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Thermal tolerance of a northern population of striped bass Morone saxatilis

Authors

  • A. M. Cook,

    Corresponding author
    1. * Department of Plant and Animal Sciences, Nova Scotia Agricultural College, Truro, Nova Scotia, B2N 5E3, Canada and Diadromous Fish Division, Department of Fisheries and Oceans, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2, Canada
      †Tel.: +1 902 494 3680; fax: +1 902 494 3736; email: amcook@dal.ca
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  • J. Duston,

    1. * Department of Plant and Animal Sciences, Nova Scotia Agricultural College, Truro, Nova Scotia, B2N 5E3, Canada and Diadromous Fish Division, Department of Fisheries and Oceans, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2, Canada
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  • R. G. Bradford

    1. * Department of Plant and Animal Sciences, Nova Scotia Agricultural College, Truro, Nova Scotia, B2N 5E3, Canada and Diadromous Fish Division, Department of Fisheries and Oceans, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2, Canada
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†Tel.: +1 902 494 3680; fax: +1 902 494 3736; email: amcook@dal.ca

Abstract

Thermal tolerance of age 0+ year Shubenacadie River (Nova Scotia, Canada) striped bass Morone saxatilis juveniles (mean ±s.e. fork length, LF, 19·2 ± 0·2 cm) acclimated in fresh water to six temperatures from 5 to 30° C was measured by both the incipient lethal technique (72 h assay), and the critical thermal method (Cm). The lower incipient lethal temperature ranged from 2·4 to 11·3° C, and the upper incipient lethal temperature (IU) from 24·4 to 33·9° C. The area of thermal tolerance was 618° C2. In a separate experiment, the IU of large age 2+ year fish (34·4 ± 0·5 cm LF) was 1·2 and 0·6° C lower (P < 0·01) than smaller age 1+ year fish (21·8 ± 0·5 cm LF) at acclimation temperatures of 16 and 23° C. Using the Cm, loss of equilibrium occurred at 27·4–37·7° C, loss of righting response at 28·1–38·4° C and onset of spasms at 28·5–38·8° C, depending on acclimation temperature. The linear regression slopes for these three responses were statistically similar (0·41; P > 0·05), but the intercepts differed (25·3, 26·0 and 26·5° C; P < 0·01). The thermal tolerance of this northern population appears to be broader than southern populations.

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