How many walleyes are in the St. Louis River?
They hope to add numbered green markings to 8,000 pikeperch this spring, like clothes on clothes in stores that are attached to the dorsal fin.
Fishery biologists use a stun gun to stun the fish, pick them up, bring them ashore to tag and measure them, record the data, and then quickly release them. The crews are also on their way to recapture fish that have already been marked.
A green label on the dorsal fin indicates that this pikeperch was tagged in 2021 as part of a pikeperch population study at the mouth of the St. Louis River. Some pikeperch may still swim with purple markings that were used during the last population study in 2015. (Courtesy photo of Paul Piszczek, Wisconsin DNR)
As they catch fish in May, keep track of how many have the new green tags. DNR experts will then pump these numbers into a computer model in the summer. The ratio of the total number of tagged fish to the number of fish recaptured provides an estimate of the total population.
“The goal is to tag 5-10% of the total population for the best results,” said Paul Piszczek, fisheries biologist for the Wisconsin Department of Natural Resources in Superior.
These efforts will take a while this spring as the walleyes spawn in seizures and bursts over several weeks due to large weather and water temperature fluctuations. On a few days, the crews dealt with more than 500 pikeperch. on other days it was less than 200.
The survey results, which should be available to the public by the end of 2021, are eagerly awaited by anglers visiting the estuary. Many hardcore river anglers report that pikeperch numbers have gradually declined over the past few decades.
In fact, the latest population survey, conducted in 2015, showed that it is. The estimated zander population in the estuary has been generally between 60,000 and 90,000 over the past 40 years. The most comparable and accurate surveys conducted using similar methods returned an estimated 76,232 pikeperch in 1981 and only 46,862 pikeperch in 2015, the last major survey conducted.
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A drop of 30% to 50% is a huge number. And it coincides with our growing concern about the zander population, ”said Brandyn Kachinske, president of the Twin Ports Walleye Association. “We found that the number and size of the pikeperch population has decreased from years ago.”
Anglers land a nice pikeperch on the St. Louis River on opening day 2018. DNR crews catch and tag pikeperch this spring and then release and recapture them to get a good estimate of the estuary’s pikeperch population. (Clint Austin / News Tribune)
Fisheries biologists counter that there will always be fluctuations in populations, as each spring brings different conditions and different spawning successes and each fishing season brings different fishing successes. But they also find that there is good news for the pikeperch and the people who love to catch them.
“There has definitely been some concern about this number (46,862 pikeperch) among anglers … but we believe this was a low estimate and that we’ve seen an upswing since then,” said Pisczcek.
This optimism is based on another type of fish survey conducted each summer by the Minnesota DNR that catches small pikeperch that spend their summers in the estuary. (Larger pikeperch spend much of their year feeding in the Upper Lake.)
These summer surveys show that there have generally been more juvenile fish in the river since 2016, and that should lead to larger pikeperch in the years to come. The 2012 and 2013 classes were particularly good, noted Piszczek, with these fish now 20 to 24 inches long and well into their spawning years – the kind of plump pikeperch anglers love to catch.
Good year classes also seem to have come in 2016, 2017 and 2018.
“We anticipate that some of these annual classes will be included in the spawning (population) assessment this year, so we anticipate that the (this year’s) population estimate will increase from 2015,” said Piszczek.
Alisha Hallam, a DNR fisheries biologist from Minnesota, agreed.
“Our rating of the summer gillnet last year was above average … and indeed it has been for most of the past few years,” Hallam said.
Last year’s summer survey showed 7.3 pikeperch per net, compared to the long-term average of 6.6. The survey ranged from a low of 2.3 pikeperch per network in 1993 to 10.5 in 2016.
Regulation changes ahead?
Some experienced anglers in the St. Louis River claim that too many large fish are held and caught by anglers, both in the estuary and especially on the south shore of Lake Superior, where many of the river’s largest pikeperch spend their summers.
While anglers can only hold two pikeperch in the river – as long as they’re 15 inches or longer – the same fishing boat can pass through Superior Entry and then catch five pikeperch (only one over 20 inches long) in Lake Superior.
It is the same population of migratory pikeperch, the same fish that roam between the lake and estuary at different times of the year, and it is not clear how or why the Wisconsin Lake Superior ceiling is different from the river boundary. (Anglers on the Minnesota side of Lake Superior can only hold two pikeperch, as can the river.)
Other anglers have asked for a maximum size limit or slot limit for fish caught in the river. Currently, anglers can hold two large pikeperch with no upper size restrictions, potentially consuming the best spawning fish in the population.
The currently two zander over the 15-inch limit “obviously protects the small fish. But the larger class is at high risk. Every year we find that some anglers hold larger fish as their limit is only two, especially anglers who are out of town or who don’t share the concerns we have, ”noted Kachinkse. “We as an association want the fish of the larger class to have a certain protection. Possibly an established slot of, say, 15-19 “that can be held for trophy purposes with one over 28”. “
Piszczek said DNR biologists will review the population survey results to see if the time has come to change the limits to make them consistent in the lake and river, and whether larger pikeperch need protection to keep those Reduce harvest.
“We’re looking at this and how we could reconcile them,” he said. “The more we learn about how they (estuarine pikeperch) use the lake, the more useful it is likely to be to look at it.”
Any change in regulations would have to clarify not just DNR officials, but also the Wisconsin Conservation Congress, often a two-year process, and then the State Natural Resources Board, lawmakers and governor before they go into effect, Piszczek said. Additionally, any changes would have to be made in coordination with the Minnesota Department of Natural Resources, which shares management of the 12,000 acre estuarine fishery.
“If we want special regulations in St. Louis, we don’t just have to catch more and bigger pikeperch,” said Kachinske from the pikeperch association. “But ultimately, to ensure that the resource is available to everyone, and especially to future generations.”
The Wisconsin and Minnesota DNR fishing teams hope to tag up to 8,000 pikeperch in the St. Louis River estuary this spring and then recapture as many as possible to gauge the estuary’s pikeperch population. Anglers can report any tagged fish they catch, but their reports are not required for the study. (Courtesy photo of Paul Piszczek, Wisconsin DNR)
When you catch a tagged St. Louis River walleye
You can share it or keep it (if it’s a legal fish). The DNR doesn’t need to know if you’ve caught a tagged pikeperch. You catch fish yourself for the population study. But they will provide the anglers with information about that particular fish – how old it is and when and where it was caught. Write down the four-digit code on the tag and email [email protected] with the information. Green tags will be used in the 2021 survey. If you find a fish with a purple tag, that fish was tagged in 2015.