Behaviour and ecology of a population of Abudefduf saxatilis (Pomacentridae, Teleostei) at Eilat (Red Sea)

Abstract

Summary This study summarizes investigations on a population of the Sergant Major, Abudefduf saxatilis (Pomacentridae), performed along the coral reef of Eilat, Gulf of Aqaba. Emphasis was placed on the schooling behaviour and reproduction, especially on the analysis of the male's action inventory, their frequencies and signicance. 1. Ab. saxatilis inhabiting shallow waters, exhibits long-term reproduction during the summer months (April to August), the individual spending the night separately in coral crevices and gathering after sunrise in groups to feed on plankton. 2. After feeding, the mature fish form a school and start to swim along the coral wall, headed by mature males searching for sites for nesting colonies. Consequently, this appetitive behaviour brings about the establishment of breeding colonies of eight to twenty mature males. 3. Ripe females attracted by special acts of the male enter individual territories and spawn. The entrance of such receptive females changes the action patterns of the male, stimulating the occurrence of the behaviour that leads to fertilization and spawn care. 4. The male spawns with several females consecutively and with each new female the reproductive behavioural pattern is partly renewed. 5. The frequency and correlation analysis of action bonds was found to be strongly connected to the strength of the producing stimulus. 6. During the winter months the schooling disappears and the fish are found in small groups in the littoral all along the reef.