Influence of tank volume on vitellogenesis and spawning performances in sea bass Dicentrarchus labrax L.

Sea bass, Dicentrarchus labrax (mean weight: 748±13 g), were maintained before and during vitellogenesis in 1, 3, 8, 16 and 32 m3 tanks, and then they were transferred to 2 m3 tanks, for the spawning season. During the first 2 months of the experiment, the growth rates were significantly lower in smaller tanks (1 m3). In August, the oocyte diameters were significantly lower in smaller tanks (1, 3 and 8 m3) than in larger (16–32 m3) tanks. At the end of the experiment, the fish mean weight in the 1 m3 tanks was significantly lower than in the 3 m3 tanks, but oocyte diameters and plasma oestradiol concentrations were not significantly different between the volumes. This shows a longer acclimation requirement in smaller volume rearing. Although all the females had not spawned, one spawn at least was collected in each volume. The variation in conditioning volume has not blocked the spawning process. The qualitative and quantitative characteristics of spawns were not significantly different between volumes. The conditioning volume of 3 m3 seems to be a minimal volume required to obtain good reproduction of sea bass.