First results on the behavior of young stages of allis shad Alosa alosa

Experiments were performed to investigate the use of space by larvae of allis shad Alosa alosa (also known as allice shad) under experimental conditions. Soon after hatching, larvae swam actively toward the surface and sank down passively to swim up again once they reached the bottom. After this phase, most of the larvae swam in the first cm below the water surface. This general pattern of water column use was observed with and without water current and irrespective of the size of the bottom substrate material. The ontogeny of larval swimming behavior has been studied in an artificial stream.The first experimental work on allis shad larval behavior, suggests a pelagic larval mode immediately after hatching. Because of a high proportion of drifting fish, most larvae would undergo a large downstream dispersal in the wild.