| CHARACTERIZING INTERANNUAL VARIABILITY OF DISPERSAL PATHWAYS IN SLOPE-SPAWNING FLATFISH IN THE EASTERN BERING SEA |
| VESTFALS, C.D., Ciannelli, L., and Sohn, D., Oregon State University, Corvallis, OR, 97331, U.S.A., vestfals@coas.oregonstate.edu, lciannel@coas.oregonstate.edu, dsohn@coas.oregonstate.edu; Duffy-Anderson, J.T., Stockhausen, W.T., Alaska Fisheries Science Center, NOAA Fisheries, Seattle, WA, 98115, U.S.A., janet.duffy-anderson@noaa.gov, william.stockhausen@noaa.gov
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| Adult spawning and juvenile settling locations of marine fishes are often geographically separated. As a result, early life history stages must rely on transport and retention features, as well as their own behavior, to move them toward or keep them within appropriate habitats for successful recruitment to the juvenile phase. However, climate variation can influence ocean circulation patterns and can potentially affect the ability of marine organisms to take advantage of certain circulation features. To understand how changes in circulation may influence recruitment and population dynamics in Greenland halibut (GH, Reinhardtius hippoglossoides) and Pacific halibut (PH, Hippoglossus stenolepis), two commercially-important flatfish species in the eastern Bering Sea (EBS), we reconstructed their dispersal pathways from their source (e.g., spawning areas over the continental slope) to sink locations (e.g., juvenile settling locations over the continental shelf). Despite similarities in their spawning times, locations and depths, GH and PH exhibit distinct differences in the distribution and abundance of their egg, larval, juvenile and adult stages, as well as their overall population dynamics. This research attempts to resolve the physical mechanisms of delivery by determining where and when GH and PH larvae make the transition from the slope to the shelf region, and whether their transit locations change across years. Annual patterns of dispersal of GH and PH larvae from spawning areas were simulated using DisMELS (Dispersal Model for Early Life Stages), a particle tracking individual-based model developed to provide recruitment forecasts for flatfish in the EBS based on advective transport patterns. Location and timing of shelf-break crossings were compared to local oceanographic and atmospheric conditions to explain interannual variability in dispersal corridors for both successful and unsuccessful settlers. Model results reveal spatial and temporal differences in the dispersal characteristics of the two species. Interannual differences in circulation may differentially affect GH and PH dispersal corridors, which could partially explain observed species-specific differences in locations where successful settlers transit from spawning to nursery areas. |
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