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Age and growth of the gulf toadfish Opsanus beta based on otolith increment analysis

Authors

  • E. Malca,

    1. University of Miami, Rosenstiel School of Marine and Atmospheric Science, Cooperative Institute of Marine & Atmospheric Studies, 4600 Rickenbacker Causeway, Miami, FL 33149-1098, U.S.A.
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  • J. F. Barimo,

    1. University of Miami, Rosenstiel School of Marine and Atmospheric Science, Cooperative Institute of Marine & Atmospheric Studies, 4600 Rickenbacker Causeway, Miami, FL 33149-1098, U.S.A.
    2. Fisheries & Aquaculture Program, Peninsula College, 1502 E. Lauridsen Bvd. Port Angeles, WA 98362, U.S.A.
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  • J. E. Serafy,

    1. University of Miami, Rosenstiel School of Marine and Atmospheric Science, Cooperative Institute of Marine & Atmospheric Studies, 4600 Rickenbacker Causeway, Miami, FL 33149-1098, U.S.A.
    2. National Marine Fisheries Service, Southeast Fisheries Science Center, 75 Virginia Beach Drive, Miami, FL 33149, U.S.A.
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  • P. J. Walsh

    Corresponding author
    1. University of Miami, Rosenstiel School of Marine and Atmospheric Science, Cooperative Institute of Marine & Atmospheric Studies, 4600 Rickenbacker Causeway, Miami, FL 33149-1098, U.S.A.
    2. Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5 Canada
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Tel.: +1 613 562 5800, ext. 6328; fax: +1 613 562 5486; email: pwalsh@uottawa.ca

Abstract

In the present study, sagittal otoliths of confirmed male and female specimens of the gulf toadfish Opsanus beta that were collected monthly over the course of a year from Biscayne Bay, Florida, U.S.A. were analysed. The timing and frequency of O. beta spawning seasons are reported by examination of the gonado-somatic index. The estimated ages of males and females ranged from < 1 year to 6 and 5 years, respectively. Strong sexual dimorphism in growth was apparent with von Bertalanffy parameter estimates for males of L = 393·8 mm, K = 0·30, t0 = 0·36 and females of L = 201·1 mm, K = 0·79, t0 = 0·47. Comparison with previously published growth trajectories of the more northerly distributed conspecific Opsanus tau showed that O. beta males had a higher growth rate. Female O. beta and O. tau growth trajectories appear similar, with an indication that the former becomes asymptotic at least a year before the latter. Results are discussed in the context of temperature regimes, reproductive energy allocation and waste urea excretion in the two species.

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