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Recovery Strategy for the Northern Riffleshell, Snuffbox, Round Pigtoe, Mudpuppy Mussel and Rayed Bean in Canada (Final)


II. Recovery : Goal, Objectives and Approaches

  1. Recovery Goal
  2. Recovery Objectives (5 year)
  3. Approaches to Meeting Recovery Objectives
    1. Research and Monitoring Approaches
    2. Management Approaches
    3. Stewardship Approaches
    4. Awareness Approaches

1. Recovery Goal

The long-term goals of this recovery strategy are:

  1. to prevent the extirpation of the Northern Riffleshell, Snuffbox, Round Pigtoe, Mudpuppy Mussel and Rayed Bean in Canada;
  2. to return healthy self-sustaining Northern Riffleshell populations to the Ausable, Grand, Sydenham and Thames rivers and the St. Clair River delta and;
  3. to return healthy self-sustaining populations of Snuffbox to the Ausable, Grand, Sydenham and Thames rivers and the St. Clair River delta.
  4. to return healthy self-sustaining populations of Round Pigtoe to the Sydenham, Thames and Grand rivers and the St. Clair delta and;
  5. to return/maintain healthy self-sustaining populations of Mudpuppy Mussel to the Sydenham and Thames rivers and St. Clair River delta and;
  6. to return/maintain healthy self-sustaining populations of Rayed Bean to the Sydenham and Thames rivers and St. Clair River delta and;

These populations will only be considered recovered when they have returned to historically estimated ranges and/or population densities and are showing signs of reproduction and recruitment.

2. Recovery Objectives (5 year)

  1. Determine extent, abundance and population demographics of existing populations.
  2. Determine host fishes and their distributions and abundances.
  3. Define key habitat requirements to identify critical habitat.
  4. Establish a long-term monitoring program for all species, their hosts and the habitats of both.
  5. Confirm/Identify threats, evaluate their relative importance and implement remedial actions to minimize their impacts.
  6. Examine the feasibility of relocations, reintroductions and the establishment of managed refuge sites.
  7. Increase awareness about the distribution, threats and recovery of these species.

3. Approaches to Meeting Recovery Objectives

The approaches to recovery have been organized into four distinct categories – research and monitoring, management, stewardship and awareness. Successful recovery will require consideration of approaches from all categories. A narrative has been included after each table where appropriate.

a) Research and Monitoring Approaches

a) Research and Monitoring Approaches
PriorityNumberObjective AddressedBroad Approach/
Strategy
Specific StepsAnticipated EffectThreat Addressed
Urgent1-1ii, vResearch – host fishes.Continue fish host testing for the Snuffbox, Northern Riffleshell, Round Pigtoe and Rayed Bean.Will help determine if host abundance is limiting factor for the four mussel species. Will assist with identifying critical habitat.Host Fishes
Urgent1-2ii, vSurveys – host fishes.Determine the distribution and abundance of the host species.Will help determine if host abundance is limiting the five mussel species.Host Fishes
Urgent1-3iiiResearch – Critical Habitat.Determine the habitat requirements for all life stages.Will assist with defining critical habitat for the Mudpuppy Mussel, Northern Riffleshell, Round Pigtoe, Rayed Bean and Snuffbox. 
Urgent1-4iii, viSurveys – Critical Habitat.Prepare a distribution map of areas of suitable habitat.Will assist with identifying critical habitat and potential areas of reintroduction. 
Urgent1-5viResearch – managed refuge sites.Investigate the feasibility of establishing actively managed refuge sites in the St. Clair River delta.Will determine if the Northern Riffleshell and Round Pigtoe in the St. Clair River delta can be insulated from the effects of zebra mussels.Exotic Species
Urgent1-6viPopulation augmentationExamine the feasibility of translocations and re-introductions.Will determine if small populations can be augmented or if the species can be reintroduced in historical range. 
Necessary1-7i, ivMonitoring – mussel and host fish populations.Establish a network of permanent monitoring stations throughout historic and present ranges.Will permit tracking of populations, analysis of trend patterns, and permit the evaluation of recovery actions. 
Necessary1-8iv, vMonitoring – habitat.Establish permanent monitoring sites for tracking changes in habitat.Provides trend data for key habitat and will help evaluate the relative threat of habitat loss. 
Necessary1-9vResearch – threats.Identify and evaluate threats to all life stages.Will assist with determining reasons for declines and developing remedial actions.All threats.
Necessary1-10viResearch – conservation genetics.Compare the within and among population genetic variability of Canadian populations and determine if populations show genetic structure by comparing variability between populations in Canadian and U.S.waterways.Will assist with determining if population translocation or augmentation is appropriate and determining appropriate locations. 

