Spawning adults are found in gravel riffles and runs of clear coastal streams; feeding adults usually in the ocean, but landlocked populations occur (Ref. 1998); ammocoetes in silt, mud, and sand of shallow eddies and backwaters of streams (Ref. 5723). Parasitic adults attach themselves to the side or undersurface of its prey, from which it draws blood and body fluids as food. Preys on fishes and sperm whales (Ref. 6885). Stops feeding once upstream spawning migration is underway (Ref. 1998). Rarely consumed as food; prepared fresh or smoked (Ref. 6885). Sometimes processed into meal (Ref. 27436). The effects of Pacific lamprey attacks on commercial species needs further studies (Ref. 6885).