Recovery Strategy for Gravel Chub
2.1 Recovery Objectives
Long-term Recovery Objectives
The long-term recovery goal 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.
Short-term Recovery Objectives (5 year)
- Confirm that gravel chub is no longer presentin historical areas of occurrence in the Thames River. This is important as very little field work has been done in the area of the historic capture sites of gravel chub in the Thames River;
- Determine the extent and quality of gravel chub habitat in areas of former occurrence;
- Identify key habitat requirements in order to define critical habitat and implement strategies to protect and restore historically occupied habitats;
- Identify threats, evaluate their impacts and implement remedial actions to reduce their effects;
- Examine the feasibility of relocations, captive rearing and re-introductions; and,
- Identify responses to, and evaluate the success of, recovery measures.
2.2 Feasibility of Recovery
Recovery feasibility is determined according to four criteria outlined in Government of Canada (2006):
Are individuals capable of reproduction currently available to improve the population growth rate or population abundance?
Yes. Gravel chub have not been collected from the Thames River since 1958 and it is considered extirpated. Gravel chub populations of the same subspecies (E. x-punctatus trautmani) in Ohio (S3) and Indiana (S4) are considered stable and, therefore, represent potential source populations to support re-introduction efforts if appropriate.
Is sufficient suitable habitat available to support the species or could it be made available through habitat management or restoration?
Yes; however, this needs to be assessed as per Short-term Recovery Objective ii. There may be areas of clean riffles where the current is strong enough to dislodge the silt and clay. Suspended sediment may be tolerable. Across its North American range, gravel chub is primarily found in gravel and rocky riffles where the current prevents excessive siltation. Its historic distribution in Canada was limited to a few locations along the Thames River. During the last targeted gravel chub survey, riffle habitats were present; however, habitats were affected by high levels of turbidity (Holm and Crossman 1986). No recent targeted habitat inventories have been undertaken at these sites. However, recovery approaches to improve habitat conditions and water quality are identified in the Recovery Strategy for Thames River Aquatic Ecosystem (TRRT 2005).
Can significant threats to the species or its habitat be avoided or mitigated through recovery actions?
Yes. It is believed that habitat degradation, caused primarily by increased siltation and turbidity, was the main cause of its extirpation from Canada. TheRecovery Strategy for Thames River Aquatic Ecosystem identifies recovery actions (under the Habitat Improvement and Stewardship, and Habitat Protection and Management recovery approaches) to improve aquatic habitat conditions and water quality (TRRT 2005).
Do the necessary recovery techniques exist and are they demonstrated to be effective?
Yes. 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 rearing and translocations have been used in southeastern United States towards recovery of endangered benthic fish species (Shute 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 to 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, pers. comm.).
The Thames River Recovery Team determined that gravel chub recovery to be feasible within the Thames River watershed (TRRT 2005).
2.3 Approaches Recommended to Meet Recovery Objectives
Threats to historically occupied gravel chub habitat related to siltation and turbidity, nutrient loadings, and toxic compounds are addressed by actions identified in theRecovery Strategy for the Thames River Aquatic Ecosystem (TRRT 2005). Therefore, protection and improvement of historically occupied gravel chub habitat will be undertaken through the Habitat Improvement and Stewardship, and Habitat Protection and Management recovery approaches identified in the watershed recovery strategy (TRRT 2005).
Species-specific recovery actions related to ‘Research and Monitoring’ are detailed in the following section, along with more detailed information below the table, if required.
2.3.1 Recovery Planning
Table 2. Research and monitoring approaches for gravel chub recovery.
|Priority||Number||Objective Addressed||Broad Approach /Strategy||Specific Steps||Anticipated Effect|
|Urgent||i-1||i||Monitoring- Gravel Chub Survey||Undertake a targeted survey in areas of historic occurrence. This must include sampling with a trawl net, the gear that captured them in 1958.||Will provide additional evidence for absence, or confirm presence of gravel chub.|
|Urgent||i-2||ii||Monitoring- Habitat Surveys & Mapping||Define the habitat characteristics of the gravel chub. Evaluate and map the distribution, quantity and quality of habitats in the area of historic occurrence.|
Will enable the identification and definition of critical habitat for the gravel chub as per SARA.
Will assist in identifying residence if appropriate.
Will assist in identifying threats to gravel chub habitat
Will direct habitat recovery actions.
|Urgent||i-3||iii, iv, v, vi||Research – life history characteristics of all life stages||Determine the life history characteristics of all life stages including diet, reproduction, ecological requirements. Clarify threats.|
Will assist in refining necessary recovery actions and identify potential measures of success.
Will assist in identifying residence if appropriate.
Will identify and clarify threats.
