Source: LOUISIANA STATE UNIVERSITY submitted to
IMPROVING HARVEST EFFICACY IN CRAWFISH AQUACULTURE
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
1002992
Grant No.
(N/A)
Project No.
LAB94243
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Jul 1, 2014
Project End Date
Jun 30, 2018
Grant Year
(N/A)
Project Director
Mcclain, W.
Recipient Organization
LOUISIANA STATE UNIVERSITY
202 HIMES HALL
BATON ROUGE,LA 70803-0100
Performing Department
Rice Research Station
Non Technical Summary
Harvesting methods in crawfish aquaculture is limited to a passive, continuous approach, which constitutes the most costly operating expense in crawfish farming. Typically, baited wire-mesh traps at densities of 10 to 20 per acre are lifted 3 to 5 days a week beginning as early as November and continuing through May or June of the following year. Formulated baits are effective during warm-water trapping, but baits for effective cool-water harvests are relegated to cut fresh or frozen fish, which are expensive and may become ecologically unsustainable. Efforts under this project will be directed at investigating means of increasing harvesting effectiveness and efficiency and increasing profits for crawfish producers. Alternative baits and/or formulations will be evaluated for the potential to increase catch and/or reduce cost under both cool- and warm-water harvesting conditions. Investigations will also center on trap modifications, alternative harvesting schedules, and possible bait manufacturing modifications to increase the efficacy of trap harvesting. The biological and economic potential for altering production schedules to achieve an "out-of-season" harvest of crawfish will also be investigated. It is expected that one of the outcomes from this project will be a much better understanding and appreciation of some of the key factors affecting crawfish catch when employing the baited trap. Furthermore, it is anticipated that improved baits and/or bait formulations will be forthcoming and several management recommendations will be developed that can improve harvest efficiencies and/or profits in crawfish aquaculture.
Animal Health Component
0%
Research Effort Categories
Basic
5%
Applied
90%
Developmental
5%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
3073720106060%
3073720107030%
3073720102010%
Knowledge Area
307 - Animal Management Systems;

Subject Of Investigation
3720 - Crawfish;

