Survey: St. Louis River Estuary walleye population is up
Results from an extenisve 2021 popualtion survey shows 70% more walleyes than 2015.
DULUTH — The walleye population in the St. Louis River Estuary, roaming between the Fond du Lac dam on the river and sometimes far out into Lake Superior, is strong and growing.
That’s the finding of an extensive walleye population survey conducted on the estuary in spring 2021 by Minnesota and Wisconsin department of natural resources fisheries crews with data crunched over the winter.
Preliminary survey numbers released to the News Tribune this week found the estuary population between 75,000 and 85,000 total walleyes. That’s up roughly 70% from the most recent extensive survey, in 2015, which found just 41,000-52,000 walleyes in the population. The 2021 survey is more in line with the 1981 extensive survey that found a range between 69,000 and 84,000.
“It’s a good sign. It shows there’s really nothing out there that would indicate a big problem with the walleye population. They seem to be doing very well,’’ said Paul Piszcek, fisheries biologist for the Wisconsin DNR who oversees the popular fishery.
Piszczek said the healthy population estimate indicates that the walleye population is self-sustaining, naturally reproducing and able to withstand current fishing pressure, although no recent creel survey data measuring angler harvest is available.
Fisheries crews last spring were busy capturing and tagging thousands of walleyes in the river and then recapturing as many as they could to estimate the walleye population. They put bright-green numbered tags on just over 7,000 walleyes, attached to the dorsal fin. Each fish got a different number that — when pumped into the computer — shows its age, sex and size when tagged.
Fisheries biologists boating near the dam used an electric shocker to stun the fish, scoop them up, bring them to shore to tag and measure, record the data and then quickly release them. Crews then went back out to recapture fish already tagged.
Wisconsin DNR experts in recent months pumped those numbers into a computer model in which the ratio of total tagged fish to the number of recaptured fish offers an estimate of the total population.
The survey results are much-anticipated by anglers who frequent the 12,000-acre estuary. The estimated walleye population in the estuary has generally ranged from 60,000-90,000 over the last 40 years in a river that has for the most part been getting cleaner thanks to improved sewage treatment and industrial pollution regulation. It's hoped ongoing habitat restoration projects will boost walleye numbers even more.
Fisheries biologists note that there will always be fluctuations in populations because each spring produces varying conditions, namely water levels and weather, with varying spawning success, just as each fishing season brings varying angling success.
Did flood help walleye spawning success?
It appears that the massive flood event in June 2012, while it drastically altered the estuary and in some cases made it more difficult for people to navigate and to fish, actually helped the walleyes. The 2012 and 2013 walleye spawning classes survived especially well, Piszczek noted, but were too small to show up in the 2015 survey. Now, those fish are approaching trophy size and well into their spawning years, the kind of plump walleyes anglers love to catch. Good year classes also appear to have come in 2016, 2017 and 2018.
“Those strong year classes didn’t show up yet in the 2015 survey and they did in this (2021) survey,’’ Piszczek said. “They seem to really have made the difference.”
Dan Wilfond, Minnesota DNR fisheries biologist who looks after the St. Louis River, agreed. He said some poor year-class reproduction up to 2011, and good year-classes after, probably lead to the large jump from the 2015 to 2021 population numbers. He noted that the less extensive annual surveys of the river walleye taken in recent years support the larger 2021 estimate. The less extensive 2016 survey found, for example, that the 2013 year-class made up half the fish counted.
“Year-class strength has a tremendous effect on these population estimates, especially younger year-classes that are nearly always at higher abundances than old year-classes,’’ Wilfond noted. In 2015, many of the younger year-classes were at or below historical averages, pushing the 2015 population estimate down. In 2021, the younger age fish were well-represented, “pushing our population estimates back upwards towards the 1981 estimate.”
Surveys are finding walleyes from 13 inches to larger than 30 inches, well distributed by age, sex and weight. The estuary offers both the potential for eating-size and trophy-size fish.
“It is certainly a very healthy fishery,’’ Wilfond said.
Brandyn Kachinski of the Twin Ports Walleye Association said the new survey results appear to be good news, indicating a healthy fishery. But he said the group's members aren’t seeing anywhere near the increase in fish caught as the survey would indicate.
