Fish and Wildlife Service to conduct sea lamprey control on Conneaut Creek

Apr. 17—CONNEAUT — Work will take place in Conneaut Creek at the end of April and start of May to help reduce the number of sea lampreys in Lake Erie.

According to a press release from the U.S. Fish and Wildlife Service, lampricides will be applied to the creek system between April 23 and May 2, in order to kill sea lamprey larvae in the creek. Dates could be changed based on weather and stream conditions.

Jenna Tews, Luddington Biological Station supervisor with the U.S. Fish and Wildlife Service, said the creek was last treated in 2018.

"This will be the 12th time we treated Conneaut Creek since 1986," she said.

Sea lamprey larvae live in some tributaries of the Great Lakes, and when they become juveniles, they migrate from the tributaries to the lakes, and kill fish, according to the release. Tributaries must be treated every three to five years, and the treatment is preceded by studies of water chemistry and toxicity, as well as stream flow and discharge.

The release states adding lamprcides to the stream is done over the course of 12 hours, and the levels are constantly monitored at pre-determined locations.

The lampricides are toxic to lampreys, but few fish, insect and broadleaf plants are sensitive to them. Anyone confining bait fish or other organisms to stream waters should use an alternate water source, and agricultural irrigation must be suspended for 24 hours during and following treatment, according to the release.

Tews said the lampricide is put into the stream in a highly diluted form, and breaks down in the sunlight.

"It does not persist, meaning that once the lampricide is no longer visible in the stream, which it does create a yellow or greenish color in the stream when it's present, once it moves through, in the flow or the current of the stream and is no longer present, there's no residual effect," she said. "So for the healthy fish community, there's no consumption restriction, so you can consume fish that are either caught during or after treatment."

The lampricides are not persistent in fish and 95 percent of the residues are eliminated from fish one day after treatment, according to the release.

Some fish that are more susceptible to the lampricide may be impacted by the treatment, Tews said.

"Some of those examples would be maybe some darter species that might be in their spawning colors, so they're already stressed because of spawning in the spring," she said. "Mud puppies, unfortunately, are also susceptible to the lampricide that is applied."

There will be staff walking along the stream searching for those types of fish.

"So when we see species like mud puppies, for example, that may be struggling during the treatment, we do pull them out and hold them in aerated fresh water, then release them back to the stream," she said.

Tews emphasized that the lampricide that is being applied is very diluted.

Treatments started in the 1950s, she said.

"Lampricide continues to be the No. 1 control method we have in targeting larval sea lamprey in tributaries across all five Great Lakes," Tews said.

It will be applied in the east and west branches of Conneaut Creek, but the main focus will be on Conneaut Creek itself.

"We're treating ... about 53 miles of stream, and we're starting just downstream of the town of Conneautville," Tews said. "We are targeting just over 15,000 larval sea lampreys."

Tews said the Fish and Wildlife Service waits to get the largest number of larval lampreys in the stream, to get the biggest bang for their buck.

"We're waiting to treat until the point, if we weren't to treat this spring, this fall, we would lose around 7,500 lamprey to Lake Erie," she said. "And each lamprey, once it transforms and heads out to Lake Erie, can destroy up to 40 pounds of fish."

The treatment will likely start at some time in the weekend, to allow the team to gather preliminary data before the treatment, and monitor the stream after the lampricide is applied.

If the treatment were to not take place, 300,000 pounds of fish would be destroyed, Tews said.

"For Lake Erie, that means things like steelhead, lake trout, yellow perch, walleye," she said. "Those lamprey, in Lake Erie, they're not selective."

Lamprey will parasitize fish in the lake for 24 months, before returning to a stream and spawning again, Tews said.

"When a female spawns in streams like Conneaut Creek, for example, they lay up to 100,000 eggs, just one [female]," she said. "So that's the invasive nature, and trying to control sea lamprey in the Great Lakes, the best work we can do is this in-stream work, and trying to be empathetic and diligent in ensuring that we are following rigid controls, and minimizing impacts to non-targets, to deliver effective sea lamprey control, so we're not coming back to Conneaut Creek for three to five years."

Tews said sea lampreys originated in the Atlantic Ocean, and then moved into Lake Ontario.

"They adapted to a fresh-water environment, and they were residing there in Lake Ontario until we built the Welland Canal," she said. "And by the early 1920s, they had quickly infiltrated through the Welland Canal and had reached the remaining four Great Lakes."

In the 1950s, a treaty with Canada created the Great Lakes Fishery Commission, which is charged with the sea lamprey control program in the U.S. and Canada.

There are currently about 3,500 adult sea lampreys in Lake Erie, which is at or near the Fish and Wildlife Service's target for the lake.

The work was disrupted by the COVID-19 pandemic.

"We were unfortunately unable to conduct overnight travel during 2020, and we basically ended up taking a year off, if you will, from delivering sea lamprey control because the only thing we could reach was in the immediate area of our station," Tews said. "So that was really a perfect experiment, because when we let our foot off the gas in delivering sea lamprey treatments, those numbers rebounded, some more significant than others."

She said, because of the year off from COVID, the number of adult sea lampreys increased to 7,200 in Lake Erie.

"By getting out there and treating streams, we are bringing that number back down," Tews said.