Of the four major killers of our native salmon and steelhead--hydroelectric dams, habitat degradation, over-harvest, and hatchery production--the latter causes the most confusion.
We understand that dams kill salmon in at least three ways: by blocking smolts as they migrate to the ocean and making them easy prey for birds and other fish, by pumping many of those smolts through the turbines, and by blocking the upriver migration of the adult salmon. Drive any road in salmon country and you'll see the habitat degradation: logged hillsides, spawning tribs blocked by culverts, rivers turned to channels by miles of rip-rap. Look at the all the commercial fisherman on the American and Canadian coasts, and you'll understand the over-harvest. But the harms caused by hatcheries are harder to see.
So hard, in fact, even fisheries managers have had trouble identifying why native stocks fade as hatchery programs thrive.
But thanks to ten years of illuminating science, we now have a clearer picture than ever before of the specific harms caused to native steelhead and salmon when hatchery fish share the watershed. First and foremost, hatchery salmonids have been shown to dilute the fitness of native stocks when the two groups of fish interbreed (*Chilcote 2011). Additionally, hatchery programs draw increased crowds of anglers--many of whom side-drift roe with dizzying success--causing a massive increase in the incidental catch rate of native fish. (One in ten of these released fish, according to the best science on the issue, will die--if the angler takes the utmost precaution when releasing the fish.) Hatchery salmon and steelhead harm the native populations in myriad other ways, as well; for illuminating, peer-reviewed science on the issue, I suggest visiting the Native Fish Society's excellent database of studies: http://nativefishsociety.org/index.php/conservation/science-research/wild-vs-hatchery-salmonid-interactions/#fitness
*(Chilcote, et al. 2011. "Reduced recruitment performance in natural populations of anadromous salmonids associated with hatchery-reared fish"Can. J. Fish. Aquat. Sci. Vol. 68.)
But why are hatchery salmon and steelhead different than their native counterparts? Aren't these fish the same genetically speaking?
Sometimes. Sometimes not. But, interestingly, whether the hatchery fish are of the same genetic stock as the native fish or not doesn't actually matter.
In my home state, Oregon, most of our hatchery programs are "broodstock" programs, meaning the hatchery fish are spawned from native fish (native fish are caught in the river and transported to the hatchery, where they are forcibly spawned then killed). So the hatchery fish are literally of the same genetic stock. And yet when these broodstock fish mate with wild fish, they reduce the fitness of the resulting juveniles. How could this be?
The answer lies in the hatchery itself.
Hatcheries are really just factories, and like factories everywhere, they operate on the principle of most output for the least input. In other words, hatcheries go to great lengths to protect their juvenile fish (using nets, for instance, to protect them from predators like ospreys and otters). To put it simply, these protections allow "stupid" fish to survive; when these fish make it to the redds, they pass on their "stupidness" to their offspring.
We find ourselves at a strange moment in our struggle to save native salmon and steelhead. For years, hatcheries have been seen by fisheries managers and the public as the magic cure; we can 'supplement' the native runs with our hatchery fish. So now most every river from to California to the Canadian border sees returns of hatchery salmon and steelhead--either intentionally or unintentionally through a process known as 'straying.' Much of our fishing industry--especially the gear fishing industry--is built upon these faux-runs. Our fishery managers, very literally, owe their jobs to these hatchery runs. And yet we now know that these hatchery programs are killing our native stocks.
What are we to do?
I suspect the future will hold some tough decisions for anglers and regulators alike. I only hope that we have the courage to stand up and do what's right for native steelhead and salmon--before it's too late.