Control of reproduction of greater amberjack Seriola dumerili reared in aquaculture facilities

摘要

Members of the genus Seriola have been notable species for aquaculture production worldwide, with the greater amberjack Seriola dumerili being a prominent species, partly due to its cosmopolitan distribution. A prerequisite to sustainable aquaculture production is controlling reproduction in captivity, which has been lacking for greater amberjack. The objective of the present study was to develop broodstock management and spawning induction methods using gonadotropin releasing hormone agonist (GnRHa) implants for greater amberjack reared in tanks and sea cages, and evaluate spawning performance. The advantages of sea cage rearing and spawning include optimal environmental conditions and welfare, and low cost of fish maintenance; while the advantages of tank rearing and spawning include biosecurity, ease of management and handling operations, and control of egg collection. Females reared in tanks supplied with well seawater throughout the year exhibited a significant reproductive dysfunction, such as limited gametogenesis, lower oocyte diameter at the peak of the reproductive season, low female eligibility for spawning induction and almost 0% fertilization success. On the contrary, females in three different broodstocks reared in sea cages for three consecutive years underwent vitellogenesis completely, and almost all females were eligible for spawning induction. Males reared under both conditions exhibited reduced sperm production compared to the wild, but unlike the situation in the females, tank rearing did not seem to have any negative effects on sperm quality parameters compared to rearing in sea cages. Spawning performance (eggs collected and fertilization) was best when fish were reared in sea cages during the year and then moved to land-based tanks for spawning after GnRHa treatment, resulting in the production of large numbers of eggs of adequate quality for commercial larval rearing of the species.