Western Brook Lamprey Identification Guide

Key identification features

• Small body, typically 10-17 cm at maturity, one of the smallest lampreys in its range
• Two low dorsal fins that sit close together, almost touching along the back
• Small oral disc with weakly developed, blunt teeth since adults never feed
• Dark brown to olive coloration above, contrasting with a pale cream belly
• Slender, scaleless, eel-like body with no paired fins
• Larvae are toothless and blind, living buried in stream sediment for several years before a brief adult stage

Common look-alikes

• Pacific lamprey is much larger and parasitic, with a wide oral disc bearing large, sharp rasping teeth this species lacks.
• River lamprey is intermediate in size and parasitic, showing better-developed teeth and a longer feeding adult stage.
• Other small brook lampreys look similar but occupy separate river systems, so range is often the deciding factor.

Where you'll see one

This species lives its whole life in small coastal streams and their tributaries along the Pacific Northwest, from British Columbia south through Washington and Oregon into northern California, favoring gravelly riffles and silty backwaters.