Abstract

Little is known regarding the early life transport and dispersion mechanisms, from offshore spawning areas to inshore nursery habitats, that potentially underlie recruitment variability for arrowtooth flounder in the Gulf of Alaska (GOA). We developed a biophysical individual-based model (IBM) for arrowtooth flounder early life history and dispersal with simple representations of swimming behavior, growth, and survival to explore the variability in connectivity between spawning and recruitment sites that can arise due solely to interannual variability in environmental forcing and its impact on transport. Results of our simulations for 1996-2011 show that, even in the absence of mortality, most (> 80%) individuals were unsuccessful in dispersing from presumed spawning areas along the continental shelf break to inshore nurseries in the GOA. For those that were successful, connectivity was directed in a counterclockwise fashion (southeast to northwest) following prevailing current patterns, with typical dispersion distances of 100 s of km alongshore. The most productive spawning areas were in the southeastern GOA (areas off Sitka and Cross Sound), while the most effective nursery areas were in the central and western GOA (Prince William Sound and North Kodiak areas). Arrowtooth flounder from spawning areas in the western GOA were exported from the system and likely contribute little to the population in the GOA, but may provide recruits to populations in the Aleutian Islands or eastern Bering Sea. We developed a suite of potential recruitment indices based on the connectivity results; however, none of these appeared to reflect estimated (age-1) recruitment to the population from a stock assessment model.