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Biology of Pallid Sturgeon: <br />Feeding and digestive tract analysis: <br />Fish have been noted as important food items for pallid sturgeon by many studies and <br />these results have been noted in general accounts (Carlson et al. 1985; Coker 1929-30?; Cross <br />1967; Keenlyne 1995; Mayden and Kuhajda 1997). Observations of feeding in hatcheries have <br />indicated a strong preference for fish (Bollig 1998; Bollig 2005). Studies of the morphology of <br />the mouth of pallid sturgeons reveals that they can protrude their mouth towards their prey and <br />close it before retracting it in a way similar to that used by sharks (Carroll and Wainwright <br />2003). <br />Several studies have developed and tested the efficacy and safety of techniques to sample <br />food items in the digestive tracts of pallid sturgeon. Shuman and Peters (2007) tested pulsed <br />gastric lavage on shovelnose sturgeon, found it safe for the fish and recommended it for use on <br />pallid sturgeon. Wanner et al. (2007) and Gerrity et al. (2006) used gastric lavage to sample the <br />stomach contents of hatchery-reared pallid sturgeon and both studies found that juvenile pallid <br />sturgeon were piscivorous. Colonic flushing has also been used to safely remove material from <br />pallid sturgeon digestive tracts (Hoover et al. 2007). This technique also found that fish, <br />especially Macrhybopsis chubs, made up a large portion of the diet. Comparisons of shovelnose <br />sturgeon and pallid sturgeon food habits have indicated that early in their lives they both feed on <br />invertebrates especially Ephemeroptera and Chironomids. However, shovelnose sturgeon cannot