Lampetra ayresii (Günther, 1870).

Western River Lamprey. To 34.6 cm (13.6 in) TL (Morgan et al. 2018). Tee Harbor, south-eastern Alaska (Scott and Crossman 1973) to San Francisco Bay, northern California (Vladykov and Follett 1958). Anadromous, found in estuaries and coastal marine waters for a few months in summer; depth: at sea, perhaps to 119 m (390 ft) (DFO) (taken in a midwater trawl; Maria Cornthwaite).