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2017 Lake Pend Oreille Bull Trout Survival Study Annual Project Update
Dissolved Gas Supersaturation Control, Mitigation, and Monitoring Program,
Appendix F5
Prepared by:
Susan Frawley
Natural Resources Technician
Avista
Robert Jakubowski
Natural Resources Technician
Avista
and
Ken Bouwens
Regional Fisheries Biologist
Idaho Fish and Game
Prepared for:
Avista
Noxon, MT
and
Idaho Dept. of Fish and Game
Boise, ID
January 2019
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TABLE OF CONTENTS
LIST OF TABLES ....................................................................................................................... II
Abstract ...................................................................................................................................... iii
Introduction ................................................................................................................................. 1
Methods....................................................................................................................................... 2
Results and Discussion ............................................................................................................... 3
Recommendations ....................................................................................................................... 7
ACKNOWLEDGEMENTS ........................................................................................................... 7
REFERENCES ............................................................................................................................... 8
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LIST OF TABLES
TABLE 1. Number of Bull Trout tagged, detected leaving Granite Creek, and detected re-
entering Granite Creek, 2011-2017. ............................................................................ 4 TABLE 2. Number of Westslope Cutthroat Trout tagged, detected leaving Granite Creek,
and detected re-entering Granite Creek, 2011-2017. .................................................. 4 TABLE 3. Number of Bull Trout tagged, detected leaving Trestle Creek, and detected re-
entering Trestle Creek, 2011-2017. ............................................................................ 4 TABLE 4. Number of Westslope Cutthroat Trout tagged, detected leaving Trestle Creek,
and detected re-entering Trestle Creek, 2011-2017. ................................................... 5
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ABSTRACT
A study was initiated in 2011 to estimate Bull Trout Salvelinus confluentus and
Westslope Cutthroat Trout Oncorhynchus clarkii lewisi, survival from juvenile
outmigration to adult return using half-duplex Passive Integrated Transponder tag
technology in Trestle and Granite creeks, both tributaries of Lake Pend Oreille (LPO). A
total of 1,039 Bull Trout and 1,035 Westslope Cutthroat Trout were PIT-tagged in these
two streams from 2011 through 2016 - no additional individuals were tagged in 2017.
During this time period, 178 Bull Trout and 160 Westslope Cutthroat Trout were detected
emigrating to LPO. As of 2017, a total of 44 Bull Trout and 47 Westslope Cutthroat
Trout were detected returning as adults. In addition, 6,350 Bull Trout were tagged in LPO
as part of the Lake Trout suppression program, 549 of which have been subsequently
detected in Trestle and Granite creeks. It is important to note that these data are
preliminary and should not be interpreted as survival estimates. Detection data have not
been adjusted for antenna efficiency, and not enough time has passed to allow for each
tagging-year cohort to mature, especially for more recently tagged fish
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INTRODUCTION
A study was initiated in 2011 to estimate Bull Trout Salvelinus confluentus, and
Westslope Cutthroat Trout Oncorhynchus clarkii lewisi, survival from juvenile
outmigration to adult return using half-duplex (HDX) Passive Integrated Transponder
(PIT) tag technology. Bull Trout in-lake survival will be estimated by monitoring
juvenile Bull Trout emigration to Lake Pend Oreille (LPO) from selected tributaries and
quantifying subsequent returns of adult Bull Trout to these tributaries. This project was
proposed as a follow-up to previous estimation of in-lake survival using similar
techniques, which was completed in 2008 (Ryan et al. 2009). It is anticipated that
ongoing predator suppression activities in LPO will increase in-lake Bull Trout survival
by reducing direct mortality and competition, while increasing available food resources
(e.g., kokanee O. nerka) for Bull Trout. This project will allow for quantification of in-
lake survival rates in the coming years.
Two tributaries were selected for this study: Granite Creek, a tributary on the eastern
shoreline of LPO, and Trestle Creek, a tributary entering LPO on the northern shoreline.
Both tributaries support Bull Trout and Westslope Cutthroat Trout and spawning by both
early- and late-run kokanee. Both tributaries have been influenced by habitat restoration
and conservation efforts through Clark Fork Settlement Agreement (CFSA) programs
(Avista 1999). These tributaries have accessible locations and land ownership that allow
for installation of PIT tag antenna arrays.
