I’ve been chasing and catching salmon in Lake Superior for almost 30 years. During my first 15 or so years of trolling on the big lake, both Pacific and Atlantic strains of salmon were more abundant and larger than those of today. By the mid 90’s changes occurred in the Lake Superior fishery. Where we once saw record numbers of fish and multiple state records set in an angling season, we now have to search hard for a good catch of much smaller salmon. So what happened?

Fisheries personnel usually go back to the theory that when a new, nonnative specie is introduced into an ecosystem, the population skyrockets and fills the new available space. After reaching abundance, the nonnatives often decline in numbers. Over time, the population will stabilize at a level the nonnative fish can maintain in the ecosystem. Molly Negus, MN DNR research biologist in Duluth, refers to this phenomenon as the Boom and Bust Ecological Theory. Smelt and the Pacific salmon species in Lake Superior are all thought to be included in this theory.

Dennis Pratt, WI DNR fisheries biologist in Superior, prefers to say that the smelt and salmon populations blossomed when Lake Superior was ‘sick’. This sick period was when the lake trout population, the major Lake Superior predator, plummeted due to overfishing and the appearance of the nonnative trout killer-sea lampreys. Smelt then entered the system and without the major predator to control them, the smelt population skyrocketed. By the time salmon were introduced, the smelt were super-abundant, providing a large food source for the salmon population.

The Minnesota state record for coho salmon dates back to 1970, shortly after the first stockings. The state’s Chinook record was set in 1989 and the Atlantic salmon record in 1991. Since then, lake trout have come back tremendously via both stocking and natural reproduction, and the sea lamprey population is somewhat controlled. Smelt and salmon populations are now at much lower levels. Pratt believes that once a nonnative specie reaches its stable population level and has found its ecological niche, competition from within their own population is the largest limiting factor.

Stocking of salmon in the past was once considered vital to having a good sport fishery. Over the last several years, Lake Superior fisheries managers started having serious doubts as to stocking’s effectiveness. Creel surveys showed little return to creel of stocked fish as compared to naturally reproduced fish, so salmon stocking was reduced lake wide.

Minnesota has discontinued all Chinook stocking in its share of Lake Superior. Larry Nelson, a Lake Superior fisheries expert with the Wisconsin DNR, says just over 200,000 Chinook are stocked into Chequamegon Bay from the Pike’s Creek Hatchery. Steve Scott with the Michigan DNR in Newberry reports that Michigan stocks about 350,000 Chinook in their portion of Lake Superior at four different sites along the Upper Peninsula. Small scale, private stocking of Chinook occurs on the Canadian side of the lake. There is no stocking of coho salmon anywhere in the watershed.

The one bright spot for salmon chasers today concerns coho salmon, a Pacific specie. The coho seems to have adapted to the watersheds along the South Shore of Lake Superior quite well as compared to how Chinook have adapted. According to Pratt, the Bayfield Peninsula streams have a very good ground water supply and those rivers all produce some coho. Some of these fertile streams include the Bois Brule, Flag, Cranberry, Onion, and Sioux rivers, and Whittlesey and North Fish creeks. Scott says that coho have adapted much better than Chinook in the UP, where spawning rivers include the Chocolay, Carp, Anna, and the Two-Hearted. These Michigan rivers east of the rocky Keweenaw Peninsula also have a good ground water supplies. Minnesota streams are mostly dependent on run-off for flow and produce a very minor amount of naturally reproduced salmon.