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Project 3.2 – Assessing the impact of marine mammals on the recovery of Pacific salmon and Atlantic cod

 

Marine mammals along the east and west coasts of Canada have rebounded over the past 30 years from the effects of culling and hunting. The rapid increases in seals and sea lions occurred at the same time as significant declines in some commercially important fish stocks, most notably Atlantic cod and Pacific salmon (coho and chinook). The most likely explanations for the fish population declines are fishery removals and environmental changes, and not consumption by marine mammals. However, marine mammals may be the reason why cod and salmon are not recovering following fishery closures. They may have trapped these important species of fish in “predator pits”, a phenomenon whereby a population of prey animals is regulated at low numbers by their predators.

 

 

This project will assess the impact of seals and sea lions on the recovery of Pacific salmon and Atlantic cod on the east and west coasts of Canada by determining:

 

  1. the amounts of cod and salmon consumed by seal and sea lion predators;
  2. the “predator pit” population threshold levels for these predator and prey species;
  3. the combined effects of fishing, predation and environmental conditions on recovery of cod and salmon populations; and
  4. the management options that might enhance recovery of these fish populations.


Collectively the studies will be used to evaluate management options that might enhance the recovery of cod and salmon populations, such as culling seals, extended fishing closures, enhancing alternative food sources for seals, and fishing down other species of fish that prey on salmon and cod.

 

Project Leader Contact Information

Andrew Trites and Murdoch McAllister
University of British Columbia
a.trites@fisheries.ubc.ca

 

Project Team

  • Ben Nelson - University of British Columbia graduate student (2011-present)
  • Carl Walters - University of British Columbia
  • Dan Edwards - United Fishermen and Allied Workers’ Union (UFAWU)
  • Danny Arsenault - Prince County Fishermen’s Association
  • Doug Swain - Fisheries and Oceans Canada, Gulf Fisheries Centre (GFC)
  • Francois Beaudin - Maritime Fishermen’s Union (MFU)
  • Garry Stenson - Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre
  • Hugues Benoit - Fisheries and Oceans Canada, Gulf Fisheries Centre (GFC)
  • Mike Hammill - Fisheries and Oceans Canada, Institut Maurice-Lamontagne
  • Rachel Neuenhoff - University of British Columbia graduate student (2011-present)
  • Robyn Saunders - Fish, Food and Allied Workers (FFAW)
  • Ronnie Heighton - Gulf Nova Scotia Fleet Planning Board (GNSFPB)
  • Sarah Fortune - University of British Columbia Alumni (MSc 2012)