You are hereSacramento Sucker (Catostomus occidentalis)

Sacramento Sucker (Catostomus occidentalis)


Sacramento sucker can be found in a wide variety of habitats throughout the
Basin and are a native species in the Transition Zone community. They may
occupy cool, clear streams or warm backwater but are probably most common in
pools of clear, cool streams and reservoirs at moderate elevations. Adult
suckers are abundant in the reservoirs of the Basin. Juvenile suckers are more
commonly found in the tributary streams where they hatched. Native fishes
typically associated with Sacramento sucker are hardhead and Sacramento
pikeminnow.

The different sizes of suckers inhabit different microhabitats. Postlarval suckers
can be found in warm, shallow detritus covered bottoms at the stream margins.
Juvenile suckers, approximately 2 to 10 cm, can be found in shallow, slow
moving water with sandy bottoms. Adults are mostly sedentary during the day
and are typically found at the bottom of deep pools or beneath undercut banks.
Young of the year suckers have a tendency to school and may feed almost
continuously throughout the day. In streams, most of the day is spent on the
bottom of deep pools; in lakes they are found in fairly deep water. At night,
however, suckers are most active and move into the shallows to feed.

The diet of suckers is composed of algae, detritus, and invertebrates associated
with the substrate. Postlarval suckers, with their short digestive tract and
terminal mouths, feed primarily at the surface and in the midwater on early
instars of insects. As they develop into juveniles and their mouths become
subterminal and digestive tracts lengthen, their diet shifts toward diatoms,
filamentous algae and protozoans. The diet of adult suckers is made up of
filamentous algae, diatoms, and detritus. Invertebrates consumed by adult
suckers make up less than 20 percent of their diet.

Growth in Sacramento suckers is highly variable. Generally, suckers grow more
slowly in small, cold streams with low productivity, than in larger warmer streams.
In addition, adult suckers may depress the growth and survival of juvenile
suckers by forcing the juvenile fish into less favorable habitats. Thus, yearling
fish may be 5 to 8 cm in length, depending on the habitat in which they rear.
Large Sacramento suckers may grow to approximately 45 cm and reach ten
years of age.

Sacramento suckers spawn for the first time at four to five years of age.
Spawning usually takes place between February and June, but may be as late
as July. Most spawning takes place in streams over gravels. Prior to the
spawning migration, ripe suckers will often congregate at the mouth of streams
and rivers. Temperature is the key to the migration and begins when stream
temperatures start to noticeably warm. A sudden cooling can also stop the run
until warmer temperatures return. In reservoirs, suckers may spawn along the
shoreline.

Spawning behavior in Sacramento suckers is typical of most suckers. Large
numbers of suckers gather in the spawning area and each female is
accompanied by two to five males. The eggs are broadcast over the gravels to
which they adhere. Vigorous activity by the spawners creates a slight
depression in the substrate in which the eggs fall; further activity may cover the
eggs with the shifting gravel.

The eggs hatch in three to four weeks and the young soon drift downstream into
the warm shallows. They will typically reside and rear here until they are three to
four years of age, when they will move downstream into reservoirs or larger
streams during the fall/winter high water.

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