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<br />''}UI <br />-~ <br /> <br />Lt, Colonel Dorothy F. Klasse <br /> <br />13 <br /> <br />Kaeding (1991) report that the number of razorback sucker captures in the <br />Grand Junction area have declined dramatically since 1974. <br /> <br />. <br /> <br />In the San Juan River subbasin. small concentrations of razorback suckers have <br />been reported at the inflow area in the San Juan arm of Lake Powell. Utah <br />(Meyer and Moretti 1988). and one specimen was captured in the San Juan River <br />near Bluff. Utah. in 1988 (Platania 1990: Platania et al. 1991). In Bestgen <br />(1990) additional captures of small numbers of razorback suckers also were <br />reported from the Dirty Devil and Colorado River arms of Lake Powell. <br /> <br />8eginning in May 1987 and continuing through October 1989. complementary <br />investigations of fishes in the San Juan River were conducted in Colorado. <br />New Mexico. and Utah (Platania 1990: Platania et al. 1991). In 1987. a <br />total of 18 adult razorbacks (6 recaptures) were collected on the south <br />shore of the San Juan arm of Lake Powell (Platania 1990: Platania et al. <br />1991). These fish were captured near a concrete boat ramp at Piute Farms <br />Marina and were believed to be either a spawning aggregation or possibly a <br />staging area used in preparation for migration to some other spawning site. <br />Of the 12 individual razorbacks handled in 1987. 8 were running ripe males <br />while the other 4 specimens were females that appeared gravid. <br /> <br />In 1988. a total of 10 razorback suckers were handled at the same general . <br />location. 5 of which were in reproductive condition (Platania et al. 1991). <br />Six of the ten individual specimens in the 1988 samples were recaptures from <br />1987. Also. in 1988. a single adult tuberculate male razorback sucker was <br />captured at approximately river mile 80 on the San Juan River near Bluff. <br />Utah. Particularly noteworthy is that this is the first confirmed record of <br />this species from the main stem San Juan River. The presence of this <br />reproductively mature. speCimen suggests that the razorback may be attempting <br />to spawn in some unknown location within the riverine portion of the San Juan <br />drainage. No razorback suckers were caotured in 1989. No larval sppcimpns <br />nor any other size classes of razorbacks (other than adults), have ever been <br />documented in the San Juan River drainage. <br /> <br />All recent captures of wild razorback suckers in the upper basin have been <br />mature adults. In 1994. an experimental augmentation program was initiated on <br />the San Juan River; 30 radio tagged razorback suckers and 656 razorback <br />suckers marked with passive integrated transponder tags were released in the <br />San Juan River. There-is no evidence anywhere in the Colorado River system <br />that indicates significant recruitment to any population of razorback sucker <br />(Bestgen 1990. Platania 1990. Platania et al. 1991. Tyus 1987. McCarthy and <br />Minckley 1987. Osmundson and Kaeding 1989). <br /> <br />. <br /> <br /><1 C' <br />