Survival and growth of juvenile silver pompano Trachinotus blochii (Lacepede, 1801) at different salinities in tropical conditions.

摘要

The objectives of the present study were to evaluate the tolerance of juvenile silver pompano to different salinity conditions in order to determine the minimum salinity required for survival and also to study the effect of different salinities on survival and growth. Wild caught juveniles of the silver pompano Trachinotus blochii (average initial length: 4.38+or-0.44 cm, average initial weight: 1.6+or-0.09 g) were used in the experiments. The experiments were conducted in triplicate with 15 fish per tank. Control groups were maintained at 34+or-1 ppt. Juvenile silver pompano reared at ambient salinity (34+or-1 ppt) were transferred directly to lower salinities (25, 15, 10, 5, 4, 3 and 1 ppt) and monitored for survival. Results indicated that the minimum salinity required for the survival of juvenile T. blochii is 4 ppt and 100% mortality was observed within 7-8 h in 1 ppt salinity. In another experiment, three salinity reduction protocols were followed and the three treatment groups were exposed to 25, 15 and 5 ppt salinity for a period of 56 days and the growth and survival were monitored. Survival and growth in terms of weight was not significantly different in the treatments from the control group except in the case of 5 ppt, which showed comparatively lower survival and specific growth rate (SGR). The results indicate that the culture of juvenile pompano might be feasible in salinities up to 15 ppt in tropical conditions.