A study on biology and fishery of the sea-bob-shrimp (Xiphopenaeus kroyeri) caught by artisanal fisheries on the coast of São Paulo State

Abstract

From 1979 to 1980 seventy-two samples of sea-bob-shrimp were analyzed. They were obtained from a fleet of trawling boats considered artisanal, operating in depths ranging from 4 to 10 m in three fishing terminals of São Paulo State: Peruí­­be, Perequê and Ubatuba. Samples of discarded, commercial and gross shrimp were obtained. The shrimp total weight ranged due to natural fluctuations and availability of sea-bob-shrimp in the environment, while the percentages of commercializable shrimp and discarded shrimp also depended on the seasonal oscillations in the pattern of selection utilized by the fishermen. The average percentage of rejection was 22% in the three fishing terminals (collecting stations), ranging from 11 to 36 during the year. The sex-ratio observed was about 1:1 in the category "gross", occurring predominantly immature or in maturation individuals (mainly among the females) in the studied fishing area, characterizing the environment as a growing area, and not a reproduction area for the sea-bob-shrimp. The estimated length for the first gonadal maturation was 6.2 cm for males and 7.1 cm for females, while the maturation length for 100% of the individuals occurred at 7.5 and 9.0 cm for males and females, respectively. The values of the constants Φ and ÆŸ in the mathematical formulae that relate weight to length were: Φ=3.00345x10^-3 and ÆŸ = 3.247002 for males and Φ = 3.074184x10^-3 and ÆŸ = 3.2314 for females.