Bull Trout redd counts in Granite Creek have varied considerably since standard redd
surveys began in 1983, with annual totals ranging from 0 to 217 (Jakubowski and
Bouwens 2018). Substantial in-stream habitat restoration was completed on Granite
Creek during the mid-2000’s to improve fish passage conditions. In addition, acquisition
of important properties within the riparian corridor has supported ongoing conservation
efforts in this drainage by reducing potential impacts from residential development.
Improved adult escapement in recent years has been largely credited to these efforts. The
average number of redds in Granite Creek over the last 10 years was 98, ranging from 52
in 2008 to 217 in 2013.
Trestle Creek has consistently supported one of the largest populations of spawning Bull
Trout in the LPO basin. The average number of redds counted in Trestle Creek over the
last 10 years was 166, ranging from 75 in 2017 to 395 in 2006 (Jakubowski and Bouwens
2018). Trestle Creek is considered a priority tributary for spawning Bull Trout in the LPO
watershed (PBTAT 1998). However, redd counts in Trestle creek have been steadily
declining over the past five years (Jakubowski and Bouwens 2018). Legacy effects from
past logging and road construction, as well as potential impacts from future timber
harvest and road construction through changes in forest management priorities have
largely been addressed in the watershed.
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METHODS
Remote HDX PIT tag antenna arrays have been operating nearly continuously in Granite
and Trestle creeks since 2011 to detect emigrating Bull Trout juveniles and immigrating
adult Bull Trout. Antenna arrays consist of two independent, swim-through loop antennas
that provide tag detection and allow for determination of travel direction. Antenna loops
were constructed of 10 gauge multi-stranded copper wire. Each antenna loop was
constructed to span the bankfull channel width. Wire loops were encased in standard
garden hose and/or PVC-lined air hose for protection. Wire loops were suspended from a
rope spanning the creek channel and anchored to the channel bottom using rebar stakes
with affixed hooks. Antennas were operated by multiple-antenna HDX readers (Oregon
RFID). A single multiple-antenna HDX reader was installed at each tributary location to
operate two antennas positioned in an array approximately 10 m apart. Readers were
powered by 120 volt AC power and converted to 12 volt DC power, either through an
AC/DC power converter or through the use of a DC battery charging system.
The PIT tag antenna arrays were operated continuously after installation. Antenna
performance was monitored and stored data were downloaded at least monthly during
operation. When antenna performance was found to be limited or failures were found, the
antenna were re-tuned or repaired as soon as possible. A waterproof marker tag (Oregon
RFID) mounted within the field of one antenna loop per array was used to monitor
antenna operation between data downloads. The marker tag was programmed to produce
detections at approximately 15 minute intervals. Marker tag detection was used as an
indication of proper antenna operation.
Juvenile Bull Trout and all Westslope Cutthroat Trout were tagged with 12 mm HDX PIT
tags to monitor emigration and subsequent immigration in LPO tributaries. Juvenile fish
were collected for tagging opportunistically throughout the occupied reaches of each
stream using standard electrofishing techniques between July and September. Collected
fish were anesthetized, measured for total length (mm), PIT-tagged, and released. Only
fish 100 mm or greater were tagged. Each PIT tag was injected in the anterior dorsal
sinus using 1.4 mm syringes. Upon recovery from anesthesia, tagged fish were released
within the same general area in which they were collected.
Individual tag detections downloaded from the PIT tag array readers included tag
identification number, time and date of detection, and a record of which antenna in the
array detection occurred. Tag detections at each antenna in the array allowed for
determination of the direction of travel. Direction of travel was determined by looking at
the order of detection between paired antennas in the array. For the purposes of initial
reporting, in instances where fish were detected on only one of the antennas in the array,
it was assumed the fish passed the other antenna and had moved past the array.
Assumptions were made regarding direction of travel based upon the initial tagging date
and detection history. Further analysis regarding direction of travel and detection
probability will be conducted when enough time has passed for all tagged fish to have
migrated to the lake, matured, and returned to spawn, which will likely be after
approximately 2020.
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Data were grouped by the month fish from each species and life stage were first detected
to describe migration timing for each stream. Juvenile timing was described by the first
time a fish tagged in a particular tributary was detected passing downstream of the arrays.
Adult timing was described by the first time a fish of each species, originally tagged
either in the tributaries or on the net boat, was detected migrating upstream of the arrays.
