The Gravel Chub... a Species at Risk

This species has been identified as Extirpated by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). It is listed under the federal Species at Risk Act (SARA) and has been afforded protection under the SARA as of June 2004. Additional protection is afforded through the federal Fisheries Act. Under the SARA, a recovery strategy must be developed for this species.

General Description

Erimystax x-punctatus

© Joseph R.Tomelleri

The Gravel Chub (Erimystax x-punctatus) is a member of the Minnow family (Cyprinidae) and has the following characteristics:

• Body is fragile, slender, small and somewhat compressed laterally;
• Average length of Ontario adults is 76 mm;
• Snout rounded, overhanging the small mouth; small but conspicuous barbell;
• Eye diameter relatively large;
• All fins transparent; forked tail, dorsal fin with short base;
• Overall colouration silvery with olive green on back and silvery white below;
• Scale margins randomly outlined in black creating X- or Y-shaped marks that were usually faint on Ontario specimens; and
• Ontario specimens did not show a prominent caudal spot.

Distribution

The range of the Gravel Chub is mainly central North America. In Canada, this species was only known in two locations in the Thames River; however, no specimens have been recorded since 1958. More recent attempts to find the species have supported suspicions that these localized Ontario populations no longer exist. There is no current evidence of reproducing populations in Canada.

Habitat and Life History

Ontario historical capture records, and U.S. populations indicate that the preferred habitat for this species is pool and riffle habitats with sand, rock and stone with areas of soft organics and silt. Bank cover is minimal in these areas and summer water temperatures range from 18 to 25°C. Gravel Chub have been reported elsewhere in clear to moderately turbid streams with permanent flow and well-defined sand, gravel or rocky riffles where flow is sufficient to keep the river bottom free of unconsolidated silt and clays. Little is known about the life history but spawning is reported to occur in early spring in Kansas populations.

Diet

The diet of the Gravel Chub probably consists of small benthic insects and larvae found by probing under rocksand in crevices using sensitive barbels on the snout.

Threats

Current threats include habitat loss or deterioration by siltation and increased turbidity, and impoundment of riffle areas.

Similar Species

Hornyhead and River Chubs (Nocomis biguttatus and Nocomis micropogon) are similar but have smaller eyes. Silver Chubs (Macrhybopsis storeriana) lack spotting over the body and have greater body depth.

Text Sources: Parker et al. 1987; Scott and Crossman 1998.

For more information, visit the SARA Registry Website at www.SARAregistry.gc.ca.