Testing early life connectivity supplying a marine fishery around the Falkland Islands

We used a wind-driven global circulation model to build spatially explicit predictions from rival hypotheses concerning advective supply of Patagonian toothfish (Dissostichus eleginoides) to a trawl fishery around the Falkland Islands, and tested the predictions using chemistry recorded in the otoliths of fish caught in the fishery. Model simulations indicated transport pathways from spawning aggregations off southern Chile to both the north and south of the fishing area. In contrast, simulated particles released from spawning aggregations around Burdwood Bank were transported to the south of the fishing area but not to the north, becoming fully entrained in the Subantarctic Front instead. Spatial heterogeneity in the chemistry laid down in the otolith nuclei during early life discounted the hypothesis of a single population with a spawning area on Burdwood Bank, and indicated that fish assemblages are structured by large-scale transport from both southern Chile and Burdwood Bank. By linking fish explicitly to their physical environment, the two techniques can help distinguish the life cycle trajectories necessary for populations to persist, and elucidate the interactions between hydrography and life history that structure the fish assemblages on which marine fisheries depend.