Many people are experiencing hardship because of steep and protracted declines in chinook stocks, particularly in rural Western Alaska. There are calls to fix the shortage of fish by planting fish, either from our existing hatcheries or from new facilities we'd build on the Yukon, the Kuskokwim, etc. Most fish biologists think this is a terrible idea, based on what we've seen of hatcheries in the Pacific Northwest.
Alaska's policy is to site hatcheries away from wild stocks. This is because hatcheries often work, and when they do, the wild stocks can suffer.
Consider a wild stock that can support harvest of half of its fish every year. If the hatchery is successful, each spawner will produce many more offspring, so that more than nine out of 10 could be harvested and still leave enough for brood stock. If the hatchery fish and wild fish mingle on the fishing grounds, harvesting nine of 10 will overharvest the wild-born fish, leading to a rapid decline in the stock.
In-river hatcheries mean intermingling wild and hatchery fish on the fishing grounds. They also mean mixing juveniles in the rivers where competition may further affect the wild fish, and elevated fish numbers could support increases in predators or diseases.
What if the hatchery fish spawn with the wild fish, increasing spawner abundance in the wild? As long as we use local brood stock, isn't this OK?
Many studies have shown that hatchery fish domesticate (e.g., adapt to life in crowded raceways, feeding on pellets spread on the surface, etc.) very quickly, and that once released to the wild their survival is lower than that of wild fish. "Local" is also hard to ensure; salmon home fairly precisely, and fish just a few miles apart can be adapted to the particular temperatures, flow regimes, and food sources of their location. Those differences can sometimes be seen in the different "runs" to the same river, but are often hidden, and these locally-adapted stocks are not always distinguishable with our genetic techniques.
Mixing hatchery fish with wild fish has a high potential to depress the fitness of our wild stocks, which is why Alaska's policy is to restrict hatchery fish to just 2 percent of spawners at any location.
All of the problems I've mentioned have been seen with hatcheries in the Lower 48. In addition, hatchery production there masked the decline in wild fish caused by the systematic destruction of their habitats, so that the fisheries are now dependent on this hatchery production. That history is laid out in the books "King of Fish" and "Salmon Without Rivers." In Alaska, our abundance of pristine habitat means our chinook will eventually rebound on their own, when environmental conditions improve.
We've seen it before -- in the late 1970s, salmon stocks throughout the state rebounded from cold conditions and overfishing on the high seas, leading to record salmon harvests last year. We need to help people suffering because of low chinook returns, and we need to preserve the habitat so that the fish can come back when conditions improve. On the surface, hatchery fish may look like a solution, but more likely they'd just create new problems.
Milo Adkison is a professor at the University of Alaska School of Fisheries and Ocean Sciences.
By MILO ADKISON