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Influence of Thermal and Oxygen Stratification on Lake Trout Hooking Mortality
Author(s) -
Lee Wade C.,
Bergersen Eric P.
Publication year - 1996
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8675(1996)016<0175:iotaos>2.3.co;2
Subject(s) - salvelinus , trout , fishery , fish <actinopterygii> , environmental science , thermal stratification , ecology , biology , thermal energy storage
We used dart tags and biotelemetry to determine the influence of thermal and oxygen stratification on the mortality of larger lake trout Salvelinus namaycush (>560 mm) that were hooked and released in Lake Granby, Colorado, in 1990–1992. During August and September, suitable thermal refuges (<12°C) contained inadequate dissolved oxygen (3 mg/L) for lake trout. Mortality was 87.5% for the fish released during this critical late‐summer period, but only 11.7% for fish released when the thermal refuge contained adequate dissolved oxygen (>3 mg/L). We recaptured 5.7%, of fish marked in summer with dart tags and 10.1 % of fish tagged during the rest of the year. Higher mortality of fish tagged in summer was probably caused by the lack of adequate dissolved oxygen in the thermal refuge during late summer. We believe that slot length limits for larger fish may not achieve management goals for Lake Granby because large lake trout have slow growth and high late‐summer hooking mortality that may negate the intended benefit of slot limits.