Investigator’s Annual Reports (IAR’s) for Crater Lake National Park

Bull Trout Restoration in Crater Lake National Park, Oregon

 

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

 

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