Report Number: 12783
Reporting Year: 1996
Permit Number: CRLA1996AOZD
Date Received: Jan 01, 1998
Principal Investigator:
Mark Buktenica, National Park
Service, Crater Lake, Oregon
Additional investigator(s):
Dr Gary
Larson
Park-assigned Study Id. #
CRLA1996AOZD
Permit Expiration Date:
Jan 01, 1998
Permit Start Date:
Jan 01, 1998
Study Starting Date:
Jan 01, 1996
Study Ending Date:
Jan 01, 1996
Study Status:
Completed
Activity Type:
Other
Subject/Discipline:
Fish / Ichthyology
Objectives:
Restore native bull trout to
historic numbers and distribution in Sun Creek, within the park, remove
non-native brook trout, and prevent re-invasion of non-native species in the
future.
Findings and Status:
A survey of fish populations and
stream habitat in Sun Creek during the summer of 1989 revealed a remnant
population (130 adult fish) of bull trout (Salvelinus confluentus) mixed with
introduced brook trout (S. fontinalis) in a 2 km section of stream.
Hybridization and competition with the brook trout threatened the bull trout
population with a high risk of extinction. A bull trout restoration plan was
drafted and peer reviewed in October, 1991. The goals of the plan were to
restore the remnant population of bull trout to historic numbers and
distribution in Sun Creek (within Crater Lake National Park), remove brook
trout, and prevent re-invasion of non-native fish. During the summer of 1992, a
restoration program was initiated. Brook trout were removed from Sun Creek with
electroshockers within and upstream of the bull trout section, and with a fish
toxin downstream of the bull trout section. Two log and rock fish immigration
barriers were constructed near the park boundary to prevent re-invasion of
non-native fish. Brook trout removal continues and a monitoring program is in
place to evaluate bull trout recovery.;Fourth and fifth field seasons of the
bull trout restoration project were completed in 1995 and 1996. Our continued
brook trout removal has appeared to stop the decline of bull trout and
temporarily stabilized bull trout abundance. Results from 1996 show an increase
in the bull trout population. We hope to see a continued increase in bull trout
abundance in 1997. Brook trout removal efforts in the headwater section of Sun
Creek have been successful; three small male brook trout were removed during
triple passelectrofishing above the natural waterfall (fish migration barrier)
in 1996. No brook trout were found in 1996, one brook trout was found and
removed above the falls in 1994, 22 were removed in 1993, and 234 were removed
in 1992. Brook trout removal in the bull trout zone has reduced the brook trout
to bull trout ratio from approximately 3:1 in 1992, to less than 1:1 in 1996
prior to annual brook trout removal.;Brook trout removal will continue and a
monitoring program is in place to evaluate bull trout and macroinvertebrate
recovery. A peer review panel will be held in 1997 to evaluate the status and
direction of the project.
For this study, were one or
more specimens collected and removed from the park but not destroyed during
analyses?
No
Funding provided this
reporting year by NPS:
55000
Funding provided this
reporting year by other sources:
5000
Full name of college or
university:
n/a
Annual funding provided by
NPS to university or college this reporting year: 0