RESULTS AND DISCUSSION
Based on marker tag detection, our HDX PIT tag antenna arrays on Granite and Trestle
creeks were operational for the reporting period in 2017. No specific operational issues
occurred during this period.
No additional fish were tagged in Granite or Trestle Creeks in 2017. From 2011 through
2016, 530 Bull Trout and 528 Westslope Cutthroat Trout were tagged in Granite Creek,
and 509 Bull Trout and 507 Westslope Cutthroat Trout were tagged in Trestle Creek
(Tables 1-4). From 2011 through 2017, a total of 178 Bull Trout and 160 Westslope
Cutthroat Trout were detected emigrating to LPO. During this same time period, 44 Bull
Trout and 47 Westslope Cutthroat Trout were detected returning as adults.
During 2011-2017, 24.33% of the Bull Trout (Table 1) and 18.56% of the Westslope
Cutthroat Trout (Table 2) PIT-tagged upstream of the antennas were detected leaving
Granite Creek. Through 2017, 24 Bull Trout returned to Granite Creek from LPO, 16 of
which were tagged in 2011 (Table 1). During the same time period, 25 Westslope
Cutthroat Trout returned from the lake of which 12 were tagged in 2012 and 11 in 2013
(Table 2).
During 2011-2017, 9.63% of the Bull Trout (Table 3) and 12.23% of the Westslope
Cutthroat Trout (Table 4) PIT-tagged upstream of the antennas were detected leaving
Trestle Creek. Through 2017, 20 Bull Trout returned to Trestle Creek from LPO, 17 of
which were tagged in 2011 (Table 3). During the same time period, 22 Westslope
Cutthroat Trout returned from the lake (Table 4).
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TABLE 1. Number of Bull Trout tagged, detected leaving Granite Creek, and detected re-entering Granite Creek, 2011-2017.
No. Detected Out No. Detected Back
Year
Tagged
Number
Tagged 2011 2012 2013 2014 2015 2016 2017 Total
2011 2012 2013 2014 2015 2016 2017 Total
2011 263 21 30 0 0 0 0 0 51 0 0 0 0 9 6 1 16
2012 20
5 8 0 0 0 0 13
0 0 0 0 3 1 4
2013 0 0 0 0 0 0 0 0 0 0 0 0 0
2014 83
13 6 0 0 19
0 0 0 2 2
2015 164
40 3 3 46
0 0 2 2
Total 530 21 35 8 13 46 3 3 129 0 0 0 0 9 9 6 24
TABLE 2. Number of Westslope Cutthroat Trout tagged, detected leaving Granite Creek, and detected re-entering Granite Creek, 2011-
2017.
No. Detected Out No. Detected Back
Year
Tagged
Number
Tagged 2011 2012 2013 2014 2015 2016 2017 Total 2011 2012 2013 2014 2015 2016 2017 Total
2011 0
2012 199
13 5 3 0 1 0 22
0 6 1 2 3 0 12
2013 162
29 30 1 0 0 60
0 0 1 9 1 11
2014 37
0 2 0 0 2
0 0 0 0 0
2015 130
0 14 0 14
0 1 1 2
Total 528 0 13 34 33 3 15 0 98 0 6 1 3 13 2 25
TABLE 3. Number of Bull Trout tagged, detected leaving Trestle Creek, and detected re-entering Trestle Creek, 2011-2017.
