Effects of Salinity, Temperature, and Weight on the Survival of Young‐of‐Year Shortnose Sturgeon

Abstract

Anthropogenic modifications of rivers and estuarine habitats have reduced the growth and recruitment of shortnose sturgeon Acipenser brevirostrum throughout its native range. This study used data from laboratory experiments to examine the individual and interactive effects of salinity, temperature, and fish weight on the survival of young‐of‐year shortnose sturgeon. The shortnose sturgeon in these experiments ranged from 56 to 187 mm in total length, from 0.4 to 42.8 g in weight, and from 66 to 144 d posthatch in age. Survival in 23°C water declined as salinity increased, but salinity tolerance increased with body size. The salinity lethal to 50% of the test fish after 48 h ranged from 14.8‰ to 20.9‰. Survival in freshwater declined as temperature increased, but temperature tolerance increased with body size. The temperature lethal to 50% of the test fish after 48 h ranged from 28.2°C to 30.7°C. In factorial experiments, salinity and temperature interacted significantly to affect young‐of‐year survival. The results of the factorial experiments were used to generate a predictive model in which the probability of survival was dependent on salinity, temperature, fish weight, and all interactions among the variables. The results of this study can be used to identify suitable habitats for young‐of‐year shortnose sturgeon. The results of this study also can be used to predict the recruitment bottlenecks that may result from additional anthropogenic disturbances to rivers in the southeastern United States.