population estimates for humpback chub - Upper Colorado River ...

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CONCLUSIONS • The adult population point estimates of humpback chub in Westwater Canyon indicated a downward trend from 1998 to 2000, though not statistically significant. • The adult population point estimates of roundtail chub in Westwater Canyon indicated a stable trend between 1998 and 2000. • Increased trammel net effort (CPUE) resulted in tighter confidence intervals but no real improvement in probability of capture (p-hat) or coefficient of variation (CV). • Growth rates of humpback chub are lower than those for roundtail chub in Westwater Canyon. • Humpback chub and roundtail chub move between Black Rocks and Westwater Canyon consistently enough to consider that these two areas contain a single population for each species. 13
RECOMMENDATIONS • Increase trammel net effort (CPUE) in Westwater Canyon. • Use hoop nets and electrofishing to improve probability of capture (p-hat) and coefficient of variation (CV). • Use smaller mesh trammel nets, hoop nets, minnow traps and electrofishing to target subadult humpback chub in Westwater Canyon. • Incorporate a fourth pass and additional sampling locations (i.e., upper Cougar, Big Hole) to improve (p-hat) and coefficient of variation (CV). • Consider Black Rocks and Westwater Canyon a single population and determine a single point estimate for each year to be consistent with the assumptions for closed population estimates. • Investigate use of most appropriate statistical programs and associated models to generate future adult humpback chub population estimates. • Include a radiotelemetry component in future adult humpback chub population estimates to provide additional resolution of movement and site fidelity within and among sampling areas of Westwater Canyon. 14
Page 1 and 2: State of Utah DEPARTMENT OF NATURAL
Page 3 and 4: ACKNOWLEDGEMENTS We would like to a
Page 5 and 6: TABLE OF CONTENTS (continued) DISCU
Page 7 and 8: LIST OF FIGURES Figure 1. Figure 2.
Page 9 and 10: EXECUTIVE SUMMARY Humpback chub (Gi
Page 11 and 12: to a much larger ongoing project en
Page 13 and 14: etween years using the same analyse
Page 15 and 16: Growth Mean annual growth rates of
Page 17 and 18: Length-Frequency The length-frequen
Page 19 and 20: population trends and population dy
Page 21: Comparison with ISMP The decreasing
Page 25 and 26: Nesler, T.P. 2000. Recovery of the
Page 27 and 28: Table 3. Population estimate (N) fo
Page 29 and 30: Westwater Canyon Humpback Chub Leng
Page 31 and 32: Humpback Chub ISMP Length-Frequency
Page 33 and 34: Westwater Canyon Adult Roundtail Ch
Page 35 and 36: Westwater Canyon Roundtail Chub Ann
Page 37 and 38: Roundtail Chub ISMP Length-Frequenc
Page 39 and 40: Appendix II. Summary of population
Page 41 and 42: Appendix III Table 2. Daily instant
Page 43 and 44: Appendix III Table 5. Mean daily te
Page 45: Appendix III Table 8. Mean daily te

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