Effect of recovery salinity on survival of acutely stressed halibut (Hippoglossus hippoglossus L) larvae

First‐feeding halibut larvae (245‐day degrees; 40 days post hatch), reared at 34 g L^?1 salinity and 7°C, were subjected to handling and allowed to recover in a range of salinities (0–34 g L^?1) and at 10°C. Survival of the unfed larvae was determined daily for 18 days. Mortality rates approached 0 after 4 days in all treatments and presumed starvation‐induced mortality started at about 11 days post handling. By 20 days post treatments, all larvae had died. Salinities in the range of 10–20 g L^?1 produced significantly (anova , P<0.01) higher initial survival (71–95%) than salinities above 20 g L^?1 (24–48%) or below 10 g L^?1 (0–19%) and this survival pattern changed little in unfed larvae for the first 10 days following the stressor. For example, 24 hour post handling, survival of halibut was improved from 28.7±16.5% (mean±standard error, n=3) at 34.0 g L^?1 to 95.2±4.8% at 13 g L^?1. A second‐order polynomial regression of 4‐day post‐handling survival data (y=?0.002x ²+0.0603x+0.0699, r²=0.3936) predicted a maximum survival at 15.1 g L^?1 salinity. These results have important implications for halibut aquaculture and research when handling of larvae is unavoidable. For practical applications, we recommend reducing salinity of receiving waters to 15–20 g L^?1 with a slow (3–4 days) reacclimation to ambient conditions.