Report Number: 12722
Permit Number: CRLA1992ADOU
Current Status: Checked in
Date Received: Jan 01, 1998
Reporting Year:
1992
Principal Investigator:
Mark Buktenica, National Park Service,
Crater Lake National Park
Park-assigned Study Id. # CRLA1992ADOU
Permit Expiration
Date:
Jan 01, 1998
Permit Start Date:
Jan 01, 1998
Study Starting
Date:
Jan 01, 1992
Study Ending Date:
Jan 01, 1992
Study
Status:
Completed
Activity Type:
Other
Subject/Discipline:
Other
Objectives:
The objective of this study was to develop a
better understanding of the ecological
role(s) of introduced fish in Crater Lake.
Findings and Status:
Originally barren of fish, Crater Lake was
stocked with approximately 1.8 million
salmonids from 1888 to 1941. Rainbow trout
and kokanee salmon are the only species of
fish now known in inhabit the lake. Kokanee
salmon exhibited cyclic patterns in
population, age structure, condition,
abundance, and biomass from 1985 to 1991.
One dominant year class of relatively low
abundance and high condition were present
from 1985 to 1987. Multiple year classes
with increasing abundance and decreasing
condition were present from 1989 through
1991. Rainbow trout maintain a diverse
population structure throughout the study
with a trend toward a relative increase of
older age classes and larger fish. Vertical
and horizontal migrations of fish occurred
with and between the nearshore and offshore
zones of the lake. Kokanee fed primarily
offshore on zooplankton and small bodied
insects. Kokanee cropped the Daphnia
population and altered zooplankton community
structure during the study period. Rainbow
trout fed nearshore on large bodied
vertebrate and invertebrates. Introduced
fish in Crater Lake exhibited the potential
to impact limnetic and benthic community
structure, nutrient flux with and between
communities, and lake clarity.
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:
4000
Funding provided
this reporting year by other sources:
0
Full name of
college or university:
n/a
Annual funding
provided by NPS to university or college this
reporting year: 0
