The Chinook salmon or King salmon - a favorite of anglers on Lake Michigan - is in decline. That’s because it’s starving. According to a study by Michigan State University, the population of the salmon’s only prey - a small invasive fish called the alewife - has dropped by more than half since 2002.
Ironically, other invasives - zebra and quagga mussels - are eating the alewives’ food.
As a result, the Michigan Department of Natural Resources has been stocking fewer King salmon. King salmon is a major draw for tourists and other anglers, says Eric Conder of Big Bird Charters in St. Joseph:
“Oh it’s a much bigger fish. Brute strength when they get ahold of your line, they peel that line out and you could be fighting that fish for 15, 20 minutes. Strong fish, clean fish. Powerhouse,” he says.
While this could be bad news for Michigan’s sport fishing industry, it’s likely good news for the lake’s native species.
Sara Adlerstein is one of the authors of the MSU study. She says, in 1966, the DNR started stocking King Salmon for two reasons: to eat alewives and to create a better fishery. With most of the alewives gone, Adlerstein says there’s no ecological need for the DNR to stock King Salmon in the lake.
“So you have those two - one invasive and an exotic - out of the system. Then you can start seeing recovery from the native food web Lake trout and walleye, Yellow perch, and Lake whitefish,” she says.
While the salmon themselves don’t hurt the lake, you can’t have King salmon in Lake Michigan without alewives. And while alewives serve as food for several fish in the lake, Adlerstein says they also keep native fish from reproducing.
“They were feeding, for example, on eggs and larvae of some of the native species,” she says.
Even if alewives don’t eat the eggs, Jay Wesley of the DNR says they have other ways to destroy them. They produce an enzyme that cuts down vitamin B levels in native fish like Lake trout.
“As a result of that Lake trout egg survival is very poor. So with lake trout now finding other food items such as round gobies - which is another invasive species - their issues with that low vitamin B are starting to go away. So we’re starting to see more natural reproduction of Lake trout,” says Wesley.
Because of the decline in alewives, Wesley says the DNR has been forced to stock fewer King Salmon.
“We’re basically just trying to balance predator and prey ratio out there,” he says.
That makes charter captains like Link and Conder nervous. Sport fishing is a multi-billion dollar industry in Michigan. John Matson is a sport fishing guide on the Pere Marquette River - one of the rivers where the salmon spawn.
Matson says if salmon populations continue to drop, that could have a huge economic impact on the state.
“You’re talking about affecting small towns like you know our river town is Baldwin. And you’re going to take a big chunk of income away from the whole town. There’s no question,” he says.
For now, Jay Wesley says the DNR will continue to stock roughly 1.7 million King salmon in Lake Michigan. Though the DNR says it may stop stocking the fish if its numbers get too low.
As for the fishing industry, it’s probably too early to tell what effect low King salmon numbers will have on business. Fishing guide John Matson says it will be about three to four years - the average lifespan of a King salmon - before we’ll know.
“We didn’t catch them good last year. I’m still booked solid for this year. So it’ll be next year or the year after that I’ll be able to tell you for sure if these folks are still going to come up here and want to go fishing,” he says.
Click here to learn more about the King Salmon.