Most of the world population is centered in the Bering and Okhotsk seas. Fur seals spend 9-11 mo each year at sea. Forage opportunistically in offshore waters on fish and squid, including anchovy, hake, rockfish, and mackerel. Feeding usually takes place at night.
Loose aggregations tend to form in areas of abundant food resources.
On land, occur in dense aggregations along rocky or sandy insular shorelines and offshore rocks. Highly philopatric, exhibiting marked site tenacity, returning to breed at birthsite. Freshwater appears to be derived through fluids in prey consumed, and metabolically produced from body fat stores during periods of fasting on land. Prefer insular breeding sites with nearby food supply and easy access to water. Breeding colony on San Miguel Island appears to remain in California waters throughout the year.