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Ignoble purrsuits

Frustratingly few people know about fishers (Pekania pennanti). This cat-sized North American mustelid used to be classified in the genus Martes, but never quite fit in. The fisher used to inhabit the whole boreal forest belt of North America, but their populations began to decline in the first half of the 20th century due to a combination of overtrapping for their fur, and timber logging, which shrunk and fragmented its range. In fact, the fisher was nearly exterminated from the southern and eastern part of its range. However, thanks to conservation efforts and sustainable trapping management, fishers are making a splendid comeback in many states, lifting it out of many local endangered species lists (and even eating unsupervised pet cats as they proceed).

US Forest Service [CC BY 2.0 DEED], via

While sharing the range, habitat and many dietary and behavioral traits with true martens such as the American marten (Martes americana) and Pacific marten (Martes caurina), the fisher is a bigger, burlier animal with a longer tail, coarser fur and heavier head; it oddly resembles a fuzzy otter with a bear’s head. Not only its looks are confusing. Fishers may look a bit clumsy, yet they are excellent tree climbers and are among the very few mammals able to descend trees head-first. Their climbing abilities are facilitated by being able to rotate their hind paws nearly 180°. Fishers are considered omnivorous, but their primary prey are snowshoe hares and North American porcupines (one of the very few predators known to hunt this species). Fishers have even been documented to be predators of Canada lynx! Fishers are sexually dimorphic, with males larger than females, and they are mostly solitary except during the mating season. Like some other carnivoran species, female fishers show embryonic diapause (also known as delayed implantation).

Even their name is misleading – fishers do not catch fish! The name is in fact a corruption of the word “fitch”, which is an old-fashioned term for the European polecat; the word “fitch”, in turn, goes back to Late Latin vissiō "foul smell from a noiseless fart". So much for nomenclatural dignity! The lasting taxonomic hassle among scholars, bouncing the fisher between different genera, was finally settled in 2008, when the fisher got assigned a genus of its own, Pekania, as one of the earliest branching lineages of the Guloninae clade, just like its similarly-sized South American relative, the tayra (Eira barbara).

Today, we release the chormosome-length genome assembly for the fisher, generated from a sample shared by the New York State Department of Environmental Conservation. We acknowledge Timothy Watson for providing fisher samples for sequencing and Roger Powell for making this genome assembly possible. Check out the interactive contact map below!

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