Name: Catostomus macrocheilus - Largescale sucker
Family: Catostomidae (Suckers)
Order:
Cypriniformes
(Suckers and Minnows)
Class: Osteichthyes (Bony Fishes)
Abundance: Common
Origin:
Native.
Active Season: Year Round
Size:
- average: 14 inches
- largest: 22 inches
Colors: yellow (underside), green (sides), white-gray (underside).
General Description: Largescale suckers are medium-sized fish, usually not exceeding five pounds. Their mouths are toothless and positioned on the underside of their head, allowing them to suck food from the bottom of the river or lake. Their anal fin is set far from their mouth, and close to their tail fin.
Similar Species:
Young suckers are easily confused with minnows, but can be distinguished by several characteristics. First, suckers have mouths on the underside of their snouts, while minnows have mouths set on the front of their snouts. Second, suckers never have barbels, which minnows sometimes have. Lastly, the anal fin is very close to the tail on suckers, while the anal fin of minnows is closer to the head. The largescale sucker can be confused with the longnose sucker (Casostomus catostomus), but the longnose sucker has a much larger dorsal fin, larger scales, and a shorter snout than the largescale sucker.
Life History: Largescale suckers move upstream to spawn in May or June. Females lay up to 20,000 sticky eggs on gravel riffles, areas of strong current, or along the edges of lakes. Eggs hatch in about two weeks, and spawning adults provide no parental care to their eggs or larvae. Larvae have high growth rates for the first four years of their life, and reach sexual maturity at about six to nine years. Largescale suckers can live at least fifteen years in the wild.
Distribution: Largescale suckers are native to the Pacific Northwest; from British Columbia south to Oregon. In Montana, they are found only west of the Continental Divide.
Habitat Description: Largescale suckers are found in slower sections of streams, rivers, and lakes.
Feeding Habits: Largescale suckers eat almost any small organism on the bottom of the river or lake, but studies have found their diet is made up mostly of periphyton and insect larvae.
Enemies & Diseases: Largescale suckers are a major food source for larger predatory fish and birds, like osprey. In Oregon, many largescale suckers have been infected and killed by a parasite, Ligula intestinalis.
Did You Know: Largescale sucker populations around the Libby dam have been declining. It is thought that the Libby dam caused stretches of the Kootenai river to slow down, and these slower stretches are no longer suitable spawning habitat for the suckers.
Glossary:
- Anal fin: the fin on the underside of a fish closest to the tail
- Dorsal fin:
a fin along the midline of the back, usually midway between the head and tail fin.
-
Periphyton: very small plants and animals that live underwater.
- Spawn:
to deposit eggs.
Contributor:
Allison Greene
ECOS is supported by the GK-12 Program of the National Science Foundation.