Shaun M. Moss

Selective breeding of Pacific white shrimp (Litopenaeus vannamei) for growth and resistance to Taura Syndrome Virus

Abstract From 1995 to 1998, the Oceanic Institute operated a breeding program for Pacific white shrimp, Litopenaeus vannamei, based on a selection index weighted equally for growth and resistance to Taura Syndrome Virus (TSV). In 1998, two separate breeding lines were established. One line was selected 100% for growth (Growth line) and a second line was selected on an index weighted 70% for TSV resistance and 30% for growth (TSV line). After one generation of selection, select shrimp from the Growth line were 21% larger than unselected control shrimp (24.2 vs. 20.0 g). The half-sib heritability (h2) estimate for growth was 0.84±0.43(s.e.) and realized h2 was 1.0±0.12. Females were 12.7% larger than males. Shrimp tails accounted for 65.1% of total body weight and males had a significantly higher percent tail than females (65.7% vs. 64.5%; P

Characterization of organic particles associated with rapid growth in juvenile white shrimp, Penaeus vannamei Boone, reared under intensive culture conditions

Aquaculture ponds possess unique ecological characteristics which contribute significantly to the growth and survival of the target species. In this study, shrimp growth rates were monitored in microcosm tanks containing flow-through water with varying concentrations of organic particles produced autochthonously in an intensive shrimp pond. Rapid growth occurred in unfiltered pond water with a mean particulate organic carbon (POC) concentration of 6.98 mg/l over six sampling days. In contrast, slowest growth occurred in well water with a mean POC concentration of 0.38 mg/l. Within the POC pool, as the percentage of living carbon increased, shrimp growth rates increased. Unfiltered pond water contained more than 45% living carbon, whereas well water had greater than 85% detrital carbon. Living biomass was dominated by pennate and centric diatoms, whereas contributions from bacteria and protozoans were minor. There was a highly significant linear relationship between shrimp growth and POC concentration (r2 = 0.895, p < 0.0001), although there appeared to be a minimum threshold concentration below which shrimp growth was unaffected. Temporal variability in algal cell density (ACD) indicated a bloom and crash cycle, suggesting that the availability of live algal cells to shrimp was sporadic. Further research on pond ecology is needed in order to manipulate organic carbon pools to improve shrimp growth.

The Role of Selective Breeding and Biosecurity in the Prevention of Disease in Penaeid Shrimp Aquaculture

About 3.5 million metric tons of farmed shrimp were produced globally in 2009 with an estimated value greater than USD

The relative enhancement of Penaeus vannamei growth by selected fractions of shrimp pond water

14.6 billion. Despite the economic importance of farmed shrimp, the global shrimp farming industry continues to be plagued by disease. There are a number of strategies a shrimp farmer can employ to mitigate crop loss from disease, including the use of Specific Pathogen Free (SPF), selectively bred shrimp and the adoption of on-farm biosecurity practices. Selective breeding for disease resistance began in the mid 1990s in response to outbreaks of Taura syndrome, caused by Taura syndrome virus (TSV), which devastated populations of farmed shrimp (Litopenaeus vannamei) throughout the Americas. Breeding programs designed to enhance TSV survival have generated valuable information about the quantitative genetics of disease resistance in shrimp and have produced shrimp families which exhibit high survival after TSV exposure. The commercial availability of these selected shrimp has benefitted the shrimp farming industry and TSV is no longer considered a major threat in many shrimp farming regions. Although selective breeding has been valuable in combating TSV, this approach has not been effective for other viral pathogens and selective breeding may not be the most effective strategy for the long-term viability of the industry. Cost-effective, on-farm biosecurity protocols can be more practical and less expensive than breeding programs designed to enhance disease resistance. Of particular importance is the use of SPF shrimp stocked in biosecure environments where physical barriers are in place to mitigate the introduction and spread of virulent pathogens.

