The establishment of impoundments and operations
associated with hydroelectric production and irrigation has modified the
environment of native redband trout in the Upper Klamath River. These
modifications include fragmentation of habitats, obstruction of upstream
and downstream passage, alteration of stream flows and water quality, and
increased competition from introduced species associated with habitat
changes. An improved understanding of the life history of these trout
populations is needed to address management concerns and guide dam
operation protocols that minimize detrimental impacts to these
populations. The Native Fish Investigations Project recently used radio
telemetry and PIT-tag technology to monitor movement patterns.
Spencer Creek is a major spawning area and recruitment source of redband
trout in the upper Klamath River. The confluence of Spencer Creek and
the Klamath River is 1.5 km upstream of J.C. Boyle dam, which was built
in 1959. Past studies provide evidence of a dramatic decline in adult
upstream passage since the dam was built and relatively little juvenile
downstream passage. However, sampling efforts to quantify the magnitude
and extent of movements by juveniles to locations downstream of the dam
were limited in scope. Operation of J.C. Boyle Dam may reduce the
likelihood that juvenile redband trout from Spencer Creek can move
downstream past the dam safely and efficiently and may reduce adult
upstream passage to Spencer Creek.
In order to better understand
juvenile and adult redband trout life history and evaluate fish passage
over J.C. Boyle dam, Native Fish Investigations Project monitored
redband trout movement in Spencer Creek and the upper Klamath River
during 2004 and 2005. We captured juvenile trout (>90 mm) as they
emigrate from Spencer Creek and tagged them with inter-peritoneal radio
transmitters (NanoTags, Lotek Wireless). Adults, upstream and downstream
of the dam, were also radio tagged. Movements of radio-tagged fish were
monitored using fixed-station receivers at locations associated with
hydropower facilities and mobile receivers in free-flowing reaches. In
addition, we marked several hundred outmigrating juvenile trout (>70mm)
in Spencer Creek, and 50 adult trout in the Klamath River, with passive
integrated transponder (PIT) tags and installed PIT-tag receiver
stations at the mouth of Spencer Creek and downstream of J.C. Boyle Dam.
Upper Klamath Basin Genetics
Questions pertaining to redband trout population
structure in the Upper Klamath Basin became evident during the
evaluation of status of the Klamath River Redband Trout SMU for the 2005
Native Fish Status Review. The degree to which redband trout move among
headwater streams, major rivers and the lake is virtually unknown.
Biologists are uncertain if Upper Klamath redband trout should be considered as one large population,
or if each spawning stream is
a relatively isolated reproductive unit, or if some
other population structure exists.
In addition questions regarding the distribution of
the two major lineages still exist. Klamath Basin contains two
subspecies of Oncorhynchus mykiss. O. mykiss irideus is a
non-anadromous form that colonized the basin from the Pacific Ocean
prior to dam construction on the lower river. The redband form, O.
mykiss newberri, is present in the upper reaches above Klamath
Falls. Historically Upper Klamath Lake had no outlet to the ocean and
was an inland basin similar to other drainages in the Great Basin.
Previous studies found that populations with access to the ocean formed
one major lineage while fish in the headwaters of the Sprague River,
Williamson River, and Jenny Creek formed a separate lineage. However,
these studies used techniques less appropriate for fine population
To address these questions the Native Fish
Investigations Project is working with Devon Pearce at the Southwest
Fisheries Science Center to analyze a collection of genetic samples
collected throughout the Upper Klamath Basin. Our objectives are to
identify distinct populations and lineages of O. mykiss and
estimate the potential and ongoing gene flow among tributary reaches.
Annual Reports and
Initial Findings: 2004
Starcevich, S.J., S.E. Jacobs, and W. Tinniswood. 2006.
dams on redband trout life history in the Upper Klamath River: A summary and synthesis of past
and recent studies. Oregon Department of Fish and Wildlife,
Information Report, Corvallis.
Pearse, D. 2007.
Population genetics of
mykiss in the Upper Klamath Basin. Report of Devon Pearce, Southwest Fisheries Science Center to the
Oregon Department of Fish and Wildlife, Corvallis, Oregon.
Jacobs, S.E., S.J. Starcevich, and W. Tinniswood. 2008.
Effects of impoundments
and hydroelectric facilities on the movement and life history of redband trout in
the upper Klamath River: A summary and synthesis of past and recent studies.
Pages 67-75 in R.F. Carline and C. LoSapio, editors. Sustaining wild trout in a
changing world. Proceedings of the Wild Trout IX Symposium, Joseph Urbani & Associates, Bozeman, Montana.