Size structure, age, and growth of the blue shark, Prionace glauca (Linnaeus, 1758) in southern Brazil.

Autor: Marquez R; Laboratório de Recursos Pesqueiros Demersais e Cefalópodes, Instituto de Oceanografia, Universidade Federal do Rio Grande, Rio Grande, Brazil., Barreto R; Centro Nacional de Pesquisa e Conservação da Biodiversidade Marinha do Sudeste e Sul do Brasil, Instituto Chico Mendes de Conservação da Biodiversidade, Itajaí, Brazil., Cardoso LG; Laboratório de Recursos Pesqueiros Demersais e Cefalópodes, Instituto de Oceanografia, Universidade Federal do Rio Grande, Rio Grande, Brazil.
Jazyk: angličtina
Zdroj: Journal of fish biology [J Fish Biol] 2024 Jul; Vol. 105 (1), pp. 46-58. Date of Electronic Publication: 2024 Apr 15.
DOI: 10.1111/jfb.15758
Abstrakt: The blue shark is a highly migratory species with a worldwide distribution, making it susceptible to multiple fishing fleets across the globe. In southern Brazil, it is an important target, comprising up to 40% of the total biomass landed by the commercial surface longline fleet. This study aims to contribute to a better understanding of how the species uses the region and to update its life-history information available for future assessments. Over five consecutive years (2018-2022) of landings and onboard monitoring, we gathered size data and vertebral samples to describe the species size composition in the region, as well as its seasonal and interannual variability and to update estimated life-history parameters. The results showed that southern Brazil is mainly inhabited by large juvenile males that arrive during winter (July-September) and stay until spring (October-December), when their frequency decreases. Small adult males are present throughout the year but in higher frequencies during summer. A small number of adult females are present with higher frequencies during spring and summer, which decreases during the austral autumn and winter. Some variability in the presence of each life stage was observed among years. The estimated life-history parameters were as follows: L∞: 255.02 cm fork length (FL), k: 0.20, L 0 :35.68 cm FL for males; L∞: 246.47 cm FL, k: 0.23, L 0 :36.77 cm FL for females; and L∞: 269.58 cm FL, k: 0.18, L 0 :36.19 cm FL for pooled sexes. However, the estimated values must be cautiously interpreted, as the obtained samples cannot be construed as representative of the entire harvested stock due to the lack of consistent presence of some life stages in the study region.
(© 2024 Fisheries Society of the British Isles.)
Databáze: MEDLINE
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