Tag, you're it!

SANDUSKY — Lake Erie is home to more than 100 fish species. But there isn't much known about smallmouth bass and Zak Slagle, a fisheries biologist with the Ohio Division of Wildlife, is determined to change that. Slagle is currently working on a research project involving the movement of smallmouth bass within the lake. "Smallmouth have not been studied much in Lake Erie," Slagle said. He referenced a previous study done in the late 1990s. Smallmouth were tagged, but the project relied on anglers to catch the fish and report where they were caught. A vast majority of tagged fish were recaptured within a mile of where they were tagged, Slagle said. Slagle wants to know if smallmouth are capable of making long-distance movements. "It has important implications for management," Slagle said. "When it comes to management, we're worried about overfishing populations and stuff like that. If fish don't move that much, then we have the potential to overfish certain local populations." Slagle tagged about 215 smallmouth bass in Lake Erie over two years. He plans to study them through December 2027 and report his findings. Fish tagging This past spring, Slagle and a team of his co-workers caught smallmouth through angling and electrofishing near the bass islands, Kelleys Island, Sandusky Bay, Lorain, Fairport Harbor and Ashtabula. Slagle tagged the fish by implanting a small transmitter — about the size and shape of an AA battery — into the belly of the fish. The transmitter within the fish emits acoustic signals underwater that are unique to each fish. The signal, which isn't audible, can travel up to a mile. There are about 500 receivers in the lake that listen for the signals. When a receiver detects a transmitter, it records the date and time. This allows researchers to see where the fish traveled. "We can piece together a trail of the fish going around in the lake," Slagle said. The system isn't live, so Slagle can't see where the fish he tagged are whenever he wants. He has to wait until data is pulled from the receivers, which happens every six months to one year. The data recorded by the receivers is shared across the Great Lakes Acoustic Telemetry Observation System. The system acts as a way for researchers to collaborate together, Slagle said. All sorts of fish — including walleye, lake trout, lake sturgeon, drum and other fish — in the lake are tagged. Fish with transmitters will be recorded on the receiver no matter the species. "The telemetry allows us to monitor the fish across the entire lake and throughout the winter," Slagle said. "We don't have to worry about needing anglers to catch them." It's still possible for anglers to catch the tagged fish, but what happens if they do? Slagle said an external tag on the fish includes the division's office phone number, so anglers can report it. He wants to gather the date, location and most importantly, the tag ID number. The number matches to a specific fish. "I can tell the person where it was tagged and where it has been," Slagle said. Anglers can choose to either keep the fish or put it back in the water. Although Slagle prefers it goes back in the water, so it can be studied more. If the fish is harvested, Slagle requests that the transmitter inside the fish be given back, so it can be reused for future projects. Because of recapture reports, Slagle discovered that some of the fish have been caught twice. "I had one angler catch three tagged fish in a day," Slagle said. All of the information Slagle is receiving is helping him learn more about the fish. Slagle analyzed data based on the 60 smallmouth bass he tagged in spring 2023. He determined most of the fish haven't made big movements so far. Though a couple of fish have made huge moves. For example, a fish tagged near North Bass Island went up the Detroit River and to Lake St. Clair, between Michigan and Canada. Then the fish came back down to Lake Erie. "That's pretty wild," Slagle said. "I have no idea why a bass would do that, but it did." Another fish tagged near Fairport Harbor decided to cross Lake Erie. It went to the north shore along Canada and returned to the south shore within two weeks. "We're learning that a portion of the population of smallmouth can make long-distance movements, like over 300 miles in one to two years," Slagle said. "It's something that's not well understood. Some just do it." Slagle is also looking into the personality of the fish because there are natural genetic variations. Some bass tend to be more aggressive while others are more passive. A more aggressive bass is more likely to attack a lure if it sees it. Angling was a way to select for the more aggressive fish. The other method used to catch fish was electrofishing. An electrofishing boat puts electricity in the water near the boat to temporarily immobilize the fish. The fish recover and act normal after 2 minutes to 3 minutes. Electrofishing served as the control because they weren't selecting for any specific personality types with that method. He's curious to see if the more aggressive fish are the ones making the bigger moves. Slagle recently received new data, which includes the 155 fish he tagged this past spring. He's working on processing the information and seeing how it fits into what he has learned so far. "It's like Christmas when you get new data," Slagle said. A passion for the fishery As the principal investigator of the project, Slagle is responsible for writing the proposal, organizing data and turning it into several publications. He also creates a variety of animations showing the paths of the fish. His project is funded by Ohio Sea Grant and it's a collaboration between the Ohio Division of Wildlife and the Great Lakes Acoustic Telemetry Observation System. Co-authors on the project include senior biologist Matt Faust and the late Chris Vandergoot, who was the director of the system. The most important thing Slagle wants to study is characterizing smallmouth bass movements in a Great Lakes system. Do they migrate or do they hang out? "Knowing the answer to that question will help us understand if we should have special regulations for small areas," Slagle said. The end goals of the project are to prevent overfishing, make sure there's a healthy population and providing opportunities to anglers as much as they can while having a sustainable population. Slagle will have a better understanding of smallmouth bass after his project concludes in 2027. He's been with the Ohio Division of Wildlife for nearly seven years, and he appreciates the different things his job requires. "Here, we're off the lake for four to five months. That's when we're analyzing data, going to conferences, meeting with other researchers and giving presentations," Slagle said. "There's a wide variety of work and a lot of it is pretty fulfilling." Slagle enjoys interacting with anglers and members of the public that are interested in the research because they have the same kind of curiosity. A lot of anglers like hearing about where the fish are traveling. "It's fun to talk to people who share that excitement and passion for our fishery," Slagle said.