9710

• UCREFRP Catalog Number: 9710
• Author: Connolly, P.J., I.G. Jezorek, K.D. Martens and E.F. Prentice.
• Title: Measuring the performance of two stationary interrogation systems for detecting downstream and upstream movement of PIT-tagged salmonids.
• USFW Year: 2008.
• USFW - Doc Type: North American Journal of Fisheries Management
• Copyright Material: YES

PERFORMANCE OF PIT TAG INTERROGATION SYSTEMS 413
100 -.0 II! ~ 100 .0 !J:
I2 ~ I
80 80
60 60
Upstream - low flow Upstream - high flow II
..-...
~ 4D 40
0
-
>. . Rattlesnake Creek
() 20 0 Beaver Creek 20
c:
Q)
'0 0 0
ij:: 3x2 3x1 2x2 2x1 3x2 3x1 2x2 2 x 1
Q)
c:
0
:.;::::; 100 .0 .0 -.0 .-0 100 .0 0
()
Q) -a I 12
+-'
Q) 80 80
0
60 Downstream - low flow 60 Downstream - high flow
40 40
20 20
0 0
3x2 3x1 2x2 2x1 3x2 3x1 2x2 2x1
System configuration
FJGURE S.-Efficiency of detection (mean :t SE) of PIT-tagged fish pa~sing four configurations of antenna~ at two flow levels
in Rattlesnake and Beaver creeks. The data for alternative configurations were extracted from data collected by PIT tag
interrogation systems that had three arrays with two antennas each.

some flows. Fish moving upstream may have tried to
avoid a Perceived disturbance caused by the sometimes
slow vibrating action of the hybrid antennas. If their
response included the choice of a water column depth
outside the range of the antenna or an attempt to pass
around the antenna, this would account for some of the
differences in performance that we observed. Barring
differential perfonnance issues based on technology,
this suggests that minimizing potential for negative fish
response to antennas should be considered as part of
the design.
If the entire channel can be spanned, pass-through
antennas (the so-called "swim-through" antennas
described by Zydlewski et al. 2006) may be appropriate
for maximizing detection efficiency. We believe that
this orientation, when functioning, provides the best
probability of detecting a PIT -tagged fish by any
antenna design of which we are aware. This type of
antenna is very suitable for stable-flow streams (i.e.,
those with little or no large debris) for a study limited
to investigating fish movement during low-flow
periods or if deployed in a manner that allows the
antenna to break away under a predetermined load and

be readily repositioned into an operating orientation.
The pass-through orientation is particularly suited for
taking advantage of existing structures such as bridge
crossings, culverts, or engineered study streams. In
contrast, our pass-by and hybrid antennas proved to
hold during flow and debris conditions than would
have disabled most pass-through antennas based on our
experience at other locations.
AlthougH we achieved the best results for detection
efficiency and precision with our full 3 X 2 system
design, our 2 X 1 system proved reasonably effective
for gaining information on the direction of movement
and detection efficiency. However, based on the poor
precision (Rattlesnake Creek, CV = 55%; Beaver
Creek, CV = 79%) that we gained from the 2 X I
systems for detection of upstream-moving fish, one or
more additional antennas or an additional array would
probably be warranted for deriving a population
estimate or conducting a statistical test for response.
Much also depends on the stream and site geomor-
phology. For small stream widths, or for larger streams
with good pinch points or a defined thalweg, a well-
placed 2 X I system without full stream width or water