Bigmouth Buffalo (Saskatchewan – Nelson River)

Description
Habitat
Threats
Further Information
Scientific Information

Description
The Bigmouth Buffalo (Ictiobus cyprinellus) is a member of the sucker family Catostomidae. It is 1 of 18 sucker species found in Canada. It has the following characteristics:

• Body is large, deep and laterally compressed;
• Caudal peduncle is very short and deep;
• Very large, oblique, terminal mouth with thin, faintly striated lips;
• Dorsal fin ray count at 24 to 32;
• Slate or olive bronze dorsal surface, olive yellow sides, and yellow and white belly;
• Light brownish-slate fins;
• Measures 254 to 457 mm in length; maximum reported length of 1143 mm; and
• Maximum weight reported as 36 kg.

Ictiobus cyprinellus

Illustration © J.R. Tomerelli

Habitat
The distribution of Bigmouth Buffalo is limited to central North America where it is found in the Mississippi drainage from the Gulf of Mexico northward to Minnesota and North Dakota, including the Missouri and Ohio rivers. In the Great Lakes basin, it has been reported in Lake Erie, Lake St. Clair, the Bay of Quinte, Hamilton Harbour and in several rivers including the Grand, Sydenham, Thames, Welland and Ausable. Within the Hudson Bay basin, Bigmouth Buffalo has been reported in the Red and Assiniboine rivers, as well as the south basin of Lake Winnipeg and Lake Manitoba (likely entering via the Assiniboine River floodway). This species is relatively abundant in the Qu’Appelle Lakes in Saskatchewan.

The Bigmouth Buffalo has a preference for warm, turbid, highly eutrophic waters. It is usually found in schools near the middle of the water column as well as along the bottom of medium- to large-sized rivers of low gradient and moderate to slow current. Spring flooding is an important factor in successful reproduction as it provides access to spawning areas and activates spawning activity. Also required for spawning is an increase in water temperature. Bigmouth Buffalo spawn in groups. There is no nest preparation and eggs are scattered on flooded vegetation and abandoned. Lifespan may exceed 20 years of age.

Threats
The loss and degradation of spawning habitat due to water management practices, particularly the regulation of water levels and channelization, have contributed to declines in Bigmouth Buffalo in the Qu’Appelle River basin. In addition, prolonged periods of drought, agricultural demands for water, and commercial exploitation have also reduced the population size. The genetic integrity of this fish could also be compromised through hybridization with other buffalo species.

Further Information
For the recent 2009 COSEWIC assessment of the Bigmouth Buffalo, please go to the SARA registry.

Scientific Information:

Scientific name: Ictiobus cyprinellus
SARA Status: Special Concern (June 2011)
COSEWIC Status: Special Concern (April 2009)