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Elwha River floating weir: a tool to study adult salmon during and following dam removal

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0:28- 0:51

Roger Peters, U.S. Fish and Wildlife: Well, there are a number of aging dams throughout the country that eventually will need to be removed because they are going to fail or other cases where maybe it makes sense to remove them to restore ecosystems including salmon populations. However, these projects are relatively expensive and so itís really important to that we understand whether or not that expense is worth it in order to recover these natural ecosystems.

0:51-1:05 Kent Mayer, WA Dept. Fish and Wildlife: Iím working here on the Elwha weir project, which is the first time that this project has ever been done, putting a floating weir across the Elwha River in order to determine what the salmonid response is to the dam removal.


Dan Spenser, U.S. Fish and Wildlife: A fish weir is essentially a fence that spans across a stream and blocks fish from migrating up river with the exception of a passage zone that leads to a trap box. Fish weirs have been used thousands of years as a harvesting tool. Modern biologists have taken that concept, use of modern tools, to use it for capturing fish and enumerating fish populations as opposed to harvesting fish.





Kent Mayer: Weíve trapped Chinook, Coho, chum, silvers, pinks, sockeyes, steelhead, cutthroat and bull trout. Three of those fish are either threatened or endangered, that would be the bull trout, the Chinook salmon that are out of the Elwha River as well as the steelhead.




2:20- 2:58

Kent Mayer: There are 52 three-foot panels, so the weir is about 160 feet across. They hang on a rail that is made up of 16 ten-foot sections. In addition we have some aluminum traps that are used to capture the fish. They can be fished in either the upstream or downstream or left bank or right bank position. So depending on what the flows do, what the fish do, the traps can be moved around the weir, but basically the project goes from bank to bank and itís about 200 feet. It is the largest weir on the West Coast outside of Alaska.


Dan Spenser: Adult salmon have an incredible strong drive to go up river to spawn. And as they migrate up river, they naturally encounter all kinds of barriers, be it a beaver dam, or in this case, a salmon weir. And what that fish will do is it will approve the weir and then move back and forth until it can find a gap within the weir, key in on current and that will lead that fish to the trap box where we can sample for biological data.

3:32- 3:58

Kent Mayer: It takes the natural desire of the fish to move upstream to spawn and channels it over in a way that we can collect data. Conversely, when the fish come up to the dams or perhaps come down after spawning the way steelhead can do, we have downstream traps as well that allows us not only to collect data from fish that perhaps got missed, but also it allows us to have a population estimate that serves as our baseline for this monitoring study.


Technician (Kim Roberston): We have collected data off of 400 salmon so far.

4:08- 4:44

Kent Mayer: Once the fish are captured in the trap, we hold them there just long enough to capture some biological data before we release them on their way. We look at what species a particular fish may be. We look at its length. We determine if itís male or female. We also take scale samples to determine the age of the fish, how long they have been in fresh water, how long they have been in salt water, whatís the age itís spawning. We also take genetic samples; we take a small clip using a paper punch. It goes into a vial and we hold that to determine how these fish are related to other runs in the Olympic Peninsula.

4:45- 5:02

Jeff Duda: The Elwha Weir Project is the result of a collaborative effort among the Lower Elwha Klallam Tribe, the USGS, the Fish and Wildlife Service, the Park Service, NOAA and the Washington Department of Fish and Wildlife. How about that.

5:03- 5:39




Title: Elwha River floating weir: a tool to study adult salmon during and following dam removal


This video introduces a multi-agency team of scientists and their project to install and operate a resistance board floating weir in the Elwha River. The weir is a fish trap used within a larger program for monitoring salmon populations in the Nation's largest dam removal and river restoration project.

Location: WA, Elwha River, USA

Date Taken: 12/1/2011

Length: 5:39

Video Producer: John Gussman , Double Click Productions

Note: This video has been released into the public domain by the U.S. Geological Survey for use in its entirety. Some videos may contain pieces of copyrighted material. If you wish to use a portion of the video for any purpose, other than for resharing/reposting the video in its entirety, please contact the Video Producer/Videographer listed with this video. Please refer to the USGS Copyright section for how to credit this video.

Additional Video Credits:


Jeffrey J. Duda (USGS)

John Gussman (Doubleclick Productions)

Greg Brotherton (Frenetic Productions)


For more information go to: Elwha River Restoration Project

File Details:

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Restoration (Set) RSS Media RSS Deconstructing Dams: A Sediment Story Wetland Revival
In: Water collection

Tags: DamRemoval ElwhaRiver FishTrap RiverRestoration fish trap weir


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