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Recovery Strategy for Gravel Chub

Executive Summary

 

The gravel chub (Erimystax x-punctatus) was last found in Canada in the Thames River drainage, Ontario, in 1958.  The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) designated this species as Endangered in 1985, and re-assessed it as Extirpated in 1987.  This status was re-examined based on an existing status report and confirmed in 2000.  The recovery of the gravel chub has been determined to be technically and biologically feasible.

The gravel chub is a slender, round-bodied minnow with an average length of 76 mm TL and a maximum length of approximately 100 mm TL.  It is olive-green dorsally with silvery sides and a white belly.  The scale margins on the back and sides of the gravel chub are randomly outlined in black resulting in distinct X-, Y- or W-shaped patterns.  A small black spot is usually predominant on the base of the caudal fin.  The snout is rounded and long, overhanging the mouth, which has small but conspicuous barbels in each corner.

In Canada, the gravel chub was only known from two locations in the Thames River drainage: at Munsee (Oneida Nation of the Thames) and in a stretch of the river in Mosa and Oxford townships, upstream of land owned by the Delaware of the Thames (Moravian Town) First Nation (or Delaware Nation Council (Moravian of the Thames).  These locations are approximately 300 km from the nearest American records in Ohio.

Gravel chub inhabit clear to moderately turbid, medium to large streams, containing abundant riffle areas with silt-free sand, gravel or rock substrates.

The narrow habitat requirements of gravel chub make it vulnerable to habitat degradation and declines in water quality.  Siltation and turbidity are believed to be the primary reason for the decline and eventual extirpation of gravel chub from Ontario.  Nutrient loading, as a result of agricultural and urban practices (e.g. fertilizers, manure spreading, sewage treatment), may have also contributed to its extirpation.

The Gravel Chub Recovery Team consists of representatives from various Canadian and American agencies.  As the gravel chub is one of 23 aquatic species found in the Recovery Strategy for the Thames River Aquatic Ecosystem, recovery approaches and actions related to Habitat Improvement and Stewardship, and Habitat Protection and Management are identified in, and will be addressed under, this watershed recovery strategy.  Therefore, species-specific Research and Monitoring recovery approaches are the focus of this recovery strategy.  The Recovery Team determined the long-term recovery goal of this strategy is to encourage healthy, reproducing gravel chub populations in the Thames River through habitat improvements if the species is found to be present and, if appropriate, re-introductions if the species is confirmed to be extirpated.  The team also developed six short-term (5 year) recovery objectives:

 

  1. Confirm that gravel chub is no longer presentin historical areas of occurrence in the Thames River;
  2. Determine the extent and quality of gravel chub habitat in areas of former occurrence;
  3. Identify key habitat requirements in order to define critical habitat and implement strategies to protect and restore recovery habitats;
  4. Identify threats, evaluate their impacts and implement remedial actions to reduce their effects;
  5. Examine the feasibility of relocations, captive-rearing and re-introductions; and,
  6. Identify responses to, and evaluate the success of, recovery measures.

The Research and Monitoring approaches identified by the Gravel Chub Recovery Team include monitoring and surveying populations and habitat, life history and critical habitat research, rearing and re-introduction techniques, and long-term monitoring.