The Bear Necessities: A Fall Harvest of Salmon

(c) Larry TravisIsland Tides
By Chris Darimont and Misty MacDuffee

How do salmon declines affect coastal bears? And how much salmon is required to sustain wildlife? These are questions that many people are asking in light of headlines about missing sockeye and salmon runs that fail to return as expected.

If you were a coastal grizzly, the presence of salmon would determine many things. For instance: how big you get, whether you can successfully raise children, and the number of bears in your neck of the woods (ie: size, reproductive success, and population density) are all related to salmon abundance. From the grizzly’s perspective, its ability to get enough salmon is really a matter of competition and, increasingly, the odds are stacked against the bears.

As fishermen, humans engage in what ecologists call ‘exploitative competition’—we capture salmon en route to spawning grounds before they reach the waiting carnivores. Referenced against past and current declines in salmon runs, we suspect coastal grizzlies are receiving a fraction of the salmon they used to, which ultimately manifests in population declines. Not by ‘die-offs’ as some have speculated, but through repeated years of low birth rates. Grizzlies are omnivorous and can persist even without salmon,
but they have far fewer offspring.

With both actual (Fraser River sockeye) and potential (runs in the Great Bear Rainforest) salmon calamities serving as catalysts, we believe it’s time for fisheries to start considering wildlife in their salmon management plans. We also believe it is time to establish truly protected salmon runs—runs that would be managed solely for their importance to wildlife and ecosystems. This would allow salmon to return to spawning grounds without encountering the nets of the Pacific salmon fleet. And those fish would then spawn in rivers that flow naturally without their watersheds logged, developed or otherwise impaired.

This concept of unfished salmon runs that lead to fully protected freshwater habitats is a bold and ambitious proposal that runs contrary to the philosophical underpinnings of salmon management. After all, fisheries managers have always assumed that salmon exist exclusively for human consumption.

Consequently, runs are only protected from harvest when they are overfished or endangered. Even salmon runs that spawn in protected watersheds and parks are subjected to exploitation by commercial fisheries at levels as high as 80%. Often, these parks were created to protect species such as grizzlies, black bears and wolves. But how does status quo fisheries management serve the terrestrial ecosystems that salmon nourish?

Not well. Put yourself in the paws of bears. Imagine if your annual paycheque was reduced by four-fifths. Then imagine the effect on the coastal food web economy. The nutrient subsidy used by the forest from the salmon carcasses, is also greatly diminished. As such, ‘protected areas’ that host highly exploited salmon runs are not really protected if a major ecological process is being compromised.

Of course, it is not just fishing nets that rob bears and other coastal life of this yearly bonanza. Fish farms, climate change, habitat loss, fresh water withdrawals, changing ocean conditions, and more, all influence salmon abundance. Many of these impacts are hard to predict, are indirectly related to salmon abundance, or require complex solutions. As eminent US fisheries scientist Dr Robert Lackey has stated, ‘our collective actions—from the rules of commerce to philosophies of growth and development—are not fish-friendly and tend to put relentless downward pressure on salmon numbers.’ In contrast to combating other threats, reducing or eliminating exploitation—on at least some runs—is straightforward and would have an immediate and direct positive effect on coastal ecosystems.

But how much salmon do the bears really need? Raincoast scientists are directly addressing this question. In hair collected from (harm-free) fur-snagging stations, DNA and isotopes are used to track bear numbers, estimate how much salmon coastal grizzlies are eating and elucidate the relationship between the amount of salmon and the number of bears.

We also assess hormone levels in the hair to give us information about potential stress, reproductive activity and protein deprivation bears might show in response to poor salmon returns. From this knowledge emerges an informed basis for action.

Current thinking in conservation science indicates that salmon management needs to include the bears, wolves and other wildlife that have an evolutionary reliance on the annual pulse of nutrients and energy delivered via spawning salmon.  But for elected officials to listen to scientists, the public needs to join the call. It’s time to share the harvest.

Chris Darimont is a Research Scientist at the University of California-Santa Cruz and the Raincoast Conservation Foundation.  Misty MacDuffee is a biologist with the Raincoast Conservation Foundation and lives on Pender Island.

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Research scientist, Adam Warner conducting genetics research in our genetics lab.
Photo by Alex Harris / Raincoast Conservation Foundation.