Mesoscale eddies and survival of late stage Pacific sardine (Sardinops sagax) larvae

We examined the distribution of sardine larvae relative to environmental co nditions with the purpose of identifying and characterizing habitat that en courages high larval growth and survival, based on the 1983-1998 surveys of the California Cooperative Oceanic Fisheries Investigations (CalCOFI). Lon g-term averages show that sardine 'survivors' (spatially aggregated larvae greater than or equal to 18 days old) were most abundant offshore, whereas sardine egg density, chlorophyll biomass and zooplankton volume were greate st inshore. In contrast, mesoscale eddies, observed in remotely sensed sea surface temperature imagery, were found only in offshore regions. To furthe r examine the link between eddies - which often result in locally elevated chlorophyll and zooplankton - and sardine survival, we compared the distrib ution of larvae and eddies survey by survey. Sardine survivors were most ab undant offshore in only one-quarter of the research surveys, and when they were most abundant offshore they were associated with eddies. This indicate s that the offshore eddy habitat produced exceptionally large numbers of su rvivors, as evidenced by the disproportionate effect on the long-term avera ge.