Effects of social interactions on the reproduction of the Nile Tilapia, Oreochromis niloticus : possible application for breeder management

Abstract

Behaviour and social factors are important for the reproduction of O. niloticus. The influence of social interactions on the fry production was analyzed using a domestic strain. In a first step (S1), females with high and low reproductive potential (HRP and LRP) were detected within a group of breeders. Two groups (G1 and G2) were constituted with a sex ratio of 3 males / 7 females (1:2.3). G1 presented a significant difference in the average spawning rate of HRP and LRP females (3.5 ± 0.58 and 0.33 + 0.58 spawns.female-1 respectively). We then carried out social reorganizations based on the previously established (SI) reproductive potential (RP). Two groups (GA and GB) with FRP (sex ratio: 1:3) and HRP females (sex ratio: 1:4) respectively were constituted using the G1 breeders. These social reorganizations have strongly affected individual RP and the dominance (aggressiveness) of some LRP females. Within GB, the average spawning number decreased from 3.5 ± 0.58 to 0.75 ± 0.96 spawns.female-1. These results suggest a strong influence of behavioural and social components in the RP of breeders. Interestingly, some HRP females retain their high RP following a social reorganization