Field Of Science
1070 - Ecology; 1020 - Physiology; 1060 - Biology (whole systems);
Goals / Objectives
Harvesting costs comprise the largest production expense in farming crawfish. The goal of this project is to develop information and/or management strategies that can be applied on a commercial scale to increase the effectiveness and efficiency of harvesting methodology in crawfish aquaculture. Harvesting of crawfish is relegated to passive processes, typically the baited trap, because of the continued recruitment of animals into the harvestable population, the large, shallow ponds with standing vegetation; and a population consisting of a homogenous mix of hard- and soft-shelled (molted) individuals, all of which precludes more active harvesting methods. Therefore, the overall objective of this research will focus on identifying and improving methods for increasing profits in crawfish aquaculture through improvements associated with trap harvesting. Specific objectives are: (1) identify attractants or formulations that might serve as a suitable alternative to costly and ecologically sensitive cut-fish baits for cool-water trapping; (2) investigate alternative processes for the manufacturing of formulated crawfish baits that provide greater water stability and/or longevity of use; (3) explore means to increase the efficiency of baited traps via trap modifications, alternative harvesting schedules, and/or improved bait alterations; and (4) evaluate the potential for off-season harvests by altering production schedules and management.
Project Methods
To address the stated objectives, research will primarily be conducted at the LSU AgCenter's Rice Research Station in experimental ponds managed to simulate a rice-crawfish field rotational system of production. This production strategy is used in a majority of the acreage devoted to crawfish culture in the state. Some research may also be conducted in neighboring commercial crawfish ponds. A series of outdoor pools (or mesocosms) will be utilized when conditions warrant greater control of key experimental variables, such as crawfish population density or size structure.The two primary experimental designs to be used for research under this project will be a completely randomized design and randomized block (block = pond) repeated measures (= daily crawfish catch) design. A factorial arrangement of treatments may also be appropriate for some trials whereby levels or concentrations of ingredients/attractants will be tested to ascertain minimal or optimal concentrations. Crawfish catch per trap or unit effort (CPUE) and size distribution of harvested crawfish will be the primary parameters assessed during direct harvesting trials. Yields, size distribution, and cost data may be collected and analyzed for off-season experiments. Data will generally be analyzed with the ANOVA procedure using the Micro SAS Statistical Software System.Under objective 1, research will continue to build upon a base of information established in a previous project and will utilize an effective protocol developed as a result of that project. A gelatin-based matrix made without excessive heat or processing was found to be an effective medium to test attractants and will be used to evaluate potential attractants in an in situ manner using actual commercial crawfish traps in experimental and/or commercial crawfish ponds. Experimental ingredients will be tested, both singularly and in combinations, at varying levels of "attractant" concentration by incorporating the material into the gelatin matrix, and the gelatin bait blocks will be placed in crawfish traps. Replicated bait blocks will be of uniform composition and weight and will be evaluated in standard crawfish traps constructed of ¾-inch square mesh coated wire. All attractant combinations will be evaluated and compared to the most commonly used fish baits (cut gizzard shad or menhaden) and at least one commercial formulated crawfish bait. Experimental tests will be conducted in replicated traps over several consecutive days at water temperatures ranging from 50 to 70oF.For objective 2, investigations will seek to evaluate or develop alternative manufacturing techniques or formulations that will increase the water stability of formulated crawfish baits. Current formulated bait products (pellets) typically are effective for up to 24 or 48 hours, depending upon water temperatures. Efforts will focus on new and/or different binders or alternative manufacturing processes all together that could possibly increase the efficacy of formulated baits for longer soak durations and/or allow multiple baitings at the shorter (24-hour) soak duration. For traditional pelleted baits, experiments may include higher levels or combinations of customary feed-type binders. Investigations may also include technology that is used in the food industry or artificial fish bait industry to create a different type of bait product.Under objective 3, various approaches will be investigated to increase the catch efficiency and/or reduce the cost of trap harvesting. First, various trap modifications will be evaluated to decrease the escape rate of crawfish that enter the trap - currently, a serious problem with the standard industry trap as documented by several studies. Several anti-escape devices or modifications to the trap will be tested, first in mesocosms and then in commercial ponds, using accepted marking techniques for crawfish. Impact on egress will also be evaluated. Second, catch per unit effort and per cost factor will be evaluated in a factorial design with trap soak duration, bait type, and water temperature as independent variables to determine the most cost effective trapping strategies under a variance of conditions experienced in commercial crawfish culture. Bait type will include traditional pelleted and cut-fish baits and may also include any new or experimental baits. These efficacy trials may further examine the effects of various characteristics of any new baits or formulations, such as bait hardness or toughness, access level of crawfish to the bait, or bait quantity. Response variables other than typical catch data, may also include bait stability and/or longevity characteristics or bait consumption rates at different water temperatures, soak durations, or access level.Objective 4 is intended to generate largely anecdotal evidence regarding the biological and economic feasibility of extending the crawfish season, with emphasis on supplying live, marketable crawfish from July through October, when supply is virtually non-existent, and increasing supply during the November to February period when supply is short and prices are the highest. Although some biological data may be generated at the research facilities of the Rice Research Station, commercial cooperators will be largely sought for these efforts. Producers with ponds experiencing high populations of stunted crawfish and severe forage deficiency in early spring, creating difficulties in marketing, will be encouraged to drain the ponds and immediately re-plant with rice. It is anticipated that harvest may be able to resume within weeks after flooding as holdover crawfish emerge, feed, and grow. Summer recruits to the population should be harvestable in the fall and throughout winter. Biological and economic data will be collected from several operations, over more than one year, if possible, and summarized to ascertain any preliminary findings regarding this non-traditional crop rotation approach.

Progress 07/01/14 to 06/30/18

Outputs
Target Audience:Target audiences for dissemination of findings from this project include crawfish producers and fishermen, Cooperative Extension agents and specialists, crawfish bait manufacturers and other agribusinesses, aquaculture students, and U.S. and International astacologists and other scientists. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Summer High school interns participate in this project. How have the results been disseminated to communities of interest?Results have been disseminatedto crawfish producers and agribusinesses by publications in farm magazines, reports, presentations atproducers' meetings, and by personal communication. Results have also been incorporated in a book chapter submission. What do you plan to do during the next reporting period to accomplish the goals?This is the final reporting period for this project.

Impacts
What was accomplished under these goals? Two final studies were completed under these project goals in 2017. The first study investigated the effects of bait type on crawfish catch under cool-water temperatures at different times within a season.Specifically, catch data was obtained early in the season when the population density of market-size crawfish is typically low and food resources typically high and then again at peak harvest when food resources are typically more scarce and harvestable density of crawfish higher. While the catch was substantially lower in January, the magnitude of the difference (% increase in catch) between fish baited traps and those baited with Southern Pride were much greater (468%) than the magnitude of the difference at the peak of the harvest season in March (87%).Therefore, the data suggest that fish baits are best employed over the more convenient manufactured baits early in the harvest season, but depending on the various cost variables, net profits are likely to be greaterwhen fish baits are used over manufactured baits whenever water temperatures are consistently below about 65oF, based on this and other previous studies. In the second study, due to the control afforded by large outdoors pools, these simulated pond environmentswere utilizedto test the theory for mitigating overpopulation in crawfish ponds by employing a temporary mid-season drain. Based on an establisheddensity-dependent growth response of crawfish, the theory is that if overcrowding can be adequately corrected early in the season before food resources become depleted and while sufficient molting cycles remain for a population of crawfish, surviving crawfish will exhibit compensatory growth and harvest sizewill be larger. While population density was decreased from 19 to 10 crawfish/m2by the mid-season drain in this study, this reduction was not sufficient to achieve a sizable increase in average size. Further research is needed to determine the best way to predictably achieve desired densities of 4 to 6 crawfish/m2.

