8135

• UCREFRP Catalog Number: 8135
• Author: Valdez, R. A.
• Title: Occurrence of Threatened and Endangered Fishes of the Colorado River in the Vicinity of the Proposed Jacobson Hydro No. 1 Project.
• USFW Year: 1984.
• USFW - Doc Type: Logan, Utah.
• Copyright Material: NO

5-10

5.4 Vertical Distribution of Drift
Paired sets were made with the drift nets during the 24-hour sample
effort to assess the vertical distribution of larval drift in the upper
Colorado River at the proposed JH-1 site. A total of 16 samples were taken
from each of two levels in the vertical water column. One sample stratum
(upper) was the uppermost 1 foot of water, including the water surface. The
second sample stratum (lower) extended from 1 to 3 feet below the surface of
the water with the net frame resting on the river bottom. An analysis of
variance revealed no significant difference (P=0.15) between the mean drift
density of the upper (0.3913) and lower (0.2581) groups of nets. It appears
from this analysis that there is uniform mixing of larval fishes to a depth
of at least 3 feet in the vertical water column at the headgates of the
proposed JH-1 site.