ADULT PACIFIC LAMPREY PASSAGE AND BEHAVIOR STUDY (Adult Lamprey Passage Study)
Summary
Abstract: An adult Pacific lamprey (Lampetra tridentata) passage and behavior study was conducted at Wells Dam in 2007 in accordance with the Integrated Licensing Process (ILP) promulgated by the Federal Energy Regulatory Commission (FERC). The goal of this study was to evaluate the effect of the Wells Project and its operations on adult Pacific lamprey upstream migration and behavior as it relates to fishway passage, timing, and downstream passage events (drop back) through the dam. This information will be used to help identify potential areas of passage impediment within the Wells fishways. Specific objectives of the study include: 1) conducting a literature review of existing adult Pacific lamprey passage studies at Columbia and [...]
Summary
Abstract: An adult Pacific lamprey (Lampetra tridentata) passage and behavior study was conducted at
Wells Dam in 2007 in accordance with the Integrated Licensing Process (ILP) promulgated by
the Federal Energy Regulatory Commission (FERC). The goal of this study was to evaluate the
effect of the Wells Project and its operations on adult Pacific lamprey upstream migration and
behavior as it relates to fishway passage, timing, and downstream passage events (drop back)
through the dam. This information will be used to help identify potential areas of passage
impediment within the Wells fishways. Specific objectives of the study include: 1) conducting a
literature review of existing adult Pacific lamprey passage studies at Columbia and Snake river
dams; 2) identifying and implementing methods for capturing adult Pacific lamprey at Wells
Dam; 3) documenting the timing and abundance of radio-tagged lamprey passage through Wells
Dam; 4) determining whether adult lamprey are bypassing the adult counting windows at Wells
Dam; 5) where sample size is adequate, estimating passage metrics including fishway passage
times and efficiencies, residence time between detection zones, and downstream passage events
(drop back); and 6) if necessary, identifying potential areas of improvement to the existing
upstream fish passage facilities for the protection and enhancement of adult lamprey at the Wells
Project.
A review of past adult lamprey passage studies indicated commonalities among lamprey
behavior at hydroelectric projects and trapping methodologies were developed to capture adult
lamprey at Wells Dam. During the 2007 study, 21 lamprey were captured, surgically radiotagged
and released. Of these fish, 10 were released into the tailrace and 11 were released into
the fishway between mid-August and early October. One tailrace-released fish was recaptured
and re-released into the fishway, bringing total ladder releases to twelve. Ten of the twelve
(83%) lamprey released into the middle fishway successfully ascended, with a median upper
fishway passage time of 7.9 hours. Seven of the ten (70%) lamprey released into the tailrace
were detected at the outside of a fishway entrance. Only one of these seven (14%) lamprey
entered into the collection gallery and ascended the fishway with a lower fishway passage time
of 6.1 hours and upper fishway passage time of 5.9 hours. This fish, along with at least one midladder
release, traveled through some portion of the auxiliary water supply (AWS) chamber.
Including one tailrace-released fish, 6 of 11 (55%) tagged lamprey that ascended the upper
fishway were detected inside the video bypass area. Three of the eleven (27%) fish that exited
the ladder passed through the upper fish ladder without being observed at the counting window.
No drop backs were detected by fish that exited the fishway. These results suggest that, similar
to observations at other Columbia River dams, lamprey are having difficulty negotiating the
fishway entrances and appear to be largely bypassing the adult counting windows. Unlike other
dams, lamprey at Wells are passing the upper fishway at high rates, in a reasonable amount of
time, and with negligible drop back within the ladder.
