New study maps out salmon hotspots across B.C. for bears

The long term salmon-eating habits of British Columbia's bears have been documented in a new study by the Raincoast Conservation Foundation and the University of Victoria. 

Published Thursday in the peer-reviewed open-access journal Ecosphere, the study determined which specific locations in B.C. over 1,400 black and grizzly bears had a salmon meal —  by collecting bits of their hair from single strand barb wire corrals.

"You place a really disgusting fermented fish sauce bait in a centre of the barb wire corral," said Megan Adams, a Hakai-Raincoast scholar and PhD student at the University of Victoria.

"It's a non-reward bait, there's no calories gained. When they come to check the smell, they leave tufts of hair on the wire. It's like CSI, but for bears."

From that one strand of hair, Adams says researchers can determine a lot about each bear — including how much salmon they eat, a figure that is linked to greater bear density and reproduction.

"We can tell who they are as individuals, we can tell their sex, their species ... and further to those genetic results, we can look at the chemical signature in the hair, and from that we can discern basic food groups in their diet."

Salmon eating inland

Adams highlighted two key findings from the study. One is that male grizzlies seemed to consume much more salmon than female grizzlies, and grizzlies overall ate more salmon than black bears.  

The other is geography: Adams said her team was not surprised to see a high level of fish in the diets of bears near B.C.'s coast, particularly around the Great Bear Rainforest on the central coast. 

But significant hotspots were found in rivers in the Interior, particularly for male grizzlies. 

"On the coast... it's almost a salmon conveyor belt. It's this smorgasbord that lasts three or four months. These rivers in the Interior, there might only be a single sockeye run, or the Liard River has a single chum run ... I didn't expect the level of salmon to be as high as it was in some Interior habitats."

Adams says that information is important, because a better understanding of where bears and salmon are linked in B.C. could aid conservation efforts for both species.  

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"The province of B.C. manages wildlife, the DFO manages salmon, these two systems are extremely linked ... and yet they're managed by very different bodies. We see this as a very impactful visualization of how linked these are," she said. 

"What we think this research could help do is shed some light on what other consumers of those fish might be — like grizzlies, killer whales, like eagles, like all those other animals and food webs that rely on this amazing marine subsidy that comes into terrestrial habitat. 

"Bears can help paint that picture about how many fish may be required beyond the current paradigm of management."

The full report can be read here.  

With files from Lisa Johnson