Fishery biology of the swordfish (Xiphias gladius, Linnaeus 1758) caught by surface longliners based in Itajaí, southern Brazil

Authors

  • Ana Lia Campos Quaggio OEI
  • Rosângela P. T. Lessa Universidade Federal Rural de Pernambuco
  • Jorge Eduardo Kotas ICMBio; CEPSUL
  • Celson F. Lin ICMBio; CEPSUL

DOI:

https://doi.org/10.1590/S1679-87592011000200006

Keywords:

Mantel-Haenszel test, Covariance models, Length composition

Abstract

The Xiphias gladius (Linnaeus, 1758) data used in the present study were obtained from commercial fishing cruises of the pelagic longline fleet based in Itajaí, operating in the Southwest Atlantic. For the Covariance models, fishing effort (number of hooks) and catches (kg) were pooled and categorized into the following groups: (1) year (1997, 1998, 2001, 2002 and 2007); (2) lunar phase; and (3) seasons, fishing effort being the covariate. The highest mean swordfish catch (kg) occurred during the waxing crescent moon and during wintertime. The Mantel-Haenszel procedure was applied to compare the efficiency of the two hooks tested, and showed that the "J" hook type (J 9/0 10º offset), traditionally used by the fleet, catches 1.2-fold more Xiphias gladius than the circle hook (18/0 10º offset), used as an optional device to reduce sea turtle bycatch. The conversion of individual dressed weight (kg) into total length (cm) from 2000 to 2002, showed that sub-adults represented 66% of the total catch.

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Published

2011-06-01

How to Cite

Quaggio, A. L. C., Lessa, R. P. T., Kotas, J. E., & Lin, C. F. (2011). Fishery biology of the swordfish (Xiphias gladius, Linnaeus 1758) caught by surface longliners based in Itajaí, southern Brazil. Brazilian Journal of Oceanography, 59(2), 171-184. https://doi.org/10.1590/S1679-87592011000200006

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Section

naodefinida