By DAVE FIELDER Fisheries research biologist Michigan Department of Natural Resources
“…it appears that most of the key fish species remain abundant and in good health
The St. Marys River is the connection between Great Lakes Superior and Huron. Virtually the whole of Lake Superior drains through this “connecting channel” feeding Lake Huron and the lakes below.
This important waterway also defines the boundary between the easternmost end of Michigan’s Upper Peninsula and the province of Ontario.
The river flows for 75 miles and includes an enormous variety of habitat types. There are rapids, fast-moving reaches and large islands, but also lake-like river reaches.
Despite being mostly Lake Superior outflow, the water is relatively warmer and includes cold-, cool- and warm-water fish species.
The challenge
To manage fisheries, biologists need up-to-date information on the status of fish populations, their trends in abundance, how much reproduction is occurring, age structure, etc. This is usually obtained by way of periodic netting surveys.
The Michigan Department of Natural Resources routinely conducts these assessments across the state and Great Lakes. However, when it comes to the St. Marys River, there are special challenges.
The gear of choice is variable-mesh gillnets that catch a cross-section of fish species reflecting the whole fish community. By using different sizes of mesh, most all ages and sizes of fish can be sampled.
Such a netting survey might include from six to 20 net sets in most Great Lakes situations, but in the St. Marys River, because of the diversity of habitat types, it requires 44 net sets.
For assessment purposes, the river is divided into eight different reaches, each getting five or more net sets to adequately survey the area.
Partners
This enormous effort is too much for any one government agency to conduct on its own, but another feature of the St. Marys River is the large number of agencies that share the jurisdiction.
Besides the state of Michigan, there is the province of Ontario with its Ontario Ministry of Natural Resources and Forestry. There are also federal agencies on both sides of the river, such as the U.S. Fish and Wildlife Service and Fisheries and Oceans Canada. The Biological Resources Division of the U. S. Geological Survey is another federal agency involved, as well as the U. S. Army Corps of Engineers.
There are also two Native American tribes: the Sault Ste. Marie Tribe of Chippewa Indians and the Bay Mills Indian Community, both of which maintain their own fisheries departments. There are additional groups involved, including local universities and other entities that similarly represent resources to help with fisheries assessments.
While each agency has a slightly different mission or perspective, they all hold some interest and responsibility for the stewardship of the St. Marys River fishery.
This rich yet complex suite of interjurisdictional representation offers an opportunity to share the large netting survey with many partners. This coordinated approach to assessment has now been used to jointly conduct the last seven surveys.
To facilitate the coordination of this work, the Great Lakes Fishery Commission organized the St. Marys River Fisheries Task Group in 1997.
The group is an international organization intended to help coordinate fishery management across the Great Lakes and to help bring partners together, so it was natural for the group to be formed under the commission.
The membership reflects all the same agencies and partners that have been joining to conduct the survey about every five years.
The group coordinates other work too, including a periodic creel survey that interviews anglers at the end of their fishing trip to find out what they caught and to generate estimates of harvest and catch rates. The netting survey and creel survey were last conducted in 2022.
Target species
The netting survey provides information on all species encountered, but the focal species are walleye, yellow perch, smallmouth bass, northern pike, cisco, lake sturgeon, and any salmon and trout caught.
A total of 37 different species were sampled in 2022. The survey also doubles as one means to determine if any new invasive species might be present.
Creel survey workers conducted over 1,000 angler interviews last year and included four flights a week by airplane to count boats, which is necessary for estimating the amount of fishing effort and harvest taking place in such a large river.
Results
Analysis of the survey findings from 2022 are still ongoing, but it appears that most of the key fish species remain abundant and in good health. Mortality rates, growth rates, abundance of mature females to reflect reproductive potential and other details are gauged. Results are compared to previous surveys.
The fishery measured by the creel survey is similarly robust, reflecting the diverse habitat types and fish community. Yellow perch and walleye are among the most-harvested fish, with numbers sometimes as great as 60,000 walleye and 100,000 yellow perch taken during the open-water fishing season.
The St. Marys River is one of the few places in Michigan that cisco can be predictably caught, and while patchy, total harvest in some years can be as great as 150,000 fish.
