Science Advisory Report  2010/030

2010 Canadian Marine Ecosystem Status and Trends Report

Summary

  • The status and trends of Canadian marine ecozones are changing owing to a suite of different factors.
  • Biological and ecological effects (e.g. increased natural species mortality, species range expansions and contractions, and changes in fish size, assemblages, and community structure) are occurring; however their impact on ecosystems is not always well understood.
  • Climate change and oceanographic variability are affecting most Canadian marine ecozones. In particular, ocean acidification is known to be impacting several ecozones and is an emerging issue in the others.
  • A decline in many fish stocks has occurred on the Atlantic and Pacific coasts as a result of commercial overexploitation. Although management measures have been implemented for most species, recovery has been limited in most cases.
  • Legacy contaminants, like polychlorinated biphenyl (PCB) and dichlorodiphenyltrichloroethane (DDT) for example, are decreasing, however the incidence of emerging contaminants (e.g. brominated flame retardants) are becoming an issue in most ecozones.
  • Industry and development have, or are threatening to, impact most ecosystems. The coastal zone is particularly vulnerable and is of concern as these areas are considered highly productive ecosystems.
  • Some marine mammals that were overexploited in the past are now recovering. For example: bowhead, beluga, and narwhal in the Arctic, and sea otters, stellar sea lions, harbour seals, killer whales, humpbacks, and gray whales in the Pacific.
  • Populations of grey seals in the Gulf of Maine and Scotian Shelf ecozone and harp seals in the Newfoundland-Labrador Shelves ecozone have increased dramatically.

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