There are thirteen species of otters alive today. There used to be fourteen, but the fourteenth otter, Maxwell's otter, is presumed extinct due to draining of their waters to perform genocide in Iraq.

River otters have no significant predators except man. 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. They are usually taken in steep traps. Natives in Prince William Sound once hunted otters with the aid of dogs of a nondescript type that were small enough to enter an otter den. The dogs could usually drive out the otter without a fight.