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 (Modoc County) 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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