Demographic analysis among three populations of Zidona dufresnei from the southwestern Atlantic

Abstract

Study of demographic patterns in species that support a fishing pressure is essential for the conservation and management of their populations. Zidona dufresnei is an endemic marine snail from the southwestern Atlantic, and is one of the main species caught by artisanal fisheries. It is also characterized by marked differences between its populations in terms of the maximum length attained. The aim of this study was to assess the population structure and morphogravimetric variations (intra- and interpopulations) in three locations distributed along the Argentine Sea (Mar del Plata, San Matias Gulf, San Antonio Bay). The size ranges varied between 80 and 230 mm. The smallest specimens corresponded to San Antonio Bay, while the largest ones to San Matias Gulf. In all cases, the frequency distributions of length and weight followed a unimodal distribution. No differences in weight and size between sexes were found. The width, length, and total weight of the specimens differed significantly among the three sites in both overall test and posteriori comparisons. The sex ratio did not differ from 1:1. The results obtained in this study allowed expanding the depth distributional range of Z. dufresnei from 0 to 120 m. In addition, a new maximum size for the species of 230 mm was recorded for the Argentine Sea. The differences found among the three populations studied may be due to local environmental pressures or an interrupted or reduced gene flow.