Great Lakes Fishery Commission

Updated 2021-09-29 14:55:51

Lake Erie -> 1.0 Intensively Managed Species -> Sea Lamprey

Reduce sea lamprey abundance to levels identified in the sea lamprey management plan

Sea lamprey (Petromyzon marinus) are parasitic fish native to the Atlantic Ocean and were first detected in Lake Erie in 1921 following the deepening of the Welland Canal (Grunder et al. 2020). They parasitize and kill other fish by sucking their blood and other body fluids. They were not considered a serious threat to the Lake Erie fish community until the 1970s when water quality and stream habitat improvements coupled with increased salmonid stocking resulted in the sea lamprey population increasing in abundance. Sea lamprey control in Lake Erie began in 1986 as part of lake trout restoration efforts. The objective of this control program is to suppress sea lamprey abundance to levels that will not impede achievement of fish community objectives, especially for coldwater species. The sea lamprey population is considered under control if the adult abundance is below 3,263 and the lake trout wounding rate is below 5 wounds per 100 fish (Slade 2012).

During the 2016-2020 reporting period, the average adult sea lamprey abundance index (3-year running average) was 13,400, which was well above the control objective but exhibited a downward trend (Figure 1). The abundance index in 2020 was estimated at 1,300 adults, which was below the control objective for the first time since 1995 and is the lowest index in the time series. The wounding rate index (3-year running average of the number of A1-A3 wounds per 100 lake trout > 532 mm (21 inches)) during the reporting period remained steady but well above the control objective, averaging 13.6 wounds per 100 fish (Figure 2).

Figure 1: Index (3-year running average) of adult sea lamprey abundance in Lake Erie, 1993-2020. The control objective is less than 3,263 adults.

Figure 2. Wounding rate index (3-year running average of the number of A1-A3 wounds per 100 lake trout > 532 mm (21 inches)) from standardized assessment surveys in Lake Erie, 1983-2020. The control objective is less than 5.0 A1-A3 wounds per 100 lake trout.