Gravel chub (Erimystax x-punctatus) COSEWIC assessment and status report: chapter 6

Biology

General

Nothing is known of the biology of gravel chub in Canada and little has been reported on this species for American populations (Tautman 1981; Becker 1983). Specimens from the Thames River were 52-57 mm long and, based on data for specimens from Ohio (Trautman 1981), it is probable that the Ontario specimens were adults.

Reproduction

In the United States, gravel chub have been reported to spawn during the spring in areas of rapid current over gravel riffles (Becker 1983; Parker et al. 1987). In Kansas, spawning took place in April at a water temperature of 15.5°C (Becker 1983). Non-adhesive eggs are scattered over the gravel substrate where they remain until hatching. No parental care is given (Coker et al. 2001).

Survival

There is no information on longevity of the species, but it may live up to 4 years as do other species of the genus and probably matures at 1-2 years of age (see Jenkins and Burkhead 1983).

Diet

The gravel chub is a bottom feeder, thought to eat aquatic insects. Food probably consists of epibenthic insects (Parker and McKee 1980). Davis and Miller (1967) found that taste buds on the barbels were extremely large suggesting that this species feeds by probing under rocks and into crevices with its sensitive snout.

Dispersal/migrations

Unknown.Given the narrow habitat requirements and restricted distribution, populations were probably confined to areas where there was sufficient current to keep the bottom free of silt (see Becker 1983). Scott and Crossman (1998) suggested that if gravel areas in preferred habitat become silted over, the gravel chub moves into faster, shallower areas.

Interspecific interactions

The ecological role of the species in the Thames River is not known (Edwards et al. 2007). Fish assemblages in the Thames River (Edwards and Mandrak 2006) include such piscivorous predators (McAllister et al. 1985) as rock bass (Ambloplites rupestris) and smallmouth bass (Micorpterus dolomieu), northern pike (Esox lucius) and yellow perch (Perca flavescens).

Behaviour

Unknown.

Adaptability

The species is susceptible to turbidity and siltation, and apparently does not readily adapt to perturbations in habitat quality (Becker 1983; Trautman 1981). Increases in the range and abundance of gravel chub have been reported since recent improvements to the water quality and habitat of Illinois and Ohio rivers (Retzer 2005, Yoder et al. 2005).

Captive propagation of closely related Erimystax species has been successfully undertaken (Conservation Fisheries Inc. 2001). An attempt to expand the range of the gravel chub (the western subspecies, E. x-punctatus punctatus) along the Rock River, Wisconsin was, however, unsuccessful. Survival during transfer was high, but no gravel chub were recaptured during 2-3 years of follow-up monitoring. Lack of success was attributed to the low number of individuals transferred, a lack of information on population limiting factors, and a lack of quantitative habitat data before the project began (John Lyons, Wisconsin Department of Natural Resources, personal communication 2007).

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