The fish of Lake Surprise got quite the shock last week.

In preparation for construction of a new dam this summer, the fish in the narrow Union County lake are being safely removed using a method called “electrofishing,” where they are electrocuted and momentarily float to the top to be gathered up.

Beginning this month, the dam project will replace an existing structure at the end of the lake, on the western edge of the Watchung Reservation. While upgrades have been made to the dam over the years, its earthen core dates to 1845. This project will update it further with modern safety standards, county officials said.

Loraine Mizak, president of Great Blue Lake and Pond Management, the company contracted to remove the fish, was at the lake Thursday morning to begin the electrofishing process, which she said causes no harm to the fish.

“It’s called cheating,” Mizak joked about the process. “People say, ‘Do you go fishing?’ The only fishing I do is with a boat and a wire.”

Brandon Swet and Austin Harris, two natural resource students at the State University of New York College of Environmental Science and Forestry in Syracuse, manned the boat for Mizak, trawling through heavily vegetated water, zapping and scooping as they went.

About four feet off the bow hung a circular contraption with small bars dangling from it into the water, looking like a giant set of wind chimes. The device worked in combination with a conductor on the hull to create an electrical field in the water wherever the boat traveled, with an on-board lever controlling the current.

Swet and Harris, dressed in neoprene chest waders and armed with long-handled nets, made large circles through the lake, one steering and operating the electrical lever while the other snatched up the stunned fish.

They started with a current of about four amps — “just enough to tickle them,” Mizak said — and steadily raised it until fish began rising to the surface. That came at about nine amps in Lake Surprise, but the current can be dissipated by minerals or plant life in the water, Mizak said, so every lake calls for a different charge.

The fish are stunned for about 30 seconds, just enough time to get them into a bucket before they snap back to life. On the first pass through the lake Thursday, Swet and Harris pulled in about 50 fish — including catfish, pickerel, largemouth bass, sunfish, crappies, perch and more.

Nick Healy, a senior wildlife worker with the state Division of Fish and Wildlife, was on hand to transport the fish to other Union County ponds. He said the order called for 50-100 bass to be moved to Best Lake in Watchung, and the others sent to Seely’s Pond and Nomahegan Pond.

“They’re all nice fish, they’re all mature adults,” Healy said of the first 50 fish loaded into the tank on the back of his truck. Healy works at the state fish hatchery in Hackettstown.

Though no one knew for certain how many fish would be pulled from Lake Surprise, Healy estimated the haul would be sizable.

“It’s a large pond, so it's safe to say there are several thousand fish in there,” he said.

Mizak said her team would return the next day, and then again after construction workers drained part of the lake, when the remaining fish will be concentrated and easier to collect.

“Our goal is to get as many fish as we can,” Mizak said. “We go until there’s no more fish.”

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