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California Fish Website Species
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Lost River Sucker, Catostomus laxatus
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Appearance
and Identification:
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Large sucker, up to 1 m TL (4.5kg)
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Long narrow head, small eyes, small sub-terminal mouth (almost
terminal)
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Fleshy lips, upper lip: 2-5 rows of large papillae, lower lip:
medial division, 1-3 rows of papillae
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Dorsal fin origin slightly anterior of pelvic origin
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Coloration: brown to black back, brassy sides, white to yellow
ventrally
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Fin Rays: dorsal 10-12, pelvic 10, anal 7-8
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Lateral line scales: 82-113 (13-16 scales above line, 8-12 scales
below line)
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Life History:
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Lost River suckers favor shallow lakes with clear, cool
(16-24°C), well- oxygenated water. Such environmental conditions promote the
growth of healthy aquatic vegetation and marshland, which provide food and
cover for Lost River suckers. Though
favorable, these conditions are limited, and in some lakes Lost River
suckers are only found at the mouth of inflowing rivers. Suckers begin dying when dissolved oxygen
levels drop below 1.58 mg/l, the pH exceeds 10, and when water temperatures
exceed 31-32°C. Mortality rates are
even higher when these conditions become more extreme. In Clear Lake the Lost River suckers
remain in deep water through winter and disperse throughout the lake in
summer months. Like other suckers,
Lost River suckers feed primarily on detritus by grazing the bottom of a
lake. Other food items include chironomid midge larvae, amphipods and
zooplankton. Historically
zooplankton and invertebrates may have made up a greater relative
percentage of the sucker diet.
During the period of life before the onset of maturity, suckers grow
rapidly, reaching 35-50 cm FL in 5 or 6 years. They begin spawning after 5-9 years,
making a short migration into a large tributary stream to breed. The suckers enter a stream in early
February through April when rivers are swollen with winter and spring
runoff. Spawning grounds are usually
found in gravelly or rocky riffles and runs. One female is surrounded by several males
in the swiftwater. As she releases some 102,000 to 236,000
eggs the males simultaneously fertilize the eggs. Fertilized eggs fall into the substrate
and become lodged in the interstices to incubate. When larvae emerge they
almost immediately move downstream towards lakes, though the trip may take
up to 6 weeks. In lakes the young
suckers gather in shallow shorelines where water quality is high and
aquatic vegetation is present. As
the suckers grow they progressively spend more time on the lake floor. Lost
River suckers may reach 20-30 years old, though they historically lived
over 40 years. Female suckers
typically reach greater lengths than male suckers.
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Links to Other Research
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Here's a list of California watersheds where Lost
River Suckers may be found.
© 2003 - Regents of the University of California
Division of Agriculture and Natural Resources
Communication Services
E-Mail Web Master
ANR
Non-Discrimination Statement
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