KIYI: The Story of a Fish

Deep in the cold waters of Lake Superior live the kiyi (Coregonus kiyi). A silver fish with pink or purple-tinted scales along its back, they have large eyes and can reach up to 11 inches long. They are one of the smaller ciscoes, a group of fishes related to the better-known lake whitefish.

The kiyi were once as widespread as the whitefish, living throughout the Great Lakes region and contributing to a thriving commercial fishery. They were also one of several native fish species that play an important role in keeping the Great Lakes food web healthy, providing prey for larger species like the lake trout. However, the proliferation of invasive species such as alewife and sea lamprey, as well as historical overfishing, means kiyi can only be found in Lake Superior today.

The Nature Conservancy is working with the Sault Tribe of Chippewa Indians, the Little Traverse Bay Band of Odawa Indians and the U.S. Geological Survey (USGS) to find and collect kiyi in Lake Superior during their spawning window, to answer an important question: Can we successfully raise kiyi in hatchery conditions, and if so, how?

Can we successfully raise kiyi in hatchery conditions?

Answering this question would open up the potential to reintroduce this fish in the lower Great Lakes, to restore more resilience and productivity to an increasingly fragile food web.

“In the last decade, we’ve seen declines in the invasive alewife and smelt that would prey on newly hatched kiyi,” says Matt Herbert, Senior Conservation Scientist for TNC. “It’s a window of opportunity for restoring some of these important native fish—which can help keep our Great Lakes fisheries resilient and healthy in the years to come.”

“It’s a window of opportunity for restoring some of these important native fish—which can help keep our Great Lakes fisheries resilient and healthy in the years to come.”

Matt Herbert, Senior Conservation Scientist at TNC

When TNC set out on this project, not much was known about the spawning habits of the kiyi. In fact, there are many unknowns about the life stages of this elusive fish. A few historical data points suggested that kiyi in?Lake Superior likely spawn in the winter, but there wasn’t enough data to ensure we could readily find and collect spawning kiyi—not without confirming it ourselves.

Given the harsh winds and frozen conditions found on Lake Superior in the winter, finding and catching kiyi at that time was no easy task. TNC partnered with a commercial fisher, WHS Fisheries out of Munising, to accomplish this important step. The crew was able to reach deeper waters and catch spawning kiyi in four out of the five winters spanning 2017 to 2021, dodging snowstorms and encroaching ice.

All told, they studied more than 1,400 kiyi. The data collected on these fish—catch location, length, sex, number of eggs per female and more—helped piece together a clearer picture of the kiyi’s life cycle and behavior, especially when compared to historical observations in lakes Michigan, Ontario and Superior. This was more than enough to answer some important scientific questions.

“First of all, we confirmed a lot of our suspicions about when kiyi spawn, and at what depths we can collect them during the spawning period."

Matt Herbert, Senior Conservation Scientist at TNC

“First of all, we confirmed a lot of our suspicions about when kiyi spawn, and at what depths we can collect them during the spawning period,” says Matt. “Going out mid-December through January, with nets set at least 100 meters deep, appears to be the best way to catch spawning kiyi and reduce bycatch of other species. Now, we know a lot of what we need to experimentally raise them in hatchery conditions—a step that will be crucial for any potential future restoration efforts.”

We have published the results for the first phase of research and are now working with the Sault Tribe, Little Traverse Bay Band and USGS to begin to spawn and experimentally raise kiyi in a tribal hatchery and USGS facilities. If successful, this would give fisheries management agencies the option to start re-establishing kiyi in the lower Great Lakes, benefiting commercial and recreational fishing and supporting a healthier Great Lakes system.

“Kiyi have significant potential as a species that can help strengthen the Great Lakes food web, by providing food for larger predators such as lake trout and improving nutrient flow throughout the water column,” says Matt. “In general, the more species diversity we have, the more productive a system is. The best way to support that diversity in the Great Lakes is by rebuilding the populations of native fish, like kiyi, that used to thrive here.”

Next Steps

To move into the next stage of this research and begin raising them in hatcheries, we need another successful catch of spawning kiyi. Unfortunately, both of the last two winters had sustained high winds that prevented the fisher from getting out to deeper waters to collect kiyi at the right time.

“It’s a setback, but not an insurmountable one,” says Matt. “We’ll try again next year. We’re also looking at potentially trying to collect larval kiyi after they hatch in June. Eventually, we want to test the feasibility of raising kiyi in hatcheries year-round, so that spawning fish wouldn’t need to be caught every year. Then, all it would take is a few mild, windless days.”?

Read the Research

Vinson, M., M. Herbert, A. Ackiss, J. Dobosenski, L.M. Evrard, O. Gorman, J.D. Lyons, S.B. Phillips, D.L. Yule. 2022. Lake Superior Kiyi (Coregonus kiyi) reproductive biology. Transactions of the American Fisheries Society (In Press). Available at: doi.org/10.1002/tafs.10389