1-1 & 1-2: The necessity for a period of encystment represents a potential bottleneck in the lifecycle of the mussel. Research and recovery actions focusing on the pre or post encystment period may prove unproductive if the presence of a host fish is the limiting step. In order to determine if these species are host limited it is necessary to first identify the host species and then to confirm that the distributions of the mussel and its host overlap in time and space in a manner that will permit successful encystment. The identification of high host specificity in some mussel species requires that hosts be identified for local populations whenever possible. It is already well documented that the Mudpuppy Mussel is host specific with the mudpuppy. Host species for Canadian populations of the Northern Riffleshell, Rayed Bean and Snuffbox have been identified, however, further testing should continue as results are still in progress for the Northern Riffleshell and Snuffbox (McNichols and Mackie 2004). Host species for Canadian populations of the Round Pigtoe are based on results from the United States. Once the Canadian hosts have been confirmed for these species it is necessary to ensure that host species distributions overlap with the mussel distributions. Since adult mussels are essentially sessile this can be accomplished by confirming that members of the hosts species occur in reaches with mature female mussels at times when the female mussels possess mature glochidia.

1-3 & 1-4: Determination of critical habitat is an essential component in the recovery of these species. Although adult mussels are relatively passively distributed, distinct habitat types can be associated with adult distributions suggesting that survival is linked to local habitat conditions. Habitat conditions may be equally important during the juvenile stage and attention must also be paid to the habitat preferences of the hosts. Identification of critical habitat will be a multi-stage process. For more information on the required steps see Critical Habitat sections for each species.

1-5: Remnant populations of both Northern Riffleshells and Round Pigtoes can be found in the delta area of Lake St. Clair despite the presence of zebra mussels. Metcalfe-Smith et al. (2004) reported zebra mussel infestation rates ranging from <1 to 36 zebra mussels/unionid in this area during 2003. While this rate of infestation is below the lethal limits reported elsewhere (Ricciardi et al. 1995) it may be resulting in long term chronic effects that are causing prolonged declines. Comparisons of collections made in 2001 with those in 2003 showed that abundance of all unionids had declined by about 14% while declines were much higher for some species (i.e., 80% decline of round hickorynut) (Metcalfe-Smith et al. 2004). Although the overall trend was toward declining unionid densities some sites showed stable overall abundances. These sites were associated with low zebra mussel infestation rates and high unionid diversity and may represent potential refuge sites. Since these sites are still affected by zebra mussels it is likely that unionids will need to be actively managed with regular zebra mussel removal and the active relocation of riffleshells and other mussel SAR to these locations from the more heavily infested sites.

1-7 & 1-8: A network of detailed, permanent monitoring stations should be established throughout the present and historic ranges of the five mussel species. Monitoring sites should be established in a manner so as to permit:

  • Quantitative tracking of changes in mussel abundance or demographics (size distribution, age structure etc.) or that of their hosts.
  • Detailed analyses of habitat use and the ability to track changes in use or availability.
  • The ability to detect the presence of exotic species (i.e. zebra mussels). Reservoirs represent the likely seed locations for zebra mussels in the Grand, Thames, Sydenham and Ausable rivers. Monitoring sites should be established within or close to these reservoirs to permit the early detection of zebra mussels in the event that they invade these systems. Monitoring of exotics in the St. Clair River delta will likely be conducted in close association with the managed refuge sites.

