  Identifying spatial and temporal patterns can reveal the driving factors that
govern the behavior of fish in their environment. In this study, we
characterized the spatial and temporal occupation of 37 acoustically tagged
bigeye scads (Selar Crumenophthalmus) in an array of shallow Fish Aggregating
Devices (FADs) to clarify the mechanism that leads fish to associate with FADs.
A comparison of the number of visits and residence times exhibited by the fish
at different FADs revealed a strong variability over the array of FADS, with
the emergence of a leading FAD, which recorded the majority of visits and
retained the fish for a longer period of time. We found diel variability in the
residence times, with fish associated at daytime and exploring the array of
FADs at nighttime. We demonstrated that this diel temporal pattern was
amplified in the leading FAD. We identified a 24-hour periodicity for a subset
of individuals aggregated to the leading FAD, thus suggesting that those fish
were able to find this FAD after night excursions. The modeling of fish
movements based on a Monte Carlo sampling of inter-FAD transitions revealed
that the observed spatial heterogeneity in the number of visits could not be
explained through simple array-connectivity arguments. Similarly, we
demonstrated that the high residence times recorded at the leading FAD were not
due to the spatial arrangement of individual fish having different associative
characters. We discussed the relationships between these patterns of
association with the FADs, the exploration of the FAD array and the possible
effects of social interactions and environmental factors.
