When the National Marine Fisheries Service (NMFS) unveiled its draft biological opinion of the Columbia River hydropower system on 27 July, it was accompanied by a broader strategy written by nine federal agencies covering all the factors implicated in salmon decline. Fisheries scientists have long identified these factors as the “four H’s”: hydropower dams, harvesting, habitat degradation, and hatchery misuse. According to the interagency plan, known as the “All-H Paper,” improvements in the other three H’s will provide benefits that are more certain and widespread than those from dam breaching. To be successful, this new strategy must overcome environmentalist opposition and gain the cooperation of state governments, Native American tribes, and private landowners. And because addressing the other H’s may be even more costly than breaching dams, NMFS will have to convince Congress to pump more money into salmon recovery.
Harvest. In some ways, harvest is the easiest factor to understand and control, because its effects on mortality are direct and easily measured. Protecting the endangered runs while allowing harvest of others that migrate at the same time is problematic, however. Fishers have no way of knowing whether a Chinook salmon on the line is from a plentiful Washington-coast run or a critically endangered run on the Snake River.
For most of the endangered fish in the Columbia Basin, harvest rates are already so low that further restrictions are politically difficult–and unlikely to contribute to recovery. The All-H strategy calls for continuing these low rates, while tagging most hatchery fish to enable fishers to tell them apart.
Habitat degradation. Like overharvesting, habitat degradation has been a problem since the late 1800s. By extracting ore with high-pressure hoses, miners drew water away from streams and returned a flow of sediment, burying the gravel needed for spawning. Sometimes they mined the stream itself, extracting gravel, sand, and limestone as well as gold. And logging removed trees from forests adjoining streams, increasing stream temperatures and covering spawning beds in eroded dirt.
In addition to wreaking damage directly, dams made it possible to irrigate the dry, eastern parts of the region. But irrigation takes water from streams, which harms spawning and rearing habitat. And the cattle that accompanied irrigation, if not fenced out of streams, can stir up sediments with similar effects.
Habitat degradation is pronounced in the Columbia River estuary, where the young salmon make the transition from fresh water to saltwater. Dredging to improve navigation, filling in wetlands to expand urban areas, and flood control measures have made this habitat less salmon-friendly.
The All-H strategy makes habitat protection its centerpiece. Major programs include improving stream flows by acquiring private water rights; protecting fish habitat in the lower Columbia estuary by purchasing wetlands and adjoining land; and accelerating habitat restoration on federal lands in areas identified as high priority. But these measures will require the cooperation of big private landowners, historically a problem for the Endangered Species Act.
Hatcheries. Each natural stock adapts to the characteristics of its spawning ground, including temperature, depth, flow, and distance from the river mouth. If salmon from one environment mate with salmon from another or from a hatchery, the offspring are likely to lose sets of coadapted genes, decreasing their fitness for a particular environment. For this reason, the practice of breeding hatchery fish from whatever eggs were available, regardless of species, river, or season, is a thing of the past.
But because hatchery populations today dominate salmon species, they still affect their wild cousins. To make up for losses in wild runs, for example, hatcheries allow many more young fish to survive to adulthood, relaxing the selective forces at that stage. If the hatchery fish interbreed with the wild ones, the genetic makeup of the population will likely be adversely affected.
The All-H strategy takes an aggressive stance on the hatchery issue, arguing that all existing hatcheries should be reformed to minimize the harm to wild fish. Any federal agency operating a hatchery must develop a genetic management plan, including drawing from the gene pool appropriate for a particular location. But drastically changing or cutting back hatchery operations will be resisted by the tribes, whose treaty rights to salmon and steelhead have increasingly been satisfied by harvesting hatchery fish.
Although the agencies declined to place a price tag on addressing the “other H’s” strategy, rough estimates put it at billions of dollars. The funding will have to come quickly, as NMFS intends to reevaluate salmon status in 2008 to ascertain whether dam breaching is necessary after all.
Science, Volume 289, Number 5480, Issue of 4 Aug 2000, p. 718.
Copyright (c) 2000 by The American Association for the Advancement of Science.