'Tis the eve of the fall salmon migration and the salmon fishermen are in high anticipation, with visions of full coolers dancing in their heads! Yes, it is the season when salmon leave the clear, blue waters of the Great Lakes and begin their spawning run up our coastal streams. So, a look at the life history and biology of the Chinook and coho salmon is in order.
First, a brief history of Pacific salmon stocking in our world-famous Great Lakes is needed. Coho salmon were first introduced in 1966, being stocked in two L.P. streams (Bear Creek & Platte River) and the Big Huron River in the U.P. The egg sources were the Columbia River, Cascade River and Toutle Rivers in Oregon and Washington. In 1967 and 1968, an Alaskan strain of early run (August) coho were introduced, but due to poor returns they were canceled in 1979. Today, only a few coho are stocked in Lake Superior near Munising.
Chinook were stocked a year later, in Lake Michigan with Lakes Huron and Superior following in subsequent years. Wisconsin made its first salmon stockings in 1969 followed by Illinois and Indiana in 1970. The source of Michigan eggs was Oregon and Washington. The first was a Tule strain from the Columbia River and the second a Puget Sound strain from the Green River. Chinook have been stocked in Lake Michigan every year since and have created a multibillion-dollar-a-year sport fishing industry. No chinook are currently stocked in Lakes Huron or Superior.
These two species of Pacific salmon were originally brought to Lake Michigan to control alewife populations, an invader from the Atlantic Ocean. In the early 1960s they made 90 percent of the Lake Michigan fish population, where with nothing to eat them, they exploded. Lake Michigan was basically a dead lake for fishing. Dead and rotting post spawn alewife piled 3-4 feet high on beaches, rendering them useless for any use. The smell still lingers in my nose. Now Lake Michigan is a $2 billion a year sport fishing industry, thanks to the fathers of our salmon program, Wayne Tody and Howard Tanner.
Chinook or king salmon and coho or silver are two of five species of Pacific salmon, which are native to the west coast of North America. Pacific salmon are in the genus Oncorhynchus which includes pink salmon, sockeye, chum, coho and Chinook salmon. Each of these species has a different life history strategy. Pink salmon are currently the only other Pacific salmon present in the Great Lakes and primarily in Lake Superior.
The Chinook is the largest of the Pacific salmon and also lives the longest. The Michigan record Chinook weighed in at 46 pounds, one ounce, caught in the Grand River in 1978. The largest Chinook in North America come from the Kenai River in Alaska where kings in excess of 100 pounds are caught each year.
Coho are the second largest Pacific salmon, with the Michigan record being 30 pounds, 9 ounces from the Platte River in 1976, while the Alaskan record coho is 26 pounds 11 ounces. Why? More abundant forage is found in Lake Michigan.
Great Lakes Chinook typically begin their spawning migration in September. All salmon cease feeding once they enter rivers and live on stored body fats. Peak spawning is the last week in September through the first week in October. Once spawning is complete, all salmon die. The eggs incubate in the gravel over winter and hatch in the spring, usually early to mid May. The newly hatched salmon, or fry, feed on zooplankton (microscopic animal life) and slowly begin their migration out to the Great Lakes. This process is called smolting and the young Chinook turn bright silver, which is their protective coloration for life in the Great Lakes. The peak of the Chinook smolting is mid June. A small percentage do not migrate but remain in the stream over winter and smolt the following year. In the lake, they continue feeding on zooplankton in the near shore area shallows. At night, the 3- to 4-inch Chinook feed actively on the beach on terrestrial insects that have been washed ashore. In mid June, the young kings migrate to off shore waters to feed on young of the year alewife, smelt and chubs. Most Chinook remain in the Great Lakes for 3 to 4 years, before returning to their stream of birth to spawn. Some male Chinook that return after only one year in the lake, are called jacks and are all fertile precocious males. Females stay longer, taking at least three years to develop eggs skeins.
Coho likewise ascend streams in late September to spawn and die. Their eggs also incubate in the gravel over winter and hatch in the spring. Unlike Chinook, young coho spend one summer in the stream of their birth before migrating out to a Great Lake. Their feeding pattern in the Great Lakes is similar to the Chinook. Here they typically spend two summers before returning to their birth stream. Some male coho also return as jacks after only one summer in the lake.
The word by the waterfall is salmon fishing is good at the mouths of local streams.