The Salmon are Massive in Chicago’s Southern Basin of Lake Michigan - Why? A Charter Captains Perspective.

2024 marks the best salmon fishing we’ve seen as charter boat captains in Chicago’s southern basin in decades. Both the quantity and a size of the fish are increased trip after trip with no apparent end in sight. If we look at IL. State records for both the Chinook Salmon and the Coho Salmon they were set in the 1970’s. This is just years after the salmon were introduced to Lake Michigan in order to control the exploding alewife population and die offs. Could this year year be the year the records are broken… it’s possible. Lets look at why.

The Alewife

The alewives, a herring like fish, migrated into Lake Michigan back in the 1920’s from the Atlantic Ocean. Steadily throughout the next several decades their population grew to numbers that were out of control. The alewife is a prey fish, but had no real predators other than the indigenous Lake Trout. Post spawn alewives die as natural occurrence. Hence populations grew to the point that there were major die offs which created concern for communities surrounding Lake Michigan. I remember as I kid when the alewife would wash ashore the beaches and bulldozers and backhoes would remove the rotten, stinking, decayed fish. 

The Salmon

Salmon were experimentally introduced in Lake Michigan back in the late 60’s and early 70’s as a means of controlling the alewife population. The salmon is a natural predator of the alewife. Three major things occurred when the salmon were introduced:

• The salmon began doing their job to control the alewife population
• There was cause for ongoing biological study of the predator prey relations by marine biologists
• And it kicked off a billion dollar sport-fishing industry both commercially and by charter boats

Salmon were thought to not naturally reproduce in Lake Michigan, hence a continued annual stocking program began by all states bordering Lake Michigan in a concerted effort. Chinook Salmon have a life cycle of four years, whereas the Coho is three years. This is important to know in effort to understand why a fish can grow so fast. Also, why charter boats are seeing cyclical changes in catches within just a few years.

The Relationship between DNR and Charter Captains

The DNR works closely with the charter captains for a variety of reasons. The primary reason is we put more hours on the lake and fish in the boat than recreational anglers. A second reason is that commercial fishing has been strictly reduced in favor of farm raised fisheries. Also, we are permitted and easily tracked down to assist in studies. One such study was performed in two trials to determine if there was natural reproduction of the chinook salmon in Lake Michigan and tracking migrational patterns. Without getting into the details of the study, it was found that the chinook salmon have more than a 50% natural reproduction rate. So why is this important? The chinook salmon is the biggest predator and consumer of the alewife. 

The Declining Alewife Population

There is no doubt that through annual stocking of salmon and natural reproduction the alewife population was being depleted faster than they could reproduce. In 2016 the Lake showed record low alewife numbers. But building up to this, the die off of alewife no longer occurred and the municipalities were happy. However, the charter captains were upset as the size of the fish being caught was diminished. It was difficult to catch a king salmon bigger than 15 lbs. and a 10 lb coho was a monster. Along with the alewife population being depleted, the size (biomass) of the of the alewife was shrinking as well. This is due to the predator prey relationship.

The Predator and Prey Relationship

In the 20-teens with an understanding of a declining food source (alewife) and the poor quality or size of fish being caught, the DNR reduced stocking efforts in all four states surrounding Lake Michigan. This is was in part to do with the new found knowledge that Chinook Salmon, as well as, steelhead are naturally reproducing at a rate fasted that the alewife. Charter captains were upset, believing their customers would not catch as many fish. However, the bigger picture is yet to show itself. As salmon stocking was reduced, within a few years we started to see bigger fish being caught and more alewives around the harbors and on sonar. 

The Alewife Die Off of 2022

The 2022 season created some cause for concern as there was a massive die off and wash ashore of post spawn alewives. It wasn’t yet understood why. However, it was soon proved that the die off had nothing to do with disease or environmental contamination. This die off was a natural occurrence just like back in the early 70’s. This is a very positive indicator that the reduction in salmon stocking created a rebound of the alewife population. So much so, that stocking efforts increased again to maintain the predator and prey population balance. In addition, in the 2020’s we started catching fish that were larger then recent years and healthy. Another positive indicator. One of our boats caught a king salmon that pushed toward the old state record at 34 lbs. just shy… 

The 2024 Season

We have seen the biggest coho salmon that we’ve seen in decades, the king salmon are monstrous again. The numbers of fish and the size of the salmon is just astounding. It’s like fishing back fin the 70’s when the salmon were introduced to the lake and the prey was plentiful. We are seeing seeing signs of an amazing alewife population and superb fish quality and numbers. This is directly related to the work of the DNR and Biologist dialing in on the predator prey relationship. In addition, the findings of natural reproduction of salmon. Now we just boated a Coho Salmon that once again pushed close to taking over the IL. State record. 

What Is In Store For The Future?

It is our opinion as three generations of charter fisherman that the DNR biologist are doing a fine job. The predator and prey balance has been achieved. If this is maintained, we should have charter fishing once again like only our predecessors witnessed decades ago. Is it possible to catch an IL. State record? Absolutely! Is it time to book a charter and try your hand at breaking the state records? Yes!

We hope this information was useful and let’s go catch the new state record salmon. Click the links included for more information on the topics and references.