Michigan Department of Natural Resources
Research and Development Report No. 200
Institute for Fisheries Research Report No. 1764, 1970
The Effects of Lamprey Larvicide on the Bottom Fauna and Periphyton
of the Chocolay River, Marquette County, Michigan
Robert C. Haas
Introduction.-The sea lamprey (Petromyzon marinus) gained entry to the upper Great Lakes in 1829 upon completion of the Welland Canal. By the 1930’s the sea lamprey had established itself in Lakes Huron and Michigan and a short time later in Lake Superior as well. This parasite thrived and by 1950 the commercial harvest of lake trout (Salvelinus namaycush) was down 95% from that of the 1930’s (Eschmeyer, 1957). The disastrous decline in harvest of the highly valuable lake trout prompted cooperative research and lamprey control programs between Canada and the United States as early as 1946 and a treaty for joint action was signed in 1954. The international collaboration resulted in life history studies (Applegate, 1950; Applegate and Moffett, 1955; Hile, 1957; and others) which led the way to a lamprey control program based upon the vulnerability of adults in spawning streams. Various mechanical and electrical weirs were used to block lamprey migrations both up and downstream; but high costs, time required to reach desired results, and flood conditions made weirs impracticable (Applegate, Smith and Nielsen, 1952; Erkkila, Smith and McLain, 1956). It was found that larvae of the sea lamprey, called ammocoetes, live in the spawning streams for about 5 years before maturation to the parasitic, lake dwelling adult. Hence, it was possible to treat the spawning streams with a toxic chemical, kill the larvae and eliminate several generations before they became parasitic.
Applegate et al. (1958) found a differential toxicity between fishes and larval lampreys for ten halogenated mononitrophenols. All of these compounds are more toxic to lampreys than most other aquatic organisms; however, one of them, 3-trifluormethyl-4-nitrophenol (TFM), met the requirements more closely and was selected for field use (Applegate et al., 1961). Laboratory studies with TFM (Applegate, et al., 1957; Applegate et al., 1958; and Applegate et al., 1961) established that this chemical is acutely toxic to larval lampreys at low concentrations (2-3 ppm) and that at these concentrations, it is non-toxic to other fishes.
Stream treatments with the lampricide are timed to remove the lampreys before metamorphosis. Most of these streams contain valuable resident fish populations and spawning habitat for Great Lakes fishes. Although numerous trials demonstrated that concentrations of TFM used in stream treatments (2-4 ppm) had little or no direct effect upon the resident fish, the possibility existed that this chemical might eliminate some of the stream invertebrates and algae and thus remove a part the fishes’ food supply.
In some instances, representative stream invertebrates were included in the laboratory analyses and early reports showed that crayfish and insects were not affected at the concentrations used to eliminate lampreys (Applegate et al., 1961). Field observations of actual stream treatments likewise did not indicate gross stream invertebrate mortalities. However, before the present study, an intensive investigation of the effects of TFM treatment upon stream invertebrates and algal communities under natural conditions had not been made.
In the fall of 1965, the East Branch of the Chocolay River in Michigan’s Upper Peninsula was treated with TFM to determine the chemical’s effects upon stream bottom fauna and periphyton. The purpose of this paper is to report and evaluate the short-term effects of the larvicide on these communities in the East Branch of the Chocolay River.