Siddhartha Dasgupta

A Preliminary Assessment of Growth, Survival, Yield, and Economic Return of Australian Red Claw Crayfish, Cherax quadricarinatus, Stocked at Three Densities in Earthen Ponds in a Cool, Temperate Climate

Abstract Juvenile (mean weight 8.1 g) Australian red claw crayfish, Cherax quadricarinatus, were stocked in July at three rates of 12,000/ha, 18,000/ha, and 24,000/ha into two, 0.02-ha earthen ponds in a cool temperature region of the United States (Kentucky) and grown for 70 days. Red claw were fed a pelleted marine shrimp diet twice daily. Ponds had continual aeration provided. Dissolved oxygen and temperature were measured twice daily (0900 and 1530 hours); total ammonia nitrogen (TAN), nitrite, and alkalinity were measured twice weekly; and pH was measured daily. At harvest, there were no significant (P > 0.05) differences in final individual weight, percentage weight gain, specific growth rate, feed conversion ratio, percentage survival, yield, and economic return among all treatments and averaged 58.4 g, 805%, 3.04%/ day, 7.47,42.7%, 461 kg/ha, and -

A Breakeven Price Analysis of Four Hypothetical Freshwater Prawn, Macrobrachium rosenbergii, Farms Using Data from Kentucky

2659/ha, respectively. There were no significant (P > 0.05) differences in the percentage of males and females harvested from the ponds among any stocking rate with males comprising 48.2% and females comprising 51.8%. Final individual weight of males and females was not significantly (P > 0.05) different among all treatments. These data indicate that there is no advantage to stocking red claw at rates below 24,000/ha in terms of growth, survival, yield, and economic return and that red claw can grow to marketable size in a cooler temperate region of the United States with a short (<110 days) growing season by stocking a larger-size (8 g) red claw.

Use of Turkey Meal as a Replacement for Menhaden Fish Meal in Practical Diets for Sunshine Bass Grown in Cages

ABSTRACT Freshwater prawn, Macrobrachium rosenbergii, are a relatively recent aquaculture crop in Kentucky and neighboring states. Kentucky State Universitys Aquaculture Research Center (ARC) has been involved in prawn production research in ponds since 1991. Technologies prior to 1996 involved stocking juveniles at relatively low densities (20,000-40,000/ha) and feeding a 32% protein diet, resulting in an average yield of approximately 1,000 kg/ha. From 1996 onwards, artificial substrate has been installed in ponds, which offer greater habitable area, and have increased average yields to more than 1,500 kg/ha (in 1998). Although stocking and feeding rates increased with substrate use, the average feed conversion ratio decreased, indicating more efficient feed usage. From 1998 onwards, a phase feeding practice, with higher feeding rates, was introduced. This involved feeding prawn distillers grains, 32% protein feed, and 40% protein feed at different stages of the growout period. These feeding practices, in conjunction with a higher stocking density, substrate use, etc., have produced average yields in excess of 2,500 kg/ha (in 1999 and 2000). While the technological evolution has steadily increased average yields, production costs have also increased. However, breakeven price of production (in year 2000 dollars/kg) decreased from

SELLING FRESHWATER PRAWN IN FOOD FESTIVALS: A MARKETING EXPERIMENT IN KENTUCKY

18.37/kg (1991) to

Can commercial catfish producers always feed efficiently

9.93/kg (2000). Breakeven price analyses, taking output, input quantity, and price risk into consideration, indicate that the technology developed in 2000, using intensive stocking, phase feeding and artificial substrate, is the most competitive.

Effects of Stocking Density on Nursery Production and Economics of the Freshwater Prawn, Macrobrachium rosenbergii

Abstract A 391-d feeding trial was conducted with caged juvenile (mean weight = 36.2 g, SD = 8.04 g) sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis) to evaluate growth, feed conversion, protein efficiency ratio, body composition, and fillet composition resulting from diets with decreasing levels of fish meal (FM; 30, 20, 10, and 0%) and increasing levels of turkey meal (TM; 0.0, 9.7, 17.5, and 26.4%). We stocked 100 randomly selected fish into each of 12 floating cages (3.5 m3). Twice daily, fish were fed all they could consume in 30 min. Four practical diets were formulated to contain 40% protein and to be isoenergetic. After 391 d, significant (P ≤ 0.05) differences were found in growth; fish fed the control diet (30% FM, 0% TM) had higher individual final weight, percent weight gain, and specific growth rate than fish fed 10.0% FM and 17.5% TM. However, differences for those variables were not apparent between the control group and fish fed the 20% FM and 9.7% TM diet...

Stable Car bon Iso tope Ratios and Stan dard Pro duction Data as Indices of Golden Shiner, Notemigonus crysoleucas, Per for mance in Pond Feed ing Trials

This paper evaluated consumer perceptions of cooked freshwater prawn sold in festivals. Data were collected from prawn consumers attending the Kentucky State Fair and Garretts Festival (in Lexington, Kentucky) on knowledge of prawn, seafood consumption frequency, proclivity of purchasing locally grown food, etc. A conjoint experiment was conducted in which respondents rated nine hypothetical plates of cooked prawn, differing from one another by the number of prawns, price, cooking style, and the presence or absence of side items. Results from data analyses indicated that the Garretts Festival respondents were more educated and had more knowledge of prawns than the State Fair respondents. The State Fair respondents, while indifferent to the prawn cooking style, considered the products price to be more important than the Garretts Festival respondents. All results suggest that vendors would be more successful in dedicated prawn festivals than participating in festivals of general interest, such as the State Fair.

