Researchers, tribes detail climate’s effects on salmon
Even as a record salmon run is celebrated, researchers say the fish face increasing threats from projected changes in temperature and precipitation as a result of climate change.
SEATTLE — More than 1 million fall chinook salmon are expected to pass the mouth of the Columbia River during the 2013 run, almost twice the previous record.
Tribal and state biologists attribute the record run to high spring river flows when the fish migrated downstream, increased flows to spill them over dams, projects to improve fish passages and habitats, and improved ocean conditions.
Charles Hudson, a member the Mandan/Hidatsa tribe of Fort Berthold, N.D., puts that into a tribal perspective: In 2010, he said, 1,757,334 salmon returned to the Columbia. That includes chinook, steelhead, sockeye and coho. In 1850, that number was about 17 million.
A member of the Columbia River Inter-Tribal Fish Commission, Hudson spoke during a recent seminar on climate change, sponsored by the Metcalf Institute of the University of Rhode Island and the Seattle Times.
Tribal cultures and economies revolve around the concept of “first foods,” he said — berries, salmon, game, roots and water. Any tribal decision is weighed against how it affects those first foods.
But conditions beyond the tribes’ control have been changing: “Historically, roots and spring chinook arrived simultaneously. Now chinook come later, and the roots earlier.”
Hudson said these changes are caused by climate alone, not by dams, which have been a bone of contention for many along the Columbia and Snake rivers.
“There has been a consistent rise in air temperatures in every basin. There’s more precipitation, but more of it is rain,” he said. “The tributaries are pulsing from two to 13 days earlier.”
Oliver Grah, water resources program manager for the Nooksack Indian Tribe in northwest Washington, said the consequences of climate change impact place-based native American tribes more than other communities because they cannot move to follow the natural resources they depend on.
The Nooksacks live on the South Fork of the Nooksack River, and their 186-square-mile watershed reaches from 20 feet elevation to 7,000 feet. Their main concern is the spring chinook salmon, now numbering about 8 percent of historical levels.
The fish have to deal with what Grah referred to as “legacy impacts” on the river resulting from land-use changes, such as timber harvest, channel clogging, loss of shading due to agriculture and impervious surfaces. Projected higher temperatures and changing flows will add to the obstacles the chinook face.
“Climate change impacts will be less than the legacy impacts,” he said, “but climate change might be the straw that breaks the camel’s back.”
The Nooksacks have launched a habitat restoration project to reduce predicted effects of climate change, including reforesting riparian zones and removing levees.
Salmon are a diverse species leading a complex life that have evolved through different climates, said Lisa Crozier, research ecologist at the NOAA Northwest Fisheries Science Center.
“They are strong animals,” she said, “the most opportunistic species in the world.”
Still, they are sensitive to increasing sea surface temperatures, algal blooms and low oxygen levels. High temperatures block their migration upstream, and the “blockout period” is getting longer.
Compounding pressures on salmon threaten their existence, she said. Even slightly worsening ocean conditions or shifts in the ecosystems could send them over the tipping point into extinction.
Crozier listed several measures that can mitigate the impacts on spawning grounds:
• Cold-water releases from dams can provide thermal refuges.
• Channels can be restored, and floodplains can be reconnected.
• In-stream flows can be restored.
• Riparian areas can be rehabilitated.