Metodología para la determinación del sexo fenotípico y la obtención de poblaciones de reproductores del mugílido Chelon labrosus durante la época de reposo sexual

Abstract

The aim of this study was to obtain a basic methodology for sex determination and implementation of spawning stocks for the thick lipped grey mullet (Chelon labrosus) during the non maturation period. Animals were maintained in 5 m3 tanks in the C.I.F.P. Marítimo Zaporito facilities in San Fernando (Cádiz) under natural conditions of photoperiod and constant temperature (19-20ºC). A total of 39 animals were marked whit pit-tags, a biopsy from the gonad was taken through the gonad pore using a plastic cannula, and they were bled for obtaining plasma samples to measure both 11-ketotestosterone (11-KT) and estradiol (E2). On one hand, the results from biopsies did not provide reliable information. On the other hand, sexual hormones data showed a clear differentiation between both sexes, having the males larger amounts of 11-KT respect to E2 and vice versa for females, despite the low levels of both hormones in plasma respect to the breeding period. The method was validated by sexing a control group during the breeding period.