Shawn D. Coyle

Relative prawn production and benthic macroinvertebrate densities in unfed, organically fertilized, and fed pond systems

Abstract Relative prawn production rates in unfed, organically fertilized, and fed pond systems were evaluated. Populations of benthic macroinvertebrates that potentially serve as forage organisms in these systems were also evaluated and compared with ponds without prawns to evaluate forage preferences. Juvenile prawns (x = 0.36 ± 0.02 g) were stocked into nine 0.04 ha ponds at a density of 39 520 ha −1 . Prawns in three ponds were not fed, prawns in three ponds were fed a complete diet, and three ponds received organic fertilization. Three additional ponds (0.02 ha) served as controls (not stocked with prawns and received no nutrient input). Survival averaged 86%, overall, and was not significantly different among treatments. Average weights of prawns fed complete feed or raised in fertilized ponds (36 and 33 g, respectively) were not significantly different ( P > 0.05). Prawns in unfed ponds were significantly ( P ≤ 0.05) smaller (13 g). Average prawn yields in fed, fertilized, and unfed ponds (1261, 1056, 426 kg ha −1 , respectively) were all significantly different ( P ≤ 0.05). In ponds receiving no nutrient input, macroinvertebrate densities were significantly higher ( P ≤ 0.05) in ponds without shrimp (controls) than in those stocked with shrimp. In ponds stocked with shrimp, macroinvertebrate densities in fed and fertilized treatments were significantly greater ( P ≤ 0.05) than in the unfed treatment, but not significantly different ( P > 0.05) from each other. Insect taxa showed a greater negative response to prawn predation than non-insects. Non-insect taxa demonstrated a more positive response to fertilizer and feed than insects. Although prawn production in organically fertilized ponds was surprisingly high (>1000 kg ha −1 ), economic analysis demonstrated higher net returns when prawns were fed a prepared diet, principally due to the production of greater numbers of large, high value prawns.

Effects of dietary protein level on second year growth and water quality for largemouth bass (Micropterus salmoides) raised in ponds

Abstract Juvenile largemouth bass (122.1 ± 2.6 g), trained to accept artificial diets, were stocked into nine 0.04 ha ponds at a density of 12350 fish ha −1 and fed one of three practical diets containing either 42, 44, or 47% protein (dry weight). Fish meal composed a constant percentage (53%) of the dietary protein in each diet. Fish were fed all they would consume in 30 min once daily for 12 months (May 1994–May 1995). At final harvest, fish fed the 47% protein diet had significantly higher ( P −1 ), and survival (99%), and significantly lower ( P P > 0.05) from fish fed either 42% or 47% protein. Averaged over the study period, total ammonia-nitrogen (TAN) concentrations were significantly higher ( P P

The effects of size grading and length of nursery period on growth and population structure of freshwater prawns stocked in temperate zone ponds with added substrates

Abstract In temperate regions, the relatively short growing season increases the need for development of technologies to maximize growth and production rates for freshwater prawns. Studies have shown that new technologies, such as adding artificial substrates, increasing feeding rates, using advanced nursed juveniles, and grading of juveniles prior to stocking, can increase production without sacrificing average weights. While these technologies have been evaluated in isolation, it may be possible to further increase production by combining these technologies. This study evaluated the impacts of size grading of nursed juveniles prior to pond stocking and the effects of extending the nursery period (from 61 to 133 days) when combined with added substrate in temperate ponds. Three treatments were evaluated: 61-day ungraded juveniles (current regional technology; controls), 61-day graded juveniles, and 133-day graded juveniles. Individual mean stocking weights for the three treatments were 0.67, 0.72, and 3.1 g, respectively. All ponds were stocked at 59,280 ha −1 and were provided with artificial substrate in the form of polyethylene “safety fence” oriented vertically at a rate sufficient to increase available surface area in the ponds by 50%. Compared to control ponds (61-day ungraded), grading of 61-day juveniles significantly increased ( P −1 , respectively), production/size index (PSI), and daily yield. Extending the nursery period (and thereby increasing the average stocking weight) did not significantly improve ( P >0.05) total production or average individual weight. Feed conversion ratios were significantly higher for 133-day juveniles compared to controls (2.8 vs. 2.3). The failure of animals weighing over 350% more at stocking to increase average weights or total production at harvest appears to be due to earlier sexual maturation and the resulting cessation of growth.

