Comparison of early season versus late season trap schedules for harvest of red swamp crawfish Procambarus clarkii cultured in earthen ponds without planted forage.ABSTRACT The effect of a redistribution of the majority of total trap harvest days (69) during April through October on yield of red swamp crawfish red swamp crawfish see procambarus clarkii. Procambarus clarkii Procambarus clarkii farmed crustacean in family Astacidae; called also red swamp crawfish. See Table 23. cultured in earthen earth·en adj. 1. Made of earth or clay: an earthen fortification; an earthen pot. 2. Earthly; worldly. ponds without planted forage forage Vegetable food, including corn and hay, of wild or domestic animals. Harvested, processed, and stored forage is called silage. Forage should be harvested in early maturity to avoid a decrease in protein and fibre content as crops mature. was evaluated in northeast Mississippi, USA (Latitude 33.45 and Longitude longitude (lŏn`jĭt  d'), angular distance on the earth's surface measured along any latitude line such as the equator east or west of the prime meridian. 88.82). The majority of trap days occurred from
either April through June (55.1%), early harvest schedule, or July
through October (62.3%), late harvest schedule. Twelve ponds (0.04-0.05
ha), 6 replicates per trap harvest strategy, that already contained
established populations were provided a pelleted pel·let n. 1. A small, solid or densely packed ball or mass, as of food, wax, or medicine. 2. a. A bullet or piece of small shot. b. A stone ball, used as a catapult missile or a primitive cannonball. feed during 10 mo and trap harvested according to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. a common protocol except for the different monthly schedules. For the early and late harvest schedule treatments, mean total production (2448 and 2269 kg/ha), mean number harvested per ha (105,770 and 104,411/ha), and mean individual harvest weight (23.6 and 22.1 g) were not significantly different. These results suggest that the majority of trap harvesting in ponds without planted forage can occur after trap harvest in forage based culture ponds and natural habitats is usually terminated. When traditional supply is low, price and demand can be high in certain markets. This successful shift in harvest days introduces flexibility in management strategies that could be critical to the financial success of an enterprise based on production of crawfish crawfish: see crayfish. in ponds without planted forage. KEY WORDS: red swamp crawfish, Procambarus clarkii, crawfish aquaculture aquaculture, the raising and harvesting of fresh- and saltwater plants and animals. The most economically important form of aquaculture is fish farming, an industry that accounts for an ever increasing share of world fisheries production. in deep earthen ponds INTRODUCTION Previous research has been conducted on red swamp crawfish, Procambarus clarkii, cultured in earthen ponds without planted forage to evaluate feasibility (D'Abramo & Niquette 1991), initial stocking densities (D'Abramo et al. 2003), harvesting schedules (D'Abramo et al. 2003) and addition of substrate to culture ponds (D'Abramo et al. 2006). A summary of these results and the suggested management strategies are summarized in D'Abramo et al. (2002) and D'Abramo et al. (2004). Trap harvesting in traditional or forage-based crawfish production ponds in Louisiana commonly occurs from December though May. Ponds are usually drained in either May or June, and pond bottoms are then dried and planted with an agricultural crop such as rice or sorghum sorghum, tall, coarse annual (Sorghum vulgare) of the family Gramineae (grass family), somewhat similar in appearance to corn (but having the grain in a panicle rather than an ear) and used for much the same purposes. . Ponds can be drained as early as February or as late as August and this management decision is based on economic considerations. Extended harvests in forage-based ponds more likely occur at comparatively higher latitudes. The crawfish harvest season in Louisiana natural fisheries fisheries. From earliest times and in practically all countries, fisheries have been of industrial and commercial importance. In the large N Atlantic fishing grounds off Newfoundland and Labrador, for example, European and North American fishing fleets have long , centered in the Achafalyan Basin, can extend the availability of crawfish into June depending on