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 ( h 2 ) estimate for growth was 0.84±0.43(s.e.) and realized h 2 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 h 2 for percent tail was 0.15±0.12. In the TSV line, there was an 18.4% increase in survival to TSV between select and control shrimp after one generation of selection (46.4% vs. 39.2%). Realized h 2 for TSV resistance was 0.28±0.14 and h 2 on the underlying scale was 0.30±0.13. However, select shrimp in the TSV line were 4.6% smaller than control shrimp (22.6 vs. 23.7 g) and there was a negative genetic correlation between mean family growth and mean family survival to TSV [−0.46±0.18(s.e.)]. Percent females per family ranged from 39.7% to 69.2% and averaged 51% female, but h 2 for sex ratio was zero, indicating that it is not feasible to select for a higher percentage of females. Significant improvements in growth and TSV resistance can be made in L. vannamei through selective breeding; however, the negative genetic correlation between growth and TSV resistance must be considered when developing breeding plans.