatures (20 and 28 C) for up to 120 days. Response variables to be measured on each species of crawfish will include growth rate, survival distribution, percent survival, inter-molt time duration, and number of molts. The effects of water temperature on growth and molting frequency of red swamp and white river crawfish will be determined by exposing juveniles (10-12 mm TL) to 10, 15, 20, 25, and 30 C for up to 120 days. The acute and chronic effects of selected toxicants on red swamp and white river crawfish will be determined in the laboratory and in field mesocosms. The 96-h LC50 will be determined for hydrogen sulfide and selected agricultural pesticides. Experimental ponds will be randomly assigned to the following flooding regimes: 1 May, 1 June, and 1 July, 1 August, 15 August, 1 September, 15 September, and 1 October, to assess the potential for out-of-season and early-season crawfish production. Crawfish will be sampled monthly to monitor growth and relative density. Crawfish will be harvested with baited traps. Data will be analyzed with the analysis of variance to determine the effects of flooding date on crawfish yield and size at harvest. The capture efficiency of various trap mesh x trap density combinations will be evaluated from crawfish marking and recapture experiments. Marked market-size crawfish will be released into large experimental ponds, and the crawfish will be harvested 2 or 3 days per week after either 24 or 48 hour trap soak times. The number of recaptured marked crawfish, and the overall number of crawfish caught will be recorded at each harvesting event. Sequential crawfish mark and recapture samplings will provide data on the portion of harvestable size crawfish standing stock that is removed (harvest efficiency) as a function of mesh size, trap density, bait type, and water temperature. Findings of these research activities will be delivered at professional meetings, and presentations will be made to crawfish farmers in Louisiana at educational training meetings and workshops.

