The presence of wild Senegalese sole breeders improves courtship and reproductive success in cultured conspecifics

The life cycle of Senegalese sole (Solea senegalensis) is not closed in captivity due to a reproductive dysfunction related to the lack of participation of cultured male breeders in the courtship. To discern a possible solution to this social reproductive dysfunction, the main objective of this study was to determine the effect of the presence of spawning wild Senegalese sole breeders on the courtship and reproduction of cultured breeders. Three experimental groups were formed: Control group (n = 10) formed with only cultured sole; groups M1 and M2 constituted of mixed-origin sole (10 cultured and 8 or 9 wild breeders). All cultured breeders were from the same stock, which had never successfully reproduced, whilst the wild broodstock had spawned viable eggs in captivity. All groups were held in the same captive conditions and spawning, and behaviour were recorded for each group over four spawning seasons. All spawns were collected, and the parameters registered were floating and non-floating eggs, fertilization and hatching rates. In addition, parental analysis was made of larvae from viable spawns. Behaviour was studied with video recordings to compare locomotor activity and courtship behaviours including the Follow behaviours where sole swim after each other in a procession. Fertilized spawns were obtained from the mixed-origin groups (M1 and M2) including spawns involving a cultured male. The cultured males also participated actively in the Follow behaviours with the courting wild sole and this participation of cultured males increased significantly over the four years of the experiment. Male percentage participation in the Follow behaviours was positively correlated (R = 0.81) to participation in spawning to indicate the importance of increasing cultured male participation in the Follow behaviours. A total of seven spawns were obtained from a cultured male that fertilized eggs from one cultured female and two wild females. The same cultured female also spawned with a wild male. No viable spawns were obtained from the Control group and locomotor activity and courtship behaviour counts were significantly lower than in the experimental mixedorigin groups. This is the first report of cultured male breeders participating in reproductive behaviour and spawning, which could be associated with social learning processes, mate selection and dominance where cultured males copied the behaviour and spawning of wild Senegalese sole breeders.