Black bears need access to different species of salmon rather than huge numbers of a single variety in order to be healthy, a new study by Canadian researchers indicates.

Lead author Christina Service said if bears have access to a "portfolio of different salmon species" then the animals have access to more food for a greater part of the year.

"It is the equivalent of humans going to an all-you-can-eat buffet for just a couple of days versus having one good meal a day for many months," said the PhD candidate from the University of Victoria, adding that the timing and location of salmon runs vary by species.

When they have access to the fish for a larger part of the year, they end up eating more salmon overall and are in better health, she said.

The team of researchers tested hair samples from 379 black bears and 122 grizzly bears between 2009 and 2014 to estimate their salmon consumption, which also indicates population health.

They studied animals across a 22,000-kilometre stretch along coastal British Columbia's "Great Bear Rainforest," in collaboration with the Wuikinuxv, Nuxalk, Heiltsuk and Kitasoo/Xai'xais First Nations.

With bears hibernating in winter, they have only certain windows where they're able to eat, Service said.

So by having access to salmon earlier in the year bears can start fattening up sooner, she said.

'Difficult time to be a salmon these days'

Kitasoo/Xai'xais First Nation Chief Councillor and study collaborator Douglas Neasloss said he is concerned that the federal government's current salmon management focuses on large salmon runs and often ignores smaller runs that contribute to diversity.

Study co-author Chris Darimont said researchers have expressed concern about the health of all salmon populations.

"It's a difficult time to be a salmon these days with climate change, reduced ocean productivity, over-exploitation, diseases from salmon farms and neglect in management," he said.

Service said the federal government should think about the management of fisheries in a holistic sense.

This means thinking of fisheries as benefitting not just commercial and recreational interests but other wildlife and ecosystems too, she said.

"We need to consider species diversity and not just abundance."

That means paying attention to maller runs too, she said. "Those runs really matter for bears."

She said research shows the more variety of salmon that bear eat, the bigger they get, the more offspring they are able to have and the better those offspring do.

Bear-salmon relationship and the ecosystem

Bears play an important role in moving nutrients on land, she said, explaining that bears carry salmon inland from the water and act as gardeners by fertilizing the ground with fish carcass which helps trees and other plants.

"It is important to care about bears because they are bears and they have intrinsic value, but the bear-salmon relationship is also very important to ecosystem," Service said.