Reproductive cycle of leopard grouper Mycteroperca rosacea (Streets, 1877) held in captivity: relationship between gonad development and sex steroid concentration

摘要

In this study, sex steroids (E2, T, and 11-KT) concentrations in blood of captive leopard grouper (Mycteroperca rosacea) and their relation to gonad development were determined during a reproductive cycle. Each month, gonad samples from 24 fish were obtained to analyze gonadal maturation and blood was extracted to determine steroid levels. Throughout the year, ovaries showed a higher percentage of primary oocytes. In January, oocytes at early and late vitellogenesis stages increased progressively; from March to June, ovulation rates were high. In females, estradiol levels increased from March and decreased after the spawning season. Lower levels of testosterone were found during the spawning season and 11-KT remained without significant changes throughout the year. Males exhibit a significant increase in E2 from March until July; testosterone remained without significant variation throughout the year, and 11-KT plasma levels increased from March until July and decreased after the spawning season. In this study, we verified the sex change of an organism and the concentrations of sexual steroids were determined and discussed.