Smallmouth bass are getting bigger in Michigan. Thank catch-and-release

LANSING – Every spring for the last 15 years, Gene Gilliland and some friends have gone smallmouth bass fishing in Lake St. Clair in Southeast Michigan for a week.

He and one friend travel from Oklahoma. Two others visit from Tennessee. Two more drive from Pennsylvania, and another comes from Florida. Over the years, the group also has included friends from Missouri.

That’s because Lake St. Clair has gained a reputation over the last two decades as one of the best bass fisheries in the world.

“It’s been a real boom, and a lot of people will say that the good ole days in bass fishing are now,” Gilliland said.

Smallmouth bass in the lake are bigger than they used to be because they live longer, according to a recent study by the Department of Natural Resources and published in the Journal of Great Lakes Research.

That’s largely due to fishers adopting catch and release practices. 

Bass are often released back into the water instead of going home with fishers, so they live longer and can grow bigger. 

Bass have indeterminate growth – meaning that the fish keep growing until they die.

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According to the study, smallmouth bass in the early 1970s averaged about 4.5 years old. In 2023, they were generally 6.5 years old on average.

Gilliland is the national conservation director of the Bass Anglers Sportsman Society, or BASS, which works to preserve bass fishing and organize tournaments.

He said in the early 1970s, the founder of the organization started promoting the idea of catch and release – at the time called “don’t kill your catch” – to sustain the tournaments.

BASS, based in Alabama, hosts a significant number of tournaments. Gilliland said fishers release more than 95% of the fish caught at its events.

In Lake St. Clair, that same percentage is voluntarily thrown back into the water, said Dan Kimmel, the conservation director of the Michigan Bass Federation and the Michigan Bass Fishing Coalition – groups mainly for bass tournament fishers.

Statewide, he said 60% are caught and released.

Technology on boats helps keep more fish alive and in good shape to survive when released, Kimmel said.

That’s equipment like oxygen systems, aerators, pumps and chemicals.

But there are other factors that could contribute to bass sizes increasing over the last 50 years, according to the study and Kimmel.

The Clean Water Act of 1972 and Canada Water Act of 1970 improved water quality in the Great Lakes – so fish are healthier.

In 1995, the minimum size limit to keep a smallmouth bass in Michigan increased from 12 inches to 14. That protects young, small fish and allows them to get bigger.

“One researcher told me that might be the only regulation they’ve ever done that they could say made for bigger bass,” Kimmel said.

Gilliland, the national conservation director, said the Great Lakes warming over time means bass have longer growing seasons – it’s the same idea as for plants.

“Even though it may only be a matter of days or weeks that the growing season is longer, that is a pretty significant difference in terms of the potential for those fish to grow bigger sizes as they get older,” Gilliland said.

There’s also a theory that the invasive round goby – a small, bottom-dwelling fish – might help sustain bass.

When zebra and quagga mussels invaded the Great Lakes and its connected waterways, they took nutrients for themselves, messing up the food web for native fish.

When gobies arrived in the early 1990s, bass got a new food source.

“Gobies are getting eaten like crazy by the smallmouth. I’ve done camera work for a few TV shows, and I’ve seen underwater video of them where gobies come into a nest and the bass just eat one right after the other,” Kimmel said.

Jan-Michael Hessenauer, a fisheries research biologist for the DNR and author of the study, said he was surprised that his research didn’t support the goby theory.

“The population [fish size] is changing at the same trajectory now as it was before the round goby invasion, which is not what I expected,” Hessenauer said.

He said because of this misconception, people might be deliberately introducing goby to inland waterways that wouldn’t naturally be exposed to the invader from the flow of waterways.

“People shouldn’t be spreading fish of any kind, but especially invasive species like round gobies,” he said.

Hessenauer said the study shows how dramatically anglers’ behavior can affect fish populations, but that there is rarely a single factor that makes a good fishing spot.

This story was originally published by the Capital News Service.