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Waders pulled chest-high, Polaroid sunglasses protruding from their noses, fishing nets. But they also lugged a device not found in most tackle boxes — an electronic contraption Zanon called the “shocker.”
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SMU environmental biology student Jacob Zanon, 21, holds a viewing tank Thursday containing 3 of the 9 lamprey larvae he helped capture in Beaver Creek near Elba, Minn. The lampreys are recorded, measured and released.
(Photo by Melissa Carlo/Winona Daily News)
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This wasn’t just any fishing day. These men were in search of the elusive brook lamprey.
Lampreys, primitive jawless fish that look like eels, indicate ecosystem health, and waning populations concern researchers such as Cochran, a Saint Mary’s University biology professor, and Zanon, an SMU science student.
The Minnesota Department of Natural Resources awarded Cochran and Zanon a grant to study the local distribution of the five native lamprey species in the area’s streams and rivers. They also want to know how the August flood affected the fish.
“There was already a concern about the population of native brook lamprey in streams,” Cochran said. “And you throw on the flood, it makes you wonder how the larval stage made it through.”
Scientists say lampreys are a misunderstood fish, mainly because of the lack of information on their ecology, history, distribution and population. Their underground lifestyle adds elusiveness to the mystery.
That’s where Zanon’s “shocker” comes in handy. Technically, it’s called electrofishing.
On a recent field day, Zanon swept a diamond-shaped wire on an electrofishing pole across a muddy mound of sediment along the edge of Beaver Creek, near Elba, Minn.
“Oh! There’s a little one,” Cochran said.
The direct current from Zanon’s battery-powered backpack coaxed a wriggling lamprey larval from the goo.
“I saw him try to burrow back in,” said Zanon, who watched Cochran quickly net the stunned lamprey larva.
Their study will build upon the work of longtime lamprey researcher and Winona State University biology professor Neal Mundahl.
While Mundahl found native lampreys throughout the region in previous surveys, he concluded populations declined in many streams and disappeared in others. He blamed the decline on human activities that add chemicals and erode soils into streams.
“We almost know nothing about them except for what Phil and Neal are doing,” Sorensen said. “It’s very, very hard to get good numbers on this. There are almost none. The numbers I would suspect are a tiny fraction of what they were hundreds of years ago.”
Lampreys first gained notoriety for their blood-sucking, trout-decimating ways in the Great Lakes. Unfortunately, it’s hard for the Minnesota-native lampreys to shake the bad image of their parasitic distant relative from the Atlantic Ocean, the sea lamprey.
“They’re relics from 400 million years ago,” said Peter Sorensen, professor of fisheries, wildlife and conservation at the University of Minnesota. “They’re just one of those creatures that have been here so long and if they start to disappear you have to worry about the whole global situation.”
Sorenson began studying lampreys in 1990. His pheromone research, along with a male lamprey sterilization program, has been used to control parasitic sea lampreys in the Great Lakes.
Lampreys live in river and stream bottoms, filtering and removing fine organic particles and microscopic algae. They increase oxygen in sediments, making it easier for other organisms to thrive.
“Lampreys in general are extremely efficient filter feeders and seem to play an enormous role in food webs,” Sorensen said. “They are a sentinel of ecosystem health.”
He suspects lampreys are in crisis throughout the world. For example, populations have crashed in the Pacific Northwest, where lampreys are an important food source for indigenous people, much like salmon is for Americans, he said.
Similar concerns exist in the southern hemisphere near Australia and New Zealand, he said, and wild populations of sea lampreys in the Atlantic Ocean have become endangered in Portugal and Finland.
“Outside the bubble we live in, it’s a big and growing concern,” Sorensen said. “In the Great Lakes, there’s an overabundance, and it’s a big problem. Everywhere else they look to be in trouble.”
The conservation of native lamprey and sea lamprey is important, he said. But the problems largely go neglected.
It’s not like they’re cute, fuzzy bunnies.
Native lampreys live an underground life. As larvae, they burrow in fine silt for three to seven years. They ascend streams to spawn between late April and mid-June and then die.
Juveniles, such as the ones Zanon and Cochran caught, have a hood-like mouth. When lampreys become adults their mouths change to a suction cup disk, their eyes become prominent and they develop new esophaguses.
The first time Cochran saw a native lamprey was in the 1970s, when he was a SMU student studying fish. He went on to study sea lampreys at the University of Wisconsin-Madison.
“The sea lampreys paid a lot of my bills, but the native lampreys became more of a passion,” Cochran said.
He was the first to record a northern brook lamprey in the Lake Superior drainage in the 1980s. He also discovered southern brook lampreys in southern Missouri, the Black River drainage in Wisconsin and in Minnesota in the St. Croix River drainage and Crooked Creek in Houston County.
Cochran and Zanon found lampreys in all but one of the sites they’ve sampled so far. They still have 15 field days left of sampling and are yet to study the flood-ravaged Whitewater River.
“So far so good,” Cochran said. “I think some of these fish are more resilient than we give them credit for.”
Contact reporter Amber Dulek at amber.dulek@lee.net or (507) 453-3513.
