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Aspects of energetics of adult walleye pollock, Theragra chalcogramma (Pallas), from Alaska
Author(s) -
Smith R. L.,
Paul A. J.,
Paul J. M.
Publication year - 1988
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.1988.tb05485.x
Subject(s) - pollock , biology , energetics , zoology , starvation , metabolic rate , body weight , gadidae , growth rate , fishery , fish <actinopterygii> , ecology , endocrinology , atlantic cod , gadus , geometry , mathematics
Body energy partitioning was examined for field‐caught, adult walleye pollock; additional laboratory studies were conducted on fish held under controlled temperature conditions at Seward, Alaska. Average consumption for pollock feeding daily was 0.5% of body weight (3100 cal) at 5°C, resulting in an average growth of 0.12% body weight day −1 . These results suggest that large pollock grow at similar rates and have similar food conversion efficiencies to those of Atlantic cod held at similar temperatures. Resting metabolic rates measured on adult fish were combined with similar data from juveniles to calculate a regression of specific metabolic rate against wet weight: y = 173x −026 . Maintenance rations amounted to 4.8 cal g −1 day −1 at 5°C, very close to the 0.28% value for juveniles. Estimation of metabolic rate using maintenance ration data resulted in values that were 55% higher than those obtained from oxygen consumption data for unfed fish. Weight loss during starvation was 0.18% of body weight day −1 at 5°C, corresponding roughly to a starvation metabolic rate 50% lower than the resting metabolic rate we report. We estimate that an adult pollock will lose about 37% of its prespawning body weight and about 46% of its body energy during spawning. These losses result, primarily, from changes in the weight of gonad, liver and somatic tissues as opposed to changes in specific energy content of those tissues.