Smallmouth bass are one of the top fish in Lake Erie’s fishery, contributing to the lake’s $1 billion fishing industry. Yet until recently, scientists were unaware of how the fish move around the lake — insights that could help ensure the fishery is sustainable.
To track bass movement in Lake Erie, researchers are using a technique called acoustic telemetry. Fish with electronic transmitters, or tags, broadcast soundwaves into the water that are picked up by an array of receivers, providing useful location data.
Researcher Zak Slagle plans to implant such tags in a total of 180 fish by next year as part of a new study funded by Ohio Sea Grant, a program within The Ohio State University College of Food, Agricultural, and Environmental Sciences and NOAA Sea Grant. The study, which began this spring, will help anglers and fisheries managers better understand the presence and movement of smallmouth bass.
“Getting the fish and tagging them, that really is the biggest challenge,” said Slagle, fisheries biologist for the Ohio Department of Natural Resources (ODNR) Division of Wildlife.
Historically, the fish were understood to be relatively sedentary, not moving more than 3 or 4 miles over the course of many years. However, using acoustic telemetry, Slagle found that’s not always the case.
“We found that bass can move far, with some fish traveling over 100 miles in a year,” Slagle said of his previous research. “That was counter to what the existing bass literature says for Great Lakes-sized systems. It was the first time we’ve seen them make huge movements somewhat regularly.”
Now, Slagle hopes to find out what percentage of smallmouth bass move long distances and whether those fish tend to be vulnerable to angling. The study will also uncover whether Lake Erie is home to one population or multiple subpopulations of the fish.
“Bass have individual personality types,” Slagle explained. “Some are more aggressive, more likely to bite on a lure, and some are shier. For those high vulnerability fish that want to bite lures, science suggests that they’re better at guarding their nests, have higher metabolisms and therefore they might be the fish that are prone to higher movement rates.”
This spring, Slagle and his team tagged 60 fish around the Bass islands and Fairport Harbor, with 120 additional tags planned for next year. They used angling to catch vulnerable fish and electrofishing for a neutral selection of fish.
Once all the fish are tagged, researchers will rely on an array of hundreds of receivers operated by the Great Lakes Acoustic Telemetry Observation System, or GLATOS, a collaborator on the project. The receivers are anchored on the bottom of the lake and essentially “listen” for tagged fish swimming nearby. Researchers deployed additional receivers around the Bass islands and Kelleys Island as well.
“This project has really just begun. From here on, we’ll be doing receiver maintenance and waiting for data to come in,” Slagle said. “Once the data comes in, you can’t tell much from looking at it. It shows the fish was detected at this location at this date and time.”
Then, Slagle will use software to show how the smallmouth bass move, ultimately creating lines and animations that estimate fish movement patterns. Thanks to acoustic telemetry, results will show how fish move year-round, across the entire lake — contrasting with previous studies that relied on anglers to catch tagged fish.
“Because we have receivers spread all over the place, and not specifically in bass habitat, we can actually see where these fish are going in the wintertime,” Slagle said. “We can see if they’re going out into the main lake and areas where we wouldn’t be able to check them otherwise if we had to rely on angler tag returns.”
“I’m already excited to see what the results are going to be. Few studies like this have been done before, so hopefully it will inform regulations across the Great Lakes and in any big lake system”
The results will have implications for smallmouth bass fisheries across the Great Lakes, Slagle said. If vulnerable bass are moving long distances, then angling might be impacting the connectivity of their populations. Conversely, a lack of long-distance movement and genetic mixing could signal that overfishing is a concern in some areas.
While the smallmouth bass fishery in Ohio is mostly catch-and-release, the fish do face a potential threat: displacement from tournament fishing. In bass fishing tournaments, anglers typically bring fish they caught to a centralized weigh-in location and then release them at that site. Whether those fish can return to their original habitats is an important question, Slagle said.
“If those fish can’t return to that area, that could function as harvest and we could have localized overfishing,” he said.
Thankfully, Slagle is working with the Ohio Bass Federation to share information about the ongoing research and find solutions. He also plans to present results to GLATOS and national conferences.
“Some of this research is maybe painting tournament anglers in a bad light, but they’re also the ones that care the most about the resource,” Slagle said. “They’re fascinated with it, and they want to understand what they can do better to have a sustainable fishery.”
Results from the study could help inform state agencies — possibly creating no fishing zones or providing guidelines for bass tournaments — or tournaments could change their own protocols for releasing fish.
“It could just involve informing anglers of what’s going on, saying ‘this is something that might be kind of concerning,’ and we might see that they change their tournament protocols based on that,” said Slagle. “Tournaments could use release boats or catch-weigh-release formats to minimize how far fish are displaced.”
The study will last five or six years, Slagle anticipates. The batteries in the implanted tags will last three to four years, and then researchers will collect and analyze the data from all the receivers.
“I’m already excited to see what the results are going to be,” Slagle said. “Few studies like this have been done before, so hopefully it will inform regulations across the Great Lakes and in any big lake system.”
Ohio Sea Grant is part of The Ohio State University College of Food, Agricultural, and Environmental Sciences, School of Environment and Natural Resources, Ohio State University Extension, and NOAA Sea Grant, a network of 34 Sea Grant programs nation-wide dedicated to the protection and sustainable use of marine and Great Lakes resources. For more information, visit ohioseagrant.osu.edu.