Curtis Mulch eases the paddle-wheeled weed harvester slowly past the docks of the homes in Roxbury’s Silver Spring section, clearing a swath of the shadowy plants that lurk just below the surface.
The removal of the weeds, which might otherwise be clipped by a boat propeller and float in dying clumps on the surface or sink to the bottom to rot, creates both boat channels and fish habitat, said Michael Calderio, harvesting supervisor for Lake Hopatcong.
Brad Garie, president of the Knee Deep Club, said the weed harvesting is key to maintaining the improving fish habitat in the 2,600-acre lake.
“The channels cut by the weed harvester creates fish habitat for a number of species,” Garie said. Both game fish and bait fish “like to hide” in the underwater weeds, he said.
Based on the size of fish caught in recent contests and general observations, Garie said the lake’s fish habitat is good.
For the next 30 months, the state will test that hypothesis with a series of samplings and an inventory of the fish population, said Larry Ragonese, press director of the New Jersey Department of Environmental Protection.
The Lake Hopatcong sampling is being carried out to measure water quality and clarity, and the health of the fish population.
“There is no indication of any problem with the lake,” Ragonese said. “This is part of a long-term plan. It gives us a snapshot of the fish population and water quality, to see if anything needs to be done.”
The results of the program will be available in 2015.
“We are looking for changes in the number of species, the health of the species, any new species and any indication of changes” in the fish population, Ragonese said.
Scientists will also measure water quality, clarity and turbidity, he said.
Lake Hopatcong is one of 140 lakes statewide that will be tested, he said.
The program will begin this summer when biologists with the state Division of Fish and Wildlife perform onshore line seining to capture and identify fish species, he said. Water samples will also be collected.
Beginning in the fall, the biologists will use electroshock techniques—using a low-level pulse of electricity to stun fish—to gather larger quantities of fish, Ragonese said.
The last full fish inventory was done in 1995- 96, Ragonese said.
Since then there have been periodic tests for dissolved oxygen and water temperature, he said. In 2008, scientists performed a shore-side seining to test for non-native species. It was routine testing, not triggered by any alarm, he said.
Lake Hopatcong is home to three species of bass, three species of trout, chain pickerel, muskellunge, walleye, three species of catfish, carp, perch, crappies, sunfish, bluegills, and small baitfish.
The attraction of a varied fish population draws both recreational and sporting fishermen. Ragonese said that while the fish inventories and water testing are done for environmental reasons, the department recognizes the economic impact of the activities on the lake community.
In 2008, the DEP estimated the lake generated annual economic activity worth between $280 and $455 million.
Garie said the health of the fish stock has improved as the lake’s water quality improves. He cited the addition of sewers in some towns, the mandated use of non-phosphorus fertilizers, storm-water management efforts, and the weed harvesting for contributing to better water quality. “The health of the fishery is very, very strong,” he said.
Contestants in club-sponsored events are landing good-sized fish of all varieties, he said. In recent contests, winners landed a 7-pound striped bass and the top three brown trout in a recent contest topped 3 pounds, with the winner landing a 4-pounder.
The Knee Deep Club stocks a variety of fish species, Garie said, augmenting the state’s stocking efforts.
The club stocks trout, walleye, striped bass and chain catfish, he said. This year the club stocked 1,000 trout and in 2012, it stocked 1,500 trout, including some of trophy size.
The state stocks trout, walleye and muskellunge.
This spring the stat stocked 9,600 trout averaging 10.5 inches and in 2013, the state stocked 9,480 trout. In 2011, the state stocked 81,000 walleye and 2,600 muskellunge according to DE reports.
In 2006, the DE floated a plan to reduce trout stocking in some lakes, including Lake Hopatcong in favor of putting more trout in some of the state’s river and streams. The plan was abandoned after wave of protests arose including numerous comments from the Lake Hopatcong community and members of the Knee Deep Club.