Not many people know what a fisher (Pekania pennanti, formerly Martes pennanti), sometimes called a fisher cat, is. Unlike what its name suggests, it is not a fish hunter or a cat. In fact, a fisher may not hunt fish, but will eat fish lying on the river bank as they are opportunistic feeders.   A fisher is a meso-carnivore, which means a medium-sized animal that eats mostly meat in the form of small mammals, in addition to insects, plants and nuts.

A fisher is a forest dwelling creature that resembles a ferret or weasel.  They mostly live in tree cavities.  They measure up to 3 feet, including a very long and bushy tail. Males weigh about 12 lbs and females can be 8 lbs.  Their average lifespan is roughly 7 years, but some have been known to live longer.

Fishers are mustelids which weasels, martens, ferrets, minks, otters, badgers, skunks and wolverines.  Fishers only exist in North America, but their populations have been heavily fragmented due to the excessive harvesting of their pelts from the 18th century to the early 20th century.   Habitat conversion from continuous logging practices has also severely impacted them.  Existing populations reside along the US and Canadian border, New England, Appalachian Mountains, Pacific Northwest, and the Sierra Nevada Mountains.  The Pacific fisher is currently being petitioned to be recognized as an IUCN threatened species.

Wild Lens project director and wildlife researcher, Sean Bogle was first exposed to fishers during his employment with the Hoopa Valley Tribe on a fisher demography study.  “The study entailed trap and release methods that allowed us to collect a variety of biometrics (i.e. blood, teeth, hair, parasites, lengths and weights). We affixed radio collars to individuals and used radio-telemetry to track the movements of males and females within the Hoopa reservation to record their home ranges. During denning season we would track females to dens where they gave birth and raised their kits.  There were instances where we discovered and collected mortalities to be examined during necropsies.  This project was a unique opportunity for me to learn about such an elusive creature.”

Like many species, fishers have been faced with population declines due to human interference.  Historically, the fur trade and timber harvest had the greatest impacts.  Recently, it has been discovered that fishers are encountering a new challenge that is heavily impacting the population in the Sierra Nevada range.  This new obstacle is the use of anticoagulant rodenticides in illegal marijuana cultivation.  Deceased fishers have been examined and had traces of rodenticide in their system, and ultimately the cause of death.  Not only are the toxicants affecting the fisher population, but they are becoming prevalent within the entire ecosystem. Other wildlife such as black bears, wood rats, spotted owls and even snails have been poisoned by the rodenticides.  The impact on the fisher is but one example of how dire the situation is.   It is a simple illustration of the food web and how one stone in a pond can create a ripple effect.

Public and private lands are being polluted with trash by the illegal cultivators as they live in the grow sites until the marijuana is harvested.   The watershed has also been greatly impacted due to diverted streams to irrigate these pot farms. In addition, the rodenticides are penetrating the soil and showing up in the water system, which may affect aquatic species.  These areas have also become dangerous for everyday people who wander the forests because the cultivators will protect their crop at any cost.  Some of these growers are connected to crime organizations from Mexico.   It’s only a matter of time before humans are severely afflicted by these dangerous and illegal acts.

Wild Lens has teamed up with Will Goldenberg, wildlife biologist and filmmaker, to explore the life history and survival of the Pacific fisher as the species faces these issues.

Banner photo credit: Mark Higley



Pacific fisher resting on tree. Photo credit: Rebecca Green



Pacific fisher in cavity. Photo credit: Kerry Rennie



Pacific fisher in cavity. Photo credit: Kerry Rennie