Growth rates, nucleic acid concentrations, and RNADNA ratios of juvenile white shrimp, Penaeus vannamei boone, fed different algal diets

It is generally assumed that shrimp cultured in intensive aquaculture systems receive little or no nutrition from natural pond biota. However, recent experiments indicate that even under intensive growout conditions, shrimp growth is enhanced by unknown growth factors produced autochthonously in an intensive shrimp pond. As part of an ongoing research effort to characterize the growth factors contained in shrimp pond water, an experiment was conducted to compare the effects of pond water, with selected solid fractions removed, on the growth of juvenile white shrimp, Penaeus vannamei. Fractions were removed from pond water by passing the water through a series of mechanical and activated carbon filters. In the presence of water-column solids between 0.5 and 5.0 μm, shrimp growth rates increased by 53% over growth rates attained in clear well water, while solids > 5.0 μm improved shrimp growth by an additional 36%. These solids consisted predominantly of microalgae and microbial-detrital aggregates. Solids <0.5 μm, including dissolved organic carbon, did not appear to contribute to shrimp growth. Water-column solids produced autochthonously in shrimp ponds are also known to improve growth in oysters, brine shrimp, and calanoid copepods. Efforts continue to further characterize these solids and to explore the possibility of their extraction, preservation, and use as feed additives.

Production of growth-enhancing particles in a plastic-lined shrimp pond

Macro- and microalgae are potentially important food resources for penaeid shrimp inhabiting coastal nursery grounds and aquaculture ponds. However, there are few data on the nutritional contribution of different algal species to juvenile shrimp growth. In this study, changes in whole body weight, RNA and DNA concentrations, and RNADNA ratios of juvenile white shrimp, Penaeus vannamei Boone, fed different algal species were compared to assess the nutritional contribution of each species to shrimp growth. Shrimp fed a diatom culture composed primarily of Chaetoceros sp. were significantly heavier (p < 0.05) than shrimp fed a monoculture of the green alga, Nannochloropsis oculata, fronds from the leafy macroalga, Ulva sp., or fronds from the filamentous macroalga, Enteromorpha sp. after 5 days. In addition, RNA/DNA ratios were significantly greater (p0.05) in abdominal muscle tissue from diatom-fed shrimp. About 76% of the variation in shrimp growth rate could be explained by changes in RNA concentration, whereas RNADNA ratio accounted for about 80% of the variation in growth rate. Diatoms can contribute substantially to short-term shrimp growth, and are probably important in coastal nursery grounds and aquaculture ponds when other food resources are scarce or to supplement available food.

Growth and reproductive performance of broodstock shrimp reared in a biosecure recirculating aquaculture system versus a flow-through pond

Suspended organic particles produced in an intensive shrimp pond with an earthen substratum can significantly enhance shrimp growth. However, the role of the substratum in eliciting this effect is unknown. It was hypothesized that clay particles, derived from the substratum, are important in transferring suspended organic particles to the pond bottom where they become available to shrimp. To test this hypothesis, it was determined if suspended particles, produced in a plastic-lined pond without an earthen substratum, can improve shrimp growth. Juvenile Penaeus vannamei were reared in 120-liter microcosm tanks at a density of 40 shrimp/m2. A 2 × 2 factorial experiment was conducted in which triplicate tanks received flow-through water from either a 337-m2, plastic-lined pond used for intensive shrimp culture or from a seawater well. In addition, shrimp were fed either a commercial diet ad libitum or were unfed. After 14 days, there was a highly significant water source effect on shrimp growth (P < 0.001). Growth rates of shrimp in pond water + feed (1.20 g/wk) were 62% greater than growth rates of shrimp in well water + feed (0.74 g/wk). Unfed shrimp in pond water grew 0.23 g/wk, whereas unfed shrimp in well water lost weight (−0.045 g/wk). These results indicate that algal-clay flocculation is not an important mechanism in eliciting the growth-enhancing effect of shrimp pond water and that particles suspended in pond water may not need to interact with the substratum in order to contribute to shrimp growth.

Evaluation of a fluorescent, alphanumeric tagging system for penaeid shrimp and its application in selective breeding programs

Abstract Over the past decade, viral pathogens have caused mass mortalities of farmed shrimp throughout the major shrimp farming regions of the world. In addition, the global shrimp farming industry has been criticized for negatively impacting coastal environments. These issues have raised concerns about the sustainability of traditional shrimp farming practices, and have prompted farmers and researchers to develop biosecure technologies that promote a sustainable industry. Current technologies include the use of specific pathogen free (SPF) shrimp that are grown to market size in recirculating systems that rely on pathogen exclusion. Inherent in this approach is the need to produce SPF broodstock under biosecure conditions. However, there is a paucity of information on broodstock growth and reproductive performance when they are reared in recirculating systems. The present investigation compares shrimp growth and reproductive performance in two trials where shrimp were cultured from market size (∼20 g) to broodstock size (∼40–60 g) in a recirculating aquaculture system (RAS) versus a flow-through earthen pond (EP). In trial 1, mean growth rates of males and females in the RAS were 0.83 and 1.33 g/week, respectively. In the EP, males and females grew 1.07 and 1.48 g/week, respectively. In trial 2, mean growth rates of males and females in the RAS were 0.90 and 1.53 g/week, respectively, whereas in the EP, males and females grew and 1.24 and 1.78 g/week. Slower growth rates in the RAS may be attributed to the lack of natural productivity, which provides supplemental nutrition to the shrimp. In addition to growth rates, reproductive performance of broodstock reared in the RAS was compared with historical reproductive performance of broodstock reared in the EP. Data on spawning success and production of viable nauplii revealed no significant differences (P>0.05) between broodstock shrimp reared in these two systems. These results indicate that broodstock shrimp can be cultured in a biosecure RAS while maintaining good growth and high survival. In addition, reproductive performance of broodstock shrimp reared in a RAS is not compromised when compared with broodstock shrimp reared in a conventional, flow-through pond.

