Our new Biological Assessment is out - Klamath Basin Crisis

Klamath Project Operations Biological Assessment
Endangered Suckers: Environmental Baseline for Suckers
Emigration from Upper Klamath Lake
Retention of juvenile suckers in UKL likely aids recruitment of adult suckers into
population. Although not fully quantified, there is evidence that larval and
juvenile suckers leave UKL via the Link River in relatively large numbers from
June through September (Gutermuth et al. 1999, 2000, Foster and Bennetts 2006,
Tyler 2007, Markle et al. 2007 Juvenile). Two factors that appear to influence
sucker emigration from UKL are entrance and retention of suckers by the internal
gyre in the lake, which is influenced by wind events, and the coarseness of the
shoreline (i.e., wetland vegetation; Markle et al. 2007 Juvenile). Water quality
conditions in the Keno reach of the Klamath River, from Lake Ewauna to Keno,
more frequently reach thresholds lethal to suckers for longer periods than UKL
(see water quality discussion). Thus, the unknown numbers of young suckers that
leave UKL via the Link River must find suitable habitat in a hostile environment
until they reach a size capable of using the Link River fish ladder, presumably
several years, to return to UKL. The fate of emigrant suckers is not fully
understood but it has been hypothesized that UKL is a better environment for
suckers due to its food rich environment, the loss of connectivity between habitats
below the Link River, and frequent poor water quality events in the Link to Keno
reach of the Klamath River (Reithel 2006). The overall impact to the total sucker
population resulting from emigration from UKL is not yet fully understood;
however, retention of more juvenile suckers in UKL increases the likelihood of
adult recruitment in this popualtion.
Future Climate Conditions
Climate variability may play a large role in driving fluctuations water abundance
in the Upper Klamath Basin. Such indices as the El Nino-Southern Oscillation
and Pacific Decadal Oscillation (PDO) can influence weather patterns on a
regional scale. The indices are useful in providing a likelihood forecast for
general weather patterns in the Pacific Northwest. As a generality, in the Klamath
Basin, warm years tend to be relatively dry with low summer stream flow and
light snow pack. Conversely, cool years tend to be relatively wet with high
summer stream flow and heavy snow pack. (SCS 2004).
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