Progress 01/01/12 to 12/31/12

Outputs
OUTPUTS: Findings from crawfish aquaculture research and production management guidelines were orally disseminated to 25 commercial crawfish farmers at a Louisiana production workshop. Updates on crawfish aquaculture research and best management practices were provided to LSU AgCenter extension parish- and state specialists to use in their parish extension programming efforts. Findings from this project were disseminated in five crawfish newsletters mailed to over 1,800 stakeholders per issue. LSU AgCenter crawfish aquaculture research updates were presented to members of the Louisiana Crawfish Promotion and Research Board and members of the crawfish and catfish commodity group of the Louisiana Farm Bureau. Data were provided to aquaculture colleagues at Auburn University to be used as input into calculating carbon emission and sequestration budgets for crawfish aquaculture for the Southern Regional Aquaculture Center project "Evaluation of Impacts of Potential "Cap and Trade" Carbon Emission Policies on Catfish, Baitfish and Crawfish Farming." A proposal was submitted to the Louisiana Crawfish Promotion and Research Board to study the simulated impacts of storm surge and saltwater intrusion on crawfish production. The Southern Regional Aquaculture Center published the final report for the multistate and multi-investigator project "Management of Aquacultural Effluents from Ponds." Two abstracts were published and poster presentations developed on a crawfish habitat suitability index model for the Louisiana "2012 State of the Coast Conference" in support of the 2012 Louisiana Comprehensive Master Plan for a Sustainable Coast. A history of the LSU AgCenter's aquaculture program was published in the spring 2012 issue of Louisiana Agriculture. New and revised publications were placed on the LSU AgCenter's crawfish web page. PARTICIPANTS: Romaire, Robert. (PI). Pfister, V., LSU AgCenter. TARGET AUDIENCES: The target audiences for this research project are aquaculture researchers and extension specialists in the southern USA, where crawfish are farmed and marketed. Other target audiences include crawfish industry stakeholders (producers and buyers), print-radio-TV media, Louisiana Crawfish Promotion and Research Board, the Louisiana Crawfish Farmers Association, the crawfish advisory committee of the Louisiana Farm Bureau, the Louisiana Wild Crawfish Taskforce and the Louisiana Office of Coastal Protection and Resources. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
In 2012, procambarid crawfishes were cultivated in 189,000 acres of managed impoundments by nearly 1,300 producers in Louisiana. Estimated farm-gate receipts to producers were $196 million. Crawfish producers in the Louisiana coastal zone have reported significant increases in salinity in surface water, from drought, and in groundwater, associated with saltwater intrusion into the Chico aquifer. Changes in salinity from present and future coastal wetlands restoration and protection projects can potentially affect wild and farmed crawfish habitat when the changes alter essential habitat. Results of short-term laboratory studies indicate that crawfish can tolerate moderate levels of mineral(salt) in culture water, but field trials are needed to assess the impact of long term (at least one production cycle) exposure to low and moderate salinity. Outdoor aquatic mesocosms with nominal salinity concentrations of 0.6, 2.5, 5, 7.5 and 10 g per L (parts per thousand) were stocked with equal numbers of red swamp crawfish (RSC) and white river crawfish (WRC) juveniles at 10 per m2. After 7 months, survival, mean individual weight and total biomass at 0.6 g per L (freshwater) was 42%, 31.2 g and 1,165 kg per ha, respectively, and at 2.5 g per L salinity, 4%, 33.2 g and 126 kg/ha, respectively. No crawfish survived at salinities of 5, 7.5 and 10 g per L. Survival of RSC and WRC did not differ within salinity regimes. RSC and WRC appear to have a lower tolerance to hyposaline water than was previously postulated, and long-term exposure of crawfish to slightly brackish water may be problematic to coastal crawfish farmers. Crawfish mortality in commercial ponds and soft-shell facilities has been linked to stress from exposure to hydrogen sulfide, which is common in hypoxic ground water. Adult RSC were exposed to total sulfide concentrations of 0, 4, 8, 12, 16, and 20 mg total sulfide per L for 96 hours in static renewal acute toxicity trials. The LC50s of total sulfide at 48, 72 and 96 hours were 15.4, 5.9, and 2.7 mg per L, respectively; and the 96-h LC50 of un-ionized dihydrogen sulfide was 27 micrograms per L, an environmental level that has been measured in commercial crawfish culture systems. Crawfish exposure to ambient levels of sulfide in aerated groundwater could be potentially problematic for crawfish in ponds and soft-shell systems. Research continued on development and calibration of a crawfish habitat suitability index (HSI) model. Computer simulations showed that modeled crawfish HSI identified known optimal habitat for RSC and WRC in coastal Louisiana, with the most suitable habitats being the Atchafalaya-Vermilion, Mermentau Lake and Calcasieu-Sabine eco-regions. Simulated crawfish habitat suitability declined 10% to 20% over 50-years in Louisiana's 12 coastal eco-regions with implementation of 2012 Coastal Master Plan projects. The Atchafalaya-Vermilion eco-region shows the most significant decline in crawfish habitat by year 2060, with little change in the Mermentau and Calcasieu-Sabine eco-regions.

Publications

  • Romaire, R.P. 2012. Management of aquaculture effluents from ponds. Publication No. 6004, Southern Regional Aquaculture Center, Mississippi State University, Stoneville, MS, 29 p.
  • Romaire, R.P. 2012. A crawfish habitat suitability index model in support of Louisianas 2012 Coastal Master Plan. [abstract]. In: State of the Coast 2012 Conference, 2012 June 25-27, New Orleans, LA, USA.
  • Baltz, D., S. Dobson, M. Green, M. Kaller, P. Leberg, J. Andy Nyman, A. Owens, C. Richard Parsons, D. Reed, R. Romaire, T. Soniat and N. Snider. Upper trophic level modeling in support of Louisiana's 2012 Coastal Master Plan. [abstract]. In: State of the Coast 2012 Conference, 2012 June 25-27, New Orleans, LA, USA.
  • Romaire, R.P., T.R. Tiersch and J.W. Avault, Jr. 2012. Louisiana ideal for aquaculture. Louisiana Agriculture Volume 55(2). On-line Version. 6 p.
  • Romaire, R.P., C.G. Lutz, W.R. McClain and M.G. Shirley. 2012. Crawfish News. Volume 5, No. 1, March. LSU Agricultural Center, Baton Rouge, Louisiana, 4 p.
  • Romaire, R.P., C.G. Lutz, W.R. McClain and M.G. Shirley. 2012. Crawfish News. Volume 5, No. 2, April. LSU Agricultural Center, Baton Rouge, Louisiana, 4 p.
  • Romaire, R.P., C.G. Lutz, W.R. McClain and M.G. Shirley. 2012. Crawfish News. Volume 5, No. 3, June. LSU Agricultural Center, Baton Rouge, Louisiana, 4 p.
  • Romaire, R.P., C.G. Lutz, W.R. McClain and M.G. Shirley. 2012. Crawfish News. Volume 5, No. 4, July. LSU Agricultural Center, Baton Rouge, Louisiana, 8 p.
  • Romaire, R.P., C.G. Lutz, W.R. McClain and M.G. Shirley. 2012. Crawfish News. Volume 5, No. 5, September. LSU Agricultural Center, Baton Rouge, Louisiana, 4 p.


Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: Findings from crawfish aquaculture research were disseminated to over 100 commercial crawfish farmers at six Louisiana production workshops. Updates on environmental best management practices and crawfish grading and harvesting research were provided to LSU AgCenter extension personnel to use in aquaculture extension programming efforts. Findings from this project were disseminated in five crawfish newsletters mailed to over 1,200 stakeholders. LSU AgCenter crawfish aquaculture research updates were presented to the Louisiana Crawfish Promotion and Research Board. A proposal was submitted to the National Science Foundation, in cooperation with other AgCenter researchers, to study nanomaterial toxicity, transport and fate in crawfish aquaculture environments. A proposal was submitted to the Louisiana Board of Regents Industrial Ties Program, in cooperation with a Louisiana crawfish processor, to investigate the feasibility for extending the marketing opportunities for Louisiana crawfish through cleaning and processing fouled (dirty) crawfish. A project to develop a crawfish habitat suitability index model for wild populations of procambarid crawfishes was funded by the Louisiana Office of Coastal Protection and Restoration. A final report for the project "Management of Aquacultural Effluents for Ponds" was written and submitted for publication by the Southern Regional Aquaculture Center. An LSU AgCenter environmental best management practices manual was published on crawfish aquaculture and an article published in Louisiana Agriculture on water resource use in Louisiana aquaculture. Two abstracts from presentations at the World Aquaculture Society were published. Articles on the LSU AgCenter's crawfish web page were updated and additional publications were added. PARTICIPANTS: R. Romaire (PI), W. McClain, and V. Pfister, LSU AgCenter. TARGET AUDIENCES: The target audiences for this research project are aquaculture researchers and extension specialists in the southern USA, where crawfish are farmed and marketed. Other target audiences include crawfish industry stakeholders (producers and buyers), print-radio-TV media, Louisiana Crawfish Promotion and Research Board, the Louisiana Crawfish Farmers Association, the crawfish advisory committee of the Louisiana Farm Bureau, the Louisiana Wild Crawfish Taskforce and the Louisiana Office of Coastal Protection and Resources. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
In 2011, crawfish were cultivated in nearly 180,000 acres of managed impoundments by 1,200 producers in south-central and southwest Louisiana. Farm-gate impact was estimated to exceed $150 million. Significant harvest of white river crawfish (WRC) from ponds can reduce sales because red swamp crawfish (RSC) are preferred by consumers. Elimination of WRC from production ponds is desirable, but little information is available on the interaction of these two sympatric species that communally occupy shallow water habitats. Outdoor aquatic mesocosms (tanks), planted with rice to simulate commercial crawfish operations, were stocked with RSC and WRC juveniles alone and in-combination (100%RSC, 75%RSC:25%WRC, 50%RSC:50WRC; 25%RSC:75%WRC, 100%WRC) at an optimal total density of 10/m2. After six months, survival of both species was comparable and neither species displaced the other. In experimental treatments where the two species were co-stocked, WRC harvest size (g/individual) was 35 to 65% larger than RCS and yield of WRC (g/m2) was correspondingly higher. No difference in survival, harvest size or yield was observed in treatments stocked with 100% RSC and 100% WRC. Neither species gains a significant completive advantage over the other when juveniles are recruited simultaneously into a population. A crawfish habitat suitability index (HSI) was developed to evaluate the potential effects of coastal protection and wetland restoration projects on crawfish habitat quality. The crawfish HSI model had three component equations that impact habitat quality. Input functions included modeled data on salinity, water temperature, water depth, water level fluctuation and vegetative habitat class. Crawfish HSI output was modeled over a 50-year planning horizon, and the output will be used by coastal planners in wetland restoration projects. The cumulative catch of crawfish with three-funnel pyramid traps, made from 0.75-inch and 0.88-inch square-mesh plastic-coated welded wire, were compared to each other and to a treatment consisting of both trap types in equal number in six large demonstration ponds (two ponds per trap type or trap combination). Crawfish were harvested from January through May (total trap density, 60/hectare; 41 trapping days; 48-h trap-soak). Mean total yield with 0.75-inch square mesh traps (893 kg/ha) was 23% higher than with 0.88-inch square mesh traps (727 kg/ha) or a combination of 0.75-inch+0.88-inch mesh traps (758 kg/ha). The findings of this study were comparable to the findings of an earlier, smaller-scale, research study that showed 0.75-inch traps should catch about 1/3 more crawfish (by weight) than 0.88-inch mesh traps. Mixing the two trap-mesh sizes in equal density did not increase the yield compared to the larger mesh-size. Crawfish yield is increased by using 0.75-mesh traps; but much of the additional harvest is comprised of smaller, less valuable animals.

