Impacts of Changing Environmental Conditions on Larval Fish Dispersal and Population Connectivity: A Case Study of the Northeast US Shelf Ecosystem

Abstract:

Population connectivity is the inter-generational movement of individuals among geographically separated subpopulations and is an important factor in both understanding population dynamics and establishing useful species management strategies. For many marine fish species, population connectivity is largely determined by dispersal patterns of the species’ pelagic larvae, which are directly related to ocean circulation and species-specific reproductive strategies. As environmental conditions in the oceans change, oceanic circulation patterns are expected to change as well. These changes, coupled with expected shifts in spawning and settlement habitats, may dramatically modify the connectivity patterns of many fish species on the Northeast US Shelf. Here, we use a Lagrangian tracking model that incorporates known environmental conditions conducive for species-specific spawning and settlement, as well as known larval durations, to simulate spawning, dispersal, and metamorphosis of pelagic larvae of six important fisheries species in the Northeast US Shelf ecosystem. These models were replicated across two time periods with different temperature and circulation regimes. Our model suggests species-dependent shifts in population connectivity patterns and reveals possible mechanisms behind observed shifts in species distributions in recent decades. Our modeling analysis can help predict future distributional shifts under continued climate change scenarios, which will be important in the development of future species and ecosystem management strategies in the Northeast US Shelf ecosystem.