Recognizing Ontario’s Marine Mammals on World Oceans Day

Happy World Oceans Day!

Technical difficulties prevented this blog’s posting on Friday, in time for World Oceans Day. We regret the delay.

World Oceans Day – an idea Canada first proposed at the Earth Summit in Rio de Janeiro in 1992, and the United Nations officially recognized in 2009 – is celebrated every June 8th to honour the world’s oceans, celebrate the marine life within them, appreciate the oceans’ intrinsic value, and recognize the challenges they face.

Here in Ontario, we can celebrate World Oceans Day by recognizing and appreciating Ontario’s own connection to the seas. Many Ontarians might be surprised to realize that Ontario boasts a marine coast – on Hudson and James Bays – where a variety of marine life can be found. This includes marine mammals, like polar bears, seals and even whales.  Although Ontario’s marine mammals may be far from the public eye, these magnificent animals have unique contributions to the biodiversity and natural heritage of the province, bringing with it an obligation to protect their future.

Polar bears are distributed globally all over the arctic, and most of the bears found along Ontario’s marine coast belong to the Southern Hudson Bay subpopulation (≈ 900 animals) – the most southern population in the world. While stable over the past 20 years, this subpopulation is believed to be at an ecological “tipping point”. The greatest threat to these bears is climate change, which is expected to melt sea ice and reduce bears’ access to mating and feeding platforms, affect the distribution of prey, reduce permafrost and the availability of maternal den sites, and affect bears’ growth and reproductive rates. As a result, scientists fear that the subpopulations of polar bears found in Ontario will be wiped out within the next 45 years.

Ringed seals and bearded seals – the primary prey of polar bears – are also highly dependent on sea ice. Found all over the arctic, they can be seen in Ontario during ice-free periods along the Hudson and James Bay coasts and in large river estuaries where they use boat docks, gravel bars and shorelines to “haul-out” and rest. While the distributions of these animals are likely driven by food availability and ice conditions (both of which are expected to be affected by climate change), human hunting and predation by polar bears are likely the main causes of mortality.

Between July and October, about a few hundred walruses haul out along the Ontario coast of Hudson Bay, on shoals near Cape Henrietta Maria. These shoals may provide a refuge for walruses, since Cree hunters in the area do not have a strong tradition of walrus hunting, unlike hunters from Nunavut and northern Quebec on Hudson Bay. Walruses have a low reproductive rate, narrow diet and restricted seasonal distribution, making the species vulnerable to environmental perturbations and particularly to over-hunting.  In 2006, the federal Committee on the Status of Endangered Wildlife in Committee (COSEWIC) reported that the Atlantic walrus “is near to qualifying for threatened status and requires an effective plan to manage hunting.”  And while COSEWIC has identified the Atlantic walrus as a species of special concern, the Atlantic walrus has not yet been listed under the federal Species at Risk Act (SARA) or Ontario’s Endangered Species Act, 2007 (ESA). Moreover, current regulations on hunting walruses in Canada (and trading walrus parts internationally) offer limited protection, and it is unknown whether the few hunting quotas that have been set are sufficient to prevent over-harvesting.


Perhaps in an attempt to increase Ontarians’ awareness and appreciation for the province’s wild marine mammals, in September 2011, MNR tweeted that “beluga whales live in Ontario (and not just at Marine Land).” While such a claim might surprise most Ontarians, the Western Hudson Bay population of beluga whales does indeed spend its summers primarily off the western coast of Ontario and Manitoba, entering the estuaries of large rivers, perhaps to moult, feed, calve or avoid predators. The most significant threat to this population is likely hunting. Even though there is no known beluga hunt in Ontario, the Western Hudson Bay population is heavily hunted in parts of its range (by western Hudson Bay and southeast Baffin communities). In 2004, COSEWIC identified the Western Hudson Bay population of belugas as a species of special concern due to the unknown consequences of hunting on this little-studied population. While the beluga has not yet been listed under SARA and is therefore only afforded federal protection under the Fisheries Act, in Ontario, beluga whales are listed under the ESA as a species of special concern.


The marine mammals that inhabit and visit Ontario’s marine coast sadly face numerous threats, particularly as a result of a warming climate. Climate change will have profound effects – some of which may be unpredictable and transformative – on arctic and sub-arctic mammals. For example, as climate change continues to melt sea ice, killer whales (orcas) – which are generally prevented from surfacing and navigating ice-covered waters because of their immense dorsal fins – may be able to access previously unreachable waters and feed on belugas, seals and other marine mammals in Hudson Bay. Because killer whales are major predators that can reshape marine ecosystems, killer whales could trigger an ecological shift, replacing polar bears as the arctic’s dominant natural predator.

Further Reading