Will enable population modeling for potential re-introduction efforts.
|Urgent||i-4||iii||Research – Critical Habitat||Determine the habitat needs of all life stages.|
Will assist with defining critical habitat so that it can be protected under SARA.
Will direct habitat recovery actions.
|Necessary||i-5||v||Research – Captive Rearing and Re-introduction|
Determine the feasibility and appropriateness of re-introductions in areas of suitable habitat.
Where re-introductions are deemed appropriate for restoring populations (historical or degraded), develop a re-introduction plan.
|Will assess the need for re-introductions to meet long-term recovery goals, investigate whether potential source populations exist, determine the feasibility of captive rearing, and establish/adopt a husbandry protocol if captive rearing is feasible.|
|Beneficial||i-6||v, vi||Monitoring – Long-term Habitat and Population Monitoring|
Evaluate the quality of habitats in areas of planned re-introduction. Information from the activities suggested in i-2 should determine where re-introductions occur.
Survey locations of gravel chub re-introduction, should this take place.
Will determine when habitat conditions are suitable for re-introductions.
Will determine if re-introduction efforts are successful at re-establishing viable populations.
Prior to developing re-introduction plans, it is necessary to confirm through intensive sampling that gravel chub are no longer present. The last targeted gravel chub survey was undertaken in 1985. To be consistent with past sampling efforts, sampling should occur during July and October and utilize a trawl, seine nets and electro-fishing gear. Backpack and boat mounted electro-fishing units have been very effective at collecting gravel chub from Ohio and Wisconsin rivers (Schimdt 2000, Yoder et al. 2005). As the last collections of gravel chub from the Thames River in 1958 were from trawls, the use of fine-mesh trawl nets must be attempted. Based on past records of capture in Wisconsin, late fall (October/November) is considered to be the period of greatest likelihood of capture for gravel chub (Schimdt 1993), so sampling during these months should also occur.
Re-introductions should not be considered until the factors for extirpation are understood and addressed. The extirpation of the gravel chub is presumed to be the result of habitat degradation (increased siltation and turbidity). In Wisconsin, water pollution (pesticides, sewage and other point source discharges) have also been identified as causes for extirpations (Schmidt 2000).
The success of a re-introduction will depend on a sufficient quantity of suitable habitat being available at the repatriation site. The failure to quantify potentially limiting habitat or water quality parameters, before translocation attempts in Wisconsin, was considered to have limited the likelihood of success (J. Lyons, pers. comm). Therefore, surveys need to be undertaken to characterize current habitat and water quality conditions and identify appropriate actions to improve degraded habitats.
Source populations to support re-introductions need to be identified. Ideally, source populations possess a high level of genetic diversity and genetic composition developed under similar historic conditions as the repatriation site. Gravel chub populations of the same subspecies (E. x-punctatus trautmani) in Ohio (S3) and Indiana (S4) are considered stable and, therefore, represent potential source populations to support repatriation. Removal of individuals from source populations should not negatively affect the status of these populations.
The preferred method of introduction (e.g. adult transfer versus captive-rearing) needs to be determined. If captive propagation is the preferred option, propagation and rearing methods and an appropriate rearing facility will need to be identified. Captive propagation of closely related Erimystax species has been successfully undertaken (Conservation Fisheries Inc. 2001).
To successfully establish self-sustaining populations and preserve the genetic composition, the number of individuals to be introduced, appropriate life-stages and the frequency and duration of supplemental stockings needs to be determined. Population Viability Analysis (PVA) or other population modeling approaches may help to provide this information. Proper application of PVA tools, however, will require improved information on the life history and demographics of gravel chub.
All proposed re-introductions associated with this strategy will involve the preparation of a re-introduction plan that will address the logistic and ecological aspects discussed above. Re-introductions should follow the American Fisheries Society Guidelines for Introductions of Threatened and Endangered Fishes (Williams et al. 1988).
Long-term monitoring is required should re-introductions take place to ensure that newly established gravel chub populations are viable, that the stocking rate is appropriate and habitat conditions continue to be suitable. Fall monitoring is recommended as it increases the likelihood of capture of multiple life-stages (young-of-the-year, sub-adult and adult).
2.4 Critical Habitat
As defined by SARA, critical habitat is“the habitat required for the survival or recovery of a listed species”. The identification of critical habitat requires a thorough knowledge of the species’ environmental needs during all life stages, as well as an understanding of the distribution, quantity and quality of habitat across the species’ range. At present, this information is not available for the gravel chub, although Table 3 outlines activities that would assist with obtaining the required information if gravel chub is reintroduced. These activities are not exhaustive, but outline the range and scope of actions identified by the recovery team as necessary to identify critical habitat for reintroduced gravel chub. If it is confirmed that gravel chub is extirpated from the Thames River, then defining critical habitat may require research to be undertaken in other parts of its range outside of Canada. Until critical habitat can be defined, the recovery team has identified the areas listed as historically occupied habitat as areas in need of conservation.
