Kevin Fisher
Sea Lamprey in the Great Lakes
Retrieved from: https://upload.wikimedia.org/wikipedia/commons/6/6f/Diversas_lampreas.1_-_Aquarium_Finisterrae.JPG on 11/02/2017
Sea Lamprey (Petromyzon marinus) (depicted above) is an invasive, eel like, jawless fish that looks like something straight out of a horror film. It was first reported to have invaded from Lake Ontario to Lake Erie in 1921, believed to have been facilitated through the opening of the Welland Canal. Sea Lamprey were initially not a problem, but with the enactment of policies to prevent pollution, salmonid stocking programs and stream restoration they began to proliferate and soon spread to the other Great Lakes (Sullivan et al., 2003). Sea lamprey have a very unique life history (shown below), spending the majority of their life in a larval stage, called an ammocoetes, in which they are sedentary filter feeders living in stream beds. Once they have reached a certain point, they emerge from stream beds and transition to a parasitic phase in lakes. One adult parasitic Sea Lamprey can apparently kill up to 40 pounds of fish in its life time (Morrison, 2017). The parasitic life stage of Sea Lamprey is especially devastating to Lake Trout (bite mark pictured below), whose population declined rapidly with increased abundance of Sea Lamprey in Lake Erie. This led the Great Lakes Fisheries Commission to establish an integrated Sea Lamprey management plan in 1986 (Sullivan et al., 2003). Control measures taken rapidly saw declines in the populations of Sea lamprey through the use of pesticides, barriers to reproduction, trapping, and even the release of sterile males (Klassen et al., 2004). With the initial success of the program people believed that the program may be able to successfully eradicate Sea Lamprey from the Great Lakes (Sullivan et al., 2003). While the program has been extremely successful, decreasing the amount of fish killed from 100 million pounds to 10 million pounds per year in the Great Lakes (Morrison, 2017). The complete eradication seems unlikely. A recent report from the Great Lakes Fisheries Commission also conveyed a startling discovery, Sea Lamprey populations have been increasing for the past few years in Lake Erie and Superior (Morrison, 2017). While the current levels are still near historic lows, the recent trend of increasing populations has fisheries managers worried (Morrison, 2017). No one really knows why there has been an increase in these populations, but two hypotheses have been given that may explain why this trend has occurred. The first, is that the restoration of stream habitats have allowed the Sea lamprey to establish into new tributaries that they were historically not present. The second, is that the mild winters that have been experienced throughout the Great Lakes region in the last two years have led to more favorable conditions during spawning (Morrison, 2017). While the integrated Sea Lamprey management plan has been a great success in curbing the spread of this species, there are still unknown factors which require continued vigilance to keep this invasive threat under control.
Retrieved from: https://greatlakesinform.org/sites/default/files/sealamprey_lifecycle_seagrant%20UMN_with%20credit.jpg on 11/2/2017
Klassen, W., Adams, J.V., Twohey, M.B., 2004. Modeling the suppression of sea lamprey populations by the release of sterile males or sterile females. Journal of Great Lakes Research 30, 463–473.
Morrison, A. A., Oct. 24 2017. Sea Lamprey on rise in Lakes Erie and Superior. Great Lakes Today. Retrieved from: http://news.wbfo.org/post/sea-lamprey-rise-lakes-erie-and-michigan on 11 November 2017.
Sullivan, W.P., Christie, G.C., Cornelius, F.C., Fodale, M.F., Johnson, D.A., Koonce, J.F., Larson, G.L., McDonald, R.B., Mullett, K.M., Murray, C.K., 2003. The sea lamprey in Lake Erie: a case history. Journal of Great Lakes Research 29, 615–636.