Grad student looks for a safer way to solve fishy mysteries

A Central Michigan University graduate student hopes that a safer way to solve the mysteries of a legendary Great Lakes fish lies in its upper jaw. The fish also happens to occupy a special place in Michigan’s heart.

“Coaster brook trout might be the state fish, but there’s not a lot known about them,” said Kevin Pangle, a faculty member in the biology department. “We’re trying to change that.”

Michigan’s state fish is the brook trout. Coasters are brook trout that spend part of their lives in Lake Superior and are bigger than brook trout that stay in inland waters, but both share the same genetics, Pangle said.

Why some brook trout stay in inland waterways and why some move into open water is one question scientists seek to answer, he said. Another mystery is why some streams have coaster populations near the mouth, but a stream just a short distance away doesn’t.

Sara Gillette is a graduate student in Pangle’s lab. She is investigating whether there is a safer way to study coasters so that scientists can learn more about their life cycles.

Right now, the best way to study coaster life cycles is by examining concentric rings in three sets of bones in the fish’s ear, she said. It’s like looking at the rings in a tree stump. Based on the chemical composition, scientists can determine what waters the fish lived in. The drawback is that removing the bones kills the fish.

One possible alternative is to gather the same information from part of a coaster’s upper jaw, she said. Fish can continue to eat and grow if that bone is removed.

Samples of coaster brook trout jaw are sent to Gillette, who turns them into slides that are analyzed. The analyzing equipment takes hundreds of measurements at several locations on dozens of fish. Each slide produces approximately 140,000 pieces of data.

It’s a lot of data to process, but every biology student at CMU gets experience working with big data sets, Pangle said.

The research is part of a multi-agency effort across Michigan, Wisconsin, Minnesota and the province of Ontario to study coasters and restore their populations.

Coasters live exclusively in Lake Superior. They were once abundant but overfishing and habitat loss have caused their numbers to dwindle.

Because of their size, beauty and because they have their own lore, coasters are highly sought by anglers, Pangle said.

“Anglers are very excited about the opportunity to catch coaster brook trout,” he said.

Gillette started the research as her senior capstone project and continues it through the biology department’s accelerated graduate degree program. It is one of 24 programs at CMU that allows undergraduates to get their master’s in five years instead of six.

When she graduates, she hopes to take her lab experience and master’s degree and get a job as a fisheries biologist, she said.

There are jobs available, Pangle said.

“There are opportunities for students coming out with fisheries degrees,” he said. Those opportunities are available at tribal, state and federal agencies.