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BiologyFreshwater, in streams and lakes (Ref. 89241). Inhabit clean, clear gravel riffles and runs of creeks and small rivers (Ref. 3814). In Delaware, occurs in small streams with relatively slow current, usually 0.03 m/s or less, with water temperatures throughout the year 4.0-19.0 °C, dissolved oxygen 5.6-14.0 ppm, and pH 6.0-7.3. In Kentucky, occurs in small to medium size, clear creeks with sand-gravel substrate, either among debris (adults) or in mud banks with silt deposits (ammocoetes) (Ref. 89241). Ammocoete larvae occur in spring-fed wetlands and quiet pools and backwaters of small, sandy or muddy bottom streams (Ref. 3814). Larval period varies from 2.5 to at least 5.4 yrs. Metamorphosis in early September and maybe even mid- to late August. In Maryland, metamorphosis has been reported as late as February (Ref. 89241). Adults enter riffle areas to spawn at 10-16°C water temperature (Ref. 10294). Non-parasitic (Ref. 3814). Fecundity, 572-3,816 eggs/female and relative fecundity, 373-687 eggs/g body weight. Egg diameter, 0.66-1.36 mm. In Delaware, spawning occurs at the end of March at a water temperature of 13.8 °C, dissolved oxygen 11.6 ppm, and pH 6.6. In Maryland, spawning occurs from 10 April to 10 May when the water reaches 16 °C. Both sexes participate in nest building. Stones up to 2.5 cm in diameter are moved using their oral disc. Nests are circular or oval, 15-2 cm in diameter and about 7 cm deep. They are built in streams 4.5-.3 m wide and 15-1 cm deep with a substrate of sand and fine gravel. From 2-5 lampreys share a nest. Up to two males will spawn with one female. Average size at hatching, 3.4 mm TL. Modal length at age 1 is 27-8 mm TL and at age 2 is 50 mm TL. Most growth occurs during the spring season, intermediate growth in summer and fall and very little during winter. In Kentucky, mean length at age 1 is 39 mm TL, at age 2 is 65 mm TL, and at age 3 is 89 mm TL (Ref. 89241).