DULUTH -- Crews from Wisconsin and Minnesota departments of natural resources have been busy capturing and tagging thousands of walleyes in the St. Louis River estuary this spring, and then recapturing as many as they can to estimate the walleye population.

They hope to put green, numbered tags on 8,000 walleyes this spring, like garment tags on clothing at stores, attached to the dorsal fin.

Fisheries biologists use an electro-shocker to stun the fish, scoop them up, bring them to shore to tag and measure, record the data and then quickly release them. But crews also are out recapturing fish already tagged.

A green tag attached to the dorsal fin indicates this walleye was tagged in 2021 as part of a walleye population study on the St. Louis River estuary. A few walleyes may still be swimming with purple tags used during the last population study in 2015. (Photo courtesy Paul Piszczek, Wisconsin DNR)
A green tag attached to the dorsal fin indicates this walleye was tagged in 2021 as part of a walleye population study on the St. Louis River estuary. A few walleyes may still be swimming with purple tags used during the last population study in 2015. (Photo courtesy Paul Piszczek, Wisconsin DNR)

As they net fish into May, they keep track of how many have the new green tags. DNR experts will then pump those numbers into a computer model over the summer. The ratio of total tagged fish to the number of recaptured fish offers an estimate of the total population.

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“The goal is to get 5-10% of the total population tagged to get the best results,” said Paul Piszczek, Wisconsin Department of Natural Resources fisheries biologist in Superior, Wis.

That effort is taking a while this spring as big fluctuations in weather and water temperatures had the walleyes spawning in fits and spurts over several weeks. On some days, crews were handling more than 500 walleyes; on other days, it was less than 200.

The survey results, which should be available to the public by the end of 2021, are much-anticipated by anglers who frequent the estuary. Many hardcore river anglers say they have seen walleye numbers declining gradually in recent decades.

In fact the most recent population survey, conducted in 2015, showed that to be true. The estimated walleye population in the estuary has generally ranged from 60,000 to 90,000 over the last 40 years. But the most comparable and accurate surveys, done with similar methods, showed an estimated 76,232 walleyes in 1981 and just 46,862 walleyes in 2015, the last major survey conducted.

A decline of 30% to 50% “is a huge number. And it coincides with our growing concern with the walleye population,” said Brandyn Kachinske, president of the Twin Ports Walleye Association. “We have noticed that the number and size structure of the walleye population has dropped from what it used to be years ago.”

Anglers land a nice St. Louis River walleye on opening day in 2018. DNR crews are capturing and tagging walleyes this spring, and then letting them go and recapturing them to get a good estimate of the estuary's walleye population. (Clint Austin / News Tribune)
Anglers land a nice St. Louis River walleye on opening day in 2018. DNR crews are capturing and tagging walleyes this spring, and then letting them go and recapturing them to get a good estimate of the estuary's walleye population. (Clint Austin / News Tribune)

Fisheries biologists counter that there will always be fluctuations in populations as each spring produces varying conditions and varying spawning success, and as each fishing season brings varying angling success. But they also note that there is some good news for the river walleyes and the people who love to catch them.

“There was definitely some concern with that number (46,862 walleyes) among anglers … but we believe that was a low estimate and that we have seen a rebound since then,” Piszczek said.

That optimism is based on yet another type of fish survey, taken each summer by the Minnesota DNR, that nets small walleye that spend their summers in the estuary. (Larger walleyes spend much of their year feeding in Lake Superior.)

Those summer surveys show generally higher numbers of young fish in the river since 2016 and that should mean more bigger walleyes in coming years. The 2012 and 2013 classes were especially good, Piszczek noted, with those fish now 20 to 24 inches long 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.

“We’re expecting to see some of those year classes come into the spawning (population) assessment this year, which is why we think that (this year's) population estimate is going to go up” from 2015, Piszczek said.

Alisha Hallam, Minnesota DNR fisheries biologist, agreed.

“Our summer gill net assessment last year was above average … and, in fact, it has been most of the recent years,” Hallam said.

Last year’s summer survey found 7.3 walleyes per net, up from the long-term average of 6.6. The survey has ranged from a low of 2.3 walleyes per net in 1993 to 10.5 in 2016.

Regulation changes ahead?

Some veteran anglers on the St. Louis River contend that too many big fish are being kept and caught by anglers, both in the estuary and, especially, 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 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 catch five walleyes (with only one over 20 inches long) in 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 is different than the river limit. (Anglers on the Minnesota side of Lake Superior can keep only two walleyes, same as the river.)

Other anglers have called for a maximum size limit, or a slot limit, for fish caught in the river. Currently anglers can keep two big walleyes with no upper-size restrictions, potentially depleting the best spawning fish from the population.

The current two walleyes over 15-inches limit “obviously protects the small fish. But it leaves the larger class at a high risk. Every year we notice that some anglers are keeping larger fish as their limit is only two, especially anglers who are from out of town or do not share the concern we have,” Kachinkse noted. “We as a club would like to see the larger-class fish also have some protection. Possibly an established slot of say 15-19 inches that can be kept with one over 28 inches for trophy purposes.”

Piszczek said DNR biologists will scrutinize the population survey results to see if it’s time to change the limits to make them consistent in the lake and river, and whether to protect bigger walleyes to reduce harvest.

“We’re looking at that and how we might bring them in line,” he said. “The more we are learning about how they (estuary walleyes) are using the lake, it probably makes sense to look at that.”

Any regulation change would not only have to clear DNR officials, but also the Wisconsin Conservation Congress, often a two-year process, and then the state Natural Resources Board, Legislature and the governor before taking effect, Piszczek said. Moreover, any changes would have to be done in concert with the Minnesota Department of Natural Resources, which shares management of the 12,000-acre estuary fishery.

“Wanting special regulations in the St. Louis is not just for us to catch more and bigger walleyes,” the walleye association’s Kachinske said. “But ultimately to make sure that the resource is there for everyone, and especially future generations, to enjoy.”

Fisheries crews from the Wisconsin and Minnesota DNRs hope to tag up to 8,000 walleyes in the St. Louis River estuary this spring and then recapture as many as possible to estimate the estuary's walleye population. Anglers can report any tagged fish they catch, but their reports aren't needed for the study. (Photo courtesy Paul Piszczek, Wisconsin DNR)
Fisheries crews from the Wisconsin and Minnesota DNRs hope to tag up to 8,000 walleyes in the St. Louis River estuary this spring and then recapture as many as possible to estimate the estuary's walleye population. Anglers can report any tagged fish they catch, but their reports aren't needed for the study. (Photo courtesy Paul Piszczek, Wisconsin DNR)

If you catch a tagged St. Louis River walleye

You can release it or keep it (if it’s a legal size fish). The DNR doesn’t need to know if you caught a tagged walleye. They are recapturing fish for the population study on their own. But they will provide anglers with information on that specific fish — like how old it is and when and where it was captured. Record the four-digit code found on the tag and email Paul.Piszczek@wisconsin.gov with the info. Green tags are being used in the 2021 survey. If you find a fish with a purple tag, that fish was tagged in 2015.