the amount of rainfall, water level and subsequent boat accessibility within the basin (Huner 1997). Eversole (1988) evaluated two trap harvesting schedules in forage-based ponds in South Carolina South Carolina, state of the SE United States. It is bordered by North Carolina (N), the Atlantic Ocean (SE), and Georgia (SW). Facts and Figures Area, 31,055 sq mi (80,432 sq km). Pop. (2000) 4,012,012, a 15. and despite a significant reduction in forage present, similar production was achieved by utilizing a trap schedule that occurred from April to May or extended through June. June through October is when crawfish are not typically available and price and demand can be high in certain markets. Utilization of this trapping trapping, most broadly, the use of mechanical or deceptive devices to capture, kill, or injure animals. It may be applied to the practice of using birdlime to capture birds, lobster pots to trap lobsters, and seines to catch fish. schedule could provide a producer the ability to extend product availability and provide the opportunity to maximize profit by avoiding harvesting and marketing during periods of high supply and low price. The objective of this experiment was to evaluate the effect of two trapping schedules with different temporal arrangements Noun 1. temporal arrangement - arrangement of events in time temporal order temporal property - a property relating to time chronological sequence, chronological succession, succession, successiveness, sequence - a following of one thing after another of trap days on total production, the number of crawfish harvested per ha and the mean individual weight of harvested crawfish in earthen ponds without planted forage. MATERIALS AND METHODS Experimental Treatments and Ponds There were two experimental treatments, early and late season, referring to when the proportionately higher level of trapping occurred during a 7-mo period of April 1 to October 24. A total of 69 trap days occurred for each of the two treatments. For the early season treatment, 55.1% of the trap days occurred during April through June, whereas for the late season, 62.3% of the trap days occurred from July through October (Fig. 1). Each treatment was randomly assigned to six replicate ponds. [FIGURE 1 OMITTED] A total of 12 freshwater earthen ponds ranging from 0.04-0.053 ha in surface area and a mean depth of 1.2 m were used. The ponds were rectangular shape, between 1.5 and 1.8 m at the deepest point. Ponds were stocked 4 or 5 y before the initiation of this experiment and the resident population of crawfish originated from natural recruitment. All ponds had been in continuous production for 4 or 5 y and had been previously used for experiments investigating various management strategies for the production of red swamp crawfish without planted forage. Vertically suspended within the water column and below the water surface of all the experimental ponds was a substrate consisting of orange, plastic safety barrier fencing (30.5 m length and 1.2 m height). The area of substrate in each pond was equivalent to 50% of the bottom surface area of the pond and was estimated by assuming it was a one-sided solid sheet (36.6 [m.sup.2]). The substrate was attached to 1.5 m steel reinforcement bars (four bars per 30.5 m length of substrate) with twine twine: see cordage. (D'Abramo et al. 2006) and had been in the ponds In the Pond is a 1998 novel by Ha Jin, who has also written Under the Red Flag, Ocean of Winds, and Waiting. He has been praised for his works relating to Chinese life and culture. continuously for three years of growth, harvest and recruitment of crawfish populations associated with previous experiments. Feed A 32% crude protein, sinking, formulated feed manufactured by pelletization (Producers Feed Company, Isola, MS) was added to the experimental crawfish ponds during the entire calendar year. The feed is considered to serve principally as an indirect organic fertilizer rather than a direct source of nutrition, serving to stimulate the rates of natural productivity in the ponds. The total amount of feed provided to each pond during the 12-mo period prior to and during the harvest of crawfish was 6,750 kg/ha. Monthly feeding rates were based on the estimated resident biomass of crawfish and water temperature (Table 1) and followed recommendations of D'Abramo et al. (2002). Harvesting Three funnel (3.8 cm inner diameter entrance) pyramid traps constructed with hexagonal hex·ag·o·nal adj. 1. Having six sides. 