Blue Sucker

Characteristics

A slender, dark-colored sucker with a small head and a long, sickle-shaped dorsal fin. Blue-black or dark olive back and sides with brassy reflections and a white belly. Breeding males are very dark and have small tubercles over most of its head, body and fins. Small eyes are closer to the rear margin of the gill cover than to the tip of the snout. Its mouth is small, horizontal, and distinctly overhung by the snout. Lips are covered with numerous wart-like papillae. Lateral line is complete, with 55 to 58 scales. Body length is about four to five times greater than body depth. Fins dusky or black, dorsal fin with 28 to 33 rays.

Distribution

The Blue Sucker is rarely found in fish collections in Iowa, but is widespread in the Mississippi and Missouri Rivers and the lower reaches of their larger tributaries. It has never been documented in the upper reaches of our interior streams. Abundance has declined since the early 1900's, but the species remains unprotected.

Foods

Aquatic insects and their larvae, crustaceans and plant material including algae, which they glean from the bottom in the typical vacuum-like manner.

State Record

15 lbs. 6 oz.; 33.25 in. - Iowa River, Johnson County, 4/11/2011 - Steven Jones, Iowa City

Expert Tip

These fish are mostly likely found at the lower end of tributaries to the Mississippi and Missouri Rivers.

Details

Blue Suckers prefer the deep, large rivers and are usually in the narrow chutes and swift channels where the current is moderate to swift over a bottom of gravel, sand and rocks. They are tolerant of high turbidity. Past records show this species made important spring runs up the Cedar River to the dam at Palisades State Park near Cedar Rapids, but they have nearly disappeared from this river stretch.

The Blue Sucker is most widely distributed in the Missouri and Mississippi Rivers and can occasionally be found in the lower reaches of their tributaries. There is no record of Blue Suckers ever being caught in the upper reaches of Iowa’s interior streams. Because it is virtually invulnerable to normal collecting most of the year, the Blue Sucker is likely more abundant and widespread than is reported.

The Blue Sucker prefers the swift waters of big rivers overlying firm substrates such as sand, gravel or rock. Researchers have found that it also lives in the channels of deep lakes. It prefers clear channels and pools with moderate current. As a migratory species, the Blue Sucker has declined in abundance since 1900 as dam construction increased. Dams have also limited its habitat by decreasing current velocity and increasing siltation. Due to its sensitivity to heavy pollution and siltation, the Blue Sucker can serve as a guide to judge water quality.

Little is known about the Blue Sucker life history in Iowa. Fisheries literature reveals that an upstream spawning migration into riffle areas takes place in late April to early May at water temperatures of 50 to 60 degrees. They are gregarious spawners broadcasting the semi-adhesive eggs over gravel and rubble bottoms directly in the current. Sexual maturity occurs at ages 2 and 3. How long eggs ares incubated and how many eggs are produced is unknown.

Growth of this species has been documented in the Cedar River in Wisconsin. Twelve fish in the study that ranged from 4 to 11 years averaged 3.5, 8.9, 14.8, 19.2, 21.1, 22.6, 24.0, 25.2, 26.2, 27.2, and 28.6 inches at the end of each year of life. 

Like the other sucker species in Iowa, these fish have minimal importance to anglers. It is viewed as vulnerable according to the Iowa Wildlife Action Plan, but it not on the threatened or endangered species lists in Iowa (571 IAC 77.2(2) (2015)).

Recent stream sampling information is available from Iowa DNR's biological monitoring and assessment program.

Sources:

Harlan, J.R., E.B. Speaker, and J. Mayhew. 1987. Iowa fish and fishing. Iowa Conservation Commission, Des Moines, Iowa. 323pp.

Iowa Department of Natural Resources, Iowa Wildlife Action Plan

Loan-Wilsey, A. K., C. L. Pierce, K. L. Kane, P. D. Brown and R. L. McNeely. 2005. The Iowa Aquatic Gap Analysis Project Final Report. Iowa Cooperative Fish and Wildlife Research Unit, Iowa State University, Ames

Pflieger, W.L. 1997. The fishes of Missouri. Missouri Department of Conservation, Jefferson City, Missouri. 372 pp.

Photo Credit: photo courtesy of Konrad P. Schmidt, copyright Konrad P. Schmidt