Environmental Contaminants and Cholinesterase Activity in the Brain of Fisher (Martes pennanti) Harvested in Northern Wisconsin

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The fisher (Martes pennanti), a member of Mustelidae, was once common in the northern forested region of the upper Great Lakes, including Wisconsin. Fishers are medium sized carnivores (2.5 kg for females; 6.5 kg for males) which feed on a wide range of food items (Powell and Zielinski 1994; Powell 1993; Gilbert and Keith, unpublished data) and require closed canopy forests with large diameter trees for den sites (Powell 1994, Thomasma et al 1991, 1994, Wright and Gilbert in prep). Fishers were extirpated from Wisconsin in the 1920’s due to a combination of over-harvest and habitat destruction (Pils 1983, Powell 1994). From 1956 to 1963 fishers were translocated from New York and Minnesota into Wisconsin in order to reestablish a self sustaining population and to achieve porcupine (Erethizon dorsatum) control. Kohn and Creed (1983) concluded that this reestablishment was successful. In 1985 the fisher was designated a game species and the first trapping season in 50 years was established. Harvests initially occurred over a portion of northern Wisconsin but now include the entire northern part of the state.


Bioaccumulation; Cholinesterases; Fisher (Mammal) – Reintroduction; Great Lakes Region; Martes pennant; Pollutants; Wisconsin


Animal Sciences | Environmental Health and Protection | Environmental Sciences


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