Effects of stocking different fractions of size graded juvenile prawns on production and population structure during a temperature-limited growout period

Abstract Size grading of juvenile prawns prior to pond stocking is used to disrupt negative social interactions. Animals graded off the upper end of the size range can outperform ungraded animals by 20–50%. However, reports differ on the performance of the lower grade fraction. Some studies indicate that lower grade prawns can out perform ungraded populations within a 120–140-day growing season while other studies indicate that >140 growing days are required. The objective of this study was to compare the growth of this lower grade fraction with the upper grade fraction and an ungraded fraction of the same population within a temperature-constrained growing season of 100–120 days. Prawn juveniles that had been nursed 60 days were separated into three groups. Approximately 50% of the population was maintained ungraded with the full range of size variation. The other 50% was separated into two fractions (large=upper grade; small=lower grade) using a #13 bar grader (0.5-cm spacing). Ponds were randomly assigned to receive one of the three treatments (ungraded controls, upper grade, and lower grade) with average stocking weights of 0.5±0.3, 0.8±0.4, and 0.2±0.1 g ( x ±S.D.), respectively. There were three replicate 0.04-ha ponds per treatment. All ponds were stocked at 59,280 ha −1 . Artificial substrate was added to ponds at a rate to increase available surface area by 50%. After 104 days, there was no significant difference ( P >0.05) in survival of prawns from the three fractions (overall average 88%). Total production, marketable production (>20, >30 g) and average individual weight was significantly greater ( P P >0.05) in total production or average individual weight of prawns stocked from the ungraded or lower graded fractions. Impacts of grading procedures on population structures were much more pronounced in females than in males with upper graded animals having a significantly higher ( P ≤0.05) percentage of sexually mature reproductive females. Compared to ungraded juveniles, projected net returns were lower for lower graded prawns, higher for upper graded, and higher for combined lower and upper under all model farm scenarios. In summary, stocking of the upper graded fraction increased total production, average weights, and marketable production. There was no difference in lower graded and ungraded animal production variables.

Effects of Different Types of Dietary Lipids on Growth and Fatty Acid Composition of Largemouth Bass

Abstract The effects of feeding diets supplemented with oils of varying sources and fatty acid compositions on growth, survival, and biochemical composition of juvenile largemouth bass Micropterus salmoides were evaluated under controlled conditions in aquaria for 12 weeks. Feed-trained juvenile largemouth bass (15.7 ± 0.6 g) were stocked into eighteen 114-L glass aquaria at 25 fish/tank and were fed one of five experimental diets (3 replicate aquaria/diet). All diets were formulated to be approximately isocaloric (4,200 kcal gross energy per kilogram) and isonitrogenous (40% crude protein), containing protein primarily from solvent-extracted fish meal and soybean meal. Each diet was supplemented with 5% oil (by weight) using lipids from various sources and with different fatty acid compositions. These included fish oil, corn oil, sunflower oil (high oleic), linseed oil, and a fungal oil (high arachidonic acid). Fish were fed twice daily to apparent satiation. At the end of the study period, there were no...

A standardized comparison of semi-intensive pond culture of freshwater prawns Macrobrachium rosenbergii at different latitudes: production increases associated with lower water temperatures

