The lives of salmon and bears in B.C. are inextricably linked and new research by scientists at Raincoast Conservation and the University of Victoria underlines the importance of conservation managers looking at entire ecosystems in order to keep both species healthy.
The wide-ranging study of the amount of salmon eaten by bears in different areas was conducted by a group led by Megan Adams, Hakai-Raincoast scholar and PhD candidate at UVic and was published today in the peer-reviewed journal Ecosphere.
Researchers looked at more than 1,400 hair samples from 886 grizzly and black bears, which ranged over almost 700,000 square kilometres of B.C. from 1995 to 2014.
The huge database has produced a pattern showing salmon hotspots and demonstrating how the health of bears improves and population density increases when there is an abundance of salmon and declines when salmon runs fail — illustrated by bear deaths on the Central Coast when sockeye runs crashed.
“The more meat that bears get, and especially more fish, the healthier they are. They have a larger body size and they have more cubs,” Adams said in an interview with DeSmog Canada.
“I like to look at these hotspot maps as health indicators of the ecosystem. If it is thriving, you have fishy, fitter bears,” she said.
Male grizzlies are the biggest consumers of salmon and one surprise of the study was the discovery that it is not only bears living in coastal areas such as the Great Bear Rainforest that rely on salmon — bears living 1,000 kilometres from the coast prefer a fishy diet.
Salmon Conservation Would Help Bear Populations
“We are letting the animals tell the story themselves. One of the exciting things to me is how far into the interior this predator/prey system goes,” Adams said, pointing out that the maps show salmon/bear hotspots stretching up to the Alberta border.
However, in the interior of B.C., the bears cannot access as many fish and, in those vulnerable areas, where every fish counts, salmon conservation efforts would help bear populations.
The study shows that protected areas with plentiful salmon produced the fittest bears and resource managers looking at new protected areas should focus on areas with high salmon availability, Adams said.
One of the problems in salmon/bear management is the federal Department of Fisheries and Oceans is responsible for salmon while the provincial government is responsible for bears.
Adams would like to see barriers broken down and different levels of government working cooperatively together.
“These results demonstrate important connections between land and sea over huge landscapes,” Adams said.
“Fisheries and land-use management would benefit from integrating beyond discrete geo-political jurisdictions to take ecosystem processes into account.”
Salmon Play Role in Human-Bear Interactions
Ensuring bears have sufficient salmon to eat would also benefit humans as the study shows that bears eating high-salmon diets show decreased levels of stress hormones.
Fishy bears are happier bears and that is likely to mean fewer human/bear conflicts, Adams said, linking the research to a previous study by Raincoast Conservation biologist Kyle Artelle.
Artelle, who is also a co-author on Adams’ study, looked at patterns of bear-human conflicts that resulted in bears being killed by private individuals or conservation officers, over the last 35 years.
Usually the bear is killed if it comes too close to town and the study looked at whether there were patterns indicating why there were more conflicts at certain times and in specific areas, Artelle said in an interview.
“We found that in the years with very low amounts of salmon, there was a disproportionate amount of conflict. There was a strong association,” he said.
“Most likely bears take greater risks in times of food insecurity and come closer to humans … Salmon are so important to bears and salmon are strongly associated with conflict,” he said.
Artelle’s study found that, contrary to some expectations, increased hunting had no effect on conflict.
“At first you might think that, if you up the hunting, you have fewer bears to get into trouble, but there is no data to support that,” Artelle said.
It also found that removing bears that were seen as “bad apples” had no effect on future incidents.
Bears are already facing challenges ranging from trophy hunting — the largest source of mortality across all grizzly populations — to climate change and development and Adams wonders what the hotspot maps would have looked like a century ago, before development, ecosystem fragmentation in the Interior and dams on the Columbia River wiped out populations of salmon and grizzly bears.
Megan Adams conducts research in her lab. Photo: A.S. Wright
“For both male and female grizzlies, there’s a big hole in the interior, all up the main passage of the Fraser (River). That’s because bears have been extirpated — there are no grizzly bears living along that huge salmon thoroughfare,” she said.
Now, with research showing the importance of salmon runs, the emphasis should be on ensuring plentiful fish because the bears are the final consumers after salmon have survived orcas, hungry seals and the fishing fleets, scientists emphasize.
Danielle Shaw, Wuikinuxv Nation stewardship director, who has collaborated with Adams on the Central Coast Bear Working Group, said the health of salmon stocks are a direct indicator of the health of the ecosystem and consideration must be given to all the consumers.
“By looking at what other species need to ensure theirr own sustenance, we are progressing towards a more ecosystem-based approach to conservation and management.”
“We have a responsibility to ensure all other species are fed before we fill our own bellies,” she said.
Image: Grizzly bear. Photo: A.S. Wright