Biologists studying decrease in Connecticut River’s lamprey eel population

  • Scientists Boyd Kynard, right, and his son Brian Kynard, left, cast a net searching for lamprey eel larvae in the Pauchaug Brook. STAFF PHOTO/PAUL FRANZ

  • Left to right, Elijah Goldstein, Boyd Kynard and Brian Kynard identify aquatic life in Pauchaug Brook in Northfield. STAFF PHOTO/PAUL FRANZ

  • Student Elijah Goldstein measures a lamprey eel larva found in Pauchaug Brook. CONTRIBUTED PHOTO

Staff Writer
Published: 8/19/2019 11:19:08 PM

NORTHFIELD — River management groups have recognized the lamprey eel as a key contributor to the Connecticut River’s ecological health. But they’re also a resource that is dwindling.

That’s why Boyd Kynard, a marine biologist who works with his son, Brian Kynard, at their lab in Erving, have teamed up with Biocitizen, a Westhampton-based environmental philosophy summer program for students, to survey the Connecticut River’s tributaries and find which ones have eels.

“There’s something going on in these streams,” Boyd Kynard said while surveying Pauchaug Brook in Northfield last week. He explained the population of lamprey eels in this area is about one-third of what it was 10 years ago.

Lamprey eels have historically used the Connecticut River’s tributary streams for their breeding grounds. In the spring, adult eels swim from the ocean up the Connecticut River to spawn in the smaller streams. The larvae hatch early in the summer, and stay here for the first five years of their life, feeding on random bits of detritus.

When they’re large enough, the eels swim into the ocean and switch to feeding parasitically by latching onto fish and sucking their blood, riding up and down the East Coast until they’re ready to return to the river to spawn.

Because they go back and forth between the ocean and the river, the eels bring certain nutrients to the river that wouldn​​​​​​’t be there otherwise, making them significant contributors to the Connecticut River’s ecosystem, Kynard explained.

Looking for eels in the Pauchaug Brook, the students waded into the water and dropped a net, one side weighted with chains and the other held up with floats, then used a metal rake to kick up the mud, and pulled up whatever came out.

At the mouth of the brook, where it meets the Connecticut River, they found small fish, but no eels.

Further up the brook, they started finding the larvae — eels the size of earthworms. The critical difference between the two spots was probably the soil quality, Kynard said. The river’s soil is mostly clay, too tough for the eels to burrow in. Upstream, it’s clay mixed with sand.

Students gathered the eels into a bucket, then with their hands took them out one at a time to measure on a board marked in millimeter increments. At this age the eels have no teeth, so they are safe to pick up. To make the eels easier to catch from the bucket, Kynard added a few drops of clove oil, a natural anesthetic that wears off after 10 minutes.

Measuring the eels lets the scientists determine their age. In the batch from the Pauchaug Brook, there were some eels hatched this season and some 4-year-olds, but not many in between — meaning that the eels didn’t spawn in this brook for a few years, for whatever reason, Kynard said.

Kynard and his son are continuing to survey the tributaries of the Connecticut River, and eventually will expand to sample other rivers in Massachusetts. The goal is to determine the general distribution of where in Massachusetts the eels are spawning now, he said.

This is the data-gathering stage of the project. After that, Kynard said they can start to hypothesize about why the population has decreased.

Reach Max Marcus at or 413-772-0261, ext. 261.


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