Mapleleaf mussel (Quadrula quadrula) COSEWIC assessment and status report: chapter 12

Technical Summary: Saskatchewan - Nelson population

Quadrula quadrula

Mapleleaf Mussel - Saskatchewan - Nelson population – Mulette feuille d’érable

Range of Occurrence in Canada:

Manitoba

Extent and Area Information: Saskatchewan - Nelson population

Extent of occurrence (EO) (km²) (calculated using polygons on 1:50,000 maps)

27,306 km²

Specify trend in EO

Decline

Are there extreme fluctuations in EO?

No

Area of occupancy (AO) (km²) (see text for details)

  • 2.5 km² in Assiniboine River above Portage Diversion
  • 7.5 km² in Assiniboine River below Portage Diversion
  • 18.15 km² in Red River
  • 0.99 km² in Roseau River
  • 7.2 km² in Bloodvein River
  • Total = ~36.34 km²

Specify trend in AO

Likely declining

Are there extreme fluctuations in AO?

No

Number of known or inferred current locations

5

Specify trend in #

Declining

Are there extreme fluctuations in number of locations?

No

Specify trend in area, extent or quality of habitat

Declining

Population Information

Generation time (average age of parents in the population)

Unknown; estimate 10 years

Number of mature individuals

Unknown

Total population trend:

Decline

 % decline over the last/next 10 years or 3 generations.

Unknown

Are there extreme fluctuations in number of mature individuals?

No

Is the total population severely fragmented?

No, rivers are connected so genetic mixing (via fish hosts) is possible

Specify trend in number of populations

decline

Are there extreme fluctuations in number of populations?

No

List populations with number of mature individuals in each:

Unknown, total population estimated to be at minimum 1-4 million individuals

Threats (actual or imminent threats to populations or habitats)

Habitat loss and degradation resulting from agricultural activity (siltation, loss of riparian vegetation and streambank erosion and especially nutrient loading), municipal and industrial pollution, and urbanization.

Rescue Effect (immigration from an outside source)

Status of outside population(s)?

USA: Status apparently secure within most of US distribution. In same watersheds as Canadian populations (Red River) it is either not ranked or is S2 or is in the same state of decline as Canadian populations.

Is immigration known or possible?

Not possible

Would immigrants be adapted to survive in Canada?

Likely, needs to be confirmed by testing

Is there sufficient habitat for immigrants in Canada?

unknown

Is rescue from outside populations likely?

No

Quantitative Analysis

Not available

Current Status

COSEWIC: Endangered (2006)

Status and Reasons for Designation

Status:  Endangered

Alpha-numeric code: B2ab(i,ii,iii,iv)

Reasons for Designation: Small area of occupancy; all localities but one are in one system, the Red Assiniboine drainage, and a major event could extirpate the population; no evidence for recruitment (few small individuals), numerous threats including degrading water quality from agriculture, domestic waste, commercial and industrial activities. 

Applicability of Criteria

  • Criterion A (Declining Total Population): Not applicable.
  • Criterion B (Small Distribution, and Decline or Fluctuation): B2ab(i,ii,iii,iv)
  • Criterion C (Small Total Population Size and Decline):  Not applicable
  • Criterion D (Very Small Population or Restricted Distribution): Not applicable
  • Criterion E (Quantitative Analysis):  Not available

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