Idade, crescimento e avaliaÃÃo de estoque da serra Scomberomorus brasiliensis (Teleostei: Scombridae), na plataforma continental do Nordeste do Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

The spanish mackerel, Scomberomorus brasiliensis, represents an important fishery resource in Northeast Brazil. Aiming to analyze the age structure composition of the artesanal fisheries catches and to assess the stocks in the area, 6148 specimens were sampled at the continental shelf between 1998 and 2001. This activity was carried out in the extent of the REVIZEE Score-NE Program. The samples were taken at the landing points from Piauà to Bahia States. The specimens was sexed, measured and weighted. Sizes varied between 102 and 960 mm fork length. The sampleâs mean length size decreased from 1998 to 2001. Age and growth was estimated from 831 otoliths sagittae, from September 1999 to April 2001. Significative biometric relationships were determinated (ANOVA-p<0.01). Differences in the sexual proportion were found, where 654 were males (59%) and 461 were females (41%). The relative marginal increment analysis showed that the species at the area prints one ring per year between November and March. A maximum of 8 periodic marks were found, with lengths between 115 and 758 mm. The following growth parameters were obtained: Northeast Region L∞ = 963 mm K = 0,15 ano-1 and t0 = -0,211 yr; East Coast L∞ = 845 K = 0,176 and t0 = -0,122; Northern Coast L∞ = 945 K = 0,164 and t0 = -0,061. The growth parameters for each sex were: L∞ =781 K=0,188 and t0 = -0,383 for males and L∞ = 1142 K=0,113 and t0 = -0,414 for females. The growth curves were compared using the Kappenmanâs method and did not show significant differences (p >0,05) neither by sex or region. Stock assessment was carried out using the growth parameters obtained for the whole region. Based on the catch curve the following exploitation rates were estimated: total mortality Z = 0,54; natural mortality M = 0,36; fishery mortality F = 0,18 and exploitation rate E = 0,33. The yield per recruit models, knife edge and selection ogives, led to estimate a maximum sustainable exploitation rate of E = 0,61 and E = 0,50, respectively. The cohort analysis based on ages estimated a biomass of 5591 ton with a yield of 1412 ton and a stock exploitation of 25% per year. Using actual mortality rates, the Thompson &Bell model was used to predict future exploitation. There was obtained an average biomass of 5603 ton, with a yield of 1406 ton and a cost of R$ 7.032.148 exploiting 25% of the stock per year. The models used showed exploitation rates (E) between 0,33 to 0,47, with stockâs exploitation of 25% per year approximately. These values show that the species is already near from its maximum exploitation sustainable limit, with indicium of population decline. Management actions, aiming to increment the size at catch, are necessary for the conservation of this important resource in the region

ASSUNTO(S)

ciencias biologicas peixe serra (scomberomorus brasiliensis) - estudo etÃrio biologia pesqueira peixes marinhos - brasil(ne) - dinÃmica populacional

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