Fisher, a carnivorous digitigrade mammal, belonging to the family mustelidae, subfamily martinoe, and genus mustela (Linn.); this animal (called also Pennant's marten, black cat, and pekan) and the pine marten are the only two species of the genus found in North America. The fisher (M. Pennantii, Erxl.) is the largest known species, the length of the body being over 2 ft., and the tail 1 1/4 ft. The dental formula is: incisors 3-3/3-3, canines 1-1/1-1, premolars 4-4/4-4, molars, 1-1/2-2=18/20. 38 in all; the lower carnivorous tooth has a rounded lobe on the inner side, indicating a less sanguinary disposition than that of the weasels. The general appearance is fox-like; the head is long and muzzle rather pointed; the ears short, rounded, and wide; the eyes large; body slender; tail long and bushy at the base; feet short, stout, and armed with strong sharp claws, five on each foot; no anal pouch, but a small gland which secretes a musky fluid. The fur is of two kinds, the outer long and coarse, the inner fine and soft. The general color is blackish, with a grayish tinge on the head and shoulders; some specimens are brownish, and a few with light tints; there is sometimes a white spot on the throat.
Specimens vary so much in size and coloration that it has been supposed that two species are confounded under the name. A specimen measuring 23 in. in length of body, with the tail 14 in., would weigh about 8 1/2, lbs. Occasionally seen in Pennsylvania and New York, and even as far south as North Carolina, it is common in Canada and in the Lake Superior mineral region; it is found as far north as lat. 63°, and across the continent to the Pacific. It is eminently an arboreal species, very agile, though less so than the squirrel, which it is fond of pursuing; it is generally nocturnal in its habits: it preys upon hares, raccoons, squirrels, grouse, mice, and any small bird or quadruped which it can seize. Though called fisher, there is no certain evidence that it catches fish, but it is fond of the fish with which the hunter baits his traps for the pine marten; in this respect the fisher is a great nuisance, as it breaks into the traps from behind, sometimes robbing every one in a line of miles, escaping itself and preventing the capture of the more valuable pine marten. Fishers have been often kept in confinement, where they become docile if taken when young; but the temper is very changeable, and they quickly become angry without apparent cause.
From their agility, strength, and ferocity, they are difficult to obtain unless severely wounded. Like the other fur-bearing animals, the fisher's pelage is finest in winter and in high latitudes; a skin is worth about $1 50, while that of the smaller pine marten is worth $2 50; their fur is not much used in the United States, but is generally sent to Europe, where it is used for linings of more costly furs, for trimmings, and for robes. It brings forth its young once a year toward the end of spring, from two to four at a birth, depositing them in hollows in trees at a considerable height above the ground. This animal is called by Schreber M. Canadensis.
Fisher (Mustela Pennantii).