2. Containing a hexagon or shaped like one. 3. Mineralogy wire mesh wire mesh, wire netting n → tela metálica (1.9 cm diameter openings) (Gulf Coast Wire Products, Kaplan, LA) were used and positioned along the perimeter of each pond at a density of 81/ha. The traps had necks that extended above the water surface and were longer (60 cm) than the necks of traditional pyramidal traps to accommodate the greater depth characteristic of ponds without planted forage. At the top of the necks, polyvinyl chloride polyvinyl chloride (PVC), thermoplastic that is a polymer of vinyl chloride. Resins of polyvinyl chloride are hard, but with the addition of plasticizers a flexible, elastic plastic can be made. (PVC PVC: see polyvinyl chloride. PVC in full polyvinyl chloride Synthetic resin, an organic polymer made by treating vinyl chloride monomers with a peroxide. ) retaining rings (9 cm height) were located to prevent escape of crawfish through the top of the trap. Each time a trap was baited, approximately 100 g of artificial bait (Gros Rouge Crawfish Bait, Cargill, Minneapolis, MN) was added. Trap days were scheduled differently for each treatment to achieve the necessary number of trap days designated for each month (Fig. 1). Traps were harvested on Monday, Tuesday, Thursday and Friday; or Tuesday, Thursday and Friday; or Thursday and Friday or Friday only to accommodate the necessary number of trap days assigned per month. Soak times for the traps were either 24 or 48 h depending on the number of trap days per week. If the next scheduled trap day was more than 48 h in the future, traps were inverted inverted reverse in position, direction or order. inverted L block a pattern of local filtration anesthesia commonly used in laparotomy in the ox. and reset 24 h prior to the next scheduled harvest. Trapping protocol based on water temperature, as described by D'Abramo and Ohs (2003), was followed. When trapping occurred during warm water conditions (>19[degrees]C), bait was included in the traps. At temperatures between 15[degrees]C and 19[degrees]C, traps were not baited and allowed to soak so crawfish could passively move into the traps, possibly seeking refuge. For each harvest day, the total number and total weight of crawfish harvested from each pond were determined and recorded. Water Quality Water temperature of the ponds was recorded twice daily, and dissolved oxygen was recorded twice daily except during June through September when it was measured three or more times per day. When the dissolved oxygen concentration was anticipated to decrease below 5 ppm, aeration aeration /aer·a·tion/ (ar-a´shun) 1. the exchange of carbon dioxide for oxygen by the blood in the lungs. 2. the charging of a liquid with air or gas. aer·a·tion n. was provided to the ponds by a 0.5 hp aerator aer·a·tor n. One that aerates, as a machine for aerating turf or a device for aerating liquids. Noun 1. aerator - an apparatus for exposing something to the air (as sewage) (Aerolator Corp., Kansas City Kansas City, two adjacent cities of the same name, one (1990 pop. 149,767), seat of Wyandotte co., NE Kansas (inc. 1859), the other (1990 pop. 435,146), Clay, Jackson, and Platte counties, NW Mo. (inc. 1850). , MO). Additional, emergency aeration was provided by a tractor driven paddlewheel when the dissolved oxygen concentration decreased below 3 ppm. Every third day, from May through August, pH was measured and recorded at approximately 13:00. All ponds were treated with gypsum gypsum (jĭp`səm), mineral composed of calcium sulfate (calcium, sulfur, and oxygen) with two molecules of water, CaSO4·2H2O. It is the most common sulfate mineral, occurring in many places in a variety of forms. at approximately 181.6 kg/ha in June as a prophylactic treatment prophylactic treatment n. The institution of measures to protect a person from a disease to which he or she has been, or may be, exposed. Also called preventive treatment. to minimize the potential for potentially lethal alkaline pHs to occur. Statistics A one-way analysis of variance (ANOVA anova see analysis of variance. ANOVA Analysis of variance, see there ) was used to determine if differences existed between treatments for mean production (kg/ha), number of crawfish harvested (number/ha) and overall mean individual weight (g) (SAS (1) (SAS Institute Inc., Cary, NC, www.sas.com) A software company that specializes in data warehousing and decision support software based on the SAS System. Founded in 1976, SAS is one of the world's largest privately held software companies. See SAS System. 