Author: (Richardson, 1836)
FBname: Pacific lamprey
Remark: The landlocked population in the Sprague River, Klamath River Basin, Oregon, appears distinctive from other conspecifics in a number of characters and would benefit from a closer examination. For example, four of the five specimens from the Sprague River examined by Vladykov and Kott (1979a) did not possess wings on their velar apparatus and had counts between 7-10 tentacles, while typically, <i>E. tridentatus</i> possesses wings and 11-18 tentacles. Hubbs (1924) suggested that the population in Goose Lake, Oregon (the lake also straddles California) represented a separate but unnamed race. This requires further investigation (Ref.89241).  Consequently, <i>Entosphenus astori</i> (Girard, 1858) is questionably a synonym of <i>Entosphenus tridentatus</i> (Richardson, 1836) (Ref. 89241).
Comments: Anadromous, but also a number of permanent freshwater resident populations (Cultus Lake, British Columbia; Sprague River, Klamath River Basin, Oregon). In marine waters, adults mostly inhabit the mesopelagic zone down to 800 m depth and have been documented as far as 117 km off the coast of Oregon. In fresh waters, ammocoetes and adults inhabit lakes, rivers, and creeks. Ammocoetes occur in soft sediments in shallow areas along stream banks (Ref. 89241); in silt, mud, and sand of shallow eddies and backwaters of streams (Ref. 5723).  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).  Stops feeding once upstream spawning migration is underway (Ref. 1998). 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).  Adults are found in the Strait of Georgia from December to mid-June. The duration of the feeding phase at sea has been estimated at 20-42 months. In British Columbia, return to fresh water begins as early as April and is completed by September. In the Columbia River, prior to the completion of the Grand Coulee Dam in 1941, spawning migrations of 800 km up to Kettle Falls, Washington occurred. In order to cross barriers such as falls, they use their suctorial disc to attach to the vertical surfaces and slowly make their way up. In British Columbia spawning is in June to the end of July, while in Oregon, it begins in May at water temperatures of 10-15 °C and continues through July. Fecundity, 98,300-238,400 eggs/female in Oregon populations from Clear, Trout, and Cow creeks, respectively, in the John Day, Molalla, and Umpqua river basins. Death of spawners follows 3-36 days after spawning. Eggs are eaten by two species of fish in the Umatilla River, Oregon (Ref.89241). Rarely consumed as food; prepared fresh or smoked (Ref. 6885).  Sometimes processed into meal (Ref. 27436). The Native American tribes of the mid-Columbia River Plateau have an ongoing tradition dating back hundreds of years of harvesting Pacific Lamprey.  The adults are caught either by hand or dipnet in areas where they congregate prior to spawning. They are prepared for human consumption either by drying or roasting. Caloric values for Pacific Lamprey range from 5.9 to 6.3 kcal/g wet weight. Their oil is also extracted and used for medicinal purposes. Ammocoetes are used as bait for introduced <i>Micropterus dolomieu</i> in the John Day River, Oregon. In 1812, Americans of European descent obtained Pacific Lamprey from the Umatilla tribe of Oregon for the purposes of consumption. In the early 1900s, fur trappers utilized Pacific Lamprey as bait for coyotes. A fishery for adult lamprey has existed at Willamette Falls on the Willamette River, Oregon at least since 1913. That year, 24.5 metric tons were harvested and ground into fishmeal for young hatchery salmon. Between 1943 and 1949, 740 metric tons in total were harvested and used for vitamin oil, food for livestock, poultry, and fishmeal. In 1994, about 1.8 metric tons were exported to Europe for human consumption. The North Carolina Biological Supply House regularly collects adults from this locality for use as teaching material (Ref.89241). The effects of Pacific lamprey attacks on commercial species needs further studies (Ref. 6885).