First results of greater amberjack (Seriola dumerili) larval rearing in mesocosm

Species diversification is considered a major approach for the sustainable development of aquaculture. The greater amberjack (Seriola dumerili) has particular characteristics-advantages making it an appropriate candidate: high growth rate, large size, and established worldwide market. In the present study, the mesocosm method for larval rearing was applied, since it has been shown to be effective in the larval rearing of several species so far. This method is a semi-intensive technology, based on daily exogenous food addition, but also having the capacity of some endogenous productivity. Greater amberjack eggs were obtained from wild-caught fish matured in captivity in 6 years, after induced spawning with implants containing gonadotropin-releasing hormone agonist (GnRHa). A total of 9800 eggs survived after embryo appearance and were incubated in a 40-m3 tank with natural seawater of 40 psu. Rearing lasted 40 days. After mouth opening on day 2 post hatching, exogenous feeding with rotifers, Artemia nauplii and inert feed was initiated, while endogenous produced copepods contributed as food for the larvae from day 7 post hatching onwards. During rearing, larvae grew with an exponential rate of 0.073 day−1 in terms of total length (TL), and reached 39.9 ± 5.4 mm and 0.5 ± 0.1 g body weight at the end of the trial. All larvae inflated their swim bladder and completed metamorphosis at about 5 mm and 8 mm TL, respectively. Schooling behavior was first observed when larvae reached 9-10 mm TL, while aggression against the smallest individuals was first noticed the same period. The final population of about 350 individuals (3.5% survival) was transferred at the end of the trial for subsequent on-growing. The results obtained indicate the reliability of the technology for the larval rearing of the greater amberjack, and also its appropriateness for diversification with difficult marine species.