“On the Columbia River, there’s a very sad history for sockeye
salmon in general. In the late 1800s, there were over half a million fish
landed annually,” says Hyatt, a scientist with Canada’s Department of
Fisheries and Oceans, Pacific Biological Station, in Nanaimo, British
Columbia. Yet in the last century, “it’s declined to very low levels, to the
point where there are very few sustainable fisheries.”
Salmon already lead a punishing life by human standards, without
even considering the effects of climate change. First of all, they essen-
tially quit eating when they are ready to leave the Pacific Ocean to
return up rivers to spawn. So they’re burning their fat reserves as they
journey hundreds of miles up rivers. They swim against the current
the whole way, flinging their bodies headlong over waterfalls, boulders,
fallen logs, and other obstacles. Chunks of skin, sometimes flesh, hang
from their bodies by the time the lucky few salmon that make it this far
finally arrive at their ancestral spawning area. Tired, hungry—now it is
time to fight. They compete with other salmon for mates. They com-
pete for an ideal particular spot to spawn. Upon mating, they gasp their
final breaths and die. With the past century’s advent of dams, over-fish-
ing, and the detrimental effects of human development, fish hatch-
eries, and streamside logging, wild salmon numbers have plummeted.
Climate change aside, they face a precarious existence. Hyatt has
found that warmer temperatures have made it that much harder for
sockeye salmon.
Sockeye live by strict temperature rules. The rules work like this:
Adult salmon will stop their arduous journey to their spawning sites
whenever the water temperature hits 70°F. It is simply too stressful to
continue. They will wait for temperatures to turn. For Okanagan sock-
eye, anything above 63°F is stressful, and 77°F is lethal. So they wait.
And wait. Migrations actually will resume at 72° or 73° so long as the
salmon sense that the temperatures have crested and now are defi-
nitely declining. It can be a long wait—on average, 40 days, but as long
as 72 days. “Delays have been increasingsteadily in association with
climate warming during the 1985 to 2000 interval,” Hyatt says. That
further tires and stresses the fish before they even begin the final leg
of their odyssey. Salmon now spawn about 8 days later due to warming
waters. Since 1985, on average, the peak spawn date for Okanagan
Pacific Northwest 151