Review of fish associative behaviour:: toward a generalisation of the meeting point hypothesis

Associative behaviour is defined as the spatial relationship between an animal (or a group) of a given species and another animal of another species, which is based on a decision by at least one of the two individuals to maintain contact with the other associate, but not for the purpose of feeding on the other. This definition is expanded to include objects and topographic structures (seamount, island, etc) that are not the exclusive habitat of the associated animal. Associations between fish and objects, mammals, topographic structures and other species of fish are reviewed, and the different hypotheses for these associations analysed. Finally, a generalisation of the meeting point hypothesis, fitting all types of association, is proposed. This hypothesis, initially applied to the association between tuna and floating objects, proposes that fish make use of animate or inanimate targets to increase the encounter rate between isolated individuals or small schools and other schools in order to constitute bigger schools that are more efficient to the survival of the species. It is strongly recommended to move from the scientific description of the association to specific experimental studies aimed at identifying ethological processes. This would provide a better understanding of the dynamics of associative behaviour of pelagic species, which in turn would permit better stock assessment and fishery management.