The links between functionally distinct adult assemblages of Sardinops sagax: Larval advection across management boundaries

Abstract

Otolith increment data were used to age larval Sardinops sagax collected from shelf waters between Kangaroo Island in South Australia (SA) and Albany in Western Australia (WA). Distributions of both ages and hatch-dates were compared between six regions across this broad area to examine the hypothesis that larvae arising from spawning sardines in WA may be advected by the Leeuwin Current to the central coast of SA prior to metamorphosis. Current and wind data were analysed to estimate potential rates of passive transport. It appears likely that larvae arising from commercially exploited S. sagax populations in WA can be passively transported close to the region of the S. sagax fishery on the central coast of SA prior to metamorphosis. The potential for links between distant (>1000 km) management units requires reconsideration of the scale over which the population dynamics of southern Australian S. sagax operate. This study provides an example of how information on larval dynamics, including the influences of oceanographic factors, gained from a relatively short period of field work (1 month) can significantly increase our understanding of population dynamics of exploited fish and subsequently have direct relevance to resource management. © 2001 International Council for the Exploration of the Sea.