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Hook selectivity as a mitigating measure in the catches of the stingray Pteroplatytrygon violacea (Bonaparte, 1832) (Elasmobranchii, Dasyatidae)

Authors

  • L. D. Ferrari,

    Corresponding author
    • PGSISCO - Pós Graduação em Sistemas Costeiros e Oceânicos, Pontal do Sul, Brasil
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  • J. E. Kotas

    Corresponding author
    1. Centro de Pesquisa e Gestão de Recursos Pesqueiros do Litoral Sudeste e Sul CEPSUL/ICMBio, Itajaí, Brasil
    • PGSISCO - Pós Graduação em Sistemas Costeiros e Oceânicos, Pontal do Sul, Brasil
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Author's addresses: Luana D. Ferrari, PGSISCO - Pós Graduação em Sistemas Costeiros e Oceânicos, Av. Beira-mar s/n, CEP: 83255-000, Pontal do Sul, PR, Brasil.

E-mail: luanaferrari@ig.com.br

and

Jorge E. Kotas, Centro de Pesquisa e Gestão de Recursos Pesqueiros do Litoral Sudeste e Sul CEPSUL/ICMBio. Av. Ministro Victor Konder, 374, 88301-700, Itajaí, SC Brasil.

E-mail: jekotas@gmail.com

Summary

Hook selectivity, sex ratio of catches and relative abundance (Catch Per Unit Effort – CPUE) were assessed for the pelagic stingray Pteroplatytrygon violacea (Bonaparte, 1872), caught by longline gear in the southwestern Atlantic Ocean over the continental slope and adjacent oceanic area. The catches were carried out at depths of 200–4000 m by research cruises in 2002 and 2003, from Cabo Frio (22°52′S) to Laguna (28°28′S); and by hook selectivity experiments from 2004 to 2008, from Itajaí (26°54′S) to Tramandaí (29°59′S). Hook selectivity experiments indicated higher catches of stingrays with ‘J’ hooks (9/0, 10° offset) commonly used by the pelagic longline fleet than with ‘circle’ hooks (18/0, 10° offset). ‘circle’ hooks reduce the longline by-catches of this species. Most of the stingrays caught were males (6 : 1). One female aborted mid-term embryos at the time of capture. CPUE was highest between spring and autumn and lowest during winter.

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