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Commission: Great Lakes lamprey declining

Posted on October 10, 2013

Ann Arbor, Mich. — A draft Great Lakes Fishery Commission assessment of sea lamprey populations in the Great Lakes contains good news and, well, not-so-good news.

Sea lampreys in the Great Lakes basin have declined by nearly 50 percent from 2012. Populations in lakes Superior, Michigan, and Ontario are within target range. Lake Huron lamprey populations are still high, but are trending downward, and those in Lake Erie remain “frustratingly high,” according to GLFC staff.

“This is great news with respect to lakes Michigan, Superior, and Ontario,” said Marc Gaden, spokesman for the commission. “Northern Lake Huron and Lake Michigan have been a real challenge for the last decade or two because lampreys were coming out of the St. Mary’s River in such massive numbers that they were knocking the stuffing out of the Lake Huron and Michigan fisheries.

“Lake Huron is still a work in progress, but we are way above target in Lake Erie,” Gaden said.

The draft 2013 Sea Lamprey Assessment, released in early September, found the total number in the basin declined from 511,000 lampreys in 2012 to 275,000 in 2013. The report, based on computer modeling and the results of marking and recapture studies, also found: “More than half of the total number of adult sea lampreys across the Great Lakes basin in 2013 was attributed to 19 streams.”

The decline is attributed to the cooperative sea lamprey-control efforts of the GLFC and other agencies, like Fisheries and Oceans Canada, the U.S. Fish and Wildlife Service, and the U.S. Army Corps of Engineers. Lamprey control involves applying chemical lampricides to infested streams to kill young lampreys before they mature and swim out into the Great Lakes.

The challenge still ahead for Lake Erie will involve finding the lamprey nurseries that are feeding the lake. Gaden said past efforts to treat 10 known infested tributaries did not do the job, though most every lamprey in those streams was killed. The Lake Erie lamprey population spiked following treatment in 2009, jumping from 2,666 lampreys to 32,558.

“We think they are coming in from somewhere else,” Gaden said, “likely from Huron-Erie corridor, the St. Clair River, Lake St. Clair, and the Detroit River.

“Not a lot of lampreys are produced in Lake Erie, but they do have a huge effect on the lake. We now have about 16,577 lampreys there. That’s three times our target level.”

Targets levels are those above which damage occurs to the fishery, Gaden said. Lower targets are typically not cost-effective.

“There is a place where the cost of going after the next mating pair of lamprey isn’t worth it,” Gaden said. “Lampreys are here to stay. Total eradication is not possible.”

The GLFC typically spends $22 million to $23 million annually for lamprey-control efforts basin-wide. That has dropped to $21 million due to federal budget sequestration, and is expected to drop more in 2014. Gaden said $25 million is really needed to do the job.

Anglers on lakes Michigan and Huron have said they are glad the numbers are coming down.

“This is really encouraging,” said Denny Grinold, a 30-year veteran Lake Michigan fishing charter captain at Grand Haven. “We haven’t seen a lot of lamprey this year. We’ve only recorded a half-dozen in the boat, but we are also catching fewer salmon.”

Most were attached to chinook salmon, according to Grinold, but one was attached to a steelhead. In the old days, he might have boated 20 to 30 lampreys in a season.

Frank Krist, a member of the Hammond Bay Anglers Association and chairman of the Lake Huron Citizens Advisory Committee, said he saw “quite a few” this year, but only for a couple weeks early in the season.

Lake Michigan is now estimated to have nearly 58,000 adult sea lampreys. GLFC staffers warn that those numbers do fluctuate. The target range is 50,000 to 75,000, according to Gaden. At peak infestation in the 1960s, there were approximately 600,000.

Lake Superior, he said, is estimated to have nearly 51,000 lampreys today. The target range is a few thousand to 50,000 lampreys. Peak abundance was 790,000 lampreys in the late-1950s.

Lake Ontario has been hovering at target levels since the 1980s, between 23,000 to 30,000 lampreys. This year’s estimate is 26,000. At peak, in the late 1970s, there were 2.9 million lampreys.

Lake Huron is currently estimated to have 124,000 lampreys. Peak abundance was 700,000 in the 1960s. The target range is from 50,000 to 100,000, Gaden said.