Great Basin Redband Trout Overview
Lake and Warner Lakes SMU's
Great Basin Overview:
The summer 2010 field
season marked the completion of the fourth of a six year sampling effort
to assess the distribution and abundance of redband trout (Oncorhynchus
mykiss newberrii) in the six interior basins of Oregon’s high
desert: Catlow Valley, Chewaucan, Fort Rock, Goose Lake, Malheur Lakes,
and Warner Valley basins.
In addition, the 2007 and 2010 sampling years
complete the population level sampling for the Goose Lake and Warner
A total of 972 site surveys were conducted
over the course of the study covering over 2% of the entire 2,420 km
sampling frame. Abundance of age-1+
redband trout at the basin level remained relatively stable during 2007
- 2009. However, 2010 estimates indicate a considerable decline when
compared to 2007. Estimates of landscape-wide abundance were of similar
magnitude and had comparable precision across all four study years,
averaging 802,000 + 16%.
Goose Lake SMU is comprised of 13 populations,
of which 6 exist in California and were not assessed in this study. The
7 remaining populations were grouped into 5 areas (Drews, Dry, Eastside,
& Thomas-Bauer). Landowner participation
in these areas allowed for sampling at 73% of sites located on private
property - best of any basin.
Continued landowner participation is key to
furthering our understanding and conservation of redband trout.
During 2007 and 2010,
Goose Lake SMU was monitored intensively where
surveys were completed at a total of 177 sites and
230 sites over the entire study.
Abundance of Goose Lake age-1+ redband trout were highest in 2007.
Abundance declined by 61%
since 2007 and has remained consistently low during
Abundance of redband trout likely
fluctuates with annual stream flow. Higher water years preceding 1999
and 2007 may have contributed to higher abundance
in those years.
Patchy distribution and low fish densities may be due to habitat
quality or a less accurate sample frame.
SMU is comprised of 3 populations:
Deep, Honey, and Twentymile. Landowner participation in these
areas allowed for sampling at 66% of sites
located on private property. During 2007 and 2010, the
SMU was monitored intensively where surveys
were completed at a total of 132 sites
and 186 sites over the course of the entire study.
Warner Lakes redband trout
abundance declined by 23% since last surveyed intensively in 2007. However, 2010 estimates show
over a 50% decline from the previous two SMU level sampling years.
Note that in population level sampling years 30 sites
from each population are surveyed where in SMU level sampling years 30
sites total over the entire SMU are sampled. Variability
in the level of sampling may account for some of the difference in
abundance which suggests that SMU level sampling over estimates
abundance in this SMU.
Redband Trout Stressors:
Factors, other than seasonal flow, that likely affect
trout productivity are flow diversions, migration barriers, riparian
habitat, competition with exotic salmonids, and climate regime.
Continued habitat fragmentation,
degraded habitat quality and limited connectivity may hinder movement
and reduce abundance. Protection of current
populations requires increasing the size and extent of populations,
maintaining genetic and life history diversity, increasing connectivity,
minimizing anthropogenetic stressors, and improving adaptive management.
Lake Fish Working Group handout - 2010
Project Overview (PowerPoint
Miller, S.A., S.E. Jacobs, S.L. Gunckel, and S. Richardson.
of a sampling approach to monitor the status of Great Basin redband trout in Southeastern Oregon.
Oregon Department of Fish and Wildlife, Information Report 2010-02, Corvallis.
ODFW Oregon Native Fish Status Report (2005)
Dambacher, J.M., K.K. Jones and H.W. Li. 2001.
The distribution and abundance of Great Basin redband trout:
an application of variable probability sampling in a 1999 status review. Oregon Department of Fish and Wildlife,
Information Reports 2001-08, Portland.