Steve Coghlan Jr. steadfastly clings to his view of sea lamprey as “charismatic” critters that build impressive nests and play important roles in healthy stream ecosystems. Unfortunately, the lamprey has an image problem that not even a public relations professional could easily negate.

A lamprey looks like an eel, or, perhaps, a wriggling monster from a science fiction flick. Its mouth is a gaping hole — a sucker disk, actually — lined with toothlike appendages. It feeds by latching onto passing fish or seals and burrowing into them with its “rasping tongue,” and slurping away. Lamprey have been blamed for the collapse of the lake trout fishery in the Great Lakes.

Spend a morning with Coghlan, though, and the University of Maine assistant professor of  freshwater fisheries ecology will convince you that you have it all wrong. After a bit, you may even admit that lamprey, while not as glamorous as some other sea-run fish, are intriguing, or impressive … or even charismatic.

“They get a bad rap [in the Great Lakes],” Coghlan said Thursday as he stood near Sedgeunkedunk Stream in Brewer, the site of an ambitious research project that is studying, among other things, sea lamprey. “They damaged a very lucrative and popular sport fishery, so most people’s idea of sea lamprey comes from all the bad press they got out there.”

Here, Coghlan said, lamprey are not invasive. They’re native. And after two dams were removed from the Sedgeunkedunk, which flows into the Penobscot River in South Brewer, lamprey were finally able to access the stream to spawn in 2009. The stream had been inaccessible for more than 200 years before the dam removals.

Coghlan, graduate student Rob Hogg, and their crew of technicians are focusing on those spawning lamprey in a project that is monitoring the effects of dam removal on sea-run fish. The crew captures incoming lamprey in a trap net, tags them twice (once with a visible marker, another with a unit that can be read with an electronic scanner), and releases them to swim upstream and spawn.

Hogg, who became interested in lamprey while attending Southern Oregon University, said he virtually begged Coghlan to let him come to Maine to participate in the research.

“The lamprey is just a fascinating lifestyle to me,” Hogg said. “The way they make their living, and they go through that transformation, which is [impressive].”

Sea lamprey live in fresh water silt as filter-feeding ammocoetes, or larvae, for three to 15 years, according to Coghlan. At some point, they migrate to the ocean, where they begin feeding as parasites. During the final stage of their lives — which is being played out now in the Sedgeunkedunk — lamprey return to fresh water to spawn and die.

And while few people probably realize that lamprey are even present in Maine streams, once you know what to look for, it’s hard to miss the signs of their presence.

Lampreys are prolific nest builders, often building “community nests” that can be several feet long and stretch across an entire stream. Lampreys move rocks — some of them as large as softballs — into a mound and dig a pit behind that mound.

“What they’ll do is take their sucker-disk mouth and latch onto the rock,” Coghlan said. “They arch their back and bring their tail down in the substrate and beat their bodies back and forth violently, and they’ll actually wiggle the rock loose. Then they’ll sort of do a somersault backward and they’ll drag this rock with them. They’ll build a mound like that.”

Walk along a stream like the Sedgeunkedunk and the nests are instantly recognizable: During the nest-building process, the sediment on the stream bed is displaced, leaving large swaths of silt-free rocks that look as if they’ve been pressure-washed.

“As you can see, [the stream bed] is glowing,” Hogg pointed out one nest site where three lamprey were pitching in on the rock-moving chores. “It’s like a gemstone. You walk along this dark stream and boom, [you see it].”

Each day, Coghlan, Hogg and their crew walk six kilometers (about 3.7 miles) of stream and record every lamprey they see. The spawning run is brief, lasting just a few weeks. And after the run is over and the data is compiled, some comparisons can be made.

In 2010, the crew documented 131 lamprey and computer modeling estimated the population of returnees at 140. Already this year, nearly 70 lamprey have been tagged.

Research on the Sedgeunkedunk began in 2007, before the dams were removed. Coghlan said that prior research, when combined with the present work, provides a crucial before-and-after picture of a now free-flowing stream.

“Sedgeunkedunk Stream is like a living laboratory,” Coghlan said. “It’s a small system, it’s a really good size where we can work in it and get a good handle on what’s going on.”

Two things that are going on: Lamprey are returning in healthy numbers. And they’re not alone.

“Three days after this dam came out in 2009, we found juvenile Atlantic salmon upstream,” Coghlan said, standing at the former dam site on Mill Street in Brewer. “And this year we found salmon fry about halfway upstream, so that’s the first successful spawning that we’ve had since the dams came out.”

Coghlan also has been trying to determine whether the changes that lamprey make in the stream bed during their nest-building is beneficial to spawning Atlantic salmon and feeding juvenile salmon, who may eat the aquatic insects that are dislodged.

As part of the Penobscot River Restoration Project, two main stem dams will be removed from the river and a fish bypass will be provided at another. Coghlan said studying the river and tributary streams before and after dam removal makes perfect sense, but isn’t as common a practice as you might think.

Coghlan said a UMaine colleague determined that monitoring was paired with dam removal in only 5 percent of projects nationwide.

“Over 95 percent of dam removal [projects] are basically take the dam out [and say], ‘OK, we took the dam out. Hopefully that did what we wanted it to do,’ with actually no monitoring around it,” Coghlan said.

And though his crew’s monitoring of a post-dam Sedgeunkedunk is in only its second year, Coghlan said changes have been dramatic already.

“A lot of what we do in science is, we probably know or think there’s a pattern out there but there’s so much noise and variability that sometimes it’s hard to see the pattern,” Coghlan said. “In this stream, the pattern was so clear that we saw it immediately, with a lot of things.”

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John Holyoke

John Holyoke has been enjoying himself in Maine's great outdoors since he was a kid. He spent 28 years working for the BDN, including 19 years as the paper's outdoors columnist or outdoors editor. While...