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Recovery Strategy for the Carmine Shiner (Notropis percobromus) in Canada [Proposed] 2007

Appendix 1 – Threats Assessment Analysis

Knowledge of the threats to a species and potential to mitigate those threats is fundamental to a species’ recovery. In this assessment, the Carmine Shiner Recovery Team identified the following threats for consideration:

  • Over-exploitation
    • Bait fisheries
  • Species introductions
    • Predation
    • Competition
    • Food chain disruption
  • Habitat Loss/Degradation
    • Flow alteration
    • Shoreline/riparian development
    • Landscape changes
    • Climate change
  • Pollution
    • Point Sources
    • Non-point Sources
  • Other
    • Scientific Sampling
    • Hybridization

Because so little is known of the species’ life history and habitat requirements, the assessment of each potential threat was qualitative rather than quantitative, with each factor being rated as “low”, “moderate” or “high”. These assessments were based on the best professional judgement of the Recovery Team, and determined by consensus following discussions. For each potential threat at each location where the species is known to occur, the following factors were considered:

  • Likelihood of Occurrence – The probability of a threat occurring. Those that presently affect the species were rated “high”.
  • Extent of Occurrence - The spatial range of each identified threat. Those that affect most or all of the area occupied by the species were rated “high”.
  • Severity of Impact – The severity of the direct or indirect impact of a threat on the survival or recovery of the species. Impacts with the potential to extirpate the species were rated “high”.
  • Immediacy of Impact - The immediacy of the anticipated impact from a threat. Ongoing threats that are impacting the species were rated “high”.
  • Threat Significance – The risk of damage to a carmine shiner population from a particular threat, based on its likelihood and extent of occurrence and on the severity and immediacy of its impacts. Threat significance was rated “low” where severity of the impact was deemed low, and otherwise was difficult to predict given present knowledge.
  • Mitigation Potential - The biological and technical feasibility of mitigating a threat. Where there are no biological impediments and proven technology exists to successfully mitigate threats, the mitigation feasibility was rated “high”.

The results of these assessments are tabulated in Tables 6 to 9, summarized in Table 1, and discussed in Section 3. In the tables, questions marks (?) denote uncertainty, and the need for research. Comments provide background on each threat or its assessment.


Table 6. Assessment of potential threats* to the carmine shiner and its habitat in the Whitemouth River system and in the Winnipeg River near the Whitemouth River outfall, Manitoba.
Identified ThreatMechanism/ SourceLikelihood of Occurrence*Extent of Occurrence*Severity of Impact*Immediacy of Impact*Threat
Significance*
Mitigation
Potential*
Comments
Over-exploitationBait fisheriesLLLLLHThere are commercial bait fish harvesting blocks encompassing the Whitemouth River, Whitemouth Lake, and Birch River. Minnows are not approved for harvest as live bait and are not so abundant as to support a fishery for frozen bait on these waters. Anglers may harvest some minnows for bait.
Species introductionsPredation, competition, food web disruptionMHHLMLSmallmouth bass and rainbow smelt are present in the Winnipeg River, but Whitemouth Falls prevents their unassisted entry into the Whitemouth River. Sauger are also absent from the Whitemouth River, but walleye have been introduced to Whitemouth Lake and trout into the Birch River. There is some limited potential for the transfer of biota from the Lake of the Woods watershed. The potential impacts of these species introductions are unknown. Smallmouth bass and carmine shiner do coexist in other waters.
Habitat Loss/ DegradationFlow alterationHH?H?HThe Whitemouth River is not affected by hydroelectric development. A fixed-crest weir regulates flow from Whitemouth Lake, and there is a small stone weir across the river channel at Elma. Agriculture, highways developments, and peat harvesting have altered watershed runoff patterns. There are more barriers along the river during dry years. In the past the river was dammed at Whitemouth during dry years to impound water for community use, and several old stream crossings have not been fully removed. Crossings and rock weirs have also altered flow in the Birch River (Schneider-Vieira and MacDonell 1993; Clarke 1998).
Shoreline/ riparian developmentHM?HMMThere is extensive shoreline development along reaches of the Whitemouth River system north of Highway 1 related to communities, agriculture, and seasonal homes or cottages.
Landscape changesHM?H?MForestry and peat moss operations are the main developments in the river basin south of Highway 1. To the north there are agricultural developments, communities, cottages, permanent homes, and a peat moss operation near the river.
Climate Change?????LThe potential effects of climate change are unpredictable on a local scale and cannot readily be mitigated.
PollutionPoint SourcesHM?H?MPeat moss extraction operations may be a point source of sediments. Agricultural feedlots, highway drainage ditches, and the Whitemouth sewage lagoon outfall may all be point sources of nutrient, sediment, or other chemical inputs. Clarke (1998) identified 12 significant point sources affecting the Birch River tributary.
Non-Point SourcesHM?H?MDownstream from Highway 1, the Whitemouth River system is subject to water quality degradation through nutrient and sediment loading from modern agricultural practices. This threat is extensive and immediate, but has good potential for mitigation/restoration. Chlorinated water from the Winnipeg Aqueduct has leaked into the Birch River in the past (Clarke 1998). Some pollutants are likely deposited by long-range transport, but this problem is ubiquitous.
OtherScientific SamplingHHLHLHSmall samples of carmine shiners have been collected from the Whitemouth River system for scientific purposes. The threat from further sampling is likely low and can be controlled.
HybridizationLLLLLLCarmine shiners will hybridize with several other shiner species. There is no evidence of any anthropogenic influence toward hybridization in the Whitemouth River.

*H= High, M=moderate, L=Low.


