Warm fresh water is not the only problem the salmon have. Warm ocean water is also a problem. It brings predators from the South. In the early 1960s, during the last major El Niņo episode, fishermen complained about the large populations of mackerel that had migrated north from California. In the 1990s, the mackerel came back, venturing as far north as Southeastern Alaska.
At a conference on ocean conditions in Newport, Oregon in March 1996, a Canadian researcher reported on the effects of mackerel predation off the west coast of Vancouver Island. As the researcher put it, if he had taken a long weekend, he would have missed the story. A release of eight million smolts from a hatchery on the Island hit the ocean, and a huge school of mackerel showed up to feast on them. One mackerel was found to have 13 salmon smolts in its stomach.
But aside from anecdotal evidence like this, fishery agencies have made no effort to estimate the amount of damage done to salmon runs in the 1990s from the influx of mackerel. Nor have they made any effort to promote a mackerel fishery. Truly optimal and adaptive fishery management would single out fish populations that are rapidly growing, particularly at the expense of other valued populations, and promote fishing for such fish.
Localized effects, like the mackerel attacks, are symptoms of large scale cycles in the ocean that tend to have a very significant effect on overall salmon populations. During the 1960s and 1970s, ocean conditions were good for salmon populations south of Vancouver Island. But in the winter of 1975/1976, there was a major shift in regional climate that produced unfavorable marine conditions for salmonid production in the area south of Vancouver Island, and highly favorable conditions farther north in the Gulf of Alaska.14 This commenced a climate-driven downward spiral in ocean conditions and onshore weather patterns salmon need to survive off the coasts of Washington, Oregon and California.15
While harvest agencies craft salmon recovery plans based on river flow as the most important variable in salmon survival, as Drs. Chapman and Giorgi have pointed out, [o]cean conditions overrode any effect that may have been caused by flows during the outmigrations of 1992 and 1993.16 The 1993 smolts left the river during outstandingly good flow conditions with high spill and high discharge, yet will return a run in 1995 about half as large as the smolt run of 1992, or about 10% of the ten-year average. Both runs likely were decimated as smolts when they reached the continental shelf rearing areas.17
Many scientists believe that good ocean conditions are correlated with cooler, wetter weather in the Pacific Northwest. On the positive side, 1996 had the highest rainfall measured at the Portland, Oregon airport since 1950: about 60 inches. But during the historic peaks of salmon runs, rainfall in downtown Portland was 67 inches.18 And in the summer of 1894, the greatest recorded flow in the history of the Columbia actually drowned the famed Cascade Rapids. A steamboat attempted to race upriver, but could not combat the current.19
Unfortunately, as of 1997, a new, and very strong, El Niņo event seems to be occurring.20 And temperatures remain above average. There is still room for optimism, however. According to a recent paper by three Northwest scientists, the cycle of poor ocean conditions prevailing since the late 1970s "appears to be one of the longest in the past five centuries".21 They think more patience is required in salmon recovery programs. "[W]ith costly decisions with regard to altering operations of, or removing Columbia River dams being imminent, we urge decision makers to consider newly-acquired information on the potential for a climate shift."22
14 U.S. Army Corps of Engineers, "Interim Status Report", at 2-8 (citing Graham, Simulation of Recent Global Temperature Trends, 267 Science 666-69 (1995)).
15 AP, Global climate changes may affect salmon, Tri-City Herald, June 27, 1997.
16 D. Chapman & A. Giorgi, Comments on Work of Biological and FCPRS Alternative Work Groups, at 5 (1994).
18 S. Tomlinson, Heavy rains make a run on a 46-year record, The Oregonian, Dec. 3, 1996, at A1
19 R. White, The Organic Machine 30.
20 W. Rudolph, Mackerel Are BackAnother Sign of Impending El Nino, Clearing Up, June 30, 1997, at 9.
21 J. Ingraham, C. Ebbesmeyer & R. Hinrichsen, quoted in W. Rudolph, "Another Possible Sign of Shift to Colder, Wetter Climate Regime", Clearing Up, July 14, 1997, at 3.
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