1988). Differences were considered significant at P [less than or equal to] 0.05. RESULTS There were no significant differences between treatments in mean total production (P = 0.48), mean number harvested per ha (P = 0.93), or mean individual weight of harvested crawfish (P = 0.19) (Table 2). The 20.3% increase in the number of trap days that occurred in June through October for the late season treatment resulted in a corresponding 16.5% increase in total production and a 15.3% increase in the number of crawfish harvested during this same period. Accordingly, by assigning more trap days later in the harvest season (June through October) the total amount of crawfish harvested increases by approximately 375 kg/ha. Monthly trap days, harvest yield (kg/ha) and number harvested/ha, expressed as a percentage of the total, are presented in Table 3. DISCUSSION The results of this investigation provide insight into the true seasonality of crawfish production at the latitude where the study occurred. Obtaining this information is only possible through the use of a management practice that does not include planted forage. By utilizing the management strategies in the present experiment, it seems that production of 2200-2500 kg/ha/year can be perpetually achieved in properly managed 0.5 ha earthen ponds during a 7 mo period with 69 trap days, regardless of which of the present study's trapping schedules is followed. Recently initial attempts to incorporate this method of crawfish production into one 0.81 ha pond produced harvested annual yields slightly less (~2000 kg/ha) than what has been achieved in the experimental ponds. Farmers who use earthen ponds without planted forage do have the option of these two management strategies for harvest. In the current study, only 20.3% of the trap days were shifted from April and May to June through October. Previous research has shown that trap days can extend over a 12-mo period during some years with a possible exception of January and February, typically the coldest months of the year (D'Abramo et al. 2003). Therefore, it may be possible to shift more trap days to later in the year with a corresponding reduction in trap days in March. Nonetheless, sufficient trapping effort should most likely be maintained during April and May when the resident biomass of crawfish is highest. This strategy of continued removal by harvest should reduce the possibility of decreased growth and production, which could occur if high population densities are allowed to persist for prolonged pro·long tr.v. pro·longed, pro·long·ing, pro·longs 1. To lengthen in duration; protract. 2. To lengthen in extent. periods. In addition, an appropriate level of harvesting of the resident population probably contributes to reductions in cannibalism cannibalism (kăn`ĭbəlĭzəm) [Span. caníbal, referring to the Carib], eating of human flesh by other humans. and emigration emigration: see immigration; migration. . The maximum trapping effort that can be imposed without altering the rate of natural recruitment is not known. Mean individual weight data collection over many years of experiments have shown that in a typical 0.05 ha research pond, a reduction in mean individual size does not occur until more than 100 trap days per year are extended over 10 mo (D'Abramo et al. 2003). It may be possible to maintain the same trapping effort during periods of the highest population density and further increase the number of trap days to the later portion of the harvest season. This strategy may further increase total production and potential profit, whereas not reducing the resident population to a level whereby natural recruitment for harvest during the following year is adversely affected. Wholesale prices for crawfish vary from month to month. Mean monthly wholesale prices in Louisiana are $3.85 per kg in November and decrease to $1.32 per kg in June (Romaire et al. 2005). In Louisiana, the lack of a cultured or captured product from July to October means a wholesale price does not exist. If available from July to October in Louisiana, the product may not likely command the November price of $3.85 per kg because of lower demand caused by a large supply of other readily available seafood such as crabs and shrimp. The application of wholesale prices of crawfish in Louisiana to markets outside of Louisiana