Resumen

TAVARES, Rafael  y  AROCHA, Freddy. Species diversity, relative abundance and length structure of oceanic sharks caught by the Venezuelan longline fishery in the Caribbean Sea and western-Central Atlantic. Zootecnia Trop. [online]. 2008, vol.26, n.4, pp.489-503. ISSN 0798-7269.

This study examines the species diversity, relative abundance, and length structure of oceanic sharks caught by the Venezuelan longline fishery targeting swordfish and tuna. Shark catch data was collected by scientific observers during the period 1994 to 2003. The total shark catch was comprised of 25 species, in which the most frequently caught were Prionace glauca (34.8%) and Carcharhinus signatus (20.2%). Other common species in the catch composition were C. falciformis (8.5%), Sphyrna mokarran (6.8%), and Isuru oxyrinchus (6.2%). The inter-annual variation of the Shannon-Wiener index was characterized by an apparent loss of the shark diversity throughout the time series. Kriging map showed that areas with relative high diversity values were located in the southeastern Caribbean Sea, primarily in areas close to the islands and coast of Venezuela. Other areas with significant diversity values corresponded to the inner arc of the Lesser Antilles and the Suriname shelf. The analysis of catch per unit effort trends for the five most common species revealed that all series had a negative slopes, but only one (C. falciformis) was statistically significant. Shark catches for the most important species comprised a large proportion of juveniles. Major efforts will be needed to generate steady scientific information required for stock assessment.

Palabras clave : blue shark; CPUE; diversity; elasmobranchs; fishery; variogram.

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