Great Lakes Walleye Tagging

On my home body of water of Lake Erie, we enjoy a very healthy fishery with a walleye population arguably as big as it’s ever been. It wasn’t always that way, however.

As a fishing guide I still get asked yearly if the fish are able to be eaten. Most of this is in response to when the Cuyahoga River caught fire in June of 1969. Since then, actions such as the Clean Water Act have gone a long way to improving water quality and the overall ecological system.

An often-overlooked component of a healthy fishery is the work our Ohio DNR has done with fish management. I think we all could think of a few places that have been poorly managed through the years.

The Ohio DNR has worked with agencies like Great Lakes Acoustic Telemetry Observation (GLATOS) and the Great Lakes Fishery Commission on many fishery projects, but the acoustic telemetry project being the one that has been getting a lot of buzz lately.

Receivers have been placed on the bottom of Lake Erie within close proximity to each other that the entire system can monitor fish equipped with tracking receivers, regardless of where they swim in Lake Erie.

Having seen various parts of the program, I knew I wanted to see the actual tagging part itself—up close. Earlier this spring, I finally spent two days on boats with the Ohio DNR fisheries folks and the United States Geological Survey (USGS) to experience their tagging process.

The first day we were on two large aluminum boats. The first boat was equipped to use gill nets to quickly acquire walleyes that would have tracking tags added to them. The gill nets were set near some spawning reefs and had a mesh size that was intended to catch smaller to mid-size males. The term “gill nets” makes most fisherman shriek, but it should be noted that a lot of trial and error has gone into the process to ensure fish health so that they can live as long as possible to provide data for the biologists. The nets are only “soaked” for approximately 15 to 25 minutes before being pulled to ensure that the fish are in the best condition possible. Once removed from the nets, the fish are immediately put in a large holding tank and then moved over to the second boat.

It's at this second boat where a four-person team from the USGS received the walleyes from the net boat and placed them into a large, aerated holding tank so they can recover and remain healthy. Once health is assured, a surgeon places the walleye upside down into a sling and another team member places a tube in the fish’s mouth to get fresh cool water over its gills.

They also use a stim system—much like a chiropractor might use to relax muscle groups—to keep the fish calm and from jumping around during the process. A small incision is made in the belly and the tracker is then placed inside. A couple sutures are then used to close the cut. The fish is then put in another aerated holding tank to allow it to recover. The entire operation time is typically less than a minute. The fish’s size is recorded and entered into a laptop to keep track of in subsequent years.

It was obvious that these seven people on the two-boat crew had done this before due to the speed and fluid motion of the process. If you think it’s easy to gather fish, transfer them to another boat and sew up a tracker in their bellies all while bouncing all over in a boat, I promise you it’s not.

The mission on day one was to get tags in around 40 male walleyes, but that isn’t always the case. The biologists strive to gather a variety of size and age structures to provide a larger sample size of where these fish are going, what are they doing and hopefully more clues as to why they are doing it.

The surprise for me was on day two when we got into a flat-bottom aluminum boat with a jet motor and ventured deep within the Sandusky River at dusk. The mission this day was to tag white bass. The stretch of river we were on wasn’t much deeper than chest height and frequently knee deep or less. Instead of nets, electro fishing was used to shock up the fish and the desired species and size were netted and placed into a holding tank. A conductivity probe was used to measure the conductivity in the water. This reading helps the biologist set the power to the proper level to shock the fish without putting too much strain on them.

The chosen fish in the holding tank were then driven a short distance back to the ramp where basically the same surgical process was to be completed—same as the previous day. The combination of the river, darkness and small boat left little room for anyone or anything that wasn’t absolutely necessary, and conducting the surgery on shore was a must.

While it wasn’t surprising that species such as perch and smallmouth bass were also being tagged, I was surprised to find out that invasive species such as grass carp and sea lamprey were also tagged as a means of following the larger concentrations of them with the intent of removal from the system. Looking at the movements and health of the overall system is important according to the biologists and not just the prized walleyes that most people travel to Lake Erie to catch.

At this current time the battery life in the receivers will last up to 10 years. Earlier models of the receivers were larger, had less battery life and weren’t capable of relaying as much information. Some of the fancier receivers are capable of even telling how deep in the water column the fish is. Like anything else with technology, the longer this project has been in the works, the more it’s advanced. A lot of the funding from this project comes from grants, USGS and the Great Lakes Fishery Commission. As you might imagine, all this technology and manpower comes with a price tag.

Ohio fisheries biologist Matt Faust has been one of the leads in helping implement the tagging project on Lake Erie.

“GLATOS has enabled fisheries managers across the Great Lakes to get an unprecedented view into the movements of popular sportfish like walleyes,” he said. “Management agencies like the Ohio Division of Wildlife can design projects to address important questions without having to commit substantial resources to purchase equipment that is already in place thanks to GLATOS, which allows folks like me to work with other biologists around Lake Erie and beyond to dive into the thousands of observations from our tagged fish and ultimately make more informed decisions about how to manage our fisheries.” Much in the same way, there are many intricacies with high-level fishing, the fisheries biologists put in a lot of work behind the scenes to make sure that our fisheries will be just as strong in the future. The GLATOS website</a has some worthwhile resources and fascinating information.

Capt. Ross Robertson

Bigwater Fishing

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