Some anglers not seeing increase
“We’re seeing pretty good numbers of those 15- to- 17-inch fish,’’ Kachinski said. “But we’re still not seeing nearly as many large fish as we used to, the 25- and 27-inchers … the big breeding females that are the best spawners just don’t seem to be there. Or maybe they are more illusive? Maybe they’re out in Lake Superior most of the time. But we used to see a lot more of those in the river.”
Jarrid Houston, a Wisconsin-based fishing guide and News Tribune fishing columnist who spends dozens of days fishing the estuary each year, said the 2021 survey results don’t match what has been a long-term decline in how many fish anglers catch. So far, he said, those extra fish since 2015 just haven’t shown up on the end of angler’s lines.
“Fishing success on the river continues to decline and is no way as good as it once was,’’ Houston said. “As a very avid river rat, I can attest that the size and numbers continue to decrease every year.”
Houston noted that even if the new estimate is accurate, the number of catchable fish is finite and anglers should limit what fish they keep beyond the already restrictive two-fish daily limit, namely letting larger fish swim free to reproduce.
“There are just way more fishermen than fish these days in our area of the world,’’ Houston noted. “Match that up with increased angler success on account of technology … and we need to be very careful.”
Recent studies have found bigger walleyes in the system spend far more time in Lake Superior than previously believed. For bigger walleyes, as much as half their food came from Lake Superior species of forage fish as opposed to river species. Some of the tagged walleyes in past years have been caught as far away as the Keweenaw Peninsula in Michigan, 250 miles away.
Minnesota and Wisconsin DNRs had planned to conduct the extensive surveys every five years but, after 2015, the 2020 survey was delayed until 2021 due to COVID-19 precautions. It’s not clear if the next survey will be in 2025 or 2026.
Regulation changes needed?
Some veteran anglers on the St. Louis River Estuary — including Kachinski and Houston — continue to contend that too many big fish are being kept by some anglers, both in the estuary and along the South Shore of Lake Superior where many of the river's biggest walleyes spend their summers.
While anglers can keep only two walleyes daily while in the river — as long as they are 15 inches or longer — the same boat of anglers can motor out through Superior Entry and then keep five walleyes (with only one over 20 inches long) in Wisconsin waters of Lake Superior.
It's the same population of migratory walleye, the same fish that move between the lake and estuary at various times of year, and it's not clear how or why the Wisconsin Lake Superior limit became different from the river limit. (Anglers on the Minnesota side of Lake Superior can keep only two walleyes, the same as the river.)
Other have called for a maximum size limit, or a slot limit, for fish caught from the estuary system — such as requiring anglers to release all walleyes 18-28 inches long and keep only one longer as a trophy. Currently, anglers can keep two big walleyes in the river with no upper-size restrictions, potentially depleting the best spawning fish from the population.
Any regulation change would have to clear both Wisconsin and Minnesota state systems for the jointly managed estuary that divides the two states between Duluth and Superior.
Estuary mercury warnings remain
Walleyes from the St. Louis River Estuary system have unusually high levels of toxic mercury contamination. Studies recently found those higher levels likely come from legacy mercury pollution deposited in the watershed decades ago and not from current mercury pollution that comes from global and local air emissions, such as from coal-fired power plants.
People are warned to limit their meals of walleye from the estuary population, especially larger walleye. Women who may be pregnant and all children are warned not to eat any walleye over 22 inches from the river; men and women who won’t become pregnant are advised to limit their meals of large walleye to one per month. Smaller walleyes contain less mercury.
Mercury is a potent neurotoxin that can cause severe health problems especially in children and developing fetuses.
Catch a tagged fish? Find out how old it is
If you catch a St. Louis River Estuary walleye with a long, thin tag attached near the rear dorsal fin, you can find out when the fish was captured and how old and large it was at the time of capture.
Email the tag number to firstname.lastname@example.org . Bright-green tags are from the 2021 survey. Purple tags were attached in 2015. Anglers may also encounter walleye tagged in Lake Superior with red tags (2013 and 2015) gray tags (2017) yellow tags (2019) and orange tags (2021).