12766 – Bull Trout Restoration in Crater Lake National Park, Oregon

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

Bull Trout Restoration in Crater Lake National Park, Oregon

 

Report Number: 12766

Reporting Year: 1995

Permit Number: CRLA1995AOLQ

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. # CRLA1995AOLQ

Permit Expiration Date: Jan 01, 1998

Permit Start Date: Jan 01, 1998

Study Starting Date: Jan 01, 1995

Study Ending Date: Jan 01, 1995

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.;The fourth field season of the bull trout restoration project was completed in 1995. Our continued brook trout removal has appeared to stop the decline of bull trout and temporarily stabilized bull trout abundance. One hundred and eighteen bull trout were observed in 1995, 120 were observed in 1994, 58 were observed in 1993, and 113 bull trout were observed in 1992. We hope to see an increase in bull trout abundance in 1997. Brook trout removal efforts in the headwater section of Sun Creek have been completely successful; no brook trout were observed during triple passelectrofishing above the natural waterfall (fish migration barrier) in 1995. One brook trout was found and removed above the falls in 1994, 22 were removed in 1993, and 234 were removed in 1992. Within the bull trout section (upstream of the artificial barriers and downstream of the natural waterfalls) 144 brook trout were removed in 1995. Brook trout removal in the bull trout zone has reduced the brook trout to bull trout ratio from approximately 3:1 in 1992, to 1:1 in 1995 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.

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

 

<< previousnext >>