So how do the sockeye in rivers far further south and much warmer... still seem to make it work?
Beats me. I guess there are slight differences in the 100 genetically distinct populations of fish that allow some to survive in warmer waters.
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The only other runs of sockeye south of the Fraser are a tiny run into Lake Washington on Puget Sound which is from Frazer stock, and a once major native run on the Columbia River. Both runs troubles have nothing to do with water temperature.
What the writer omits from her story is the causes of the warmer waters on the Fraser.
Cause Number 1:
There are lots of aluminum plants along the lower reaches - all of which use river water for cooling. This water, warmed by the cooling molten aluminum, is discharged back into pools along the river. Many fish following the scent go into the pools and die. The warm water from the pools flows into the river, warms the lower reaches and the fish die.
The two major Fraser sockeye runs - the Chilko and Adams runs - go far up the river, beyond human habitation, where the water is much cooler. These two runs enter the river much hardier then those that spawn in the lower reaches and so survive the warm water in better condition - usually.
Cause Number 2:
The elimination of the International Pacific Sockeye Fisheries Commission (IPSFC). Formed just after the Hells Gate Side, this was a nonpolitical body dedicated solely to the restoration of the Frazer runs.
To make a long story short, after decades of work and sacrifice, they - along with federal US and Canadian funds (and tax monies directly from the catches of commercial salmon fishermen) - restored the river to historic run sizes: in the range of 65,000,000 returning fish each year.
In 1974, during the waning days of the Nixon Administration, US funds were eliminated. The Canadians did the same. The Commission hung on into the early 80s, then in a tearful announcement, ended. The run management was turned over to the highly politicized Canadian Dept of Fisheries in Ottawa. Aluminum smelters were given the green light and discharged more hot water than ever.
Nixon Administration's action could have been reversed by Reagan, but he sold out the major fisheries for reasons unknown - the Frazer fisheries, the Tuna fisheries, the lobster and cod fisheries were virtually destroyed as American industries and major generators of new monies for the US Balance of Trade.
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While not on topic, it should be pointed out for the younger set that the Nixon Administration fundamentally changed America almost on the same order as Obama is currently. EPA, OSHA, Tribal Sovereignty, and so on are some of the wonders brought to the American scene by the Nixon Administration and solidified under Reagan.
Well, the one thing that we don’t want to go back on, which does obstruct migratory patterns for spawning for Salmon, is hydroelectric power. However, few people want to destroy the dams, because the running water is renewable energy.