K. R. Bestgen, K. A. Zelasko, and G. C. White. Monitoring ...

• Sampling for larvae in the lower White River where reproduction was documented for
the first time in 2011 should continue at levels outlined in Project 22f.
• Sampling in the lower Yampa River for razorback sucker larvae may be warranted but at
a low level that may include near shore seine sampling conducted within 1–2 weeks after
first appearance of middle Green River larvae.
• Sampling for razorback sucker larvae in the Colorado River should proceed in
accordance with plans to evaluate razorback sucker reproduction in the lower Gunnison
and Colorado rivers per Project 163. When higher levels of reproduction there are noted,
the monitoring program should be revised to incorporate new information on distribution
of larvae relative to spawning areas and establishment of sentinel locations that can be
used to monitor timing of reproduction and population abundance over time.
• Although early life stage sampling programs are efficient, additional experimental
sampling program evaluations are needed to verify what we think sampling data suggests.
Those experiments include but are not limited to light trap attraction distances and
sampling efficiency studies in the lab and the field, and field releases of marked larvae
near spawning areas and wetland breaches to assess dispersal and wetland colonization.
Occupancy analyses may also aid in determining colonization probabilities of larvae in
wetlands, given that detection probabilities of larvae in wetlands may be less than one.
• Morphological techniques are the benchmark for identification of larvae and are reliable.
Verification of identity of larvae via appropriate genetic techniques, especially identities
that are questionable, would be useful. Minimally, such a study needs to be conducted
with an appropriate design, including development of sufficient taxonomic markers, and
reliably identified reference populations from across the ranges of candidate taxa.
• Real-time monitoring requires continued real-time identification of razorback sucker
larvae in samples collected in the middle Green River. Annual updates of early life
history sampling and data collection is needed to inform management.
• Existing sampling programs, especially Colorado pikeminnow abundance estimation
sampling, provides useful data with which to monitor razorback sucker populations in the
Green and Colorado rivers.
• Although estimates generated from analyses of razorback sucker recapture data were
mostly unreliable, some were noteworthy. Relatively low population sizes were apparent
in spite of large numbers of stocked fish in the system, supporting previous analyses that
48