Entosphenus tridentatus (Richardson, 1837) .

Pacific Lamprey. To 85 cm (33.5 in) TL (Orlov et al. 2008b). Honshu (Orlov et al. 2008b), and Hokkaido, Japan (Nakabo in Nakabo 2002); eastern Chukchi Sea (Mecklenburg et al. 2002), and Bering Sea to Punta Canoas, northern Baja California (Miller and Lea 1972), and likely to Isla Clarión, and Islas Revillagigedo, Mexico (Renaud 2008). Southernmost freshwater occurrence is currently in the Big Sur River, central California (Reid and Goodman 2016). Depth: at sea, near surface to 1,508 m (4,946 ft) (min.: Eschmeyer and Herald 1983; max.: Hoff and Britt 2003). Anadromous, may be found at sea, often far offshore, any time of the year. Previously as Lampetra tridentata (Richardson, 1836) . The author of the species description is sometimes given as Gairdner, or Gairdner in Richardson, but authorship evidently is correct as Richardson, or Richardson (ex Gairdner) (Eschmeyer 1998 and online edition 8 November 2004).