Coho salmon were shipped to the Great Lakes to eat an invasive fish
A Pacific fish now swims in every one of the Great Lakes. Coho salmon were first released into Lake Erie in the 1920s to control alewives, and large-scale stocking began in 1966 with 660,000 fingerlings in Lake Michigan. By 1970 they were present in all five lakes, though most populations still depend on hatcheries.
Coho, also called silver salmon, are one of six Pacific salmon species, native from Hokkaido and eastern Russia around the Bering Sea to Alaska and south to Monterey Bay. Their English name comes from a word in the Halkomelem language spoken around Vancouver, while the scientific name echoes the Russian kizhuch. At sea they are silver with dark blue backs; on returning to fresh water they turn bright red, and spawning males grow a pronounced hooked jaw called a kype.
At three or four years old, coho push upstream as far as they physically can, sometimes into water just 5 centimetres deep. Females dig as many as seven gravel nests, called redds, with sweeps of their tails and fight fiercely over sites. A female usually picks the largest male, though smaller males often sneak in to fertilise the eggs too. After spawning, the adults stop eating and die. Their young spend one to two years in streams before heading to sea, and some precocious males, known as 'jacks', come back to spawn at just two.
Numbers swing wildly. Along the Southern Oregon and Northern California coast, naturally spawning fish fell from an estimated 150,000 to 400,000 in the 1940s to fewer than 10,000, blamed on El Niño, sea lions, seals and logging. Four West Coast populations are listed under the Endangered Species Act. Yet in 2009 more than 680,000 coho returned to Oregon, double the 2007 run, after cooler waters brought richer plankton, and food banks froze 40 tonnes of surplus fish.
Anglers prize them for the reckless way they chase lures, and cooks rate their moderately fatty flesh. For several Indigenous peoples coho has long been a staple, a trade good and a symbol of life.
Source: Coho salmon
