Global Short Term Trend: Decline of 10-30%
Comments: At least 50 stocks have been extipated; see Nehlsen et al. (1991) for a review of the status of various at-risk/special concern populations from California, the Oregon coast, the Columbia River basin, and Puget Sound. Of 866 stocks in British Columbia and Yukon, Slaney et al. (1996) categorized 17 as extirpated, 47 as high risk, 6 as moderate risk, 7 as special concern, 330 as unthreatened, and 459 as unknown status. Regarding spring runs outside the Sacramento-San Joaquin population: the run in Salmon River drainage (North and South forks, and Wooley Creek, California) apparently was stable at 1000-1500 adults in the 1980s; the flood of 1964 reduced available habitat for population in the South Fork of the Trinity River, and the population there now is much smaller than previously; most individuals in the Klamath-Trinity drainage are derived from hatchery stock. Ratner et al. (1997) conducted a population viability analysis of spring chinook salmon in the South Umpqua River, Oregon (this is part of the Oregon Coast ESU) and found a 95% probability of persistence of 200 years with no further habitat destruction; with continued habitat destruction, the population was projected to be almost certainly extirpated within 100 years.