ROTTERDAM Most of the fish caught Thursday in the Mohawk River were returned to the water, but at least one was not.
One 18-inch fallfish caught by state Department of Environmental Conservation and United States Geological Survey technicians and biologists has a new home — preserved in ethanol at the New York State Museum in Albany alongside more than a million specimens dating back to 1840.
“That’s about as big as they get,” said Anthony Bruno, a DEC technician, as Scott George, a USGS biologist, pulled it out of a pool of about 25 fish that turned up during a 15-minute survey of the river along Scotia. Crews surveyed the river throughout the day and used an electrofishing boat to stun the fish before scooping them up.
As crews worked to measure and weigh the fish at the Rotterdam Kiwanis Park boat launch, a New York State Museum representative on hand said he had never seen a fallfish that large. And it was in a breeding state, as evidenced by the tubercles on its scales, making it a good specimen for the museum.
The work is part of a three-year study of the river’s fish species that started last week — a collaborative effort of the state DEC and USGS.
“The goal of the survey we’re doing on the Mohawk River is really to assess the current status of the fishery,” said George, the USGS project coordinator and a University at Albany graduate student majoring in ecology and evolutionary biology. “Most of the past research that’s been done on the Mohawk fish community was through the early ’80s, and there’s been a lot of changes that have occurred since then.”
Those changes include a new invasive species called zebra mussels colonizing the river and the substantial decline of the blueback herring, which run from the Atlantic Ocean and used to be the “dominant biomass in the river,” he said.
“So the primary forage in the river has changed substantially,” he said.
The water levels are managed differently, too, he said, with levels being brought down periodically now when floods threaten.
“So possibly a hydrologic modification to be evaluating,” he said, “but ultimately trying to compare back to historical fisheries data to see how it may have changed in the last 30 years.”
For example, crews will try to find out if and how the changing environment has affected the size of the river’s fish. By Thursday, they had already collected scales from smallmouth bass and walleye — the scales are used to determine age.
“Maybe fish of the same age are now smaller than they were 30 years ago, or maybe not,” George said. “Those are questions we hope to answer.”
The $245,541 study is being funded by the DEC and the USGS with the state agency paying $147,730 and the USGS contributing $97,811. It targets fisheries in the main stem of the Mohawk River, which extends from Lake Delta Dam near Rome downstream to where it meets the Hudson River near Cohoes.
All fish collected will have their species, size, abundance and distribution documented, and most will be returned to the river. The DEC will continue its efforts to monitor and collect samples of the declining blueback herring species. The study will also identify management practices that could lessen anticipated effects of invasive species, climate change or other factors that could impact fish.
During the 15-minute survey of the Scotia reach, crews found 25 fish from five species: fallfish, spottail shiner, smallmouth bass, white sucker and yellow perch. Other than the big, breeding fallfish, none were all that surprising.
But earlier in the week they found goldfish — the kind typically found in a glass bowl or won at the fair — and walleye, a popular target of anglers.
“We got two walleye, which are hard to shock or fish,” said Scott Wells, a DEC biologist. “They’re a very popular species. Smallmouth bass and walleye are the big-dollar species.”
Russell MacDougal, who was bicycling through Rotterdam Kiwanis Park on Thursday, has done his own surveying of the river’s fish with his 7-year-old son, Dustin — using fishing rods and worms.
“Walleyes, trout, bass, northerns — big northerns,” the Scotia man said, pausing on his bike to observe the tent where workers processed the fish. “Some of the biggest northerns I’ve ever seen come out of here. Some of the biggest walleyes I’ve ever seen come out of here, too.”
Working under the tent, Walt Keller, a retired DEC fisheries manager, weighed a tiny fallfish. Before retiring in 1999, he worked for the DEC for 31 years.
“It’s changed quite a bit,” he said of the river’s fish supply. “We’re finding really spotty distributions.”
Like the fallfish, nearly all of the river’s fish are “spring spawners,” he said, and they’re mostly found in the spawning areas.
“You go along for long distances and there’s no fish, and then there are areas where there are a lot of one species,” he said. “So from an ecological perspective, that’s a really interesting thing. And also from an environmental perspective … because those habitats are really important to protect.”
After surveying the Scotia reach, the crew headed to Lock 8 in Scotia, where the boat’s electroshocking booms left a giant carp motionless at the surface. (The bigger the fish, the harder it gets hit by the electricity.)
Wells guessed that this one weighed about 20 pounds. The state record for carp — an invasive species from the Middle East — is about 50 pounds, he said.
“That’s the biggest carp I’ve ever seen,” said Alexander Smith, a DEC research scientist. “That thing was massive.”