Lake herring are a species of native freshwater fish that inhabit the open waters of the Great Lakes. These fish were once found in all of five of the lakes, but their populations were drastically reduced by overfishing, invasive species and a decline in water quality.
However, a small population in the southwest corner of Michigan could soon change that.
“Historically, lake herring played a key role in Great Lakes food webs and were also very important commercially,” said Matt Herbert, a Conservancy aquatic ecologist.
“Recent food web changes in Lake Huron and Lake Michigan have impacted the fish populations that top predators like lake trout and chinook salmon need to survive—including lake herring. The need to recover lake herring in the Great Lakes is greater than ever, and the conditions are right for doing so now.”
Last December, the Conservancy began working with the Michigan Department of Natural Resources and the Little Traverse Bay Band of Odawa Indians to assess a spawning population of lake herring in an inland lake in southwest Michigan. Since some lake herring migrated into tributary rivers to spawn historically, it is possible that inland lake and Great Lakes lake herring populations are not inherently different from each other.
“If they are the same, then they may be used interchangeably to help recover populations in Lake Michigan and associated inland lakes,” Matt explained.
The Conservancy and partner organizations are studying these inland lake herring to better understand where and when they spawn, as well as artificially spawning the fish and raising them in a hatchery alongside Lake Michigan herring in what is known by scientists as a “common garden” experiment.
“Raising the two populations alongside one another will allow us to evaluate whether they develop and behave similarly as they mature, and to genetically compare the inland lake and Lake Michigan herring,” Matt explained.
If the inland lake herring populations within the Lake Michigan basin are indistinguishable from Lake Michigan populations in both form and behavior, and if no significant genetic differences are identified, they can be considered part of the same population. This means that inland lake fish could be used for Great Lakes stocking efforts, or vice versa.
“Attaining this information will greatly improve decision-making regarding lake herring management,” Matt said. “In addition, we are learning more about lake herring in inland lakes, which will help to protect and restore these populations as well.”