"Dinâmica populacional de raias demersais dos gêneros Atlantoraja e Rioraja (Elasmobranchii, Rajidae) da costa sudeste e sul do Brasil" / Populational dymanics of skates genera Atlantorala and Rioraja (Elasmosbranchii, Rajidae) of Southeastern and Southern Coastal of Brazil

AUTOR(ES)

Luiz Miguel Casarini

DATA DE PUBLICAÇÃO

2006

RESUMO

The proportions of the skates Rioraja agassizi, Atlantoraja cyclophora, A. platana and A. castelnaui landed by commercial fishing boats were analyzed. Data were collected from 358 hauls of 20 trips made by 11 double-otter trawlers and pair-trawlers. Fisheries were carried out between 10 and 430 m deep and from 23° S (State of Rio de Janeiro) to 31° S (State of Rio Grande do Sul) between 1995-1997 and 2001-2003. A. cyclophora was the most frequent in all hauls between 60 and 265 m deep among the studied species, with a wide distribution between 23°30’ S and 27°20’ S. The analyses of the fisheries suggested that depth and latitude, along with other variables, have importance only for A. cyclophora catches. The skates carcasses were landed in three types of cuts from which the body weight was estimated. The population structures of the four species were also evaluated. The growth parameters estimates, the disc width (DW) at first sexual maturation and the instantaneous natural mortality rate (M) for males and females were, respectively: R. agassizi: DW = 289 mm and 425 mm; K= 0,142 and 0,078 year-1; t0 = -1,653 and -1,811 years; DW50 = 270 and 330 mm, M = 0,061 and 0,052 year-1; A. cyclophora: DW = 478 and 518 mm; K= 0,077 and 0,073 year-1; t0= -4,518 and -4,485 years; DW50 = 355 and 415 mm, M = 0,085 and 0,085 year-1; A. platana: DW = 733 and 823 mm; K= 0,057 and 0,052 year-1; t0= -1,267 and -1,225 years; DW50 = 500 and 550 mm, M = 0,061 and 0,021 year-1; A. castelnaui: DW = 794 and 1004 mm; K= 0,066 and 0,046 year-1; t0 = -1,978 and -2,235 years; DW50 = 670 and 740 mm, M = 0,069 and 0,047 year-1. In some years, the relative yield-per-recruit model resulted values similar or higher than the biological reference points estimated for males of R. agassizi and females of A. platana and A. castelnaui. The exploitation ratio and the instantaneous fishery mortality rate for A. cyclophora increased between 2001 and 2003.

ASSUNTO(S)

skates rendimento crescimento mortality pesca mortalidade growth raias yield fisheries

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