When you think about Department of Natural Resources fisheries biologists doing research, what comes immediately to mind?

Salmon? Trout? Sturgeon?

The truth is fisheries biologists pay attention to all sorts of aquatic creatures, not just the sport/glamour/endangered species that capture the public's imagination.

In fact, some of the most interesting fisheries research going on today fits neither the sporting nor the glamour categories, but is focused on such species as the purple wartyback and elktoe, two freshwater mussels that are of "Special Concern" in Michigan.

Researchers, working on a project led by Marquette-based DNR Fisheries Biologist Jessica Mistak, are studying these and other freshwater mussels in the Menominee River watershed, trying to determine their populations as well as unlocking the secrets to where they live.

"There is limited information about mussels in general, and in the U.P., there's even less known about them," said Mistak. "If we can determine their habitat preferences, perhaps we can protect some of that habitat for those mussels to prosper, especially the rare species."

Mussels are among the most threatened and endangered species in Michigan. More than a third of the native species are imperiled. Though many of them are rarely seen, they are an important part of the ecosystem, serving as an important food source for both fish and wildlife.

"Their life cycles are fairly complicated, which makes them especially susceptible to environmental threats and development," Mistak said. "They are the canaries in the coal mine. They are great indicators of environmental health.

"When we think of endangered species we usually think of wolves, sturgeon or Kirtland's warblers, but we don't often think of mussels. Really, the public may see them when they're out wading a river of from the shore of a lake, but they generally don't pay much attention to them. They don't know their importance."

Besides playing a role in the food chain, mussels help provide clean water by filtering nutrients and sediment, Mistak explained.

"They also provide habitat, especially in sandy-bottom streams, by providing a hard surface for aquatic insects to attach to," Mistak continued. "They play an integral role in the whole stream cycle or the whole lake cycle, but a lot of people just don't understand it."

The research, which is being conducted with the assistance of Lake Superior State University, Michigan Natural Features Inventory, and Inter-Fluve, Inc., is designed to provide information on both the status of mussel populations and their habitat preferences in the Menominee River watershed.

Researchers, who worked on the Paint River last summer, selected stretches of river that they could wade in and where they were able to get permission from landowners to access the stream. They then created a grid with rope, placed the grid on the stream bottom and randomly sampled certain squares for mussels. If the mollusks were present, the researchers not only identified them, they tried to determine what sort of habitat was holding the mussels.

In-the-water research last summer was conducted by students Kate Harriger of Gaylord and Jen Johnson of Iron Mountain, who were studying under Dr. Ashley Moerke at Lake Superior State. This year, when the research crew moves to another river, Mistak will be working with different researchers, she said.

Although the students are still analyzing the data they gathered last summer, their preliminary findings suggest relatively low populations and species of mussels in the Paint River system, compared to Lower Peninsula streams.

"We surveyed 39 sites and found six species," Mistak recalled. "But we also did some preliminary reconnaissance on the Sturgeon River and we're excited about this summer's work. We expect to find quite a bit more, both in numbers and in diversity."

The research project is funded as part of the hydroelectric dam relicensing agreement between We Energies and the Federal Energy Regulatory Commission. Because dams often form barriers that make it impossible for fish to travel upstream, they may have a significant impact on mussel populations.

Mistak said it starts with the complex reproductive cycle of many mussel species. After a female's eggs are fertilized, she holds them internally until the eggs grow into larvae (glochidia). The female mussel then creates a lure from her mantle, which looks like a fish or aquatic insect, to attract the appropriate host fish. When a fish tries to bite the lure, the female ejects her larvae, which attach to the gills of a preferred host fish. If they do not attach to a host, they will be unable to continue their life cycle and metamorphose into juveniles.

"So the habitat available to the mussels is limited to that available to the host fish," Mistak said. "Eventually, we hope to correlate the mussels to their required habitats and different types of substrate -- sandy or coarse -- and even to the quality of the water."

A final report and database including locations and habitat use by freshwater mussels will be available by winter 2009-2010. This information can be used by managers to identify river areas in need of protection, guide restoration and mitigation plans, inform the public and promote public policy changes, and understand trends and predict impacts of changing watersheds on freshwater mussel populations.

To view an audio slide show of the DNR's freshwater mussel survey, click here.