Southern Resident Orcas Need Columbia River Chinook Salmon to Survive
Salish Sea Watershed and Columbia Basin
The Salish Sea includes marine waters from Puget Sound, Washington to Georgia Strait, British Columbia. Orca forage and travel throughout the inland waters, and also depend on salmon returning to the Columbia River, especially in winter months.
(Please put map here so people can see it – Map http://myweb.facstaff.wwu.edu/~stefan/SalishSea.htm)
Southern Resident orcas need plentiful salmon year round to stay healthy, During winter the orcas are believed to have depended for millennia on salmon from the Columbia River, which produced two million spring chinook annually until a century ago. Fattened up to run hundreds of miles upriver, the fish were famous for their oil-rich flesh. But in the mid- to late-1990’s salmon runs were at historic low levels throughout the Salish Sea and Columbia River watershed. By 1999, upper Columbia spring chinook had collapsed to near extinction and were listed as endangered under the federal Endangered Species Act (ESA). According to the Washington Dept. of Fish and Wildlife (WDFW), “the single greatest loss of food for Southern Resident killer whales in the past 50 years may have been from the decline of salmon in the Columbia River basin.” Overall salmon returns during the 1990’s averaged only 1.1 million fish each year, a decline of 90% from historic levels, leaving this tight-knit extended orca family undernourished month after month. Puget Sound chinook also fell far below earlier counts and are listed under the ESA. The chinook and coho that remain are also much smaller in size than they were just 20 years ago.
When fish are few and far between, resident orcas tend to split into smaller groups and spread out miles apart, searching high and low and moving great distances to find food, and hunger begins to take its toll.
Beginning in 2000 a significant upswing in salmon returns began when more chinook swam up the Columbia River than had been seen for the previous 20 years. Puget Sound has also seen improved returns of chinook, coho, pink and chum salmon and steelhead and runs have continued to grow each year between 2000 and 2005. These increased salmon runs are related to a large scale weather cycle of 20-plus years, called a “decadal oscillation,” that has been occurring for possibly thousands of years but was only recently recognized. Cooler ocean temperatures along Washington’s coast have provided more food for salmon, dramatically increasing their growth and survival, in turn providing needed food for orcas. The cooling trend has also offered a natural experiment to test the correlation of orca survival with salmon abundances. Since the 2001 low point of only 78 members in the Southern Resident Community, the total population in early 2006 is at 87, counting four calves born since early October, 2004. Hopefully all the newborns will survive to become reproductive adults in 15 to 25 years, but ocean conditions are already showing signs of turning back to El Nino-like warming, which could again decimate salmon runs and deprive the Residents of needed food.
Even with improved salmon runs the orcas may have problems finding enough to eat. Most of the increased runs are hatchery fish, not the hundreds of smaller runs of diverse wild salmon subspecies that once thrived, each superbly adapted to a particular river and stream system. While hatchery-bred salmon runs occur sporadically in large numbers, wild salmon endlessly adapt to spawn in every streambed niche and season in nature. For more than 10,000 years, until about 100 years ago, there were salmon aplenty in the Salish Sea virtually 12 months a year, and many more along the outer coast.
The orcas are certainly benefitting from current ocean conditions during peak runs, but even in these bountiful years, some weeks and possibly months go by with very slim pickings between hatchery runs, leaving the whales without sufficient food for long periods.
Columbia and Snake River Salmon – A treasure on the Verge of Extinction
Two hundred years ago, when Lewis and Clark entered the Northwest, up to 16 million salmon filled the Snake and Columbia Rivers every year. It was the greatest salmon watershed on earth. Since salmon support a profusion of other communities,- including orca and humans – as they live and die, it was also one of the world’s richest, most productive river basins.
But no longer. 12 species of Columbia and Snake River salmon are now listed as endangered or threatened, on the brink of extinction. In the 30 years since the installation of the four lower Snake River dams obstructed 140 miles of free-flowing river and migratory passage for salmon and steelhead, their numbers have plummeted nearly 90%. (Columbia and Snake Rivers Campaign www.wildsalmon.org)
From Orcas in Our Midst: The whales who share our inland waters by Howard Garrett of Orca Network www.orcanetwork.org.
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