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Hybridization <br />Incidences of hybridization of pallid with shovelnose sturgeon have been found in parts <br />of its range (Carlson et al. 1985, Keenlyne et A 1993). Hybridization may be occurring <br />in over 50% of river reaches within the range of pallid sturgeon and hybrids may <br />represent a high proportion of remaining sturgeon stocks ( Keenlyne et al. 1994 in Hopfar <br />1997). Hybrids tend to use habitats more similar to those of shovelnose sturgeon, and <br />have diets more like pallid sturgeon (Carlson et A 1985). <br />A suspected hybrid was captured in the lower Platte River in 1996 ( Hopfar 1997). This <br />fish was age 9 (750mm) and had characteristics that were intermediate between pallid <br />and shovelnose sturgeon, as documented by Carlson et al. (1985). <br />Biology <br />Reproduction <br />Little is known about pallid sturgeon reproduction or spawning activities. Throughout its <br />range, no spawning beds have been located (Kallemeyn 1983, Krentz 2000, Peters et al. <br />2001). <br />Fogle (1961) reported that pallid sturgeon males mature at age 4, while females matured <br />between ages 5 and 7 (in Peters 2000). Keenlyne and Jenkins (1993) found that males <br />reached sexual maturity at age 5 -7 and that females began egg development at ages 9 -12. <br />Keenlyne and Jenkins (1993) found that spawning first occurred at age 15. Spawning <br />bands on pectoral fin rays of females age 25 and 41 were identified. A 41 year old, 17 kg <br />female contained an estimated 170,000 eggs; this is the oldest reported pallid sturgeon <br />( Keenlyne et al. 1992 in NatureServe Explorer 2001). <br />Keenlyne and Jenkins (1993) reported that males do not spawn every year, and females <br />may take up to 10 years between spawnings ( Keenlyne and Jenkins 1993 in Duffy et al. <br />1996). <br />Draft Baseline Report — Pallid Sturgeon Section <br />