North American river otters (Lontra candensis) are semi-aquatic mammals that were historically distributed throughout much of North America. Otters are native to Ohio but were extirpated by the early 1900s. In 1986, the Ohio Division of Wildlife began a seven-year project to reintroduce the species to the state. Over this period, 123 otters were captured in Arkansas and Louisiana using modern foothold traps and were released in the Grand River, Killbuck Creek, Little Muskingum River, and Stillwater Creek watersheds. Since then, river otter presence has been confirmed in 75 watersheds throughout the state.
Otters are highly adapted for swimming, possessing a long, tapered body with sleek, short, dense fur. Its small head widens to the neck and shoulders. There are long, stiff and highly sensitive facial whiskers behind and below the nose that aid the otter in finding and capturing prey. Their teeth are like those of other carnivores--adapted for grasping, grinding, shearing, and crushing. Their large feet are completely webbed. The tail is flattened and is well muscled; the tail is important in the animal's swimming ability and makes up about 50 percent of its total body length. Maximum length is reached at three to four years of age. Adult weight ranges from 11 to 33 pounds.
Breeding occurs in early spring following the birth of a litter. Newborn pups are silky black, blind, toothless, and helpless. They grow rapidly and emerge from the den at two months of age. Young eat solid food at this age as well; however, they are not weaned until they are three months old. Litters are cared for by the female otter.
Young otters are self-sufficient by the time they are five to six months, but the family group remains intact for at least seven or eight months or until just prior to the birth of a new litter. Yearling otters can disperse up to 20 miles or more from where they were reared.
Habitat & Behavior
Otters live in aquatic habitats--rivers, lakes, and marshes. Otters can live in both marine and freshwater environments. They prefer tributaries of major, unpolluted drainages where there is minimal human disturbance. Log jams and submerged trees provide resting and feeding habitat. They typically eat fish, aquatic insects, crayfish, snakes, frogs, and, to a lesser extent, waterfowl and mammals. Often dens are in abandoned beaver lodges and bank dens.
Otters are generally nocturnal (active at night) or crepuscular (active at dawn or dusk), although diurnal (daytime) activity is not uncommon in undisturbed areas. River otters are often seen in family groups in the summer and early fall.
Research & Surveys
Since the initial reintroduction, the abundance and distribution of river otters has increased across Ohio. River otter population trends are tracked through annual river otter bridge surveys, reported sightings, and harvest trends. River otter presence has now been confirmed in 83 of 88 counties. Increases in otter numbers are likely the result of improved aquatic habitats, an expanding beaver population, and similar restoration efforts in neighboring states. Continued population growth has provided additional opportunities for viewing river otters, especially in eastern Ohio. River otter populations remain most abundant near the original release site watersheds, particularly Grand River watershed in Northeast Ohio and Little Muskingum River watershed in Eastern Ohio.
A highly regulated and limited trapping season has been open in eastern Ohio since 2005. In response to increases in otter abundance and distribution in the central and western portions of the state, trapping opportunities were made available statewide during the 2018-2019 season.