Growth of Larval to Juvenile Green Sturgeon in Elevated Temperature Regimes

Abstract

To determine the effect of high river temperatures on post-yolk-sac larval to early juvenile green sturgeon Acipenser medirostris, growth rates at elevated and cycling temperature regimes were measured. Water temperatures were chosen based on temperature regimes in their highly altered natal rivers. Post-yolk-sac fish (15 d after hatching) were placed into twenty-four 60-L tanks. Fish were kept on a natural photoperiod, receiving continuous well water and aeration and ad libitum commercial rations. Significant differences were found between final wet weights, total lengths, and specific growth rates (at 24°C and at cycling 19–24°C > 19°C) because of increases in food consumption, despite increases in activity (both significantly greater at 24°C than at 19–24°C or 19°C). Elevated and cycling temperatures in the 19–24°C range do not adversely affect juveniles (body size range, ∼0.1–10 g), when abundant food and oxygen are available.