Sobering Projections for Hudson Bay

For several years now, Polar Bears International has been helping support the Churchill Bear Smart Working Group as part of its work to minimize conflict between people and polar bears, and to help map out a healthy future for the bears. Churchill is a small community on the shores of Hudson Bay in Canada. Polar bears gather around the community in large numbers each fall, waiting for the sea ice to form so they can return to hunting seals. 

Members of the working group have long had questions about the ecological future of Hudson Bay, as the climate crisis erodes the bay’s sea ice. They wanted to put together a group of experts to help answer their questions, and so the Churchill Barber Symposium was born. It was named in part in honor of Dr. David Barber, a prominent Arctic researcher from the University of Manitoba. He sadly passed away before the symposium was organized. 

In late September of this year, Polar Bears International worked with local people, government experts, and the University of Manitoba to mount the symposium. The morning was an information-sharing session amongst the experts and members of the working group.  

Sea ice loss in Hudson Bay

Setting the stage was a sobering presentation by University of Manitoba ice scientists Dr. Julienne Stroeve and David Babb. They showed the latest projections for the bay’s sea ice cover. Their data showed that for the past 40 years, Hudson Bay has been losing its winter ice cover at the rate of one day per year. Over the past 40 years, the bay has become ice-free for 40 more days. The ice-free period is projected to stretch to almost the whole year by the end of this century if we remain on our current emissions path. If we hold temperature rise to 1.5 degrees, the bay will be ice-free for lengthy periods, but not for as long as the current emissions scenario. 

That change in sea ice will have effects on the entire ecosystem in the bay. Speakers were not entirely sure what effect the change will have on the base of the web—the plankton and seaweeds—partly because they’re still trying to map out what’s there right now. When it comes to larger animals, researchers were better able to project what the changes might mean.

Whale and seal populations

Dr. Stephen Petersen, director of conservation and research for Assiniboine Park Zoo, outlined the effects he thinks are coming to the whale and seal populations of the bay. He believes that the species composition is already changing in the bay and may change further still. Seals adapted to life on ice, such as ringed seals, will probably decline, while harbor seals that are not dependent on snow lairs on sea ice to reproduce will likely increase.

Whales found in Hudson Bay are mostly belugas. It’s uncertain how the sea ice loss will directly affect them, but another indirect effect is the increasing presence of killer whales that hunt and eat belugas. Killer whales are not well adapted to living around sea ice, but when the ice is gone, they’re free to cruise the bay in search of other whales and seals. Dr. Petersen thinks they may eventually displace polar bears as top predator in the bay, “We're going to have the shift from polar bears being our dominant, top predator, to more killer whales in the system.”

Impacts on polar bears 

The effects of all the coming climate-driven changes on the bay’s polar bear populations was the final focus of the symposium. Not all those changes are the result of sea ice changes. As Dr. LeeAnn Fishback of Parks Canada pointed out, increased forest fires on land where the polar bears den and give birth could affect future denning success. All the challenges to polar bear populations in Hudson Bay were laid out by Dr. Nick Lunn, a polar bear researcher with Environment and Climate Change Canada. Those include loss of habitat (sea ice), a shrinking prey base (ringed seals), low reproductive rates, and potential effects of environmental contaminants and diseases new to the north. 

“Should we be concerned? I think we should.” he concluded, “Probably more important than anything else is that normal conservation methods cannot preserve the habitat. It's not as simple as saying we're not going to log a forest anymore or we're going to put a fence around a particularly sensitive area at a particular time of the year. We're talking about sea ice, circumpolar Arctic, and we're talking about a warming climate.”

Participants ended the symposium by talking about what needed to be done. One thing on which they all agreed was that future opportunities to share information with each other would make the job of projecting future changes much easier.

Clive Tesar teaches Northern Studies at Carleton University in Ottawa, and specializes in northern policy and communications.