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Growth and survival in the early life history stages of white sturgeon (Acipenser transmontanus)

University of British Columbia

Several populations of white sturgeon (Acipenser transmontanus) are experiencing chronic recruitment failure, likely due to low survival in the early life history stages. Despite great conservation interest, knowledge gaps about the basic biology of the early life history stages persists. My first objective was to investigate how periods of starvation after the exhaustion of the yolk sac and the presence of substrate during the yolk sac stage affect growth and survival of the larval stages. I reared newly hatched larvae at 7 levels of starvation after yolk exhaustion (0, 3, 6, 9, 12, 15, and 18 days of starvation). Yolks were exhausted at 11 days post-hatch (dph). After the starvation period, larvae were fed ad libitum to 35 dph. Larvae reared in substrate during the yolk sac stage were 12% heavier in wet mass and 27% heavier in dry mass at the end of the stage (11 dph) than larvae reared without substrate. Masses were not significantly different at 35 dph, after 24 days of feeding. Larval mortality rates were not affected by substrate presence or starvation duration. For starvation resistance, all larvae gained wet mass regardless of starvation duration. However, larvae that faced nine or more days of starvation lost dry mass over the study period, indicating that dry mass may be a better metric of growth for larval sturgeon. My second objective was to examine the effect of fish density and food ration on the growth and survival during the early juvenile stage. I reared 2.5-month-old juveniles at four densities (1, 3, 5, or 7 fish/tank) and two ration levels (50% or 100%) for four weeks. Specific growth rate in the first week was 0.69 ± 1.45 %/day for the fish that survived, and -1.19 ± 0.82 %/day for fish that died. Fish that survived for the duration of the experiment grew at 1.94 ± 0.97 %/day over four 3 weeks, regardless of density or ration treatment. Density significantly and positively influenced the mortality rate, but ration did not. My results indicate that abundant food is critical to the success of white sturgeon in the first year of life.

Text

2021-04-19

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/77825

Forestry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/