The Osprey: Hatchery Pink Salmon Hog North Pacific Salmon Habitat
Long-time readers of The Osprey know that we often publish articles about ocean conditions as they relate to Pacific salmon and steelhead, and particularly for our ongoing coverage of the impacts of climate change on the ocean environment, and what that might mean for wild fish.
We have another ocean cover article for this issue of The Osprey. But this time we are featuring something a little different. Scientist Greg Ruggerone has taken a look at how the release of huge numbers of hatchery pink salmon into the north Pacific Ocean to support the commercial salmon fishing industry is affecting the ocean food chain, and especially on how that impacts wild salmon and steelhead. It’s an important, but under-reported story. Some of his findings are expected while others may surprise you.
When it comes to pink salmon, the numbers are impressive. In abundant years, pink salmon numbers may be as high as 650 million. While only 16 percent of those fish are hatchery origin (mostly from Alaska hatcheries in the north Pacific) they eclipse the combined number of Chinook and coho salmon, and steelhead. Pink salmon, believed to originate from Russian hatcheries are beginning to invade Atlantic waters of Norway, Scotland and Iceland.
ALSO IN THIS ISSUE
• SKAGIT RIVER STEELHEAD CATCH AND RELEASE
• 2019 WORLD SALMON FORUM
• ROGUE RIVER RESILIENCY BAD NEWS FOR BRITISH COLUMBIA STEELHEAD
In the Columbia River, which includes mixed-species runs that are often made up of both hatchery and ESA-listed wild salmon and steelhead, fishing seasons — both recreational and commercial — are largely driven by the incidental catch of protected wild fish.
Ruggerone and his colleagues have found distinct correlations between high abundance years of pink salmon with lower numbers of Chinook, coho and steelhead. In addition to the unsurprising findings that hatchery pink salmon do not survive as well in the as wild pinks and that, as when large numbers of hatchery salmon and steelhead are dumped into rivers and streams, they overwhelm the wild fish and compete with them for food resources.
More surprising is that they are abundant enough to not just compete with wild salmon and steelhead for food, but to cause a trophic cascade by eating large amounts of prey species such as small fish and squid to change food chain dynamics. This is not only impacting wild salmon and steelhead, but also seabirds, and possibly orcas by interfering with their hunting behavior.
Wild fish advocates have long known about the negative impacts of stocking hatchery fish into freshwater streams and are fighting to end or at least limit the practice.
We also need to realize that many of the same negative effects of hatchery fish in freshwater are also playing out at sea, where it is more difficult to see, study and control. However, it is clearly another threat to the survival of wild Pacific salmon and steelhead that we need to ensure remains on our radar.