The amount of fishing effort on the St. Marys River (across all jurisdictions) amounted to 64% of all the fishing effort in the Michigan waters of Lake Huron that same year. The St. Marys River has quickly grown a reputation for outstanding and diverse fishing and is now routinely part of professional walleye and bass tournament circuits.
An exciting trend on the St. Marys River is an increasing number of young lake sturgeon caught in the netting survey. This native species was once greatly abundant in Lake Huron but suffered from overharvest and habitat degradation during the 20th century, reducing the population to a small fraction of original numbers.
Much effort is going into lake sturgeon recovery in Michigan, and the St. Marys River is one of the bright spots, with increased numbers captured in the river over the last five years. When captured in the netting survey, the fish are internally tagged with a passive integrated transponder, or “PIT tag,” that will allow that individual fish to be recognized in the future if encountered again and then released back into the river.
Costs
In 2022, the netting survey cost $140,000 and the creel survey $250,000 to conduct. Fortunately, these costs are spread across the participating agencies of the task group, which reduces the burden for any one partner.
This survey series is only conducted periodically, to maximize the information while minimizing the cost. The real value is in the critical information obtained, which fishery managers then use to make decisions. These data have been used to evaluate harvest regulations, fishing seasons, stocking decisions and more.
Invasive species
A great deal more fisheries work takes place in the St. Marys River in addition to the netting and creel surveys.
One example is the intensive surveillance for invasive species led by the U.S. Fish and Wildlife Service, conducted most every year in partnership with others to cover all waters of the river.
Multiple methods, including trawling, electrofishing and netting, are used to search for invasive species to determine trends and whether any new invasive species have become established.
The invasive Eurasian ruffe, a perch-like fish, has become established in parts of Lake Superior and, in recent years, the St. Marys River. There is considerable concern over effects it may have within the river and if it ever reaches downstream waters, such as Saginaw Bay.
The St. Marys River is a conduit for international shipping, with freighters passing through the Soo Locks in Sault Ste. Marie between Lakes Huron and Superior. This means the river is especially vulnerable to colonization by new invasive species, since many have been transported into and around the Great Lakes in freighter ballast water.
Quite possibly the most significant invasive species in the St. Marys River is the sea lamprey. This parasitic, eel-like fish feeds on lake trout and other fish in the open waters of Lake Huron.
Sea lamprey, however, spawn in rivers, and their juveniles will live there for about the first three years of life. The USFWS and Fisheries and Oceans Canada expend an enormous effort, both logistically complex and costly, annually to control sea lamprey in the Great Lakes.
Agency staffers use a selective lampricide to kill the juveniles in the streams and rivers before they can mature and become parasitic. It was discovered in the late 1990s that the St. Marys River was one of the major contributors of sea lamprey to Lake Huron. However, the river is too large to treat with lampricide using traditional methods.
A great deal of research and mapping took place to pinpoint the hot spots in the river where the juveniles resided in the sediment, and using a granular form of the lampricide, which sinks to the bottom, the specific problem areas in the river are targeted and treated.
, sea lamprey numbers have been brought down in Lake Huron to, or near, target levels.
Thriving resource
The St. Marys River is a tremendous resource, but that fact can get lost on many people because of the abundance of water Michigan enjoys. The rapids in the Canadian Soo are a spawning destination for migrating steelhead, Chinook salmon, lake whitefish, lake sturgeon and many more species.
The river has attracted anglers from all over the world and was one of author Ernest Hemmingway’s favorite places to fish.
The St. Marys River still faces many challenges.
Beyond the potential for invasive species, the area around Sault Ste. Marie remains one of the U.S. Environmental Protection Agency’s Areas of Concern for pollution. The river itself has also been greatly modified by heavy channelization to accommodate the large iron ore freighters that navigate it every day and hydroelectric facilities that provide power to both Michigan and Ontario. This alteration also changed the natural fish habitats in many parts of the river.
With the aid of the survey work coordinated by the St. Marys River Fisheries Task Group and with the cooperative multijurisdictional projects occurring in the river, fishery managers are well positioned to meet the challenges of a new century for protecting the important and extensive fishery in the great St. Marys River.
Check out previous Showcasing the DNR stories in our archive at Michigan.gov/DNRStories. To subscribe to upcoming Showcasing articles, sign up for free email delivery at Michigan.gov/DNREmail.
