SeaDoc Society Science Director Joe Gaydos is on the editorial board of the excellent Encyclopedia of Puget Sound, a program of the University of Washington's Puget Sound Institute. Joe’s latest entry offers up all you need to know about river otters. Get a sampling below and read in full here.
By Joe Gaydos
While not true marine mammals, river otters do use and rely on marine resources. The expansion of their populations since the early 1900s is a true conservation success story. Ecosystem recovery efforts and river otter reintroductions restored otter populations to much of their historic range. River otters often live in small social groups that include mother and offspring or other unrelated adults.
North American river otters (Lontra canadensis) are semi-aquatic mammals that range over most major river drainages, large lakes, and coastal marshes of North America. On the west coast, from Northern California (Bouley et al., 2015) to Alaska (Bowyer et al., 2003), river otters forage in and rely on healthy subtidal and intertidal zones where they feed on a variety of marine fish and invertebrates. The subspecies L. c. pacifica is found throughout the Salish Sea’s rivers, estuaries, coastlines, and coastal islands and plays an important role in the nearshore marine ecosystem. They are often confused with sea otters (Enhydra lutra) by the public because they are otters swimming in the sea. River otters do use and rely on marine resources, but taxonomically, they are not considered marine mammals like sea otters.