Publications

  • Type: Other Status: Published Year Published: 2017 Citation: McClain, W.R. 2017. Exploring a means of reducing bait cost in crawfish production? Louisiana Farm and Ranch. 13(2):28-29.
  • Type: Other Status: Published Year Published: 2017 Citation: McClain, W.R. 2017. Crawfish boil talking points. Louisiana Farm and Ranch. 13(3):14-15.
  • Type: Other Status: Published Year Published: 2017 Citation: McClain, W.R. 2017. Bait considerations for the upcoming crawfish season. H. Rouse Caffey Rice Research Station Newsletter, July 2017.
  • Type: Other Status: Published Year Published: 2017 Citation: McClain, W.R., and J.J. Sonnier. 2016. Annual summary of environmental conditions and crawfish aquaculture research. Ann. Res. Rpt., Rice Res. Stn., La. Agri. Exp. Stn., L.S.U. Agricultural Center, 108:312-334.


Progress 10/01/15 to 09/30/16

Outputs
Target Audience:Target audiences for the dissemination of findings from this project include crawfish producers and fishermen, crawfish bait manufacturers and other agribusiness leaders, Cooperative Extension agents and specialists, aquaculture students, and U.S. and International astacologists and other scientists. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?Results have been disseminated, principally, to crawfish producers and agribusinesses by publications infarm magazines, reports, presentations at parish crawfish producers' meetings, and by personal communication. What do you plan to do during the next reporting period to accomplish the goals?Research will continue to investigatefactors that affect harvest effectiveness and efficiency in crawfish aquaculture and will focus on developing management recomendations for improving yields,harvesting efficacy, and marketing size. Investigations will continue to examine potential bait formulations, harvesting protocols, and methods for assessing and controlling population density.

Impacts
What was accomplished under these goals? Three separate harvest-related studies were completed within this reporting period: 1) Comparison of bait efficacy for cut fish and a formulated crawfish bait at various temperatures; 2) Investigation of means for extending fresh fish in crawfish bait; and 3) Investigation of decreased yields of market-size crawfish as a result of overcrowding. In the first study, results indicated a clear profit advantage when using the cheaper, more convenient formulated crawfish bait at water temperatures above 65oF, but at cooler temperatures fish bait provided greater profits, with those benefits being amplified as water temperature decreased and/or as market prices increased. In the second study, the total amount of fresh cut fish used for crawfish bait could be lowered by 25 to 50% without a significant reduction in catch when minced fish was employed as an ingredient in alginate-based bait blocks.The feasibility or cost savings are questionable at current market prices. Results from the third study may help explain why yields in some crawfish aquaculture ponds fail to meet expectations when young-of-year recruitment appears to be strong and populations appear to be high early in the season. Due to a strong density-dependent growth response, increasing crawfish densities may be associated with increased percentages of the population that fail to reach sizes retained by traps. Increased number and size disparity of sub-market size runts were associated with increased initial population densities.

Publications

  • Type: Other Status: Published Year Published: 2016 Citation: McClain, W.R. 2016. Historic flood of 2016: will it have an impact on crawfish aquaculture yields? Louisiana Farm and Ranch. 12(10):34-35.
  • Type: Other Status: Published Year Published: 2016 Citation: McClain, W.R. 2016. Crawfish stocking dos and donts. Louisiana Farm and Ranch. 12(5):8-10.
  • Type: Other Status: Published Year Published: 2016 Citation: McClain, W.R. 2016. Evolution of the Louisiana crawfish industry. Louisiana Agriculture. Vol. 59, No. 1, Winter 2016.
  • Type: Other Status: Published Year Published: 2016 Citation: McClain, W.R. 2016. Study sheds light on problem with runts in crawfish aquaculture. Louisiana Farm and Ranch. 12(3):30.
  • Type: Other Status: Published Year Published: 2016 Citation: McClain, W.R. 2016. Proper transport and storage of crawfish. Louisiana Farm and Ranch. 12(1):22-23.
  • Type: Other Status: Published Year Published: 2016 Citation: McClain, W.R., and J.J. Sonnier. 2015. Annual summary of environmental conditions and crawfish aquaculture research. Ann. Res. Rpt., Rice Res. Stn., La. Agri. Exp. Stn., L.S.U. Agricultural Center, 107:280-300.


