RAT ROOT RIVER — Sitting at the front of a jon boat last week, Ben Vondra held out a circular antenna.
“Over there,” he said pointing, as he listened to an increasingly loud “beep” that emitted from a receiver box hanging from his shoulder.
Brent Flatten piloted the boat upstream from the swimming hole bridge on the Rat Root River in the direction Vondra pointed.
The signal showed the specific frequency assigned to one of 12 radio transmitters that had been inserted into female walleye captured in an electrofishing sampling earlier this spring by staff with the Minnesota Department of Natural Resources.
Pinpointing the location of where the fish had expelled their transmitters and eggs is part of a larger project intended to help identify where walleye spawn in the traditionally productive run.
Prompted by the strong radio signal, the boat was brought to shore and the men — despite air temperatures hovering around 37 degrees and a leak in Flatten’s waders — carefully walked into the waste-deep, 40-degree water. Vondra, DNR large lake specialist, carrying an underwater antenna and magnet on a stick, attempted to find the transmitter. Flatten, DNR fish specialist, raked the nearby bottom of the river with a fine mesh scupt net, periodically looking at the net for fish eggs.
The strong signal of the transmitter along with a few walleye eggs found in the same location verified that the walleye had expelled the transmitter from her vent as she laid her eggs. The location was recorded by Vondra, who would later mark the spot via GPS.
The DNR telemetry project provides technical support and information to help support a larger project intended to restore and enhance the Rat Root River walleye run. A Conservation Partners Legacy grant provided to the Rainy Lake Sport Fishing Club and Koochiching Soil and Water Conservation District will fund further improvement efforts. Already, DNR and district staff and club have identified and removed many log jams that impeded water flow and may have limited the run over the past years.
In the last couple weeks, Vondra has pinpointed the location where eight of the 12 walleye expelled their transmitters. The four other fish equipped with transmitters, he noted, either expelled their tags in a location outside the section of river the DNR has been able to work or did not expel the tags and exited that area of the river.
“The objective with the transmitters was to help us locate specific walleye spawning sites on the Rat Root River,” Kevin Peterson, DNR Fisheries supervisor, told The Journal.
Although the DNR has been monitoring the walleye spawning run on the river since the 1980s, Peterson said the agency has never been able to zero in on specific spawning sites. “This project allowed us to do that and our ultimate goal is to see if there is anything we can do to improve these sites,” he said.
He said previous DNR efforts have not involved getting out of the boat, feeling the structure beneath the water, and looking for walleye eggs. “We’ve always assumed they were laying eggs up there somewhere, but we’ve never been able to get out of the boat and look for them,” he said.
DNR staff are devoting more time and effort than ever before to the Rat Root River spawning run to support the work that will be funded by the CPL grant.
“The DNR did not receive any additional special funding to do this work,” said Peterson. “We’re doing this within our regular operating budget, which is supported by fishing license dollars. This is people’s fishing license dollars at work.”
The DNR has also been placing yellow tags in walleye captured in the Rat Root run to help identify where the walleye go after they spawn. Anglers have been asked to report the tag numbers to the DNR and the DNR has been recapturing the tagged fish during spring electroshocking, which stuns, but does not harm the fish. Tagged walleye have been reported in catches as far away as the North Arm of Rainy Lake, about 25 miles from the Rat Root River.
Vondra reported that this spring 331 walleyes, including fish that were captured multiple times, were caught and 149 new (no previous tags) fish tagged this year. That leaves 182 walleyes that already had tags in them, called recaps, when caught this year. The DNR tagged a total of 524 fish in 2010 and 2011 (369 in 2010 and 155 in 2011). He noted that 145 of the recaps this year were originally tagged in 2010 or 2011, and 37 were recaps of tagged walleyes that were “newly” tagged in 2012.
Meanwhile, Vonda and Flatten said they began the telemetry effort, after the fish were equipped with radios, by following the transmitter frequencies. The first time they simply scanned and listened for the signal from the radios, which produce a signal range of a couple hundred feet. Prior to expelling the radio with the eggs, the men said they could travel with the fish swimming in the river by following the signal.
Vondra said this effort may be the first ever to use the radios to determine where walleye spawn.
The public’s interest in the river’s walleye production has been piqued by the DNR activity, as well as the RLSC’s role in the improving spawning habitat.
Flatten and Vondra said they are often asked about the project by people along the river, and on this day, the men answered questions about the project posed by a man standing alongside his pickup on the Galvin Bridge.
