Effects of hunting, fishing and climate change on the Hudson Bay marine ecosystem: II. Ecosystem model future projections

Simulations testing the future impacts of harvest and climate change to the Hudson Bay marine ecosystem were created utilizing an existing Ecopath with Ecosim model (Hoover et al., 2013). Building on past simulations depicting known changes to the region, a suite of future scenarios was constructed to include a variety of climate change and harvest levels. Previously identified ecosystem shifts favoring pelagic species (zooplankton, planktivorous fish) over benthic species (benthos, benthic feeding fish), are further exaggerated under future climate scenarios. Environmental forcing was incorporated to mimic the declines in sea ice, and increases in temperature causing shifts in the food web from an ice algae–benthos–benthic fish pathway to a spring bloom–zooplankton–planktivorous fish dominated ecosystem. Future simulations indicate some stocks are unable to sustain current harvest levels until the end of the future simulations (2069), and may be extirpated (narwhal, eastern Hudson Bay beluga, polar bears, and walrus). Larger populations of marine mammals (ringed seals and western Hudson Bay beluga) are identified to increase in biomass even under extreme harvest and climate scenarios (a high future climate scenario coupled with a doubling in harvest rates). Harvest mortality is highlighted as an important stressor for some marine mammal stocks and should be investigated further when setting future harvest or conservation targets.

► We show future simulations of varying levels of climate change and harvest for Hudson Bay.
► Identified stocks of marine mammals likely to be extirpated due to over-harvest.
► Food web shifts from benthic to pelagic dominated system.
► Identifies species likely to benefit from climate change.
► Results indicate harvest efforts on some marine mammals should be decreased.