Steve M. Arce

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

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

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.

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

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.

Specific pathogen-free shrimp stocks in shrimp farming facilities as a novel method for disease control in crustaceans

Abstract: In 2006 more than 2 million tonnes of marine penaeid shrimp were farmed and these shrimp accounted for nearly half of the world’s total shrimp supply. With most of the world’s shrimp fisheries at maximum sustainable yield, the ratio of farmed to fished shrimp appears likely to continue to increase. This production is from a very young food-producing industry that began to emerge in the mid-1970s. The remarkable growth of sustainable shrimp farming has been accomplished in part through the successful development of domesticated shrimp stocks, many of which are free of specific diseases, and the development of the necessary infrastructure, in terms of biosecurity, diagnostic methods, and trained personnel, to successfully prevent disease or to manage disease outbreaks when they occur.

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

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.