INFLUENCE OF VARIATION IN WATER TEMPERATURE ON SURVIVAL, GROWTH, AND YIELD OF PACIFIC WHITE SHRIMP Litopenaeus vannamei IN INLAND PONDS FOR LOW-SALINITY CULTURE  

There is considerable interest in culture of Whiteleg shrimp (Litopenaeus vannamei) in inland low-salinity water in Alabama and other states in Sunbelt region of the US. However the growth season is truncated as compared to tropical or subtropical areas where this species is typically cultured, and temperature is thought to be a major factor influencing shrimp production in the US. The objectives of this study were to determine water temperature pattern on a shrimp farm in different ponds and different years; and to seek possible contribution of bottom water temperature in ponds to variation in shrimp survival, growth and production among ponds.

The study was conducted in Greene Prairie Aquafarm located in the Blackland Prairie region of west-central Alabama. Water temperature at 1.2 m depth in 20 pond and air temperature were monitored at 1-h intervals during 2012, 2013 and 2015 growing seasons using a Model 64K HOBO Pendant^® Temperature/Alarm Data Logger. Records of stocking rates, survival rates, and production were provided by farm owner. Linear mixed model analysis of variance was used.

Results showed that the monthly mean water temperature was the lowest in May; and the highest in July. The widest range of water temperature was in October; while the narrowest was in July. Fastest decrease in weekly survival rate was during July. As coefficients of variation (CV) of hourly water temperature increases; survival rate (%) and production (kg/ha) increases; While feed conversion rate (FCR) decrease. As % of hours out of the range (23-30 C°) increases; survival rate (%) and production (kg/ha) decreases; While FCR increases. Pond variability represented 4.85 % of the variability in weekly growth rate (%/wk).As weekly range of water temperature increases from 3 to 4 C°, the growth rate increases by 11.3 %/wk during May, while it decreases by 5.1 %/wk during June (Figure 1). The narrower the range of water temperature during August, the slower the rate of decrease in weekly survival rate. In conclusion, the results suggest that variation in water temperature patterns has a major influence on shrimp growth and survival in ponds. Thus, further investigation of the controllable causes of variation in water temperature is recommended.