Zooplankton patchiness and the associated shoaling response of the temperate reef fish Trachinops taeniatus

Abstract

The grouping behaviour of fishes plays an important role in the success of the group and individual in terms of foraging, reproduction and predator avoidance. The temperate Sydney (Australia) reef fish species Trachinops taeniatus was investigated between February and September 2002 to determine whether there was a relationship between shoal dynamics and zooplankton prey distribution. The diet of T. taeniatus consisted mainly of Copepoda. T. taeniatus shoals were strongly associated with the largest patches of Copepoda, with shoal size increasing as prey density increased. Available Copepoda per fish, however, decreased with shoal size, presenting a possible 'overmatching' foraging situation. The present study suggests there may be an optimum shoal size to achieve maximum prey intake, and that shoal location and size may be linked to the distribution of zooplankton prey. © Inter-Research 2005