No. Detected Out No. Detected Back
Year
Tagged
Number
Tagged 2011 2012 2013 2014 2015 2016 2017 Total 2011 2012 2013 2014 2015 2016 2017 Total
2011 197 27 7 2 0 0
0 36
0 0 0 1 7 8 1 17
2012 70 4 1 0 0
0 5
0 0 0 1 1 1 3
2013 0
0
2014 50
2 2
0 4
0 0 0 0 0
2015 192
2 1 1 4
0 0 0 0
Total 509 27 11 3 2 4 1 1 49 0 0 0 1 8 9 2 20
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TABLE 4. Number of Westslope Cutthroat Trout tagged, detected leaving Trestle Creek, and detected re-entering Trestle Creek, 2011-
2017. No. Detected Out No. Detected Back
Year
Tagged
Number
Tagged 2011 2012 2013 2014 2015 2016 2017 Total 2011 2012 2013 2014 2015 2016 2017 Total
2011 0
2012 196
0 19 0 0 0 0 19
0 0 0 2 4 0 6
2013 130
3 5 2 0 0 10
0 1 0 3 3 7
2014 42
2 5 0 0 7
0 0 1 3 4
2015 139
16 10 0 26
0 3 2 2
Total 507 0 0 22 7 23 10 0 62 0 0 1 2 11 22
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It is important to note that these data are preliminary and should not be interpreted as survival
estimates. Detection data have not been adjusted for antenna efficiency and not enough time has
passed to allow for each tagging-year cohort to mature and complete a migration cycle. We will
begin to attempt estimating antenna efficiency and quantify the individuals that avoid detections
after the completion of the 2018 annual report. We continue to notice that some fish did not
register detections on both antennas when they passed the arrays, particularly for presumed
downstream migrants. Some fish were only registered as detections on the upstream antenna, and
some only on the downstream antenna. Thus, some downstream migrants were probably able to
pass through both antenna fields quickly without being detected. This is likely based on the
orientation of the tag compared to the antenna during travel, the travel speed of the fish, the
current scanning rate (approximately 6 scans/second) of each reader, and the short detection
distance of the antennas. Upstream-traveling fish are assumed to more consistently be
perpendicular to the orientation of the antenna, allowing for increased detection rates, and to pass
through the fields more slowly because the speed of the current subtracts from their swimming
speed resulting in a higher detection probability. If we were to increase the scan rate, the duration
of the scan decreases. Given that we currently do not have an estimate for antenna efficiency or
missed detections and there are other factors influencing tag detection rates, we are not planning
to change the scan rate at this time.
In Granite Creek, 15 of 24 Bull Trout (62.5%) that were detected returning were also detected
leaving the stream. Similarly, 12 out of 25 Westslope Cutthroat Trout (48%) detected returning
were also detected leaving Granite Creek. In Trestle Creek, 12 out of 20 Bull Trout (60%) and 10
out of 22 Westslope Cutthroat Trout (45%) that were detected returning were also detected
leaving this stream. If we assume that Bull Trout and Westslope Cutthroat Trout have
approximately the same detection probability in both streams, we likely detected approximately
54% of the total number of fish that emigrated out of these two streams as juveniles. Although it
is too early to calculate a correction factor for undetected tags, this will need to be done to
account for bias when estimating survival rates.
Other PIT-tagged fish were detected in addition to those tagged as part of this study. From 2011
to 2017, 6,350 Bull Trout were incidentally caught, PIT-tagged, and released as part of the Lake
Trout suppression efforts on LPO (Wahl et al. 2015; IDFG unpublished data). Through 2017,
369 of these Bull Trout were detected in Granite Creek, of which 49 were first detected in 2017.
Similarly, 180 Bull Trout were detected in Trestle Creek, of which 35 were first detected in
2017.
Bull Trout captured in the lower Clark Fork River downstream of Cabinet Gorge Dam have also
been PIT-tagged as part of Avista’s CFSA Appendix C Upstream Fish Passage Program. None
of the individuals from this program were detected going into Granite Creek in 2017. Two
individuals that were captured, tagged, and released in the Clark Fork River in 2017 were
detected entering Trestle Creek later in 2017. Both individuals were genetically assigned to
Idaho tributaries – one to Porcupine Creek and the other to Savage Creek.
In 2017, 113 Westslope Cutthroat Trout were tagged on the Clark Fork River downstream of
Cabinet Gorge Dam as part of salmonid abundance estimates and Appendix C Upstream Fish
Passage Program capture activities (Bernall and Duffy 2018). Since 2014, a total of 1,205
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Westslope Cutthroat Trout have been PIT-tagged in these efforts. Five of these fish have been
detected in Granite Creek and 11 in Trestle Creek. For fish detected in Granite Creek, none were
detected in 2017 and only 2 of the 11 in Trestle Creek were detected in 2017.
