Thermal Refugia Restoration and Observation in the Klamath River

During this proposed project, the Yurok Tribal Fisheries Program conducted small scale restoration activities at selected tributary mouths aimed at enhancing the habitat within the associated thermal refugia. The size of these enhancements was dependent on the size of the tributary and its existing thermal refugia, however somewhere between 400 and 2000 square feet would encompass the size of most improvement areas. To achieve this goal, the Yurok Tribe used hand construction methods to improve fish passage into tributaries, and to install simple cover elements to thermal refugial areas. Tribal Fisheries personnel consolidated braided flow channels into a single coherent stream channel at Pecwan, Tully, Ke’pel Creeks and other creeks, and introduced simple cover elements at several of these sites as appropriate. Cover elements included dead brush and/or trees (where safe), which will not be permanently anchored. The changing and alluvial nature of these sites precludes the construction of permanent features. The SONCC recovery plan highlights the importance of thermal refugia to juvenile and adult coho salmon in the Lower Klamath River (volume II, page 18-14).

A secondary goal of the project was to to continue the snorkel observation monitoring that has been conducted for the past 15 years, monitoring that has demonstrated the importance of thermal refuges to both holding and rearing salmonids. Data collected added further detail to the multitude of snorkel observations already contained in the Tribe’s data set. All data collected will be compared to a range of environmental and biological river conditions. Temperature is probably the leading factor regarding salmonid thermal refugia use however other aspects of water quality may be involved.

In addition to juvenile salmonids, adult salmonids also make use of thermal refuges during times of elevated river temperatures. Snorkel observations also enumerated any adult fish that may be using this habitat feature. During past years the YTFP has documented many thousands of adult salmonids using the Blue Creek thermal refuge. This area is also known to be a critical location in observed outbreaks of the fish disease Ich (Ichthyophthirius multifiliis) and our snorkel observations can act as an early warning system for potential disease outbreaks. This is one of the most important aspects of this project. The YTFP has the ability to relay specific real time information to water managers regarding the abundance and health of both juvenile and adult salmonids using thermal refugia. This tangible result can be invaluable when dealing with disease issues on the lower Klamath River.

Project Benefit: This project will benefit Klamath River salmonids by enhancing critical thermal refugia habitat and allowing more salmonids to escape the elevated and lethal temperatures of the Klamath River. Additional benefits of the project include a census of salmonids using thermal refuge on the Lower Klamath River and the ability to provide real time data regarding salmonid congregations at thermal refugia to river managers.