Understanding the Fisher
The fisher (Pekania pennanti) is a medium-sized, carnivorous mammal, part of the weasel family (Mustelidae). Despite its name, this animal rarely consumes fish. Its body is long, thin, and low to the ground, reflecting its agility in forested environments. Male fishers are notably larger than females, weighing between 3.5 to 6.0 kg (8–13 lb) and measuring 90–120 cm (35–47 in) in total length, while females typically weigh 2.0–2.5 kg (4–6 lb) and are 75–95 cm (30–37 in) long.
Their fur color ranges from deep brown to black, appearing glossier and denser in winter. Some individuals exhibit hoary-gold or silver fur around the face and shoulders due to tricolored guard hairs, and they may have patches of white or cream-colored fur on their underside. Fishers possess large, padded feet with retractable claws, aiding their movement across snow and their ability to climb trees. While agile climbers, they primarily spend their time on the forest floor.
Fisher Presence Across Michigan
Fishers were historically present throughout both the Upper and Lower Peninsulas of Michigan. However, due to extensive logging, subsequent fires, and unregulated trapping during the 19th and early 20th centuries, the species vanished from the state by 1936. Reintroduction efforts began in 1961, with fishers being released into Michigan’s Upper Peninsula, particularly in the Ottawa National Forest. These reintroductions proved successful, leading to a thriving population in the Upper Peninsula by the late 1980s, which allowed for a limited trapping season to be established in 1989.
While fishers reestablished themselves in the Upper Peninsula, their return to the Lower Peninsula was more gradual. For many years, sightings in the Lower Peninsula were unconfirmed by official sources. In 2013, the Michigan Department of Natural Resources confirmed the presence of a fisher in Presque Isle County in the northern Lower Peninsula, indicating the species’ natural recolonization. Today, fishers are found primarily in the heavily forested regions of the Upper Peninsula and increasingly in suitable northern areas of the Lower Peninsula.
Ecology and Conservation
Fishers are forest-dwelling carnivores that prefer continuous forest habitats, including extensive conifer forests and mixed-hardwood and conifer stands. They favor areas with significant overhead canopy cover and often utilize old-growth forests. Their preferred habitat also includes areas with abundant coarse woody debris, which provide cover and hunting opportunities. In winter, they may use snow dens.
As generalist predators, fishers have a diverse diet consisting mainly of small to medium-sized mammals like snowshoe hares, mice, squirrels, and porcupines. They are one of the few animals capable of effectively preying on porcupines. Their diet also includes birds, and they are known to supplement their meals with fruits, berries, nuts, and carrion. Fishers are solitary animals, primarily active during dawn and dusk, and they associate with others mainly for mating.
Conservation efforts in Michigan have focused on reintroduction programs. The species’ return to parts of the Lower Peninsula indicates the success of habitat management and natural expansion. Fishers are currently managed species in Michigan, with regulated trapping seasons in areas where populations are robust. The presence of fishers is considered beneficial for ecosystem health, as they help regulate populations of prey species, including porcupines.