The detections of fish tagged as part of this and other studies in LPO will add to a unique dataset
that is only available because of the intensive management actions taking place in LPO and the
lower Clark Fork River. Detections of Bull Trout tagged as part of the Lake Trout suppression
program will be used as part of a larger effort to describe LPO Bull Trout population dynamics
and demography. Bull Trout have been captured multiple times during netting operations in the
lake and have also been detected as part of this project in either Granite or Trestle creeks. In
addition, Bull Trout are tagged as part of the CFSA Appendix C activities that involve
transporting Bull Trout both above and below Cabinet Gorge Dam. These repeated capture
histories lend themselves to the use of open population capture-recapture models, such as Jolly-
Seber (Pollock et al. 1990) and Cormack-Jolly-Seber (Lebreton et al. 1992), to estimate apparent
survival, capture probabilities, and recruitment. While these data are currently available for
analyses to address questions about abundance and population dynamics, the approaches
required are quantitatively challenging. In addition, access to multiple corroborative datasets
(e.g., redd counts, trap net data) provide an opportunity to build integrated population
demographic models (IPMs, see Schaub and Abadi 2011 for a review) that yield improved
estimates of vital rates (such as survival) and population growth rates. Improved understanding
of population dynamics using these tools would allow us to not only better evaluate the success
of the LPO predator suppression programs, but also to develop the quantitative basis to evaluate
the feasibility of limited Bull Trout angler harvest opportunity, a topic of longstanding interest to
many Idaho anglers and IDFG.
RECOMMENDATIONS
1) Continue to operate, maintain and monitor existing antenna arrays in Granite and
Trestle creeks.
2) Continue combining data from multiple tagging and recapture efforts and identify
appropriate analysis techniques to estimate Bull Trout population parameters.
3) Consider installing additional arrays in other major tributaries (e.g., South Gold
Creek, Strong Creek, and North Gold Creek) to better track movement patterns and
estimate survival of Bull Trout and Westslope Cutthroat Trout.
4) Complete estimate of antenna efficiency and survival estimates following the 2018
season.
ACKNOWLEDGEMENTS
We would like to thank Avista staff Wes Baker, IDFG employees Nicole Graham, Tom Whalen,
Bill Ament, Bill Harryman, and John Rankin, Hickey Bros. Research employees Steve Warwick,
Tyler Long, Travis Morhardt, and Zach Heiser for their assistance in collecting field data.
Thanks to Avista employees Shana Bernall, Paul Kusnierz, Sean Moran, and Eric Oldenburg as
well as Andy Dux (IDFG), Kevin Aceituno (USFWS), and Jason Blakney (MFWP) who
reviewed previous versions of this report. We would also like to thank Avista employees Nate
Hall, Paul Kusnierz, and Heide Evans for their oversight and administrative support.
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REFERENCES
Avista (Avista Corporation). 1999. Application for new license volume III settlement agreement
including appended PM&Es, and cultural resource programmatic agreement Cabinet
Gorge Hydroelectric Project (FERC No. 2058) & Noxon Rapids Hydroelectric Project
(FERC No. 2075). Avista Corporation, Spokane, WA.
Bernall, S. and K. Duffy. 2018. Upstream fish passage program (Bull Trout) annual progress
report – 2017. Report to Avista Corporation, Noxon, MT.
Jakubowski, R. and K.A. Bouwens. 2018. 2017 Pend Oreille Basin Bull Trout redd monitoring
project update. Report to Avista Corporation, Spokane, WA.
Lebreton, J-D, K. C. Burnham, J. Clobert, and D. R. Anderson. 1992. Modeling survival and
testing biological hypotheses using marked animals: a unified approach with case studies.
Ecological Monographs, 62(i):67-118.
PBTAT (Panhandle Bull Trout Technical Advisory Team). 1998. Lake Pend Oreille key
watershed Bull Trout problem assessment. Idaho Department of Environmental Quality,
Boise ID.
Pollock, K. H, J. D. Nichols, C. Brownie, and J. E. Hines. 1990. Statistical inference for capture-
recapture experiments. Wildlife Monographs. 107:1-97.
Ryan, R., C. C. Downs, and R. Jakubowski. 2009. Lake Pend Oreille/Clark Fork River fishery
research and monitoring, 2007 progress report. Report to Avista Corporation, Spokane,
WA.
Schaub, M., and F. Abadi. 2011. Integrated population models: a novel analysis framework for
deeper insights into population dynamics. Journal of Ornithology. 152: S227-S237.
Wahl, N. C., A. M. Dux, W. J. Ament, and W. H. Harryman. 2015. Lake Pend Oreille research,
2013. Lake Pend Oreille Fishery Recovery Project. Annual Progress Report January 1,
2013 – December 31, 2013. IDFG Report 15-13. Idaho Department of Fish and Game,
Boise, ID.
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