Abstract This study was conducted to evaluate the effects of different ambient water temperatures on growth and population structure of freshwater prawns raised under standardized culture conditions. Juvenile prawns averaging 0.26 ± 0.14 g were stocked into seven 0.04 ha ponds at two study sites. Three ponds were located in Kentucky (KSU:latitude 38 °12′) with seasonal water temperatures averaging 24–26 °C. Four ponds were located in Mississippi (MSU:latitude 33 ° 28′) with a seasonal average of approximately 30 °C. Prawn stocking, sampling, and harvest dates were identical at both locations. Juvenile prawns were single source and were harvested from the same nursery tank for stocking at both locations. The diet used at both sites was from a single production run and was stored under refrigerated conditions. Prawns at both sites were fed twice daily according to a computer generated feeding schedule. Beginning approximately 8 weeks prior to harvest, sampled prawns were also individually identified according to sexual morphotype. At harvest (117 days after stocking) all prawns at both sites were counted, morphotyped, and weighed. Prawn weights were higher at the more northerly site at all samples after 42 days post-stocking. When sampled 64 days post-stocking (5 August) no sexually mature male or females were found. Mature morpho-types were first captured in the Day 83 sampling (25 August). In the Day 106 sampling (16 September), there were no significant differences ( P > 0.05) in numbers or weights of the three male morphotypes between sites. However, among females there were significantly fewer ( P P P P > 0.05) between the two sites in prawn survival (83%), average weight (35 g), and feed conversion (2.3). Production was significantly greater ( P ≤ 0.01) at KSU (1261 kg ha −1 ) than MSU (1091 kg ha −1 ) largely reflecting higher average weights of some morphotypes and slightly higher survivals. Differences in proportions and sizes of female morphotypes probably indicate delayed sexual maturation at the more northerly site, prolonging somatic growth which normally ceases when food energies are redirected to reproductive activities.

The Effect of Photoperiod on Growth and Survival of Juvenile Freshwater Prawn, Macrobrachium rosenbergii in Nursery Tanks

Abstract To achieve marketable size (> 30 g) in the limited growing season available in temperate areas, post-larval freshwater prawn, Macrobrachium rosenbergii must be grown to a larger size (from 0.01 to > 0.2 g) prior to pond stocking. This is known as the nursery phase. Little research has been conducted on the effects of different management and environmental factors on juvenile prawn growth and survival during this 30-60 day period. The objective of this study was to evaluate the effects of three different photoperiods on growth and survival of juvenile freshwater prawn during nursery production. Four hundred post-larval (PL) freshwater prawns (0.025iö.04 g) were stocked into nine 170-L nursery tanks at 2.3 PL/L with artificial substrate added to each tank at a rate to achieve a density of 430 PL/m2 of substrate. Tanks were randomly assigned to one of the following photoperiod regimens: 24 hours darkness (L0:D24); 12 hours light: 12 hours darkness (L12:D12); or 24 hours light (L24:D0), with three replicate tanks per treatment. Freshwater prawn were fed a trout diet containing 42% protein and 8% lipid according to a feed table. After 60 days, there was no significant difference (P > 0.05) in average individual weight of freshwater prawn exposed to the different light regimens (overall mean 0.86 g). Survival was significantly greater (P < 0.05) in prawn raised under continual light conditions (L24:D0) (72%) than those raised under L12:D12 (59%) or continual darkness (L0:D24) (58%); values for these latter two treatments did not differ significantly (P > 0.05). This study indicates that continual light conditions have a positive impact on survival of freshwater prawn juveniles during the nursery phase.

The Effect of Biomass Density on Transport Survival of Juvenile Freshwater Prawn, Macrobrachium rosenbergii

Abstract In tem per ate re gions fresh wa ter prawn, Macrobrachium rosenbergii, ju ve niles are nursed to more ad vanced sizes (≥ 0.3 g) in indoor tanks, then trans ported to ponds for growout. Stress dur ing transport can pro duce im me di ate mor tal ity and un de tected mor tal ity af ter pond stock ing. This study was de signed to eval u ate the ef fect of bio mass den sity dur ing trans port in sealed con tain ers on pre-stock ing prawn sur vival. Nine rep li cate sty ro foam trans port con tain ers were pre pared. Each con tained one dou ble bagged plas tic bag with 10 L of ox y gen-sat u rated 22EC wa ter with an at mo sphere of 10 L pure ox y gen. Ju ve nile prawn weigh ing 0.26±0.02 g (av er age weight ±S.D.) were ran domly stocked into trans port con tain ers at ei ther 10, 25 or 50 g of prawn per li ter of wa ter, then sealed for eight hours (max i mum re gional trans port pe riod). There were three rep li cate trans port con tain ers per den sity. At eight hours post-stock ing, bags were opened, wa ter qual ity de ter mi na tions were con ducted, and live and dead an i mals were sep a rated and counted. To tal am mo nia-ni tro gen and un-ion ized am mo nia-ni tro gen con cen trations were sig nif i cantly higher (P ≤0.05) in con tain ers stocked at 50 g/L than in con tain ers stocked at ei ther 10 or 25 g/L, which were also sig nif icantly dif fer ent (P ≤0.05) from each other. Ni trite-ni tro gen con cen tra tions were sig nif i cantly higher (P ≤0.05) for con tain ers stocked at 50 g/L than in those stocked at 10 g/L. How ever, ni trite con cen tra tions in con tain ers stocked at 25 g/L were not sig nif i cantly dif fer ent (P> 0.05) from con tain ers stocked at other den si ties. Dis solved ox y gen was sig nifi cantly lower (P ≤0.05) in trans port con tain ers stocked at 50 g/L (1.3 mg/L) than those stocked at 25 g/L or 10 g/L (1.6 mg/L and 3.2 mg/L, respec tively), which were also sig nif i cantly dif fer ent (P≤0.05). Sur vival was sig nif i cantly lower (P ≤0.05) in trans port con tain ers stocked at 50 g/L (86.6%) than in con tain ers stocked at 25 g/L (93.0%) and 10 g/L (97.2%), which were also sig nif i cantly dif fer ent (P ≤0.05). These data in di cate that trans port den si ties greater than 10 g/L should be avoided for trans port ≥8 hours in sealed con tain ers.

