Report Number: 12706
Permit Number: CRLA1991AADO
Current Status: Checked in
Date Received: Jan 01, 1998
Reporting Year:
1991
Principal Investigator:
Mark Buktenica, National Park Service,
Crater Lake National Park
Park-assigned Study Id. # CRLA1991AADO
Permit Expiration
Date:
Jan 01, 1998
Permit Start Date:
Jan 01, 1998
Study Starting
Date:
Jan 01, 1991
Study Ending Date:
Jan 01, 1991
Study
Status:
Completed
Activity Type:
Other
Subject/Discipline:
Fish/Ichthyology
Objectives:
Document and compare the ecology of kokanee
salmon and rainbow trout in terms of length,
weight, age, growth, food habits and
distribution in Crater Lake.
Findings and Status:
The kokanee population previously dominated
by one age class, exhibited a multiple age
class structure with a large age 2+ cohort
in 1990, and large 2+ and 3+ cohorts in
1991. Age 2+ and 3+ kokanee were observed
circling the lake, following the shoreline
closely in schools as large as 200,000
during the day. Small schools of kokanee
were observed in 1989, extensive schooling
behavior, as observed in 1990 amd 1991, has
not been observed for eight years. Schools
of kokanee would disperse at dusk and were
often observed feeding at the lake surface
in the pelagic zone. Preliminary food habits
analyses indicated that kokanee fed heavily
on Cladocerans and fed less on small bodied
aquatic and terrestrial insects. Rainbow
trout continued to exhibit a more complex
age structure and food habits regime.
Predation on kokanee salmon by rainbow trout
was recorded for the first time in many
years. Spawning by rainbow trout was
observed along the shoreline near Cleetwood
Cove in mid-June, 1991. Analyses of age,
growth, food habits and the ecology of each
species relative to the limnological
characteristics of the lake continue.
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:
2000
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
