Fishers inhabit upland and lowland forests, including coniferous, mixed, and deciduous forests. They occur primarily in dense coniferous or mixed forests, including early successional forest with dense overhead cover (Thomas 1993). They generally avoid areas with little forest cover or significant human disturbance. The Fisher is adapted for climbing but is primarily ground-dwelling. It is a generalised predator with major prey of small to medium-sized mammals and birds, and carrion (Powell 1981).

Fisher has a large range in northern North America: from Quebec, the Maritime Provinces, and New England west across boreal Canada to south-eastern Alaska, south through the western mountains to Utah, Wyoming, Idaho, and California, and formerly south to Illinois, Indiana, Tennessee, and North Carolina (Lewis, J.C., Powell, R.A. and Zielinski, W.J. 2012). Extirpation from southern portion of range, mainly because of habitat loss, has been counteracted by recent natural and human-aided range expansions in the eastern U.S.; adequate population data are unavailable for much of the range, but the species currently is regarded as secure.

There are currently efforts underway to implement a conservation strategy to reintroduce the Fisher into its former range along the Pacific Coast. Genetic data indicate that British Columbia would be the most appropriate source population for translocations that may be necessary to recover populations in Washington and portions of Oregon and California (Drew et al. 2003). The species is protected in large tracts of habitat in areas well distributed throughout the range. The primary conservation measure necessary is to prevent excessive harvest.