Progress 10/01/14 to 09/30/15

Outputs
Target Audience:Target audiences for the dissemination of findings from this projectinclude crawfish producers and fishermen,crawfish bait manufacturers and other agribusiness leaders,Cooperative Extension agents and specialists, aquaculture students, andU.S. and International astacologists and other scientists. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?Results have been disseminated, principally to crawfish producers and agribusinesses, bypublications in a farm magazine, reports, presentations atparish crawfish producers meetings, and by personal communication. Data is also being summarized for publication in a peer reviewed publication. What do you plan to do during the next reporting period to accomplish the goals?Research will continue to investiage means of understanding the factors that affect harvest effectiveness and efficiency in crawfishaquacultureand will focus on developing management recomendations for improvingyields and harvesting efficacy. Investigations will continue to examine potential attractant alternatives for cool-water trapping, compare catch at various water temperatures with different bait types, determine optimal levels of fish flesh in formulated baits for cool water harvests, and continue to investigate the effects of population density on harvest parameters.

Impacts
What was accomplished under these goals? Four separate studies were completed within this reporting period: 1) Comparison of potential attractant formulations in an alginate-based bait block for cool-water crawfish harvests; 2) Investigation of a proprietary formulation and individual ingredients as potential attractants for crawfish; 3) Effects of water temperature on bait efficacy in crawfish aquaculture: a preliminary assessment; and 4) Effect of crawfish density on size distribution at harvest: year 2. In the first study, the alginate-based matrix proved effective for evaluating potential attractants for harvesting crawfish because differences in catch were clearly discernable andcorrelated to attractant. However, yields of the best combination of attractants were far less than that ofthe control treatment (cut fish). In the second study, a bait manufacturer's proprietary test formulation proved to bemore effective than current commercial formulations in warm waterbut only resulted in half the catchof the industry standard (cut fish) under cool-water conditions. Certain combinations of other test attractants, however, resulted in approximately 80% of the catch with cut fish under similar conditions. It was confirmed in the third study that approximately 70 degrees Fahrenheitis the threshold at which grain-based commercial baits approached parity withfish baits in terms ofcrawfish yield, but the disparity in crawfish catch increased greatly with fish as water temperaturesdecreased below that threshold. In study 4, it was documentedthat size disparity of harvested crawfishclearly increased with increasing crawfish population density, and the number of submarket-size individuals (runts) increased with increasing density.

Publications

  • Type: Journal Articles Status: Accepted Year Published: 2015 Citation: McClain, W.R. 2015. Consumption of rice seed in a Louisiana soil by Procambarus clarkii. Freshwater Crayfish. In press.
  • Type: Other Status: Published Year Published: 2015 Citation: McClain, W.R. 2015. Crawfish pond flood-up: A judgment call. Louisiana Farm and Ranch. 11(10):12-13.
  • Type: Other Status: Published Year Published: 2015 Citation: McClain, W.R. 2015. Aquaculture accounts for extended crawfish season. Louisiana Farm and Ranch. 11(2):34-35.
  • Type: Other Status: Published Year Published: 2015 Citation: McClain, W.R. and J.J. Sonnier. 2015. Crawfish research annual report, Rice Research Station. 106th Ann. Res. Rpt., Rice Res. Stn., La. Agri. Exp. Stn., L.S.U. Agricultural Center, 106:297-322. (Published online in 2015)


Progress 07/01/14 to 09/30/14

Outputs
Target Audience: Target audiences for the dissemination of findings from this project willinclude crawfish producers and fishermen, crawfish bait manufacturers, Cooperative Extension agents and specialists,astacologists, and various other aquatic scientists. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Research will be initiated to continueinvestigating potential attractants as alternatives to cut-fish for cool-water crawfish harvesting. Research will focus on improving the testing protocol for evaluating attractants as well as direct testing of attractants and/or products deemed as suitable candidates. Research will alsobe initiated to investigatetrap modifications to improve catch efficiency of crawfish traps. Findings will be disseminated by a variety of means, as appropriate.

Impacts
What was accomplished under these goals? Data summaries were completed from the final year of theprevious project, and plansfor futurework will continue under this new project. Contact was made with an aquatic feed company that will be sponsoring crawfish baiting research, and preliminary experimental protocols were discussed. A literature search on crustacean attractants was completed.

Publications