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sampling in these areas and acquisition of current abundance estimates is difficult. Abundance estimates <br />for these parts of the range by Duffy et al. (1996) were not considered reliable due to the lack of <br />mark/recapture data. <br />Pallid sturgeon were proposed for listing as an endangered species on August 30, 1989 (54 FR 35901- <br />35904). The species was listed as endangered on October 9, 1990 (55 FR 36641- 36647). The <br />reasons for listing were habitat modification, apparent lack of reproduction, commercial harvest and <br />hybridization in parts of its range. Most authors attribute the decline of pallid sturgeon to the massive <br />habitat alterations that have taken place over virtually all of its range (Kallemeyn 1983, Gilbraith et al. <br />1988, Keenlyne 1989, USFWS 1993). <br />Since 1988, pallid sturgeon researchers have collaborated on studies to gather information about the <br />species including estimates of fish numbers ( Keenlyne 1995). That has allowed workers to identify, <br />where populations still remain and to obtain rough estimates of present abundance of the species. Tag <br />and recapture data has allowed researchers to estimate that 50 to 100 pallid sturgeon remain in the <br />Missouri River above Ft. Peck Dam in Montana, and between 200 and 300 pallid sturgeon remain <br />between the Garrison Dam in North Dakota and Fort Peck Dam, including the lower Yellowstone <br />River (Steve Krentz, pers. comm.). One to five sightings per year have been made of pallid sturgeon <br />between the headwaters of Oahe Reservoir in South Dakota to the Garrison Dam and from the riverine <br />reach in the Missouri River above Gavins Dam to Fort Randall Dam suggesting that, perhaps as many <br />as 25 to 50 fish may remain in each of these areas. A small population also exists between Oahe Dam <br />and Big Bend Dam on the Missouri River in South Dakota with perhaps 50 to 100 fish remaining in this <br />riverine section. Unfortunately, no evidence has been obtained that any of the upper Missouri River <br />system populations are successfully reproducing because only large individuals are being reported <br />( Keenlyne 1989, Duffy et al. 1996). <br />----- P Glen Constant, at Louisiana State University, estimated the pallid sturgeon population in the Atchafalaya <br />River to range from 2750 to 4100 fish. That is based on tag returns and telemetry studies. However, a <br />high incidence of hybridization is occurring in the Atchafalaya River and Mississippi Rivers ( Keenlyne et <br />al. 1994) which makes estimation of the number of pure pallid sturgeon in these river systems difficult <br />(Duffy et al. 1996). <br />In recent years, pallid sturgeon populations have been augmented by release of hatchery reared fish. In <br />1994, the MDC released approximately 7000 fingerlings in the Missouri and Mississippi Rivers and an <br />additional 3000 fingerlings were stocked in 1997 (Graham 1997, 1999). Since stocking in 1994, <br />approximately 86 pallid sturgeon returns have been reported, mostly in the Mississippi River <br />downstream of St. Louis (Graham 1999). Thirty-five 12 to 14 -inch fish raised at Natchitoches NFH <br />were stocked in the lower Mississippi River in 1998 (Kilpatrick 1999). Also in 1998, 745 hatchery- <br />reared yearling pallid sturgeon were released at three sites in the Missouri River above Ft. Peck <br />Reservoir (Gardner 1999) and another 750 yearling sturgeon were released near the confluence of the <br />Yellowstone and Missouri Rivers (Steve Krentz, pers. comm.). <br />Status Range Wide -PS 105 <br />