b) Management Approaches

b) Management Approaches
PriorityNumberObjective AddressedBroad Approach/
Strategy
Specific StepsAnticipated EffectThreat Addressed
Urgent2-1i-viCapacity BuildingPromote and enhance expertise in freshwater mussel identification/biology and provide for the transfer of knowledge.Will ensure correct identification of mussel species at risk.All threats.
Urgent2-2v, viCooperation –  ecosystem recovery strategiesWork with existing ecosystem recovery teams to implement recovery actions.Ensure a seamless implementation of all recovery actions.All threats.
Necessary2-3vMunicipal PlanningEncourage municipal planning authorities to consider Recovery Goals in official plans.Will provide further protection for the Northern Riffleshell, Mudpuppy Mussel, Round Pigtoe, Snuffbox and Rayed Bean to ensure that future development does not degrade important habitat.Siltation and turbidity, nutrient loads, toxic compounds, thermal effects.
Necessary2-4vDrainageWork with drainage supervisors, engineers and contractors to limit the effects of drainage activities on mussel habitat.Will reduce the harmful effects of drainage activities.Siltation and turbidity, nutrient loads, toxic compounds, thermal effects.
Necessary2-5ii, iii, vFish Management PlansEncourage the development of management plans for non SAR fish species within watersheds inhabited by the Northern Riffleshell, Snuffbox, Round Pigtoe, and Rayed Bean.Will provide protection for potential host species.Host fishes.
Necessary2-6vBaitfishWork with the baitfish industry to reduce the impacts of commercial baitfishing on host species.Will provide protection for potential host species.Host fishes, exotic species.
Necessary2-7vWastewater treatment plants and stormwater management facilitiesEvaluate whether wastewater treatment plants are functioning up to specifications and encourage upgrading where appropriate.  Review stormwater management facilities for quantity and quality control in new developments, and retro-fit existing development where possible.Will improve water quality by reducing nutrient and suspended solid inputs from urban centres.Siltation and turbidity, nutrient loads, toxic compounds.
Necessary2-8vEnforcementAssist federal and provincial enforcement officers in obtaining the necessary information and/or resources required to protect these species and their habitats.Will ensure that these 5 species and their habitats receive the necessary protection.All threats.

2-1: The current capacity within southwestern Ontario to perform the necessary survey and monitoring work is insufficient. Knowledge of freshwater mussel identification, distribution, life history and genetics is limited to a small number of individuals from a limited number of government and academic institutions. Furthermore, the retirement of several key researchers is expected prior to the 5-year re-evaluation period for this strategy. A concerted effort must be made to increase this capacity by:

  • Training personnel in the identification of all mussel species with emphasis on the rare species.
  • Producing a field guide to the mussels of Ontario.
  • Encourage graduate and post-graduate research aimed at fulfilling the needs identified under Research and Monitoring.

2-2: Many of the threats to the Northern Riffleshell, Snuffbox, Round Pigtoe, Mudpuppy Mussel and Rayed Bean can be classified as widespread and chronic (Table 1) and represent general ecosystem threats affecting numerous other aquatic species. Efforts to remediate these threats will benefit many species in addition to these five mussel species and should be attempted in close connection with the aquatic ecosystem recovery teams for the Ausable, Sydenham and Thames rivers (see section II.5, Activities already completed or underway) to eliminate duplication of efforts and ensure that undertaken activities are not detrimental to other species.

2-5: The host fishes for these five mussel species must be afforded some degree of protection if the Northern Riffleshell, Snuffbox, Round Pigtoe, Mudpuppy Mussel and Rayed Bean are to recover. The greenside darter, which functions as a host for the Rayed Bean, is listed as a species of special concern by COSEWIC. This species is given consideration in the aquatic ecosystem recovery strategies for the Sydenham River (Dextrase et al. 2003), Ausable River (ARRT 2005) and Thames River (TRRT 2004) and will therefore be actively monitored and managed within these systems. The remaining host species for the five mussel species including the bluegill, bluntnose minnow, brook stickleback, greenside darter, Iowa darter, Johnny darter, largemouth bass, logperch, mottled sculpin, northern redbelly dace, rainbow darter and spotfin shiner are not listed by COSEWICand therefore not explicitly considered in any recovery plans. It may be necessary to develop formal management plans for these species to ensure that their populations remain healthy and do not hinder the recovery of the mussel species.

