Novel species interactions: black bears respond to Pacific herring spawn

Cross-ecosystem interactions between Pacific herring and black bears.

May 25th, 2015

Press Release

Sidney, BC: It is now recognized that coastal bears are often tightly coupled to spawning Pacific salmon. However, as mobile, opportunistic and abundant animals in coastal ecosystems, bears also interact with a range of other taxa, including other spawning fishes.

Each year, Pacific herring, a small silvery fish with profound ecological, cultural, and economic importance, participates in one of nature’s most spectacular events. Despite population reductions throughout parts of their range, often substantial aggregations of Pacific herring still spawn on nearshore and intertidal substrates along the Pacific coast of North America and beyond. At these events, the water turns chalk white with milt (sperm) and dense layers of eggs are laid upon the beaches, kelp forests and seafloor.

Local and traditional knowledge holders have long been aware of the relationships between black bears and Pacific herring, but science lagged behind. For the first time, scientists from Raincoast Conservation Foundation and the University of Victoria have documented that black bears rely on herring eggs that wash up into intertidal zones. Published in the scientific journal BMC Ecology and entitled Novel species interactions: American black bears respond to Pacific herring spawn, we documented that bears responded positively to herring eggs, with bears being more frequent at large spawn events. Further, the greater the amount of eggs available to bears on spawn beaches, the more eggs bears ate, with eggs being consumed by bears for over five weeks from single spawn events in Quatsino Sound, British Columbia.

Black bear eating herring eggs - Caroline Fox
Black bear eating herring spawn on kelp.

Why are these findings important? According to postdoctoral fellow Dr. Caroline Fox, “this is the first scientific evidence of a cross-ecosystem interaction between Pacific herring and black bears, two prominent species that play substantive roles in coastal ecosystems but which have not been previously linked.”

Because these bear-herring interactions were potentially stronger and more widespread historically, Dr. Paul Paquet says that “the documentation of these interactions highlights the paucity of knowledge regarding species and ecosystem interactions and in turn, the lack of information regarding their potential decline.”

For more information contact:

Dr. Caroline Fox, Postdoctoral Fellow, Raincoast Conservation Foundation & Department of Geography, University of Victoria, tel: (250) 812 1956, email:

Dr. Paul Paquet, Senior Scientist, Raincoast Conservation Foundation & Adjunct Professor, Department of Geography, University of Victoria, tel: (306) 376 2015, email: 

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