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Life history characteristics of a lightly exploited stock of Squalus suckleyi

Authors

  • C. A. Tribuzio,

    Corresponding author
    1. School of Fisheries and Ocean Sciences, Juneau Centre, University of Alaska Fairbanks, 17101 Pt Lena Loop Road, Juneau, AK 99801, U.S.A.
      Author to whom correspondence should be addressed at present address: National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Alaska Fisheries Science Centre, Auke Bay Laboratories, 17109 Pt Lena Loop Road, Juneau, AK 99801, U.S.A. Tel.: +1 907 789 6007; email: cindy.tribuzio@noaa.gov
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  • G. H. Kruse

    1. School of Fisheries and Ocean Sciences, Juneau Centre, University of Alaska Fairbanks, 17101 Pt Lena Loop Road, Juneau, AK 99801, U.S.A.
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Author to whom correspondence should be addressed at present address: National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Alaska Fisheries Science Centre, Auke Bay Laboratories, 17109 Pt Lena Loop Road, Juneau, AK 99801, U.S.A. Tel.: +1 907 789 6007; email: cindy.tribuzio@noaa.gov

Abstract

The purpose of this study was to examine the basic life history of a lightly exploited stock of Squalus suckleyi in the Gulf of Alaska to establish a baseline for future comparison and to provide critical information for stock assessments. Average total length (total length extended) of females (87·7 cm) was significantly larger (t-test, t = −12·57, d.f. = 1533, P < 0·01) than males (80·3 cm); size at 50% maturity (74·5 and 97·3 cm, males and females, respectively) and age at 50% maturity (21 and 36 years, respectively) were also significantly different between the sexes (i.e. bootstrapped 95% c.i. did not overlap). Total average fecundity was 8·5 pups per female, and individual fecundity was a linear function of either length or whole mass. The best estimate of instantaneous natural mortality was 0·097. The delayed age of maturity, low natural mortality and low rates of reproduction imply that only very low rates of fishing mortality are sustainable. Finally, this paper provides the first reported evidence that a small percentage of the adult females may undergo an extended resting period between pregnancies of ≥1 years.

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