The role of the Todos os Santos Bay for the ray and skate life cycle

Abstract

Skates and rays are important catches in the estuary system of the Todos os Santos Bay, with average catches of 936.9 tonnes in 2006. However, they are presented as "ray category" without detailed information on the species. Moreover, there is no knowledge about the population dynamics of those species. In this context, this is an important study for fulfilling this lack and also for supportting conservation decisions. The aim of this work is to describe the role of the estuary of the Todos os Santos Bay to the skates and rays life cycle, investigating its use for reproduction, growth and feeding. Also, the socioeconomic characterization and ethnobiology study will be made. The catch data (number and weight), the biometric data and viscera (liver, digestive and reproductive organs) of fish will be collected in two localities monthly for seven days during 12 months. The CPUE (kg/fisherman) will be calculated by local and gear. The population structure will be analyzed by the distribution of length classes, proportion of male and female, and maturity stage. Reproductive period will be detected by the frequency of the stages of maturity, gonadosomatic index and hepatosomatic index. The diet of the species will be described, considering spatial-temporal variability of species and resources. Detailed study of reproduction and growth will be made for the species with representative samples. (AU)