Caption: Biologists electrofish
the Upper Colorado River and its tributaries to remove nonnative species.
Evidence supporting our second hypothesis was more equivocal, in that: (1) no significant differences were found in the richness of electrofished
specialists and generalists between the two stream types, (2) two of three exclusively river tributary species were specialists, (3) four of six exclusively reservoir tributary species were generalists, and (4) four of the seven species that were significantly more abundant in river tributaries were specialists.
To check for crayfish presence in our study area, mesh traps baited with beef liver (as used by local fishermen for commercial catches) were set at irregular intervals in the electrofished
reaches between June and September 1998.
Some carp to 27lb and more than 300lb of bream were moved after being electrofished
by the BW team at Sutton Stop.
In spring, Age-1 perch were electrofished
from a boat along the shore where they were concentrated.
Each stream reach was electrofished
in an upstream direction by using pulsed direct current (DC) output.
At the inlet zone, all sites were electrofished
along the bankside; meaning that differences in bank structure were decisive in dictating species presence, despite the length of bank sampled (average 400 m).
reaches were revisited in August 2011 to assess conditions of habitat in late summer and confirm intermittency of reaches.
Each section was blocked with nets (mesh size 6 mm) and electrofished
3-5 times for depletion population estimates (Van Deventer and Platts 1986).
Personnel of Colorado Parks and Wildlife Department electrofished
Yellow Jacket Canyon at our sampling site, and McElmo Creek ca.
To identify fishes associated with either perennial or intermittent flow, we used indicator species analysis (PC-Ord 6.0, MjM Software, Gleneden Beach, Oregon; McCune and Grace, 2002; McCune and Mefford, 2011) on fish catch-per-unit-effort (CPUE, number per 100 s electrofished
) data from reaches with known flow status.
The sites were also electrofished
and angled for Arctic Grayling (Table 1).