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North Dakota's

Federally Listed Endangered, Threatened, and Candidate Species – 1995

Blue Sucker (Cycleptus elongatus )

GIF -- species photo gif--species map

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Status: Former Candidate (Note: As of February 28, 1996, this species is no longer listed as a Candidate species. However, it remains a species of management concern.)

Historical Status:
First discovered in 1817, blue suckers have since been reported from the Missouri, Mississippi, Ohio and Rio Grande Rivers and most major tributaries. Commercial Fishermen and consumers once prized the blue sucker's palatable flesh. In 1894 and 1899 alone, nearly 2 million pounds of blue suckers were collected on a 21-mile section of the Mississippi River between Keokuk, Iowa and Canton, Missouri. By 1910, after construction of a series of locks and dams, the blue sucker catch declined to 700,000 pounds on the same river section.

Present Status:
Blue suckers are occasionally collected in the Missouri, Mississippi, Ohio and Rio Grande River systems. In North Dakota, blue suckers inhabit the Missouri, Yellowstone, Cannonball, and Heart Rivers. Two individuals were collected in North Dakota in 1991. No reproduction has been documented in North Dakota; however, specimens as young as 5 years of age have been collected.

Blue suckers are designed for living in large rivers with strong currents and high turbidity. However, they do survive in reservoirs as long as nearby tributary streams provide spawning habitat. Blue suckers prefer smooth substrates of fine gravel and rocks. Juveniles occupy shallower habitat with less current. Adults winter in deep pools and move upstream in spring to rocky spawning areas. Blue suckers feed off the bottom and do not need to see to locate food. This allows them to survive in muddy streams typical of the Great Plains.

Life History:
Blue suckers become sexually mature between 3 and 6 years of age, with males maturing earlier than females. Spawning occurs in the spring and early summer (April-June) in deep (3-6 feet), rocky rapids. Large females can produce over 130,000 eggs. Blue sucker eggs average 1/16" in diameler. The eggs are adhesive and stick to the rocks so they are not swept downstream. Juvenile suckers are nearly 5 inches long by the end of their first summer. Insect larvae and filamentous algae are the primary food. Juvenile blue suckers may be preyed upon by game fish such as walleye and northern pike. Several blue suckers have been collected which were 10 years old.

Aid to identification:
Blue suckers vary in color from slate blue in spring to a pale olive-blue in the summer and fall, with slate blue fins. The blue color is very distinctive among fish. The dorsal fin is distinctively sickle-shaped and much longer than that of other suckers. The head is small and tapers to a fleshy snout. The lips of both species are covered by wart-like bumps. The head, body and fins of mature males are covered with small fleshy bumps during the spawning season. Blue suckers have been reported to reach over 3 feet in length and weigh 15 pounds. Females are larger than males at all ages.

Reasons for decline:
The decline in abundance of blue suckers throughout their range has been attributed to habitat loss associated with construction of reservoirs and lock and dam systems. Siltation, pollution, reduced water velocity, loss of spawning habitat, and blocked migration routes have each been associated with the decline of the species. Commercial fishing may have also impacted blue sucker populations.

Blue suckers are difficult to sample due to their deep, high-velocity habitat. They may occasionally be caught on hook-and-line. Report caught blue suckers to a local fisheries agency.

Life history information on the blue sucker, Cycleptus elongatus (Le Sueur), in the Missouri River, a M.S. thesis by C. D. Beal, 1963, University of South Dakota.
Fishes of Arkansas, by H. W. Robison and T.M. Buchanan, 1988. Published by the University of Arkansas Press, Fayetteville.

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