Top: Seaway Marine Group jetting work underway on Brocton Shoal, Chautauqua County
Photos taken by Philippa Kohn, TNC scientist, who is leading the dive assessments.
Bottom: Dive assessments before (left) and after (right) the high-velocity jetting project to measure interstitial depth between rocks and conduct a dreissenid mussel count.
The New York State Department of Environmental Conservation has announced the completion of an experimental aquatic habitat reclamation project on Brocton Shoal in Lake Erie.
A groundbreaking high-velocity jetting method was developed to clean and restore historical spawning habitat for lake trout.
Located approximately 10 miles southwest of Dunkirk, Brocton Shoal is a glacial deposition area containing hundreds of rock piles that were one of the main historical spawning grounds for lake trout in Lake Erie. Lake trout require clean rock containing crevices in which eggs can become lodged and protected from weather and predators. However, the habitat has been severely degraded following the introduction of zebra and quaqqa mussels (also known as dreissenids) into the system in the 1990s, rendering the habitat unsuitable for spawning. Dreissenids have plagued many of New York State’s waterways since their introduction, altering food webs, causing damage to infrastructure, and impacting fish health and spawning habitat.
Staff from the DEC’s Lake Erie Fisheries Research Unit contracted with Seaway Marine Group based in Clayton, New York, to develop and implement the innovative technique. A high-velocity jetting nozzle was designed, fabricated, and deployed in mid-September at two test sites removing silt, sand, and dreissenid mussel shells covering the rock piles. DEC staff deployed an underwater drone to evaluate and adjust the method in real time. These sites lie in 50–60 feet of water, greatly increasing the difficulty of the work and making the resulting clean rock that much more impressive.
DEC staff also worked with partners at the U.S. Fish and Wildlife Service (USFWS) from the Lower Great Lakes office in Basom, New York, and The Nature Conservancy (TNC) to gather the information necessary to conduct and evaluate this work. The USFWS used side-scan sonar to develop detailed maps of the area prior to the project and TNC staff conducted dives prior to and following the project. Preliminary results indicate that the project was successful and the overall technique holds promise for this type of habitat restoration in Lake Erie and elsewhere. DEC and TNC will continue to monitor the experimental sites for dreissenid recolonization and use by lake trout during the fall spawning period.
This habitat rehabilitation project is the latest of several important DEC initiatives to identify, assess, and restore lake trout spawning habitat. The success of this high-velocity jetting method on Brocton Shoal provides an effective option for future reclamation work. Lake trout were once the top predator in Lake Erie, with records of fish greater than 50 inches long and weighing 75 pounds. By 1965, overharvesting, habitat degradation, eutrophication, and invasive species introductions resulted in the complete extirpation of lake trout from Lake Erie. Efforts to restore lake trout began in 1982 and have mostly focused on stocking and sea lamprey control. In 2021, DEC biologists discovered wild lake trout fry representing the first evidence of wild lake trout in Lake Erie in 60 years.
To learn more about the Lake Erie Lake Trout Rehabilitation Plan, (PDF) visit DEC’s website or contact DEC’s Lake Erie Fisheries Research Unit at fwfishle@dec.ny.gov.
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