Characteristics of Baitfish Retailers in Kentucky: Evidence of a Market to Support a Regional Industry

Abstract Economically efficient feeding levels in intensively stocked ponds might be below minimum biological feeding requirements under adverse market conditions. A catfish production function that estimated relationships between yield and stocking and feeding rates was used as the basis for estimating production relationships. Feed price boundaries were developed that allowed the feeding rate to exceed the minimum biological level but still reflected economically efficient rates over a range of catfish prices and producer risk preferences. At higher stocking densities (20,000/ha), the feed price upper bound is lower than at lower stocking densities. Producers stocking at higher rates will be less likely to maximize profit and meet minimum biological feeding requirements as feed price increases than those producers stocking at lower rates. However, if feed prices exceed the upper bounds calculated in this paper, producers should engage in feeding only at levels necessary to meet farm financial and cash flow obligations until such time as the feed price decreases.

Impact of Low Catfish Prices on Economically Efficient Feeding and Optimal Stocking Densities of Channel Catfish, Ictalurus punctatus, in Multi-Batch Production in the U. S. South

ABSTRACT In temperate regions, post-larvae freshwater prawn, Macrobrachium rosenbergii, are grown to more advanced sizes in tanks prior to pond stocking. This intermediate stage of culture is referred to as the nursery period. Little research has been conducted on different management practices on juvenile prawn growth and survival during this 30-60 day period. Survival during the nursery stage has been highly variable and may be related to the cannibalistic behavior of juvenile freshwater prawn when cultured at high densities in the nursery. The objective of this study was to evaluate the effect of stocking density, relative to the provision of artificial substrate (number of prawns/m2 of substrate), on growth, survival, and economic variables for freshwater prawn juveniles during nursery production. Post-larvae (0.01%0.00 g, n = 300) were stocked into nine 1900 L tanks, each provided with 20.5 m2 of artificial substrate in the form of horizontal layers of black plastic mesh (10 mm) spaced 5 cm apart. Tanks were randomly assigned one of three prawn densities (215, 430, or 860 post-larvae/m2 of substrate), which equated to 2.3,4.6 and 9.2 prawn/L, respectively. Juvenile prawn were fed a commercial trout diet (42% protein) at a percentage of body weight according to a feed rate table. Water quality was maintained using a flow rate of 8 L/min in each tank from a reservoir pond. Temperature was maintained at approximately 28°C using heat pumps. After 56 days there was no significant difference (P >0.05) in average weight of juvenile prawn stocked at the three densities (0 = 0.58%0.12 g, n = 9). Survival was significantly lower (P <0.05) for prawn stocked at 860 m2 (62%) than in those stocked at 430/m2 (78%) and 215/m2 (94%), which were not statistically different (P >0.05). Even with reduced survival, the highest stocking density produced the greatest number of nursed juveniles based on both tank volume (5.5/l) and surface area (530/m2), at the lowest average cost.

THE ECONOMICS AND MANAGEMENT OF SMALL-SCALE FISH PROCESSING PLANTS USING PADDLEFISH PROCESSING DATA FROM KENTUCKY

Abstract This study shows the ef fect of production variables on assimilation of foods by golden shin ers, Notemigonus crysoleucas, in ponds was ex am ined in con cur rent 8-week feed ing tri als at the Uni versity of Ar kan sas at Pine Bluff (UAPB) and Texas A&M Uni ver sity (TAMU). Ten 0.04-ha ponds per site were fer til ized with defatted rice bran and stocked with golden shin ers (ini tial weight = 1.3 g) at a rate of 750,000/ha (UAPB) or 375,000/ha (TAMU). Fish in five ponds per site were fed a nu tri tion ally com plete pre pared diet at 4% of body weight, while fish in the re main ing ponds were not fed. As sim i la tion of nat u ral foods by “unfed” fish was com pared to that of fish fed the pre pared diet at each site. Stan dard pro duc tion data (weight gain, Secchi depth, dissolved ox y gen [DO]) were com pared to sta ble car bon iso tope ra tio (d1 3 C) data as an in dex of fish per for mance (weight change or fish d13 C, re sult ing from as sim i la tion of var i ous food sources). Fish weight change and fish iso tope ra tio were re gressed sep a rately against in de pend ent vari ables (feed amount, Secchi depth, DO, fed/unfed dummy vari able, and study site dummy vari able) to de ter mine their re la tion ships. Nat u ral pro duc tiv ity was con sis tently lower at TAMU than at UAPB, while temper a ture and min i mum DO were sim i lar be tween sites. Weight gains of fed and unfed fish at TAMU were higher than those of fed and unfed fish at UAPB. The d13 C of fed and unfed fish at UAPB changed lit tle dur ing the study and did not al low dis crim i na tion among their food sources. The d13 C of fed fish at TAMU ap proached that of the pre pared diet, while that of unfed fish re sem bled that of the plank ton and rice bran. Pre pared diet quan tity and the study site sig nif i cantly (P > 0.1) af fected fish weight change, but Secchi depth and min i mum DO did not. Weight gain increased with in creas ing diet in put up to a max i mum value, then de clined with ad di tional in puts. Min i mum DO, plank ton iso tope ra tio, and the fed/unfed and site vari ables sig nif i cantly af fected fish iso tope ra tio.