Thicklip (Chelon labrosus) and flathead (Mugil cephalus) grey mullets fry production in Tunisian aquaculture

Abstract

For several years Tunisia has opted to breed freshwater fish in reservoirs and artificial lakes, created for irrigation, as a strategy of providing high quality aquatic protein to the interior regions and providing work opportunities for local communities. The aim of this study was to summarize the main results accumulated by the last 20 year efforts made by the members of the National Institute for Marine Science and Technology (INSTM)-Aquaculture Laboratory to develop thicklip (Chelon labrosus) and flathead (Mugil cephalus) grey mullets fry production from captive broodstocks intended for stocking inland reservoirs (artificial lakes) and grow-out purposes Administration of human chorionic gonadotropin (hCG) at a priming dose of 10.000 IU kg−1 female bw, followed by 10.000 IU hCG and (100 or 200 μg kg−1 female bw of thicklip or flathead grey mullet respectively) as resolving dose resulted at the highest egg production for both species. Mean fecundity was 494.655 eggs kg-1 bw for thicklip grey mullet and 418.945 eggs kg-1 bw for flathead grey mullet. Fertilization rate of eggs produced was high (mean rate 83 % and 63 % for thicklip and flathead grey mullet respectively) and larvae hatched from those eggs at high rates (77 % and 88 %, respectively). The green method was more efficient than clear method to produce thicklip and flathead grey mullet fry, (i.e larvae had higher growth rate and better survival rates). The results of this study demonstrate the possibility to control reproduction and produce grey mullet fry in captivity. However, further research is needed to optimize the production protocol of eggs and fry of both grey mullet species.