Table 7. Assessment of potential threats* to the carmine shiner and its habitat in the Bird River, Manitoba.
Identified ThreatMechanism/ SourceLikelihood of Occurrence*Extent of Occurrence*Severity of Impact*Immediacy of Impact*Threat Significance*Mitigation Potential*Comments
Over-exploitationBait fisheriesLLLLLHThe Bird River is not approved for live bait harvest within the area inhabited by carmine shiner.  The potential, however, exists for the commercial harvest of minnows for frozen bait. Anglers may also harvest minnows from the river for bait.
Species introductionsPredation, competition, food web disruptionHH?H?LRainbow smelt have been present in the Winnipeg River since the early 1990's. Their impacts on carmine shiner are unknown, but they do prey on the closely related emerald shiner. The impacts of introduced smallmouth bass on carmine shiner are likewise unknown, but the two species do coexist elsewhere.
Habitat Loss/ DegradationFlow alterationHH?H?LThe lower Bird River to the first waterfalls, including known carmine shiner habitat, has been impounded by hydroelectric development on the Winnipeg River.
Shoreline/ riparian developmentHH?H?MThere are extensive cottage developments on the Bird River system, particularly at Bird Lake, and a new cottage subdivision has been proposed. Forestry operations in the headwaters are proposing to harvest the riparian buffer, to limit the spread of disease from these trees to other harvestable stands of timber.
Landscape changesHH?H?MCottage developments and forestry are the main activities with potential to effect landscape changes along the Bird River. The extent and proximity of timber harvest is controlled so its impacts on the river may not pose a significant threat. There is also potential for mining development in the watershed.                      http://www.gov.mb.ca/itm/mrd/busdev/properties/birdsill.html
Climate Change?????LThe potential effects of climate change are unpredictable on a local scale and cannot readily be mitigated.
PollutionPoint SourcesMM?H?HCottages, highway crossings, and ditch drainages may be point sources of pollutants. Most cottages in the area use septic pumpout services because they lack septic fields.
Non-Point SourcesHH?H?MCottage developments upstream may increase nutrient and sediment loading. There are also forestry and mining developments upstream. Some pollutants are likely deposited by long-range transport, but this problem is ubiquitous.
OtherScientific SamplingHHLHLHSmall samples of carmine shiners have been collected from the Bird River for scientific purposes. The threat from further sampling is likely low and can be controlled.
HybridizationLLLLLLCarmine shiners will hybridize with several other shiner species. There is no evidence of any anthropogenic influence toward hybridization in the Bird River.

*H= High, M=moderate, L=Low.


Table 8. Assessment of potential threats* to the carmine shiner and its habitat in the Pinawa Channel, Manitoba.
Identified ThreatMechanism/ SourceLikelihood of Occurrence*Extent of Occurrence*Severity of Impact*Immediacy of Impact*Threat Significance*Mitigation Potential*Comments
Over-exploitationBait fisheriesLLLLLHThe area is within an allocated commercial bait block but there is no live bait harvest.  Although the potential exists for commercial harvests for frozen bait and for bait harvest by anglers.
Species introductionsPredation, competition, food web disruptionHH?H?LTrout have been stocked in the Pinawa Channel since the 1970's but have not established reproducing populations. Brown trout were last stocked in 2002. There are reproducing populations of smallmouth bass in the Winnipeg River, and rainbow smelt have been present in the Winnipeg River since the early 1990's. The impacts of these introduced fishes on carmine shiner are unknown.
Habitat Loss/ DegradationFlow alterationHH?H?MFlow in the Pinawa Channel was altered ca. 1906 by construction of the Pinawa Hydroelectric Generating Station. This work included extensive blasting to deepen the Pinawa Channel, diking to permit impoundment upstream of the station, and a dam control structure with turbines at Old Pinawa. When the station was decommissioned in 1951, a dam was constructed across the inlet of the Pinawa Channel to divert flow to the Seven Sisters Hydrolectric Generating Station. After it was decommissioned, the dam and spillway at Old Pinawa were partially razed and still obstruct flow. The sequential effects of these alterations on carmine shiner habitat and populations are unknown.
Shoreline/ riparian developmentHH?H?MPiles of rock from channel deepening, a golf course below the inlet, dikes near the outlet with cleared agricultural fields, and a small Provincial Historical Park at the outlet are the main shoreline developments along the Pinawa Channel upstream of the Old Pinawa Dam. There are no cottages above the dam, but interest has been expressed in cottage development. There is extensive shoreline development below the dam for cottages, year-round homes, and agriculture.
Landscape changesHH?H?MForest bordering the Pinawa Channel was logged in the early 1900's during and/or following construction of the Pinawa Generating Station and has since re-grown. The extent and proximity of modern timber harvest is controlled and impacts on the channel should not be a significant threat. There is extensive cottage and agricultural development inland from the channel below the Old Pinawa Dam.
Climate Change?????LThe potential effects of climate change are unpredictable on a local scale and cannot readily be mitigated.
PollutionPoint SourcesHL?H?HCottages, homes, and agricultural operations may be point sources of pollution downstream from the Old Pinawa Dam.
Non-Point SourcesHH?H?MThere may be some nutrient enrichment and sediment loading by cottage developments and impoundments on Lake of the Woods and the Winnipeg River mainstem, upstream. Some pollutants are likely deposited by long-range transport, but this problem is ubiquitous.
OtherScientific SamplingHHLHLHSmall samples of carmine shiners have been collected below the dam at Old Pinawa for scientific purposes. The threat from further sampling is likely low and can be controlled.
HybridizationLLLLLLCarmine shiners will hybridize with several other shiner species. There is no evidence of any anthropogenic influence toward hybridization in the Pinawa Channel.

*H= High, M=moderate, L=Low.