After a 40-year population dip, the native lake herring is now considered the most abundant fish species in Lake Superior. For anglers, the record lake herring, or cisco, population means bigger, fatter game fish like salmon and trout, many of which already have bellies full of the now-abundant prey species.
Trawling data from a spring U.S. Geological Survey study confirmed what Minnesota Department of Natural Resources studies conducted in the fall of 2022 had already indicated: The lake herring population was going to hit its highest point since data collection began in 1978. The previous record year was 1984, but the USGS trawling study cemented the current population as the new standard-bearer.
“This is what we’ve been waiting for,” DNR Lake Superior fisheries supervisor Cory Goldsworthy told the Minneapolis Star-Tribune. “It’s something we’ve never seen before in our careers and may not see again.”
Lake herring support Superior’s robust commercial fishing industry, employees of which harvest the fish for their meat and roe. But the cyclical nature of the lake herring’s population makes commercial harvest a precarious pursuit. The number of less-than-14-centimeter lake herring per hectare in 2014 was zero. The projected number for 2023 is 748.
But if food is this easy to come by, how many game fish are going to hit a lure? Is the fishing going to get tougher?
“We might see that for a year or two until the cisco get too big,” Goldsworthy tells the Duluth News-Tribune. “But the fish [anglers] do catch will be bigger … We might normally see a couple of steelhead 30 inches long and 10 pounds, but this year we had numerous ones that big.”
The rebounding population might be the result of colder water temperatures lasting longer into the spring than usual. Biologists have long used ice cover as an indicator for lake herring reproductive success, Goldsworthy said. But the last two winters weren’t standouts for ice cover, even though they produced this monstrous population boost. The only other natural explanation is the cold water theory.
Once the lake herring reach their maximum length of roughly 16 inches, they transition from a prey species to a food species. That means commercial netters will enjoy a booming business once this current crop of cisco reaches maturity, in another two or three years. Until then, the silver fish will feed big game fish instead of humans.