Larger numbers that are occasionally seen together may represent a temporary association of neighboring groups. The groups have no apparent leader. Otters travel together and operate as a social unit but do not cooperate in hunting or share what is caught. They travel over a wide area, and apparently there are no exclusive territories. Fighting among otters is extremely rare, although they are wary of strange individuals.
River otters produce a variety of noises.
They growl, caterwaul, and whine. When two or more are together, they often produce a mumbling noise that seems to be a form of conversation. A bird-like chirp apparently expresses anxiety and is most often heard when members of a group become separated. They are occasionally killed unintentionally when they become entangled in fish nets or trapped in crab pots. For the last 10 years, between about 1,200 and 2,400 otters have been harvested annually in Alaska for their pelts.