Mountain Sucker (Milk River populations)

Catostomus platyrhynchus

SARA Status
No Status
NS
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

SARA Status

  • No Status NS
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX
COSEWIC Status
Not at Risk
NR
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

COSEWIC Status

  • Not at Risk NR
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX

Description

The Mountain Sucker belongs to the family of suckers that live in the western mountainous regions and western-most Great Plains of North America. Based on genetic and geographic factors, the Mountain Sucker has been separated into three Designatable Units in Canada: 1) the Saskatchewan - Nelson River populations; 2) the Milk River populations; and 3) the Pacific populations. The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has assessed the Saskatchewan-Nelson River populations as “Not at risk”; the Milk River populations as “Threatened” and the Pacific populations as “Special Concern”.

The Mountain Sucker has the following characteristics:

  • A sub-terminal mouth, no teeth and fleshy lips (a trait characteristic of suckers);
  • Snout is broad and heavy;
  • Eyes are small;
  • The body is elongate, cylindrical and somewhat compressed;
  • A relatively small body, with total lengths averaging between 127 to 152 mm. The longest length ever recorded was an Alberta specimen at 232 mm;
  • The dorsal colouring is typically dark green to grey or brown. The belly is pale yellow to white;
  • There is a dark green to black lateral band and/or five dorsal blotches of fine black pigment on the sides; and
  • During the spawning season, spawning fish develop an orange to red lateral band and both male and females develop “bumps” (tubercles) on their fins.

Habitat

The Mountain Sucker is found only in the western United States and Canada, typically at higher elevations, although they are found in lowland and prairie streams as well. In the U.S., it is found in the Green, upper Columbia, Yakima, upper Sacramento and upper Missouri river systems, as well as the Lahontan and Bonneville Basins, and in tributaries of the Colorado River, as far south as Utah. In Canada, it can be found in the Columbia, Fraser, Saskatchewan and upper Missouri River Systems (Milk River). Although locally abundant in some selected areas, the Mountain Sucker is not abundant in most Canadian waters where they are at the northern extent of their range.

Mountain Suckers are considered a cool water species, and are associated with small streams at elevations between 20 to 800 m above sea level, although they occur occasionally in lakes, reservoirs and large rivers. Flows are moderate. The materials along the bottoms of the waterbody (substrates) vary, but are typically characterized by gravel or cobble. Spawning occurs in late spring or early summer in riffles of moderate to fast flowing water often adjacent to pools. Spawners use the riffle areas, but return to deeper pools once spawning is complete. No nest is built, and the eggs are scattered over river or stream bottoms. Incubation of the eggs is likely between 8 to 14 days, with the frys’ growth rates variable between streams. Females tend to be larger, and live longer than males. Males live about seven years. Females live about nine years.

Threats

Threats to the Mountain Sucker include habitat loss and degraded habitat quality as a result of agricultural and livestock practices; urbanization and industrial development; water management practices and irrigation; and the introduction of aquatic invasive species. In south-central British Columbia and southern Alberta and Saskatchewan, risks relating to water availability may become an even greater threat under drought and climate change conditions.

Further Information

For further information, visit the SARA Registry or COSEWIC websites.

Mountain Sucker (Milk River populations)

Illustration of a Mountain Sucker (© Joseph R. Tomelleri)

© Joseph R. Tomelleri

Scientific name: Catostomus platyrhynchus
SARA Status: Threatened
COSEWIC Status: Threatened
Region: Central and Arctic

Distribution of the Mountain Sucker (Milk River populations) in Canada

Distribution of the Mountain Sucker (Milk River populations) in Canada.

Related information

Did You Know?

Diet consists of a variety of food items, including plankton, small invertebrates and microscopic organic matter they scrape off of rocks.