CODE, OF LOUISIANA. In 1822, Peter Derbigny, Edward Livingston, and Moreau Lislet, were selected by the legislature to revise and amend the civil code, and to add to it such laws still in force as were not included therein. is difficult because 90% of the crawfish produced there are consumed locally (Romaire et al. 2005). As part of the economic analysis in a previous publication on nonforage-based crawfish production systems (D'Abramo et al. 2002), a mean price of $3.31 per kg was used for the entire year. This is likely a conservative estimate from July through October, but is a good price estimate throughout the entire year in markets outside of Louisiana. Another notable difference between Louisiana markets and markets outside the region is the marketing chain and the various steps involved from producer to consumer in Louisiana (Romaire et al. 2005). These multiple steps to reach the consumer spread revenue to businesses in the various steps whereas in other regions the producer may receive a higher price because they market directly to the consumer or to a single wholesaler prior to the product reaching the consumer. Similar or higher selling prices could also be obtained by capitalizing on a seasonally based sale of crawfish as fish bait. In the present study, utilizing the late season trapping schedule and shifting 20.3% of trap days from April and May to June through October increased production during the same time period by 16.5%. The critical information from this study for a producer is that there is no significant difference in production between the two trap schedules. A late season trap schedule can extend availability of product to later in the year during periods when prices may be higher, depending on local demand and the marketing effort of the producer. This could increase annual gross receipts the total of the receipts, before they are diminished by any deduction, as for expenses; - distinguished from net profits. - Bouvier. See under Gross, a. os> See also: Gross Receipt and the potential profit of a nonforage based earthen pond crawfish production operation. ACKNOWLEDGMENTS The authors thank the staff of the Eastern Unit of the National Warmwater Aquaculture Unit for their assistance in the management of the water quality of the experimental ponds, the distribution of teed to the ponds, and the harvest of crawfish. The research was supported by the United States Department of Agriculture United States Department of Agriculture (USDA), n.pr established in 1862, USDA is responsible for the safety of meat, poultry, and egg products. It conducts ongoing research in areas from human nutrition to new crop technologies and also helps ensure open through a special grant for aquaculture research, and approved by the UF/IFAS Indian River Indian River, lagoon, c.100 mi (160 km) long, E Fla., parallel to the east coast from N of Titusville to Stuart. Along the lagoon a variety of citrus and vegetable products are grown and transported by small boats to towns on its waterway and those further inland. REC for publication as Journal Series Number R-020606. LITERATURE CITED D'Abramo, L. R. & D. J. Niquette. 1991. Seine Seine (sān, Fr. sĕn), Lat. Sequana, river, c.480 mi (770 km) long, rising in the Langres Plateau and flowing generally NW through N France. harvesting and feeding of formulated feeds as new management practices for pond culture of red swamp crawfish, Procambarus clarkii (Girard, 1852), and white river crawfish. J. Shellfish shellfish, popular name for certain edible mollusks (see Mollusca), e.g., oysters, clams, and scallops, and for certain edible crustaceans, e.g., crabs, lobsters, and shrimps. All are aquatic invertebrates with shells; they are not fish. Res. 10(1):169-177. D'Abramo, L. R., C. L. Ohs, T. R. Hanson & J. L. Montanez. 2002. Production of the red swamp crayfish The swamp crayfish, Tenuibranchiurus glypticus, is a tiny freshwater crayfish that occurs in freshwater waterways in Queensland, and is the smallest known species of crayfish. Procambarus clarkii in earthen ponds without planted forage: management practices and economics. Mississippi Agricultural and Forestry Experiment Station Bulletin 1115. D'Abramo, L. R., C. L. Ohs & K.C. Elgarico. 