The Fisher is a forest-dwelling creature native to North America. They are medium in size and their bodies are long, thin, and low to the ground. Males have coarser coats than females. In the early winter, their coats are dense and glossy. The color ranges from deep brown to black, although it appears to be much blacker in the winter when contrasted with white snow. From the face to the shoulders, fur can be hoary-gold or silver due to tricolored guard hairs. The underside of a fisher is almost completely brown except for randomly placed patches of white or cream-colored fur. In the summer, the fur color is more variable and may lighten considerably. Fishers undergo molting starting in late summer and finishing by November or December. Fishers have five toes on each foot, with unsheathed, retractable claws. Their feet are large, making it easier for them to move on top of snow packs.
Fishers are widespread throughout the northern forests of North America. They are found from Nova Scotia in the east to the Pacific shore of British Columbia and Alaska. They can be found as far north as Great Slave Lake in the Northwest Territories and as far south as the mountains of Oregon. Isolated populations occur in the Sierra Nevada of California, throughout New England and the Appalachian Mountains of Pennsylvania, Maryland, West Virginia, and Virginia. Fishers live in extensive conifer forests typical of the boreal forest but are also common in mixed-hardwood and conifer forests. They prefer areas with continuous overhead cover and are more likely to be found in old-growth forests. Fishers also select for forest floors with large amounts of coarse woody debris and tend to avoid areas with deep snow.
Fishers are generally crepuscular, being most active at dawn and dusk. They are active year-round, and are solitary, associating with other fishers only for mating. Males become more active during mating season. Females are least active during pregnancy and gradually increase activity after birth of their kits. Fishers are competent tree climbers, but they spend most of their time on the forest floor. They are able to travel many miles along ridges in search of prey. They usually shelter in hollow trees, logs, stumps, holes in the ground, rock crevices, and dens of other animals. During the winter time, these animals will use burrows under the snow with long and narrow tunnels. Fishers have very keen senses of smell, sight, and hearing. They communicate with each other with the help of scent marking. These animals have a circular patch of hair on the central pad of their hind paws marks plantar glands that give off a distinctive odor. Since these patches become enlarged during the breeding season, they are likely used to make a scent trail to allow fishers to find each other so they can mate.
Little is known about the mating system in fishers. They usually breed in late March-early April. Egg implantation is then delayed for 10 months until mid-February of the following year when active pregnancy begins. After gestating for about 50 days, the female gives birth to 1-4 kits. Young are born blind and helpless in dens which are located in hollow trees. Kits begin to crawl after about 3 weeks and after about 7 weeks, they open their eyes. After 8 weeks they start to climb and are completely dependent on their mother's milk for the first 8-10 weeks. After that, they begin to switch to a solid diet. Males do not help raise their young. After 4 months, kits become intolerant of their litter mates, and at 5 months, the mother pushes them out on their own. Females reach reproductive maturity at 1 year of age, while males become reproductively mature when they are 2 years old.
Fishers have been trapped since the 18th century. They have been popular with trappers due to the value of their fur, which has been used for scarves and neck pieces. Their pelts were in such demand that they were extirpated from several parts of the United States in the early part of the 20th century. In the 1920s, when pelt prices were high, some fur farmers attempted to raise fishers. However, their unusual delayed reproduction made breeding difficult. When pelt prices fell in the late 1940s, most fisher farming ended. While fishers usually avoid human contact, encroachments into forest habitats have resulted in some conflicts as well. In some areas, fishers can become pests to farmers when they raid chicken coops.
The IUCN Red List and other sources don’t provide the number of the fisher total population size. Currently, this species is classified as Least Concern (LC) on the IUCN Red List.
Fishers are important predators in their ecosystems thus helping to control populations of the prey species.