If you've been to the lakeshore recently, you may have noticed a large amount of dead fish washing ashore.
Michigan's Department of Natural Resources says they know what's happening here.
The massive alewife die-off has happened before. The DNR says we are witnessing the first one in over a decade.
A fishery biologist says there's good news to see this happen.
If you were walking on the Grand Haven State Park beach over the holiday weekend, you might have seen lots of dead fish.
"Their populations exploded back in the 1950s, and 60s. There basically wasn't much for predators for them," Michigan Department of Natural Resources Lake Michigan Basin Coordinator Jay Wesley told FOX 17.
Alewife is a fish that is several inches long and silver in color.
Jay Wesley with the DNR says they're one of over 180 invasive species in the Great Lakes.
"So thinking that we're going to manage for native only is just impossible. So we just got to deal with them as they come in and change our management strategy to stay on top of them," Wesley added.
This one comes from the Atlantic Ocean.
"They're coming in shallower this time of year to spawn, and that, that puts them in areas that have frequent temperature changes. And they're probably somewhat malnourished allotted when we have strong year classes of alewife they can't find enough to eat out there." Wesley said.
He says that the fish are dying off for those two reasons and living in freshwater.
"We have this year's probably in the millions," Wesley said. "No issues with, you know, pollution or anything, and like Michigan's probably the cleanest it's been since the Clean Water Act came out."
And while your beach trip might not be as picturesque for the time being, seeing all these dead fish can be good.
Alewife is prey fish, and Wesley says to better balance the ecosystem, the DNR is looking at stocking more salmon.
"Chinook salmon feed exclusively on almost 99% of their diet is alewife," Wesley said.