Reproductive features and length at first maturity of hoki (Macruronus magellanicus) in the Southwest Atlantic. 2003-2010 period

Abstract

To study hoki reproductive features, estimate length at first maturity and, in a first attempt to establish the time and geographic location of the spawning area, data of 210 trips gathered by observers on board of commercial vessels that operated between 41° S-57° S in the 2003-2010 period were analyzed. According to the distribution of the trawl stations two areas were established. Results of the maturity condition, length at first maturity and size frequency obtained showed no difference between both areas, which allows to conclude that specimens belonged to the same reproductive group. Length at first maturity, estimated considering only individuals caught during June through November was 56,50 and 56,05 cm total length (TL) for males and females, respectively. The presence of both sexes in spawning stage during those months and in developmental condition in the previous support the hypothesis that the species would spawn in the Argentine Sea between 51° S-57° S during that time close to the 200 m isobath. Although results allowed to establish a possible reproductive season, the spawning area could not be delimited because no large concentrations of spawning groups were registered. Considering the observations made in this work, it is suggested to increase samplings in the study area during Winter and Spring (June-November) in order to identify a larger number of spawning or post-spawning females.