Laserfiche WebLink
Discussion <br />Adult Fish <br />Due to the low number of captures and only one recapture, the population <br />estimate objective of the study was not met. Haines and Modde (2002) were able to <br />estimate population size, but with very low precision. Catch per unit of effort of <br />humpback chub has steadily declined from all previous studies (Table 3). The low <br />number of captures (n=13) and decrease in catch per unit of effort indicates a population <br />in decline. This is similar to the Desolation/Gray Canyon population (Jackson and <br />Hudson 2003) and the Westwater Canyon population (Hudson and Jackson 2005). It <br />appears that a population estimate will not be possible until this population contains more <br />individuals. <br />No gear seemed more effective than another at capturing humpback chub and <br />none alone caught 50%. Electrofishing captured a large proportion of our fish but may be <br />harmful to individuals in the population (Snyder 2003). Trammel netting was effective at <br />sampling the deepwater habitats of Whirlpool Canyon but has been previously abandoned <br />in Yampa Canyon due to high stress on chubs (Karp and Tyus 1990). Angling was <br />effective in localized areas but is a known source of mortality in other fishes (i. e. <br />Lindsay et al. 2004, Dubois and Dubrelzig 2004) and was labor intensive and is therefore <br />not feasible for capturing the large numbers of humpback chub needed for a population <br />estimate. Also, use of untrained volunteers in capturing humpback chub makes this <br />method questionable and should probably be avoided, or at minimum, all fish captured in <br />this manner should be scanned for PIT tags. Previous investigators have had poor <br />9 <br />