Pesca,distribuição,abundância relativa e biologia reprodutiva do agulhão branco Tetrapturus albidus Poey 1860 capturado pela frota espinheira brasileira

Abstract

The white marlin Tetrapturus albidus is a ocean, pelagic and highly migratory specie, exploted by many countries and many commercial, sportive and artisanal fisheries. Like the other bilfishes, they are mainly caught by tunas and swordfish longline fishery, as by-catch, which subject a high fishing pressure. Then, the stock have been over-exploited, although the assessment show several uncertain, because need parameters. Before this, the present work promotes: a description by the fishing operations realized in the capture of white marlin by the leased longline fleet based in northeast Brazil; a distribution and relative abundance analyses and the influence of environmental factors in the capture of the specie; standardized catch and effort rates and reproductive biology information. The statistic tool utilized to standardization of abundance indices (CPUE) and for the analyses of the influence of factors (spatial, temporal and environmental) on the capture and gonad development of white marlin was generalized linear and additive models (GLM and GAM). Year, temperature of sea surface, latitude and depth of local fishing was the factors which more influenced on captures. The pattern of distribution and abundance observed confirms the northsouth migration through the brazilian off shore, of the third to the first trimester. Also was observed that the white marlin follows temperatures strips of about 24°-28°C, and is commonly concentrate in steep drop-offs and interface of different water masses, or in areas with marine richness. The model standardized with GAM showed better adjust than the GLM model, indicating that the inclusion of the factors was significantly in standardization procedure of CPUEs. The catches of white marlinshowed decline for about 15 or 20 years, and some stability since 1999-2000. Size at first sexual maturity (L50) was estimated as 139 cm (low jaw- fork length/ LJFL), for males, and 147 cm, for females. Month and temperature was the factors with more influence on gonad development. The gonad index of white marlin in the Atlantic Equatorial was highest in the end of second and the beginning of the third trimester.