9668

• UCREFRP Catalog Number: 9668
• Author: Crowl, T. A. and e. al.
• Title: Bonytail Draft 1998 Annual Report, February 2000.
• USFW Year: 2000.
• USFW - Doc Type: Logan, UT.
• Copyright Material: NO

of the time, at middle depths 15%, and at the surface less than 1 % of the time (Fig.
1.6).
100 GLOW VELOCITY
............ ----- ---------- MEDIUM VELOCITY
p 80 WHIGH VELOCITY
W " ---------------------------- ----------------
60
U-1
----------------------------------------- --------
m 40
O

0-0 ------------ --------------------------
20
0
DEEP MID SURFACE
DEPTH
Figur a 1.6
Depth selection by bonytail in flow experiments without substrate and without red
shiners (day and night combined).
Substrate and Flow
Both the substrate and the flow experiments were combined in order to determine
which variable exhibited the most influence on the spatial distribution of bonytail.
Substrate selection during the day was not independent of velocity as determined by an
R X C test (x2=24.31, df=4, p < 0.001). During the night, substrate and velocity were
again interdependent (R X C results; x2=11.14, df=2, p<0.05). During the day, bonytail
were observed hiding in the cobble substrate at effective velocities of 0.0 m/s 75% of
the time in low velocity treatments, and 80% of the time in medium velocity treatments
and 90% of the time in high velocity treatments. However, during the night, bonytail
were hidden in the cobble substrate at effective velocities of 0.0 m/s 86% of the time in
low velocity treatments and 88% of the time in medium velocity treatments. Data for
high velocity treatments were not available.
20