Inside the DNR's Besadny Anadromous Fish Facility in Kewaunee, mid-October is one of the busiest times of the year.
"The fish come up and spawn once a year so we have to be here and ready for them," explained Jesse Landwehr, DNR Hatchery Supervisor.
Coho salmon spawning season is underway, with salmon coming into the Kewaunee River from Lake Michigan. However, these salmon are not native to Lake Michigan.
"What we're doing here is important, otherwise we wouldn't have the fish out in Lake Michigan that we have," said Mike Baumgartner, Fish Facility Manager.
It's this DNR process of gathering eggs and raising the fish that keeps the lake stocked.
"Overall we're shooting for about a million eggs total, and we'll stock back about a half a million fish as yearlings next year," Landwehr said.
After collecting eggs at the fish station in Kewaunee, the DNR brings them to a hatchery.
"Once the fish are hatched and they rear them up for a certain amount of time in the hatcheries, then the fish are stocked back into the streams," Baumgartner explained.
These salmon help control the alewife population in Lake Michigan and make for some great fishing.
"We're still maintaining that balance out on the lake, making sure that we stock enough salmon to support the fishery but also stocking enough salmon to not crash or under-utilize the alewife population that's out on the lake," said Landwehr.
The process isn't just about raising fish. It's also for collecting data to track trends.
"They'll take all kinds of tissue samples and they're looking for signs of disease or various things that they'll notice over time," said Baumgartner. "They'll take all those samples back to their lab, analyze them and then they get back to us and let us know how healthy of a spawning population we have."
Once the DNR takes the eggs and studies the fish, their life cycle is over. But they don't go to waste.
Some fish are donated to local food pantries for people to eat, while others are made into fertilizer. Some eggs are even turned into bait.
The process makes sure these popular sport fish are always swimming in Lake Michigan.
To learn more about the spawning season, visit the DNR's website here .