Drift-tube study of the dispersal potential of green abalone (Haliotis fulgens) larvae in the southern California Bight: implications for recovery of depleted populations

Abstract

Drift tubes were released over the major past and present green abalone (Haliotisfulgens) beds in southern California, USA, to investigate the dispersal potential of this species' relatively short-lived larvae. The Channel Islands presently support the important green abalone populations in this region; mainland stocks are largely depleted. A total of 2400 drift tubes was released during June and October 1981, the 2 peaks of the spawning season. Of the 1225 drift tubes released at the Channel Islands, 4 % were later recovered in the mainland, but only 0.4 % were found within a time span appropriate for green abalone larval life. There was some transport between isolated mainland populations within appropriate time periods but the present status of mainland stocks suggests that recolonization by larvae originating elsewhere will be uncommon. In contrast, high proportions of the drift tubes deployed in each general release area were transported a few kilometers and recovered in suitable habitat within reasonable times for green abalone larval development. Thus, in the absence of local brood stock, the present fishery closure is not likely to promote recovery of mainland populations of H. fulgens in the near future. These results underscore the importance of local current patterns and details of larval life histories to the understanding of patterns of distribution in any area.