Growth performance of selectively bred Pacific white shrimp, L. vannamei reared at different salinities

By Dustin R. Moss, Clete A. Otoshi, and Shaun M. Moss. Inland shrimp farming, under low-salinity conditions, is an attractive addition to traditional coastal farming for biosecurity, environmental, and economic reasons. This approach is now practiced in many shrimp farming regions around the world. Despite a global interest in low-salinity shrimp culture, little progress has been made to develop genetically improved shrimp for this type of environment. The objective of this study was to compare family growth performance of juvenile Pacific white shrimp, L. vannamei, cultured at 2 ppt and 34 ppt.
Six round, fiberglass tanks (8.8 m2) were stocked with specific pathogen free (SPF) shrimp at a density of 78/m2. Shrimp originated from the USMSFP breeding program at the Oceanic Institute. They were offspring from a lineage bred for rapid growth at 34 ppt. Each tank was stocked with shrimp from 47 full-sib families (11-15 shrimp/family/tank). Two treatments (3 replicates/treatment) were evaluated for 116 days and consisted of shrimp reared at 2 ppt and 34 ppt. All shrimp received a 35%-protein diet ad libitum three times daily and all tanks experienced a 200% water exchange per day. Water temperature, dissolved oxygen concentration, and salinity were measured daily in each tank. At the end of the study, all shrimp were identified by family (using internal elastomer tags) and weighed. Growth, survival, and water quality data were analyzed by ANOVA.
Final weight and growth rate of shrimp reared at 34 ppt were significantly greater (P <0.05) than for shrimp reared at 2 ppt. Survival was high and not significantly different between treatments. Temperature in the 34 ppt treatment (26.5ºC) was significantly greater (P <0.05) than in the 2 ppt treatment (25.1ºC), and this difference may have contributed to the growth difference. When growth data were standardized using degree days (DD), no significant difference in growth between treatments was observed. There were significant positive linear correlations (P <0.05) both for mean family weight gain and mean family survival between treatments. However, the coefficients of determination (r2) were moderate at 0.64 and 0.46, respectively.
These results indicate that shrimp selected for growth at 34 ppt exhibited good growth and high survival when reared at 2 ppt. However, because linear correlations of mean family weight gain and mean family survival between treatments were not high, it is likely that further improvements in growth and survival at 2 ppt may be possible if selection occurs under low salinity conditions.
Dustin R. Moss, Clete A. Otoshi, and Shaun M. Moss, The Oceanic Institute, 41-202 Kalanianaole Hwy.,
Waimanalo, HI 96795 USA