There is some debate about whether the sea lamprey (Petromyzon marinus) is native to Lake Ontario, but researchers agree that the creation of the Welland Canal in the early 1800’s allowed the population dispersion of the lamprey to the rest of the Great Lakes, with devastating effects on the ecosystem, particularly the indigenous lake trout (Salvelinus namaycush), a keystone species (Hansen, Madenjian, Slade, Steeves, Almeida, & Quintella, 2016). The sea lamprey can grow up to four feet in length and feeds on the blood of other fish. It has a mouth that works like a suction cup and it attaches to a fish to feed. It may stay attached until the fish dies from loss of blood, or it may release the fish and feed on it again another time. Adult lampreys live for a year, then migrate to streams where they spawn and die. The sea lamprey is classified as an invasive species because it was non-native to the Great Lakes and its introduction to the Great Lakes caused great environmental and economic harm. In fact, the sea lamprey was responsible for the collapse of commercial fishing there in the mid-20th century. Although the sea lamprey cannot be completely eradicated in the Great Lakes, control programs have cut the peak population, reached in 1961, by 90%. The suppression of the lampreys and the actions of restoration programs have increased the population growth of native species, with the goal of restoring levels to their pre-lamprey levels.
One strategy being used to control the lamprey population is the use of the chemical 3-trifluoromethyl-4-nitrophenol (TFM). TFM is put in streams where the lampreys spawn and kills the larval lampreys. TFM has been successfully used for 50 years, but has no lasting effects and must continue to be used every year. Drawbacks to the use of TFM is that it is harmful to other species of fish such as the walleye (Sander vitreus), and it is also harmful to the larvae of native lamprey species which are part of the original ecosystem.
- Hansen, M. J., Madenjian, C. P., Slade, J. W., Steeves, T. B., Almeida, P. R., & Quintella, B. R. (2016). Population ecology of the sea lamprey (Petromyzon marinus) as an invasive species in the Laurentian Great Lakes and an imperiled species in Europe. Reviews in Fish Biology and Fisheries, 26(3), 509-535. doi:10.1007/s11160-016-9440-3