Northern Pikeminnow

The Columbia River Basin of western North America is an important habitat for the 63 centimeter (cm) long benthopelagic northern pikeminnow (Ptychocheilus oregonensis). The Columbia River is the largest North American watercourse by volume that discharges to the Pacific Ocean. With headwaters at Columbia Lake, in Canadian British Columbia, the course of the river has a length of approximately 2000 kilometers and a drainage basin that includes most of the land area of Washington, Oregon and Idaho as well as parts of four other U.S. states and two Canadian provinces. The hydrology and aquatic habitat of the Columbia River basin has been adversely altered by numerous large dams. There are over 250 reservoirs and around 150 hydroelectric projects in the basin, including 18 mainstem dams on the Columbia and its main tributary, the Snake River. Water quality has deteriorated over the last century, due to agricultural runoff and logging practices, as well as water diversions that tend to concentrate pollutants in the reduced water volume. For example nitrate levels in the Columbia generally tripled in the period from the mid 1960s to the mid 1980s, increasing from a typical level of one to three milligrams per liter. Considerable loading of herbicides and pesticides also has occurred over the last 70 years, chiefly due to agricultural land conversion and emphasis upon maximizing crop yields. Heavy metal concentrations in sediment and in fish tissue had become an issue in the latter half of the twentieth century; however, considerable progress has been made beginning in the 1980s with implementation of provisions of the U.S.Clean Water Act, involving attention to smelter and paper mill discharges along the Columbia. Another large benthopelagic fish in the Columbia is the 45 cm Tui chub (Gila bicolor). Other large demersal vertebrate species occurring in the Columbia Basin are the 55 cm Brown bullhead (Ameiurus nebulosus); the 61 cm largescale sucker (Catostomus macrocheilus); the 64 cm longnose sucker (Catostomus catostomus catostomus); the 65 cm Utah sucker (Catostomus ardens); and the 76 cm Pacific lamprey (Lampetra tridentata).

Mot deep bodied, greatest depth 16.6% (TL), belly gently rounded in mature individuals. Head moderately long, its length 22.8% (TL); eye small in adults, 17.6% of head length, but larger in young 7.6 cm long, when 25.2% of head length; snout long, 33.1% of head length of adults; interorbital width 29.6% of head length; mouth large, extending back to below anterior margin of eye. All fins clear. Pelvic axillary process usually a ridge. Peritoneum present. Nuptial tubercles fine, on head and back, on pectoral and pelvic fins and sometimes on the caudal fin. Dark green or green-brown dorsally becoming silvery white or cream ventrally. The lower fins of the males become yellow or yellow-orange during spawning period (Ref. 1998). Dorsal fin usually with 9 rays; anal fin with 8 rays; 48-72, usually 51-62, scales on back from head to dorsal fin; 64-79, usually 66-75, scales on lateral line; and 12-20 scales above lateral line (Ref. 86798).

A female is surrounded by males close to the bottom; eggs and sperm are released at the same time and eggs settle in the gravel.

Dorsal soft rays (total): 9 - 10; Analsoft rays: 8 - 9; Vertebrae: 44 - 46

Occurs in lakes, pools and occasionally in runs of small to large rivers. Prefers still waters and swift streams. Young inhabit inshore waters during the summer, moving to deeper waters in the fall. Larger individuals remain offshore. Feeds on fishes, terrestrial insects, plankton, aquatic insect larvae, and crustaceans while inshore; feeds mostly on fishes while offshore (Ref. 1998).

Found in lakes, pools and occasionally in runs of small to large rivers. Large individuals occur in deep water (Ref. 5723, 86798). Feeds on fishes, terrestrial insects, plankton, aquatic insect larvae, and crustaceans while inshore; feeds mostly on fishes while offshore (Ref. 1998). Male squawfish, prickly sculpins, and newts prey on the eggs (Ref. 1998). Edible but not well appreciated (1998).

gamefish: yes; aquarium: public aquariums

The Northern pikeminnow, Columbia River dace or colloquially Squawfish (Ptychocheilus oregonensis) is a large member of the minnow family, Leuciscidae. This predatory freshwater fish is native to northwestern North America, ranging from the Nass River basin to the Columbia River basin. A good deal of concern has been expressed regarding the impact northern pikeminnow populations may have on salmon in Columbia and Snake River impoundments.