The effect of water temperature on growth and survival of largemouth bass during feed training.

Abstract Water temperature could be an important factor during the feed training phase of largemouth bass Micropterus salmoides production, as it could affect appetite and starvation time. We evaluated three water temperatures during largemouth bass feed training. Pond-reared largemouth bass fingerlings (weight = 2.1 ± 0.6 g [mean ± SE]) were randomly stocked into twelve 0.5-m3 polyethylene cages to achieve a stocking density of 350 fish per cage. The cages were suspended in six 3,800-L polyethylene tanks with a common water source housed in a greenhouse with four replicate cages per water temperature treatment (20, 24, and 28°C). Each tank contained two cages, and there were two tanks per treatment temperature. In each cage, fingerlings were initially fed freeze-dried krill, then gradually weaned onto a commercial pellet (floating trout feed; 1.5 mm) over a 24-d period according to an established training protocol. At harvest, the average weight and the percentage of fish successfully trained to commerci...

The Effect of Biomass Density, Temperature, and Substrate on Transport Survival of Market-Size Freshwater Prawn, Macrobrachium rosenbergii

Abstract After harvest, adult prawn are often transported for sales to live markets, such as ethnic Asian outlets, in major urban centers. Poor survival during transportation has hindered development and expansion of these markets. Methodologies to increase survival during transport could contribute to industry viability. Three independent trials were conducted. In the first trial, three biomass densities (25, 50 and 100 g/L) were evaluated in 100-L, open plastic containers aerated with pure oxygen and compressed air. Water quality analyses were performed prior to stocking. After 24 hours in the model transport containers, water quality analysis was conducted and all prawn were removed, determined to be alive or dead, and each group weighed and counted. There was no significant difference (P > 0.05) for prawn survival (overall mean 98%) among the three densities. Concentrations of dissolved oxygen and nitrite were not effected by hauling density (P < 0.05). Total ammonia-nitrogen and un-ionized ammonia-nitrogen concentrations increased (P < 0.05) as biomass densities increased, though values remained within what are considered tolerable ranges. In the second trial, the effect of added substrate and temperature on transport survival was evaluated with prawns stocked at the high density (100 g/L). Two water temperatures (21°C and 26°C) with and without substrate were evaluated in a 2 × 2 factorial with three replicate, 100-L model transport containers per treatment combination (12 containers total). Factorial analysis indicated no significant statistical interaction (P > 0.05) between the presence of substrate and water temperature on any measured variable. The main effects of substrate and temperature were then analyzed separately. The presence or absence of substrate had no significant impact (P > 0.05) on prawn survival. However, temperature had a highly significantly impact (P < 0.01) on survival; prawn survival at 21°C averaged 97% compared to 24% at 26°C. The third trial was a commercial verification trial in which 500 kg of live prawn were transported to New York from Kentucky. These data indicate prawn can be successfully transported at 100 g/L for 24 hours when temperatures are maintained near 21°C. Adding substrate to the transport tank appears to provide no benefit.