New York State Department of Environmental Conservation (DEC) Region 4 has announced the completion of three new artificial spawning reefs in Otsego Lake. DEC, in partnership with the State University of New York (SUNY) at Cobleskill and the SUNY Oneonta Biological Field Station, constructed the artificial reefs in hopes of creating new, clean spawning habitat for lake whitefish (Coregonus clupeaformis), a native coldwater species once abundant in Otsego Lake.
Lake whitefish thrived in Otsego Lake well into the 1980s, sustaining lake trout and other native fish species before a series of biological and environmental factors severely decreased populations, according to DEC Region 4 Acting Director John Weidman.
The presence of the invasive alewife (Alosa pseudoharengus), illegally introduced to the lake in 1986, likely contributed to decreased larval lake whitefish populations. Alewives are efficient planktivores that feed on a variety of microcrustaceans, insects, zooplankton, and fish larvae in the upper layers of the water.
Alewife and dreissenid mussels, another opportunistic species, disrupted Otsego Lake’s ecological balance, likely leading to the collapse of lake whitefish populations. Fortunately, the alewife population crashed in 2010, and is now believed to be extirpated, making restoration of the coldwater ecology possible.
Region 4 Bureau of Fisheries and Operations employees and SUNY partners constructed three new artificial reefs by hand.
Crews placed cobble-sized rocks at three predetermined locations at Clarke Point on Otsego Lake. The three reef piles, each approximately 27 feet long by 23 feet wide and three feet tall, contain monitoring wells placed in the middle of the piles and are equipped with temperature and oxygen sondes (data loggers), along with sedimentation monitoring tubes.
DEC is planning to monitor the newly constructed reefs in hopes they are used by spawning adult lake whitefish over the winter months.
The reefs may also attract spawning lake trout and cisco salmon (Coregonus artedi), which require similar spawning habitats. With assistance from the U.S. Geological Survey, DEC also placed egg collection mats atop the reefs to determine which species of fish are spawning and utilizing the reefs.
This ongoing project is expected to run for the next five to 10 years. Additional reefs are planned around Otsego Lake in historic and current lake whitefish spawning areas.
DEC and SUNY are also exploring future studies examining larval lake whitefish survival rates, available larval forage, and dreissenid mussel colonization. It’s hoped these efforts will help fisheries biologists better understand and work to restore whitefish populations.
Photos, from above, provided by DEC: DEC Bureau of Fisheries employees and partners from SUNY Cobleskill and SUNY Oneonta throw cobble sized rocks at predetermined locations in Otsego Lake to construct artificial reefs; and underwater view of one of three artificial reefs constructed in Otsego Lake with PVC monitoring wells placed in the middle.
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