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<br />The 186 collections from the Westwater station contain 2,004 fish (an average of 11
<br />specimens per collection) representing 14 species. Native species account for 33% of
<br />the fish. Percentage composition for species representing at least 1 % of the fish
<br />collected is 29% fathead minnow, 26% non-native cyprinids (early larvae offathead
<br />minnow, red shiner and sand shiner that are too small or damaged to be positively
<br />identified or too numerous to warrant separation), 19% chub, 8% sand shiner, 7%
<br />speckled dace, 5% bluehead sucker, 2% flannelmouth sucker, and 1 % each carp,
<br />Colorado squawfish, red shiner, channel catfish, and green sunfish. However, the
<br />proportion of red shiner, sand shiner, and fathead minnow among those grouped as
<br />non-native cyprinids might be quite different from those which were identified to
<br />species. Colorado squawfish are present in 10% of the collections (18 of 186), were
<br />taken from 27 June through 11 August, and measure 7-10 mm total length (TL).
<br />
<br />The 185 collections from the Moab station contain 3,653 fish (an average of 20
<br />specimens per collection) representing 10 species. Native species account for 9% of
<br />the fish. Percentage composition for species representing at least 1 % of the fish
<br />coIlected is 72% non-native cyprinids, 6% fathead minnow, 6% sand shiner, 5% carp,
<br />4% bluehead sucker, 3% speckled dace, and 1% each Colorado squawfish, chub, and
<br />red shiner. Again, the proportion of red shiner, sand shiner, and fathead minnow
<br />among those grouped as non-native cyprinids might be quite different from those
<br />which were identified to species. Colorado squawfish are present in 15% of the
<br />collections (27 of 185), and were taken from 27 June through 16 August. They
<br />measure 8-1 Imm TL for collections taken through 4 August, 11-18 mm TL for 5 and
<br />6 August, and 33 mm TL for the 16 August collection.
<br />
<br />As noted above, some Moab collections include large numbers of early red shiner,
<br />sand shiner, and fathead minnow larvae. To save time and remain within budget,
<br />many of these fish were grouped as non-native cyprinids rather than separated to
<br />species. Also, taxonomic criteria are currently inadequate to positively identifY many
<br />of the fish measuring 5 mm or less-red shiner and sand shiner are especially difficult
<br />(a detailed, comparative description of recently hatched stages of these species might
<br />resolve the problem). Still, if needed in the future, we expect that at least half of the
<br />fish grouped as non-native cyprinids can be identified to species with reasonable
<br />confidence.
<br />
<br />(c) Larval-Fish Drift-Net Collections, Colorado River, Westwater and Moab, Utah, 14
<br />July through 31 August 1995.
<br />
<br />This set consists of 166 larval-fish drift-net collections received by the Larval Fish
<br />Laboratory. Of these, 49 were taken at the Westwater station (river mile 127.5)
<br />beginning on 25 July, and 117 at the Moab station (river mile 65.8) beginning on 14
<br />July. All specimens received have been cataloged (LFL 35460-35948) and stored as
<br />part of Larval Fish Laboratory holdings for voucher and future study, possibly
<br />including detailed analysis of chubs (Gila sp.) and early non-native cyprinid larvae
<br />for species identification, questionable Colorado squawfish larvae for DNA
<br />
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