Leigh Anne Bright

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 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...

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.

Effect of Different Feeding Strategies on Production and Economic Returns for Freshwater Prawn, Macrobrachium rosenbergii, Raised in Earthen Ponds in a Temperate Climate

Abstract This study compared the current recommended technology of “phase-feeding” diets, increasing in nutrient density as the relative prawn, Macrobrachium rosenbergii, biomass increased, compared to feeding a steam-pelleted, practical diet containing 32% protein throughout the entire production period. Two treatments were evaluated. Treatment 1 was phase-feeding where prawn were fed unpelleted distillers grains with solubles (DDGS) for the first four weeks; fed a steam-pelleted prawn diet containing 28% protein for weeks 5-12; and fed an extruded marine shrimp diet containing 40% protein for weeks 13-18. In Treatment 2, prawn were fed a 28%-protein, steam-pelleted diet throughout the entire 18-week production period. Feeding rates in both treatments were based on a feeding table. There were three replicate 0.02-ha ponds for each treatment. All ponds were stocked at 87,500/ha and were provided with artificial substrate in the form of polyethylene “safety fence” oriented vertically at a rate to increase available surface area 50%. After 97 culture days, there was no significant difference (P > 0.05) between treatments in terms of production, average individual weight, FCR, or survival which averaged 2,272 kg/ha, 28.4 g, 2.2, and 92%, overall. However, the percentage of prawns which reached over 30 g was increased approximately 20% in the phase-fed treatment. The added expense of the marine shrimp diet resulted in approximately a US

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

1.00/kg increase in the break-even price in the phase-treatment compared to feeding the diet containing 28% protein exclusively. There appears to be little benefit to feeding expensive marine shrimp diets to freshwater prawn; however, if the market being addressed requires, or pays, more for large animals, some added expense may be justified.

Effect of Feed Pellet Characteristics on Growth and Feed Conversion Efficiency of Largemouth Bass Raised in Ponds

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 Effect of Biomass Density, Salinity, and Substrate on Transport Survival of Juvenile Freshwater Prawns Macrobrachium rosenbergii in Continuously Oxygenated, Vented Containers

AbstractWe investigated the growth, survival, and feed conversion of Largemouth Bass Micropterus salmoides fed one of two sizes of floating pellets or a sinking pellet for 151 d in 0.04-ha ponds. The floating and sinking pellets were made from almost identical formulas. The fish were fed once daily to apparent satiation based on observed feeding activity. There was no significant difference in survival, growth, or feed conversion of fish fed the larger floating pellet versus those fed the standard-size floating pellet or sinking pellet. Fish fed the sinking pellet were significantly larger at harvest than fish fed either size of floating pellet. The efficiency of feed utilization was not decreased with the sinking pellet. These results indicate the Largemouth Bass accept and utilize sinking pellets well. However, their use on commercial scale farms would probably require some management modifications.Received May 5, 2014; accepted August 25, 2014

Laboratory Evaluation of the Relative Effectiveness of Plant and Animal Source Oils for Control of Notonectidae in Fish Ponds

Abstract During the stocking of grow-out ponds, juvenile prawns are usually transported from regional nurseries by truck in vented tanks. Hauling stress and associated delayed mortality have been implicated as potential causes of low pond survival. An experiment was conducted to evaluate the effects of biomass density, substrate, and salinity on water quality and transport survival of juvenile freshwater prawns Macrobrachium rosenbergii. The trial was designed as a 3 × 2 × 2 factorial and evaluated three biomass densities (10, 20, and 30 g/L), the presence or absence of added substrate (plastic mesh to provide a 200% increase in surface area), and the presence or absence of added salt (0‰ or 6‰). Model transport tanks were 15-L, open styrofoam containers aerated with pure oxygen and compressed air. Water quality analyses were performed prior to stocking. After 24 h, water quality analyses were again conducted and all prawns were removed, designated as alive or dead, weighed, and counted. After 24 h of sim...

Effect of Dietary Lipid Level and Protein Energy Ratio on Growth and Body Composition of Largemouth Bass Micropterus salmoides

Abstract Predation on small finfish fry and juvenile crustaceans by air-breathing insects such as Notonectidae can be a significant problem. Effective and widely used control methods employ petroleum products to create a thin surface film that prevents insect respiration, but these products pose an environmental concern. This study was conducted to evaluate potentially safer plant- and animal-based oils as effective methods of insect control. Based on their physical properties when added to water, menhaden fish oil (MO) and corn oil (CO) were selected as the most promising candidates. These oils were then compared with two previously recommended petroleum product mixes (a 2:1 motor oil : diesel fuel mix [PC-I] and a 1:20 motor oil : diesel fuel mix [PC-II]). The two oils and two oil mixes were evaluated at two application rates (1.48 mL/m2 and 4.45 mL/m2) with three replicates of each treatment. These were tested in 8-L glass aquaria filled with 6 L of reservoir water with a water-surface area of 0.107 m2...