Species biology of elasmobranch by-catch in bottom-trawl fishery in the northern Patagonian shelf, Argentina

Abstract

The present study analyzes the species composition of elasmobranch by-catch of bottom trawlers that targeted common hake Merluccius hubbsi on the northern and central Patagonian shelf during 2001, 2002 and 2003. Six surveys were conducted, and a total of 20 species of elasmobranchs were observed. Zearaja chilensis and Squalus acanthias were present in all surveys. The mean values of relative abundance ranged between 9.12 and 151 ind. km−2 for Z. chilensis and between 8.24 and 298 ind. km−2 for S. acanthias. Bathyraja brachyurops, B. macloviana, B. magellanica, Discopyge sp. and Psammobatis lentiginosa were registered only in 1 survey, and their relative abundance did not exceed 15 ind. km−2. There were no patterns detected between the mean size of the individuals and the depth of capture for any of the captured species. Length-to-weight relationships were estimated for 14 species, and size-at-maturity was estimated for 8 species.