Publications

  • Lutz, G.,Romaire, R., LeBlanc, B.D., Sheffield,R.E., and Nix, K. 2011. Crawfish Environmental Best Management Practices (BMPs). Louisiana State University Agricultural Center, Publication No. 3186, Baton Rouge, LA. 28 p.
  • Romaire, R. and R.W. McClain. 2011. Procambarid crawfish aquaculture: a look back at the last 40 years of research [abstract]. In: Aquaculture American 2011, Meeting of the USA Aquaculture Society, 2011 February 28-March 3; New Orleans, LA, USA, p 395.
  • McClain, W.R. and R.P. Romaire. 2011. Procambarid crawfish aquaculture: A look ahead at the next 40 years of research needs. In: Aquaculture American 2011, Meeting of the USA Aquaculture Society, 2011 February 28-March 3; New Orleans, LA, USA, p 299.
  • Romaire, R.P., W.R. McClain, and C.G. Lutz. 2011. Water resource use in Louisiana aquaculture. Louisiana Agriculture 54(4):32-33.
  • Romaire, R.P., M. G. Shirley, W.R. McClain, C.G. Lutz, and R.D. Johnson. 2011. Crawfish News. Volume 4, No 1, January. LSU Agricultural Center, Baton Rouge, Louisiana, 4 p.
  • Romaire, R.P., M. G. Shirley, W.R. McClain, C.G. Lutz, , and R.D. Johnson. 2011. Crawfish News. Volume 4, No 2, March. LSU Agricultural Center, Baton Rouge, Louisiana, 4 p.
  • Romaire, R.P., M. G. Shirley, W.R. McClain, C.G. Lutz, , and R.D. Johnson. 2011. Crawfish News. Volume 4, No 3, May. LSU Agricultural Center, Baton Rouge, Louisiana, 4 p.
  • Romaire, R.P., M. G. Shirley, W.R. McClain, C.G. Lutz, , and R.D. Johnson. 2011. Crawfish News. Volume 4, No 4, June. LSU Agricultural Center, Baton Rouge, Louisiana, 4 p.


Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: Findings from crawfish aquaculture research were disseminated to 45 commercial crawfish farmers at two Louisiana production workshops. Research updates were provided to LSU AgCenter extension area agents and specialists for use in crawfish aquaculture extension programming efforts. Generalized findings from this project were disseminated in seven crawfish newsletters distributed to over 1,600 stakeholders. Updates on LSU AgCenter crawfish aquaculture research activities were presented to the Louisiana Farm Bureau crawfish advisory board and the Louisiana Crawfish Promotion and Research Board. Three proposals were submitted to the Southern Regional Aquaculture Center to address RFPs on development of cool-water crawfish baits, identification of crawfish size-grading standards, and quantifying carbon sequestration in aquaculture ponds, including crawfish ponds. A proposal was submitted to the USDA-SBIR program, in cooperation with a Louisiana commercial crawfish producer, to investigate the biological feasibility for extending the availability of live crawfish into late summer and early winter. Scientific journal articles on crawfish harvesting were published in the Journal of Shellfish Research and Freshwater Crayfish, and an article on crawfish stocking density and feeding was published in the Journal of the World Aquaculture Society. Two articles on the LSU AgCenter's crawfish web page were updated. PARTICIPANTS: Romaire, Robert. Professor. Aquaculture Research Station, LSU AgCenter (Principal Investigator); McClain, W. Ray. Professor. Rice Research Station, LSU AgCenter; Pfister, V., Research Associate. Aquaculture Research Station, LSU AgCenter; Barbee, G. Assistant Professor. School of Plant, Environmental and Soil Sciences, Louisiana State University; Matherne, William. Graduate Student, School of Renewable Natural Resources, Louisiana State University; Hardee, David. Graduate Student, School of Renewable Natural Resources, Louisiana State University TARGET AUDIENCES: The target audiences for this research project are aquaculture researchers and extension specialists in the southern USA, where crawfish are farmed and marketed. Other target audiences include crawfish industry stakeholders (producers and buyers), the board of directors of the Louisiana Crawfish Promotion and Research Board, the Louisiana Crawfish Farmers Association, the crawfish advisory committee of the Louisiana Farm Bureau, and the Louisiana Wild Crawfish Taskforce. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
In 2010, crawfish were cultivated in nearly 180,000 acres of managed impoundments by 1,200 producers in south-central and southwest Louisiana. Farm-gate impact was estimated to exceed $160 million. Population density affects crawfish growth, size at harvest, and subsequent value, but the densities at which both yield and size are optimized remains to be determined. Aquatic mesocosms (tanks), planted with rice to simulate commercial crawfish operations, were stocked with juvenile red swamp crawfish at densities ranging from 6 to 16/m2. Harvest size decreased and yield increased with an increase in stocking density. Little or no stunting (high percentage of animals less than 20 g)was observed. Preliminary calculations indicate the density that optimizes harvest size, yield, and gross revenue occurs at densities between 8 and 12/m2. The need to develop formulated baits that effectively attract crawfish in cool water (10 to 20 C) is a priority need identified by the crawfish industry. Three cool-water bait trials were conducted in large experimental crawfish ponds in February (17 to 18 C) to evaluate attractants(fish solubles, fish oil, fish meal, fresh cow blood, sugar, and a mixture of three amino acids - glycine, L-proline, and L-leucine), singly and in combination. Attractants were incorporated into a gypsum matrix as a carrier. Crawfish catch (numbers and weight) with the experimental baits was usually less than half that caught with fresh fish bait (positive control) and 20% less than a commercially formulated warm-water crawfish bait (negative control). Attractants incorporated into an oatmeal+gelatin matrix, formulated by W. Ray McClain, LSU AgCenter, were more effective baits than those incorporated in the gypsum matrix. The cumulative catch of crawfish with three-funnel pyramid traps, made from 0.75-inch (industry standard)and 0.88-inch square-mesh plastic-coated welded wire, were compared to each other and to a treatment consisting of both trap types in equal number, placed in six large demonstration ponds (two ponds per trap type or combination). Crawfish were harvested from January through May (total trap density, 60/hectare; 44 trapping days; 48-h trap-soak). Mean total yield did not differ between 0.75-inch square mesh traps (1,036 kg/ha), 0.88-inch square mesh traps(1,101 kg/ha) or 0.75-inch+0.88-inch mesh traps (1,098 kg/ha). Previous studies showed that 0.75-inch traps usually caught 33 to 40% more crawfish (by weight) compared to 0.88-inch mesh traps in high density ponds. It is probable that no differences in catch among the three trap-type treatments occurred because crawfish densities in the ponds were moderate, crawfish were relatively large (usually > 25 g)and the 48-h trap soak allowed adequate time for the smaller crawfish to escape from the smaller mesh traps.

