Featured Image Credit: NOAA Photolib Library
By Emily Persico
Killer whales are endangered. Fifty years after whale hunting was made illegal, they are now facing a new threat: Dwindling food resources. Recovery of their population off Canada’s Pacific coast will not be fast nor easy, and local anglers’ solution to the problem may be unsustainable.
Over the next decade, local anglers are planning to release millions of hatchery chinook salmon to mingle with the wild salmon populations. This will increase their catches, which have incidentally been quite low, while simultaneously increasing food resources for killer whales. Sounds like a win-win situation, right? Unfortunately, not so much.
In a Killer Whale-Salmon catch 22, artificially increasing chinook populations using hatchery stocks is risky business. While temporarily beneficial for killer whales, genetically impaired hatchery fish weaken wild populations of chinook.
“If anyone ever had any doubt about the genetic differences between hatchery and wild fish, the data are now pretty clear,” explains OSU professor of zoology Michael Blouin. “The effect is so strong that it carries over into the first wild-born generation. Even if fish are born in the wild and survive to reproduce” – Which, by the way, occurs in less than 1% of hatchery fish – “those adults that had hatchery parents still produce substantially fewer surviving offspring than those with wild parents. That’s pretty remarkable.”
Chinook salmon populations are already on the decline due to commercial overfishing, coastal pollution and habitat destruction. Rather than addressing these problems, releasing hatchery fish introduce a suite of new ones. Aside from generally reducing the fitness of wild chinook, hatchery fish also have the potential to introduce new diseases and increase competition for limited resources.
“If we know that wild fish survive better than hatchery fish, then that’s where we should make our investment—In the wild fish,” laments Misty Macduffee of the Raincoast Conservation Foundation. “All these other initiatives are sort of quick fix Band-Aid solutions that ultimately may be undermining our chances of recovering wild fish.”
Still, only 83 killer whales remain off Canada’s Pacific Coast. In a desperate decline, this species may need all the help they can get, even if the solution does ultimately lead to a less resilient chinook population.
Canada’s anglers seem to think so. With the help of volunteers, they will continue to release millions of hatchery fish into Canada’s coastal rivers over the next few years. Meanwhile, scientists around the world will keep looking for a way to close the genetic gap between hatchery and wild fish.
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