2003. Production of red swamp crawfish (Procambarus clarkii) in earthen ponds without planted forage: Evaluation of trap and seine harvest strategies. J. Shellfish Res. 22(2):527-531. D'Abramo, L. R. & C. L. Ohs. 2003. Production of red swamp crawfish (Procambarus clarkii) in earthen ponds without planted forage: establishment, maintenance, and harvest of populations. J. Shellfish Res. 22(2):521-525. D'Abramo, L. R., C. L. Ohs, T. R. Hanson & J. L. Montanez. 2004. Semi-intensive production of red swamp crawfish in earthen ponds without planted forage. Southern Regional Aquaculture Center Publication Number 2401. D'Abramo. L. R., C. L. Ohs & K.C. Elgarico. 2006. Effects of added substrate on production of red swamp crawfish (Procambarus clarkii) in earthen ponds without planted forage. Journal of the World Aquaculture Society (In press). Eversole, A. G. 1988. Diversification of crawfish management schedule. J. Shellfish Res. 7(1):211. Huner, J. V. 1997. The capture and culture fisheries of North American North American named after North America. North American blastomycosis see North American blastomycosis. North American cattle tick see boophilusannulatus. crawfish. World Aquaculture 28(4):44-50. Romaire, R. P., W. R. McClain, M. G. Shirley & C. G. Lutz. 2005. Crawfish Aquaculture Marketing. Southern Regional Aquaculture Center Publication Number 2402. 8 pp. SAS Institute SAS Institute Inc., headquartered in Cary, North Carolina, USA, has been a major producer of software since it was founded in 1976 by Anthony Barr, James Goodnight, John Sall and Jane Helwig. . 1988. SAS/STAT users guide, release 6.03., Cary, North Carolina Cary is the second largest municipality in Wake County, North Carolina and the third largest municipality in The Triangle (North Carolina) behind Raleigh and Durham. It is the seventh largest municipality in North Carolina. : SAS Institute. 1056 pp. CORTNEY L. OHS (1) AND LOUIS R. D'ABRAMO (2) (1) University of Florida University of Florida is the third-largest university in the United States, with 50,912 students (as of Fall 2006) and has the eighth-largest budget (nearly $1.9 billion per year). UF is home to 16 colleges and more than 150 research centers and institutes. Institute of Food and Agricultural Sciences The University of Florida’s Institute of Food and Agricultural Sciences (UF/IFAS) is a federal-state-county partnership dedicated to developing knowledge in agriculture, human and natural resources, and the life sciences, and enhancing and sustaining the quality of human Indian River Research and Education Center 2199 South Rock Road Fort Pierce Fort Pierce, city (1990 pop. 36,830), seat of St. Lucie co., SE Fla., on Indian River (a lagoon; part of the Intracoastal Waterway); settled in the 1860s around a fort; inc. 1901 as a city. , FL 32945; (2) Mississippi State University Mississippi State University, at Mississippi State, near Starkville; land-grant and state supported; coeducational; chartered 1878 as an agricultural and mechanical college, opened 1880. From 1932 to 1958 it was known as Mississippi State College. Department of Wildlife and Fisheries Box 9690 Mississippi State, Mississippi 39762 Corresponding author. E-mail: ldabramo@cfr.msstate.edu
TABLE 1.
Monthly and annual number of days and amount of feed provided
to each of the experimental ponds.
kg/ha % of Total Days/Montt
January 0 0 0
February 0 0 0
March 0 0 0
April 1744 20.5 30
May 1097 17.4 31
June 1041 16.5 30
July 788 12.5 31
August 506 8.1 31
September 450 7.1 30
October 506 8.1 31
November 422 6.7 30
December 197 3.1 15
Total 6750 100.0 259
TABLE 2.
Mean total production, mean number harvested, and mean
individual weight of crawfish harvested from experimental earthen
ponds according to early and late season harvest treatments.
Mean Total Mean Number
Production Harvested
Treatment (kg/ha) (number/ha)
Early season 2448 [+ or -] 160 105,770 [+ or -] 9296
Late season 2269 [+ or -] 185 104,411 [+ or -] 10,915
Mean
Individual
Treatment Wt. (g)
Early season 23.6 [+ or -] 0.69
Late season 22.1 [+ or -] 0.83
TABLE 3.
Monthly trap days, harvest weight (kg/ha), and number of crawfish
harvested per ha expressed as a percentage of the total for each of
the early and late season harvest treatments.
Early Late Early Late Early Late
Season Season Season Season Season Season
days/mo days/mo kg/mo kg/mo num/mo num/mo
Month % % % % % %
April 17.4 7.2 9.2 3.9 9.0 4.2
May 20.3 10.1 20.2 8.9 20.7 10.3
June 17.4 20.3 22.9 29.7 25.2 31.9
July 18.8 21.7 20.6 21.9 22.1 22.8
Aug 11.6 17.5 10.0 13.7 9.6 12.8
Sept 8.7 14.5 9.3 11.7 7.5 9.7
Oct 5.8 8.7 7.8 10.2 5.9 8.3
Total 100 100 100 100 100 100
|
|
||||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion