Oct. 16, 2007 issue
EMU professor finds sea lampreys suck, but not as much as expected

By Amy E. Whitesall

 

After three years of research, Eastern Michigan biology professor Uli Reinhardt has determined that the homely, invasive, eel-like sea lamprey does indeed suck, but not nearly as much as the fisheries community thought it did.

Reinhardt led Great Lakes Fishery Commission-sponsored research that looked at the sea lamprey's ability to use suction to work its way over barriers designed to keep it from swimming upstream to spawn.

PICKLED FROM THE SEA: Uli Reinhardt, an Eastern Michigan University biology professor, holds up a jar which contains a sea lamprey from either Lake Huron or Lake Ontario. Through research sponsored by the Great Lakes Fishery Commission, Reinhardt has studied the sea lamprey's ability to use suction to cross barriers designed to keep them from swimming upstream to spawn and prey on other species of fish.

"It was commonly believed (sea lampreys) can climb — that they can suck onto a barrier and inch their way up," Reinhart said. "We found this is not the case. We haven't seen (the suctioning behavior) in the lab. We faced so much doubt about our findings that, this year, we went out into the field and we saw the same thing."

The result may be smaller barriers that are friendlier to native fish and changes in lamprey trap design that exploit what Reinhardt and his students have learned about sea lamprey behavior.

Sea lampreys are fish parasites that use their teeth and sucker-style mouth to attach themselves to large fish. They feed off the host and, if they don't kill it, often leave it with a life-threatening wound. Sea lampreys started entering the Great Lakes in the 1950s and, at their peak, threatened the entire Great Lakes fishing industry. Though sea lampreys are about 90 percent controlled, they've shown a great talent for out-competing native species and the Great Lakes Fishery Commission continues to work toward eradicating them.

One control measure is the low-head barrier, 1 to 1 ½-foot tall structures, placed downstream from lamprey spawning grounds. Lampreys aren't strong swimmers, so they get to the barriers and can't go further, unlike jumping species such as salmon and trout.

But based on Reinhardt's research and collaborative work at the University of Guelph in Canada, current low-head barriers represent a bit of overkill. They're plenty tall to stop most sea lampreys, but also block certain species of native fish. Non-jumping species, ranging from minnows to sturgeon, struggle with the taller barriers. Reinhardt says the low-head barriers could be retrofitted to a smaller, simpler design — about 6 inches tall, with an inclined ramp that might further help native fish clear them.

"I'm kind of fighting a little bit with the sea lamprey control people," Reinhart said. "It's going to take a few years of research before I will have convinced anyone."

He also plans to apply what he's learned about suction behavior to build a better lamprey trap, possibly something with attachment-friendly surfaces inside the trap to encourage lampreys to stay. They can't attach to the mesh inside existing traps and might, therefore, be more likely to go looking for an escape route.

Skeptics with the U.S. Fish and Wildlife Service say they've seen sea lampreys do amazing things to get past low-head barriers, and Reinhardt puts too much stock in their experience to dismiss those observations. He plans to apply for a grant to install video cameras at several sites to get a more sustained look at what the lamprey are up to.

Meanwhile, Reinhardt's interest has expanded to include the Pacific lamprey, a non-invasive type of lamprey that lives in the fast-moving rivers of the West Coast.

Pacific lampreys, it turns out, are great climbers. They are able to suction onto surfaces and "swim" upward through a very thin layer of water. Reinhardt and his students have broken down film of the climbing process to better understand it. Just as fisheries departments put up barriers in the Great Lakes to keep lampreys from spawning, they use vertical surfaces as ladders on the west coast to guide Pacific lampreys past hydroelectric dams and back to spawning sites.

By learning more about how the Pacific lamprey climbs, Reinhardt hopes to refine his Great Lakes sea lamprey hypothesis and design more salient experiments.

"We've got two different species with quite different strategies for getting up and over things." Reinhardt said. "The sea lampreys we have in the Great Lakes have evolved on the East Coast and maybe even Lake Ontario, where there are no challenging river situations. On the West Coast, the Pacific lampreys are facing rapids all over the place."