Maturity Assessment for the Implementation of the First Fishery Regulation in Patagonian Marine Gastropods

ABSTRACT In order to establish management measures for a new resource, the size at first maturity should be studied. This measurement is a powerful tool in enabling the sustainable exploitation of marine benthic resources. Patagonian marine gastropods are captured as complementary catches during scallop fisheries. Studies related to the size at first maturity were performed for edible marine gastropods in northern Patagonia and have been used for the creation of the first regulation of gastropod catches made by the Secretary of Fisheries of Chubut Province. The minimum capture size of some of the species included in this regulation was established from preliminary studies but needed histological confirmation. The present study aims to provide accurate information on the size at maturity by an assessment that includes first gonadal maturity and population size/weight data of Buccinanops deformis and Trophon geversianus, two edible species of marine gastropods with high abundance along the Patagonian Atlantic coast and elevated nutritional values in their edible tissues. By histological methods, females of B. deformis reach maturity at 2.8 cm and males at 1.95 cm. While by an alternative histological method (inflexion point method), females reach maturity at 2.76 cm and males at 2.1 cm. For T. geversianus, females reach maturity at 3 cm (inflexion point = 2.38 cm) and males at 1.65 cm (inflexion point = 2.01 cm). The maturity assessment of B. deformis and T. geversianus revealed that males reach maturity at a smaller size than females, probably due to the fact that females require a more gradual process in maturation with a greater reproductive investment. The size at first sexual maturity provides valuable information for establishing the minimum catchable size. Therefore, we estimate a minimum size limit for B. deformis of 3.6 cm and 3.5 cm for T. geversianus and suggest that fishery measurements for these species should be established by performing a particular maturity assessment in each fishery zone.