Invasive mussel boosts Great Lakes cisco (lake herring); one biologist fears boom and bust

Cisco caught in Lake Michigan (U.S. Fish and
Wildlife Service photo by Katie Steiger-Meister)

The Great Lakes cisco, also known as lake herring, appears to be making a comeback, thanks to an invasive species, Steven Maier reports for the Great Lakes Echo, a project of the Knight Center for Environmental Journalism at Michigan State University. Matt Herbert, an aquatic ecologist with the Nature Conservancy, said invasive quagga mussels have depleted nutrients in the lakes. Since cisco do well in low-nutrient environments, they now have space to thrive.

Cisco, which typically grow about 12 to 15 inches long, but have been measured as long as 24 inches, "at one point supported one of the largest commercial fisheries in the region," Maier writes. The species disappeared in the 1950s, mainly because of overfishing, invasive species and habitat degradation. Herbert said "Lake Erie once boasted one of the largest cisco populations of the lakes, but those populations were hit especially hard and have since been lost entirely."

While work is being done to restore cisco to the Great Lakes, some experts worry that this could be a boom-and-bust story, Maier writes. Curt Karboski, a biologist with the Lower Great Lakes Fish and Wildlife Conservation Office in Amherst, N.Y., told Maier that recent "huge catches" are based on a few stocking years. "He would like to see the age distribution even out before he can feel comfortable that the cisco are on track," Maier writes.