The Fraser River Is a Safe Refuge for a Major Predator of Pacific Salmon and Herring

The Fraser River is 1,375 km in length, with the 3^rd greatest mean annual flow in Canada, and is one of the major salmon producing rivers of the world. It drains an area of 234,000 km², the 5^th largest drainage in Canada, ¼ of the area of the Province of British Columbia, flowing into the ocean through the City of Vancouver. The dominant organism in the benthos of the lower 100 km of the river is the parasitic River lamprey, Lampetra ayresii. This species is mostly restricted to the large rivers on the west coast of North America from San Francisco Bay in California to just north of Juneau Alaska. It is closely related to the non-parasitic Western brook lamprey, L. richardsoni, but can be distinguished by the different life history, differences in the number of cusps on some of the teeth and the morphology. It is a voracious predator on Pacific herring and Pacific salmon for several months in the summer. Despite its abundance and impact on fishes important to humans, it is mostly ignored.