Performance of Larval and Postlarval Pacific White Shrimp, Litopenaeus vannamei (Boone), Fed Two Commercial Liquid Diet Supplements

Abstract The ability to monitor performance of individual shrimp cultured under commercial growout conditions would provide researchers with a valuable tool to use in selective breeding programs. The objective of this study was to evaluate tag retention and readability of two sizes (standard format 1.0×2.5 mm and large format 1.5×3.5 mm) of the Visible Implant Alphanumeric (VI-alpha) tagging system (Northwest Marine Technology) in juvenile and sub-adult Pacific white shrimp, Litopenaeus vannamei , reared under laboratory and field conditions. VI-alpha tags are soft fluorescent tags with an alphanumeric coding system which provides individual identification and is implanted beneath clear tissue so that it can be read externally. For juvenile (mean weight 2.7 g) and sub-adult shrimp (mean weight 21.5 g), tags were inserted through the ventral surface of the abdomen and shrimp were maintained in either laboratory or field environments for evaluation. During the study, each experimental group was weighed and evaluated for tag retention and readability. For juvenile shrimp in the laboratory, overall tag retention was 95% for both tag sizes with 82% readability after shrimp exhibited a mean weight gain of 10.5 g over 42 days. Under field conditions, there was a 70.5% recovery of tagged juveniles with 81% readability after shrimp exhibited a mean weight gain of 21.1 g over 140 days. For sub-adult shrimp in the laboratory, overall tag retention was 99.2% for both tag sizes with 95% readability after a mean weight gain of 4.7 g over 75 days. Under field conditions, there was an 84% recovery of tagged sub-adults with 84% readability after a mean weight gain of 20 g over 110 days. These results indicate that the soft VI-alpha tagging system evaluated in this study is a valuable research tool with applications in selective breeding programs. The ability to monitor individual shrimp performance could lead to greater selection intensity, improve the accuracy of breeding values, and provide information that may be used to calculate heritability estimates by offspring/parent regression.

Effects of Artificial Substrate and Stocking Density on the Nursery Production of Pacific White Shrimp Litopenaeus vannamei

Abstract Two commercial liquid diet supplements were evaluated as a partial replacement for live foods fed to larval and postlarval Pacific white shrimp, Litopenaeus vannamei. Larvae were stocked in 20-L buckets at a density of 113 shrimp/L and fed one of four diets (5 replicate buckets per diet): (1) a control diet consisting of the diatom, Chaetoceros neogracile, and live Artemia; (2) the control diet plus Treflan (a fungicide); (3) LiquaLife liquid larval diet supplements with reduced concentrations of C. neogracile and Artemia; and (4) Epifeed liquid larval diet supplements with reduced concentrations of Artemia. Diets were evaluated by comparing shrimp rostro-caudal length and survival to PL-8, survival to osmotic and pH stress, as well as shrimp gut fullness, gut lipid content, and fouling. Rostro-caudal length and survival to PL-8 were not significantly different among the four treatments. However, mean survival to PL-8 was 12-34% greater in the Epifeed treatment than in the other three treatments. Shrimp fed Epifeed exhibited greater survival (P < 0.05) when exposed to 7 ppt water for two hours than shrimp in the control treatments. In contrast, there was no significant difference in survival (P > 0.05) among the four treatments when shrimp were exposed to apH of 3.35 for two hours. Although shrimp fed liquid diet supplements had more fouling (P < 0.05) than shrimp in either of the control treatments, commercial liquid diet supplements can be used in penaeid shrimp hatcheries to partially replace Artemia without compromising shrimp growth or survival.