2-6: While the host species of the Northern Riffleshell, Snuffbox, Round Pigtoe, Mudpuppy Mussel and Rayed Bean are not typically targeted as baitfish they are potentially collected as bycatch during legal bait harvesting activities. Effort should be made to minimize potential bycatch of these species and to ensure that gear selection and operation do not contribute to habitat degradation which may adversely affect host populations.

c) Stewardship Approaches

c) Stewardship Approaches
PriorityNumberObjective AddressedBroad Approach/
Strategy
Specific StepsAnticipated EffectThreat Addressed
Urgent3-1vRiparian buffersEstablish riparian buffer zones in areas of high erosion potential by encouraging naturalization or planting of native species.Will improve water quality by reducing bank erosion, sedimentation and overland run-off.Siltation and turbidity, nutrient loads, toxic compounds, thermal effects.
Urgent3-2vTile drainageWork with landowners to mitigate the effects of tile drainage.Will reduce nutrient and sediment inputs.Siltation and turbidity, nutrient loads, toxic compounds
Urgent3-3vHerd managementEncourage the active exclusion of livestock from the watercourse.Will reduce bank erosion, sediment and nutrient inputs.Siltation and turbidity, nutrient loads, toxic compounds, thermal effects.
Urgent3-4vLivestock waste managementAssist with establishing adequate manure collection and storage systems to avoid accidental spills, and winter-spreading of manure.Will improve water quality by reducing nutrients.Siltation and turbidity, nutrient loads.
Urgent3-5vFarm planningEncourage the development and implementation of Environmental Farm Plans and Nutrient Management Plans.Will assist with minimizing inputs of nutrients and sediments.Siltation and turbidity, nutrient loads, thermal effects.
Urgent3-6vSewage treatmentWork with landowners to improve faulty septic systems.Will improve water quality by reducing nutrient inputs.Siltation and turbidity, nutrient loads, toxic compounds.
Necessary3-7vAgency InteractionCooperating and coordinating efforts with stewardship councils and CAsWill improve the implementation of stewardship activities.Siltation and turbidity, nutrient loads, thermal effects.
Beneficial3-8vSoil testingEncourage soil testing to determine fertilizer application rates.Will reduce nutrient inputs to the river.Nutrient loads.

The stewardship activities outlined here can be described as “best management practices” and represent a selection of activities that can be encouraged within these predominantly agricultural watersheds to help reduce the impacts of terrestrial practices on aquatic ecosystems. Encouragement can be achieved through increasing awareness of these activities as well as through the provision of financial assistance to local landowners.

d) Awareness Approaches

d) Awareness Approaches
PriorityNumberObjective AddressedBroad Approach/
Strategy
Specific StepsAnticipated EffectThreat Addressed
Urgent4-1viiAwareness – stewardship actionsIncrease public knowledge of stewardship options and financial assistance available to participate in activities.Increased public participation in recovery actions and a reduction in threats to the Northern Riffleshell, Snuffbox, Round Pigtoe, Mudpuppy Mussel and Rayed Bean.All threats.
Urgent4-2viiExotic speciesIncrease public awareness of the potential impacts of transporting/releasing exotic species.Will reduce the risk of zebra mussels becoming established in the reservoirs.Exotic species.
Beneficial4-3viiOutreachEncourage public support and participation by developing awareness materials and programs.Will increase public awareness of the importance of species at risk.All threats.

Public participation in the recovery process for these species is essential as the primary threats to populations in the Ausable, Grand, Sydenham and Thames rivers result from diffuse non-point source inputs relating to the general agricultural activities within these watersheds. Recovery can not occur without the full participation of local citizens and landowners. The need for an effective public awareness program is crucial to the recovery of these species.