Improving our Understanding of Tropical Tuna Movements from Small to Large Scales

Abstract

One tactical objective of behavioural studies in fisheries sciences is to under- stand the 3-D movements of fish, with the ambitious strategic objective of be- ing able to explain some large-scale movements and distributions from knowl- edge of small-scale behaviour. The present paper reviews different possibili- ties to improve our understanding of tropical tuna movements, from small (days) to large scales (weeks and months). We propose some ideas for better observations of fine-scale movements of fish (sonic tags) and of the surround- ing environment of the tagged fish. After determining behaviour rules, appro- priate modelling should be developed in order to extrapolate results to larger- scale movements. This process can be achieved only if we can simultaneously observe the relevant factors of the environment at appropriate scales and the large-scale movements of fish (using pop-up archival tags), in order to force the models to reproduce the observed movements. This paper shows the im- portance of (i) small-scale studies, (ii) appropriate observations of large-scale movements and environment, and (iii) models of behaviour in order to extract relevant processes necessary to predict tuna dynamics