Dam removal and salmon science

 

Pacific salmon face grim times.  The plight of Canada's Fraser River sockeye has fixated fishers, scientists, and the state for decades.  Concern has grown since the 1990s as annual runs went from bad to frightening, but then last summer’s run was bafflingly great.  The Canadian government federal government in Ottawa formed the Cohen Commission in November 2009 to assess the situation.  It is still grinding through a very complex set of riverine and oceanic factors, and it is not clear members can reach consensus by their current deadline of June 30.

Evolve or die:  that seems to be the theme of many recent events. The Cohen Commission is grappling with a range of issues that include, but are not limited to, rising river temperatures, degrading ocean conditions, and harmful effects from salmon farms.  Many members seem inclined to blame a combination of the above and perhaps more, but scientific explanations for how elements interact lag behind, and controlled experiments [pdf] may not be possible.

We are witnessing very rapid changes in ecology, technology, and politics, all of which are selecting for dynamic traits.  Populations and arguments incapable of adapting may well go extinct, and this applies to fish and environmentalists.

Environmental change may moot even cutting edge research.  A forthcoming study from ICES has linked population-level shifts in Pacific salmon abundance to climate change.  Findings are complicated by the ever changing extent of artificial fish propagation and by assumptions about relationships between abundance and harvests that seem debatable, but the take home message is chum and pink salmon have done better than sockeye and much better than chinook and coho, and success corresponds to more northerly ocean ranges, itself a proxy for climate change.  Even worse news came last week in the journal Science, when researchers announced that the Fraser’s warming waters pose lethal risks to sockeye.  The authors try to be hopeful but admit that “warming river temperatures could exert strong selective pressure for physiological adaptation,” which is a polite way of saying some stocks must evolve or die.

This is unnerving enough for people who depend on salmon, but counterbalancing trends in technology pose additional threats to dearly-held assumptions.  The mantra has long been that mainstem dams on the Columbia and Snake Rivers are “fish killers,” and the only rational option is dam removalA study in 1997 [pdf] revealed that efforts to modify screens and spill flows to help juvenile salmon remained woefully short of acceptable thresholds.  A 2000 study suggested that even if Snake River dam modifications worked perfectly, runs might go extinct because of downstream dams and bird predation.  A 2004 study [pdf] found adult salmon still struggling to migrate upstream.  At one time all the research seemed to damn dams, but the situation is changing.

Nothing in what I write below should be construed to suggest that all dams are fine or that dam breaching cannot help some stocks, but dam debates are getting more complicated.  The growing sense of crisis for Columbia basin species forced governments to devote more resources [pdf] to aid salmon, shad [pdf], eulachon [pdf], and lampreys, and there is hard evidence that at least some of these reforms work.  Consider the fish transfer facility at Round Butte Dam on the Deschutes River.  Adult chinooks are recolonizing their historic ranges above Lake Billy Chinook, the facility is redirecting the reservoir’s formerly stagnant waters, and juveniles are surviving downstream transport.  Make no mistake:  a helluva lot of money was poured into this venture, money that would not have materialized but for the Federal Energy Regulatory Commission’s mandatory relicensing process and the Confederated Tribes of Warm Springs’ treaty rights, but touring the dam two weekends ago for the second time in a year gave me pause.  Watching technology create a current where there was none, and reading encouraging findings about the fish capture and transfer projects, I began to wonder if I was seeing the future.

The implications of climate change on the Fraser, awareness that hydroelectricity may be a critical means of reducing carbon loading, and the ability of dams to regulate river temperature for fish life may quickly shift the ground in this debate.  Add to that the Bureau of Reclamation’s report last week [pdf] detailing plans to add hydroelectric generation capacity at perhaps seventy sites around the West, and a crappy western economy still needing federal stimulus, and my gut says the thirty-year hiatus in western dam building might be coming to an end.  If that is the case, then the old arguments may no longer be germane.  Which is okay, really.  The more I watch ecology and technology change, the more persuaded I am that our political conversations about dams must grow more nuanced.

We who care about fish in the West also need to evolve or die.

Essays in the Range blog are not written by High Country News. The authors are solely responsible for the content.

Joseph Taylor teaches in the history department at Simon Fraser University, in Vancouver. He is the author of Pilgrims of the Vertical: Yosemite Rock Climbers and Nature at Risk, which won the National Outdoor Book Award, and Making Salmon: An Environmental History of the Northwest Fisheries Crisis, which won the American Society of Environmental History’s best book award. He lives in Oregon.

Image of sockeye salmon in Canada courtesy Flickr user Jason Drury.