2.4.2 Examples of Activities Likely to Result in Destruction of Critical Habitat
Although critical habitat has not been defined, it is possible to identify activities that would negatively affect gravel chub habitat. The following list is considered useful for the assessment of activities affecting areas of former gravel chub occurrence:
- Modification or poor management of a watercourse or surrounding watershed that leads to a significant increase in turbidity or sedimentation (may be agricultural, urban, infrastructure or forestry related);
- The construction of new dams and impoundment of upstream habitats;
- Toxic materials spills;
- Excessive nutrient loading that results in a significant decrease in dissolved oxygen at substrate level; and,
- Dredging or other instream works (e.g. pipeline water crossing) that result in increased levels of turbidity and sedimentation and the disturbance of riffle habitats.
2.4.3 Schedule of Studies to Identify Critical Habitat
Table 3. Schedule of activities to identify critical habitat of gravel chub if reintroduced.
|Activity||Anticipated Completion1 (years after finalization of recovery strategy)|
|Map and characterize the habitat along the formerly occupied reach of the Thames River||3|
|Characterize habitats of populations in the subspecies range in the United States, ifThames River populations are confirmed to be extirpated||5|
|Characterize life-history and demographic characteristics of populations in the subspecies range in the United States, if Thames River populations are confirmed to be extirpated||5|
1timeframes are subject to change as new priorities arise, or as a result of changing demands on resources of personnel.
2.5 Existing and Recommended Approaches to Habitat Protection
The Upper Thames River and Lower Thames Valley conservation authorities continue their efforts to provide habitat protection for all aquatic life in the Thames River watershed. This work is supported by the Thames River Recovery Team.
2.6 Performance Measures
The presence or absence of the gravel chub in the Thames River needs to be confirmed. If, after targeted sampling efforts, gravel chub are confirmed to exist in the Thames River, performance measures will include measurements of a healthy, reproducing population, such as multiple year classes. Research into the life history characteristics of the gravel chub will provide further insights into what indicators would be good measures of recovery performance.
2.7 Potential Impacts of Recovery Strategy on Other Species/Ecological Processes
The Recovery Strategy for the Thames River Aquatic Ecosystem (TRRT 2005) was developed to address the recovery needs of 23 aquatic or semi-aquatic COSEWIC-listed species (7 mussels, 6 reptiles, 10 fishes, including the gravel chub) that either historically inhabited or currently inhabit the Thames River (TRRT 2005). The gravel chub is found in the same area within the Thames River as the following fish species addressed by the Recovery Strategy for the Thames River Aquatic Ecosystem (based on Figure 14 in Taylor et al. 2004): bigmouth buffalo (Ictiobus cyprinellus), black redhorse (Moxostoma duquesnei), eastern sand darter (Ammocrypta pellucida), madtom (Noturus stigmosus), northern brook lamprey (Ichthyomyzon fossor), river redhorse (M. carinatum), silver shiner (Notropis photogenis) and spotted sucker (Minytrema melanops). Additionally, the following freshwater mussel SAR are also found in the same area: kidneyshell (Ptychobranchus fasciolaris), round hickorynut (Obovaria subrotunda), round pigtoe (Pleurobema sintoxia) and snuffbox (Epioblasma triquetra). The COSEWIC-listed mapleleaf mussel (Quadrula quadrula) is also found in this area in large numbers (T. Morris, DFO, pers. comm.).
As gravel chub is considered pollution-intolerant and requires non-degraded habitats, protection or restoration of its habitats will benefit the Thames River aquatic SAR listed above through general water and aquatic habitat improvements. Gravel chub recovery approaches are consistent with the Habitat Improvement and Stewardship approaches in the Recovery Strategy for the Thames River Aquatic Ecosystem (TRRT 2005) focused on reducing sediment, nutrient and toxic loadings.
2.8 Recommended Approach for Recovery Implementation
As it is one of 23 aquatic or semi-aquatic species targeted by the Recovery Strategy for the Thames River Aquatic Ecosystem (TRRT 2005), gravel chub recovery will be implemented by the TRRT. Four First Nation communities are located within the Thames River ecosystem and gravel chub recovery habitat is located within or adjacent to First Nations land. Representatives from each First Nation sit on the TRRT.
2.9 Statement of When One of More Action Plans in Relation to the Recovery Strategy will be Completed
One or more action plans relating to this recovery strategy will be produced within 5 years of the final strategy being posted on the registry. Wherever possible, recovery action plans will be linked to the existing Thames River watershed recovery team. Partnership with this recovery team will ensure that efforts are not duplicated and will eliminate implementation of conflicting recovery efforts.
- Date Modified: