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<br />1994, field identification and transport to rearing facilities of living sucker
<br />larvae.-Attempts in 1994 to identify living sucker larvae in the field and transport them to
<br />facilities at the LFL for rearing through the early juvenile period met with mixed success. Use of
<br />MS-222 (100 mg/L) to immobilize sucker larvae for field identification was successful.
<br />However, of the 5 bluehead, 6 flannelmouth, and 30 razorback sucker larvae selected for
<br />rearing from nursery habitats on the lower Green River, and 3 white, 12 bluehead, and 24
<br />flannelmouth sucker larvae selected for rearing from nursery habitats on the middle Colorado
<br />River, all but 2 lower Green River razorback sucker larvae died during transport or within the
<br />first 2-4 d of rearing. The two surviving razorback sucker larvae were still alive and in good
<br />condition (about 20 cm TL) at the submission of this report, and will be taken to hatchery
<br />facilities at Horsethief State Wildlife Area in July 1997 for continued rearing. The period
<br />between capture of sucker larvae and their arrival at the LFL was typically 2-3 d. Holding fish
<br />in styrofoam coolers for that length of time might have contributed to the high mortality. In the
<br />future, if attempts are made to artificially rear wild-caught lower Green River razorback sucker
<br />larvae, the period between capture and arrival at rearing facilities should be shortened. The
<br />U.S. Fish and Wildlife Service has been successful in rearing field-collected middle Green River
<br />razorback sucker larvae at the Ouray National Fish Hatchery; length of time between capture
<br />and arrival at rearing facilities was typically a few hours.
<br />
<br />1995, lower Green River, Millard Canyon, Anderson Bottom-Bonita Bend, and
<br />Holeman Canyon, 16-17 May, 2-8 and 20-24 June, and 7-10 July.-A total of 1,102 fish
<br />was collected in three light trap samples during 16-17 May, 3,419 in eight light trap (2,768) and
<br />three seine samples (651) during 2-8 June, 3,826 in six light trap (2,475) and 13 seine samples
<br />(1,351) during 20-24 June, and 3,120 in six light trap samples during 7-10 July (Table 8).
<br />Nonnative minnows dominated the catch in each sampling period (> 98% of total number
<br />collected during each sampling period), with red shiner (97%, GMcpe = 61.4 during 16-17 May;
<br />94%, 24.6 for light trap samples and 6.9 for seine samples during 2-8 June; 68%, 7.4, 8.3
<br />during 20-24 June; 50%,12.9 during 7-10 July), sand shiner (1%,0.4; 4%,0.6,2.4; 8%,1.4,
<br />0.7; 20%, 5.7), and fathead minnow (0; < 1 %, 0, 0.8; 23%, 6.6, 0.5; 30%, 8.6) predominating.
<br />Common carp was the other nonnative collected. Native fishes collected included Colorado
<br />squawfish, bluehead sucker, f1annelmouth sucker, and razorback sucker. Only one larval
<br />razorback sucker (12.5 mm TL) was collected in a light trap sample taken inside Millard Canyon
<br />on 21-22 June (Table 10). A total of 82 juvenile Colorado squawfish (39-240 mm TL) was
<br />captured in seines; seven inside Holeman Canyon on 4 June and 49 in a flooded wash at
<br />Bonita Bend on 6 June (GMcpe = 1.5), and 19 in a flooded wash at Bonita Bend, six inside
<br />Holeman Canyon, and one inside Millard Canyon on 22-23 June (GMcpe = 0.2). Of the 82
<br />juvenile Colorado squawfish, nine had latex marks.
<br />In 1995, near record snow packs in upper Colorado River drainages (in some drainages,
<br />snow packs were> 200% above long-term averages) combined with below normal spring-mid
<br />summer air temperatures and above normal precipitation resulted in later peak river flows.
<br />Later peak flows delayed the start of fish spawning, including razorback sucker (observations
<br />based on examinations of adult fish, radio tracking of adult razorback sucker in the middle
<br />Green River system, and captures of fish larvae). Delayed start of spawning possibly
<br />contributed to the apparent low reproductive success of razorback sucker and other native
<br />suckers; see Wick, E. J., Ph.D. dissertation, in preparation, for evaluation of physical conditions
<br />at the primary razorback sucker spawning area in the Escalante reach of the middle Green
<br />River during spring-early summer 1993-1996. Another result of later peak flows was that
<br />nursery habitats in the lower Green River, which are typically ephemeral and gone by late June
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