Fisher
Discover North America’s powerful and elusive forest predator.
What Is a Fisher?
The fisher (Pekania pennanti) is one of the larger mustelids native to North America. Closely tied to dense forest interiors, fishers occupy moist coniferous, deciduous, and mixedwood forests. Their historical range stretched from Canada’s boreal forests down through the western U.S. mountains and into eastern U.S. forests.
Although many fisher populations have been extirpated or reduced due to unsustainable fur trapping, persecution, habitat loss from timber harvest, and climate shifts, fishers have since rebounded in many areas, thanks to reintroduction programs and natural range recovery. Unfortunately, some areas, mostly in their western range, are still seeing declining fisher populations.
Identifying Features and Animal Size
Fishers have dark brown fur and long, bushy tails. Roughly the size of a large house cat, adult males typically measure 89–119 cm (35–47 inches) in length and weigh between 3–5.9 kg (6.5–13 pounds). Females are slightly smaller, ranging from 76–94 cm (30–37 inches) and weighing 1.6–2.7 kg (3.5–6 pounds).
Compared to most marten, the fisher is significantly larger and more powerful, though it still has a slim, agile build. Fishers, like martens, can rotate their hind feet almost 180 degrees, allowing them to climb down trees headfirst.
Image attributed to Matthew ZalewskiHabitat and Behaviour
Fishers are found in mature forests with dense canopy cover and complex structures, including fallen logs and standing snags. Their range includes boreal and mixedwood forests of Canada and the northern U.S., as well as coniferous and deciduous forests in the western mountains like the Rockies and Sierra Nevada. Fishers are North America's largest obligate tree cavity user - meaning that they require large tree cavities for giving birth to and raising their young.
While considered to be more active at night, fishers may also be active throughout the day and twilight period as they hunt for prey both on the forest floor and canopy. Their diet consists largely of small to medium-sized mammals, birds, and carrion, but can also include fruit, insects, and fungi. Notably, fishers are among the few predators able to successfully hunt porcupines.
Fishers breed in late winter to early spring, but the kits aren’t born until the following spring due to delayed implantation. Litters can include up to 6 kits, which begin to venture away from their mother by fall to look for territories of their own. In the wild, fishers can live up to about ten years.
Conservation and Recovery
IUCN status: Least Concern (LC)
Fishers experienced dramatic declines in the 19th and 20th centuries due to commercial fur trapping, predator control efforts, habitat loss, and historical climate events. More recently, they have regained parts of their range via reintroductions and natural expansion. Elsewhere, populations continue to decline.
Fishers, particularly those in the western U.S. and Canada, face numerous threats, including:
Agricultural expansion
Logging and wood harvesting
Oil and gas development
Unusually severe wildfires
Drought conditions
Insect-related tree die-offs
Rodenticide poisoning from cannabis cultivation
Ongoing fur trapping
Landscape fragmentation and habitat loss
Small, isolated populations are particularly vulnerable to environmental shocks, underscoring the importance of habitat conservation, forest connectivity, regulated trapping or areas without fur-harvest, and ongoing monitoring.
Fast Facts About the Fisher
Despite their name, fishers don’t eat fish!
Fishers are one of the few predators capable of taking down porcupines.
Its rotating ankle and retractable claws allow head-first descents down trees.
Fishers are the only species in the genus Pekania.
A fisher’s territory is far larger than that of most martens. In British Columbia, Canada, a male fisher territory can exceed 100 square kilometres!
Their thick fur becomes darker and denser in winter.
Fishers are increasingly returning to urban-fringe forests in the eastern U.S., highlighting growing adaptability across landscapes.
Fishers are among the largest obligate-tree cavity users in North America.