Publications

  • Romaire, R.P., M. G. Shirley, W.R. McClain, C.G. Lutz, and R.D. Johnson. 2010. Crawfish News. Volume 3, No 7, November. LSU Agricultural Center, Baton Rouge, Louisiana, 4 p.
  • Hardee, D. R. Romaire, and R.W. McClain. 2010. The effects of bait type, trap-soak duration, and a trap modification on harvest of red swamp crawfish [abstract]. In: Proceedings of the 31st Annual Meeting of the Louisiana Chapter of the American Fisheries Society; 2010 January 28-29; Baton Rouge, LA, USA, p 53.
  • Beecher, L.E. and R.P. Romaire, R.P. 2010. Evaluation of baits for harvesting procambarid crawfishes with emphasis on bait type and bait quantity. Journal of Shellfish Research 29(1):13-18.
  • McClain, W.R. and R.P. Romaire. 2010. A perspective on water temperature and crawfish production. Louisiana Farm and Ranch 6(3):24-25.
  • Romaire, R. and E. Villagran. 2010. Evaluation of stocking density and feeding regime on production of red swamp crawfish in outdoor mesocosms. Journal of World Aquaculture Society 41(3):298-307.
  • Romaire, R.P. and Beecher, L.E. 2010. Evaluation of a rotational trapping strategy in procambarid crayfish aquaculture. Freshwater Crayfish 17:61-65.
  • Romaire, R.P., M. G. Shirley, W.R. McClain, C.G. Lutz, and R.D. Johnson. 2010. Crawfish News. Volume 3, No 1, February. LSU Agricultural Center, Baton Rouge, Louisiana, 4 p.
  • Romaire, R.P., M. G. Shirley, W.R. McClain, C.G. Lutz, and R.D. Johnson. 2010. Crawfish News. Volume 3, No 2, April. LSU Agricultural Center, Baton Rouge, Louisiana, 4 p.
  • Romaire, R.P., M. G. Shirley, W.R. McClain, C.G. Lutz, and R.D. Johnson. 2010. Crawfish News. Volume 3, No 3, May. LSU Agricultural Center, Baton Rouge, Louisiana, 4 p.
  • Romaire, R.P., M. G. Shirley, W.R. McClain, C.G. Lutz, and R.D. Johnson. 2010. Crawfish News. Volume 3, No 4, June. LSU Agricultural Center, Baton Rouge, Louisiana, 4 p.
  • Romaire, R.P., M. G. Shirley, W.R. McClain, C.G. Lutz, and R.D. Johnson. 2010. Crawfish News. Volume 3, No 5, Summer. LSU Agricultural Center, Baton Rouge, Louisiana, 8 p.
  • Romaire, R.P., M. G. Shirley, W.R. McClain, C.G. Lutz, and R.D. Johnson. 2010. Crawfish News. Volume 3, No 6, September. LSU Agricultural Center, Baton Rouge, Louisiana, 4 p.


Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: Summary findings from crawfish harvesting research projects were disseminated to nearly 100 commercial crawfish farmers at four Louisiana regional workshops. Research progress updates were presented to LSU AgCenter extension area agents and specialists for use in their crawfish aquaculture extension programming efforts. Findings from this project were disseminated in two crawfish newsletters mailed to nearly 1,400 stakeholders. Research updates on crawfish processing technologies and white spot syndrome virus were presented to the Louisiana Crawfish Promotion and Research Board and the Louisiana Farm Bureau crawfish advisory board. General findings on crawfish production research were discussed with extension counterparts from other states at an extension programming workshop held at World Aquaculture 2009, Seattle, Washington. One scientific journal article on crawfish supplemental feeding was published in Aquaculture, and three manuscripts on stocking density and feeding, rotational trapping and bait evaluation were accepted for publication in the Journal of the World Aquaculture Society, Journal of Shellfish Research, and Freshwater Crayfish. One Master's of Science graduate student, whose thesis research project dealt with crawfish bait and trapping strategies, graduated in December 2009. Several articles published on the LSU AgCenter's crawfish web page were updated. PARTICIPANTS: Romaire, Robert. Professor. Aquaculture Research Station, LSU AgCenter (Principal Investigator); McClain, W. Ray. Professor. Rice Research Station, LSU AgCenter; Pfister, Vernon. Research Associate. Aquaculture Research Station, LSU AgCenter; Matherne, William. Graduate Student. School of Renewable Natural Resources, Louisiana State University; Hardee, David. Graduate Student. School of Renewable Natural Resources, Louisiana State University TARGET AUDIENCES: The target audience for this research project is aquaculture researchers and extension specialists in the southern USA, where crawfish are farmed and marketed. Other target audiences include crawfish industry stakeholders (producers and buyers), the board of directors of the Louisiana Crawfish Promotion and Research Board, the Louisiana Crawfish Farmers Association, the crawfish advisory committee of the Louisiana Farm Bureau, and the Louisiana Wild Crawfish Taskforce. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
In 2009, crawfish were cultivated in an estimated 173,000 acres of production ponds by nearly 1,120 producers located in south-central and southwest Louisiana. Estimated economic impact at the producer level exceeded $115 million. Forage deficiency and its impact on crawfish size at harvest is problematic in the procambarid crawfish industry. Experimental trials conducted in outdoor mesocosms planted with rice as forage revealed that, when compared to planted forage only, harvest size increased 5 to 30% with supplementations of rice seed, whole soybean grain, a mixture of rice seed and soybean, or formulated feed. The yield of crawfish exceeding desirable (20 g) and highly desirable (30 g) market size decreased 30 to 50% when crawfish population density doubled (10/m2 to 20/m2), regardless of feed supplementation. Rice seed was a good feed supplement at 10/m2 but not at 20/m2. Inexpensive, whole raw soybeans supported crawfish growth similar to that provided by expensive formulated feed. Low-cost single feedstuffs, such as whole rice seed and especially whole raw soybeans, may be cost-effective feed supplements for crawfish in ponds with cultivated forage. Pond-based research is needed to determine optimal feeding rates and timing of feed applications so as not to interfere with other components of the production cycle, as well as the economic feasibility of this practice. White river crawfish are problematic in commercial monocrop crawfish ponds because they have lower market value than red swamp crawfish. In a study conducted in outdoor mesocosms planted with rice as forage, survival of red swamp crawfish (35%) was nearly three times higher than white river crawfish (13%) and slightly higher than a 1:1 mix of red and white crawfish (30%). Although size-at-harvest data are being analyzed, survival data clearly demonstrate that a high percentage of white river crawfish can reduce total yield and significantly decrease potential profit to producers. Previous research has shown that crawfish survival and harvest size in forage-based systems is optimal at crawfish densities between 5/m2 and 10/m2 and, that stunting occurs at densities of 15/m2 and higher. A study was conducted in outdoor mesocosms to evaluate survival and growth of red swamp crawfish at densities ranging from 6/m2 to 16/m2. Although size-at-harvest data are still being analyzed, crawfish survival was not correlated with stocking density and overall averaged 51%. The catch efficiency of three-funnel pyramid traps made from 0.75-inch hexagonal twisted wire, and 0.75-inch and 0.88-inch square-mesh welded wire were evaluated in six large experimental crawfish ponds at the Aquaculture Research Station from March through May. No difference in average catch was observed between 0.75-inch hex mesh (508 g/trap/day) and 0.75-inch square mesh (481 g/trap/day) traps. Catch was slightly reduced when using 0.88-inch square mesh traps (454 g/trap/day) but the 0.88-inch traps captured larger, more valuable crawfish. Based on these findings, additional research will be conducted to determine the economic efficacy of larger-mesh traps.

Publications

  • Hardee, D.C. 2009. The effects of bait type, trap-soak duration, and trap modification on harvest of red swamp crawfish. Masters Thesis, Louisiana State University, Baton Rouge, Louisiana, USA. 47 p.
  • McClain, W.R. and R.P. Romaire. 2009. Contribution of different food supplements to growth and production of red swamp crayfish. Aquaculture 294:93-98.
  • Romaire, R.P., M.G. Shirley, W.R. McClain, C.G. Lutz, and R.D. Johnson. 2009. Crawfish News, Volume 2, No 1. LSU Agricultural Center, Baton Rouge, Louisiana, USA.
  • Romaire, R.P., M.G. Shirley, W.R. McClain, C.G. Lutz, and R.D. Johnson. 2009. Crawfish News, Volume 2,No 2. LSU Agricultural Center, Baton Rouge, Louisiana, USA.


Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: A new Louisiana Agricultural Experiment Station research project that addresses production needs for Louisana's crawfish aquaculture industry was approved. Summary findings from water quality and harvesting projects were disseminated to about 70 crawfish producers at five Louisiana regional workshops, and detailed research progress updates were provided to Louisiana Cooperative Extension Service agents and specialists for use in their programming efforts. Findings from this project were disseminated in six crawfish newsletters mailed to over 1,400 stakeholders. Research updates were presented to the Louisiana Crawfish Promotion and Research Board. Water quality impacts on crawfish production were presented at the 17th International Association of Astacology crayfish symposium in Kuopio, Finland. One scientific journal article on crawfish aquaculture water budgets was published in the North American Journal of Aquaculture. Two manuscripts on population management and feeding submitted to the Journal of the World Aquaculture Society, and Aquaculture, and are presently in review. One article on dissolved oxygen measurement and management in crawfish ponds was published on the LSU AgCenter's crawfish web page. PARTICIPANTS: Romaire, Robert. Professor. Aquaculture Research Station, LSU AgCenter (Principal Investigator) McClain, W. Ray. Professor. Rice Research Station (Cooperator), LSU AgCenter. Pfister, V., Research Associate. Aquaculture Research Station, LSU AgCenter. Matherne, William. Graduate Student, School of Renewable Natural Resources, Louisiana State University. Hardee, David. Graduate Student, School of Renewable Natural Resources, Louisiana State University TARGET AUDIENCES: The target audience for this research project is aquaculture researchers and extension specialists, particularly in the southern USA, where crawfish are farmed and marketed. Other target audiences include crawfish industry stakeholders (producers and buyers), and the board of directors of the Louisiana Crawfish Promotion and Research Board, and the Louisiana Crawfish Farmers Association. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
In 2008, crawfish were cultivated in an estimated 178,000 acres of production ponds by nearly 1300 producers located in south-central and southwest Louisiana. High energy expenses have dramatically increased the cost to farmers of managing water during and after flood-up. Empirical monitoring and computer modeling showed that 65 to 81% of total water input is lost in rice-crawfish rotational systems from evaporation, evapotranspiraton, seepage, and water exchange to correct oxygen deficiency. Based on these research findings, water management recommendations were updated and provided to farmers on how best to reduce water use and minimize cost by (1) avoiding early flooding to minimize evaporative water loss and to reduce the need for flushing to correct oxygen deficiency, (2) compacting perimeter levees with appropriate earth moving equipment to curtail seepage loss, and (3) implementing a muskrat control program to reduce seepage through levees from rodent burrowing activity. Harvesting is a major cost in crawfish aquaculture. Studies were conducted to evaluate trap soak-time, bait type and crawfish escape from traps made from square-mesh welded wire, a relatively recent introduction to the industry. A combination of fish plus formulated bait was a better attractant than either fish or formulated bait when used alone. A trap-soak of 24 hours caught more crawfish (number and weight) than a 48-hour soak, but crawfish were larger with the longer soaktime, an important economic consideration for producers. Only 22% of crawfish that entered traps escaped after 24 hours compared to 39% after 48 hours, explaining the reduced catch and larger crawfish observed with the longer soaktime. Based on the results of this study, no change in bait or soaktime recommendations are required because these findings are similar to previous years' studies using hex-mesh traps, on which present harvesting guidelines are based. A pilot study was conducted to evaluate traps with trap entrance funnels modified with plastic retainers to reduce crawfish egress from baited traps. A moderate increase in crawfish catch was observed in modified traps and further research is planned for 2009.

Publications

  • Romaire, R. P. Measuring oxygen in crawfish ponds. [Internet]. Baton Rouge, Louisiana. Louisiana State University Agricultural Center. 2008. http://www.lsuagcenter.com/en/crops_livestock/aquaculture/crawfish/Wa ter+Quality++Management/Measuring+Oxygen+in+Crawfish+Ponds.htm
  • Romaire, R.P., M. G. Shirley, W.R. McClain, C.G. Lutz, , and R.D. Johnson. 2008. Crawfish News. Volume 1, No 1 (Jan), No 2 (Mar), No 3 (May), No 4 (July), No 5 (Sep), and No 6 (Nov). LSU Agricultural Center, Baton Rouge, Louisiana, USA.
  • Zhang, Z. and R. Romaire. 2008. Acute toxicity of hydrogen sulfide to adult red swamp crayfish (Procambarus clarkii). Program and Abstracts, 17th International Symposium of Astacology, Kuopio, Finland. 4-8 August 2008. p. 94 (Abstract).
  • McClain, W. R. and R.P. Romaire. 2008. Water budgets for a rice-crawfish aquaculture system. North American Journal of Aquaculture 70:296-304.