News Stories

That sounds fishy: twisting traps troll tributaries in the Willamette

Portland District
Published June 17, 2021
Corps contractors monitor screw traps downstream of Big Cliff Dam, May 28, 2021.

The water flow turns a large screw creating hydraulics, which keeps small fish from escaping the trap. 

These traps are collecting juvenile salmon after they pass through Lookout Point, Cougar and Big Cliff dams.

We’ve changed operations at these dams to help with downstream fish passage – or that’s the goal. These traps will give us insight into how well we’re doing.

Corps contractors monitor screw traps downstream of Big Cliff Dam, May 28, 2021. The water flow turns a large screw creating hydraulics, which keeps small fish from escaping the trap. These traps are collecting juvenile salmon after they pass through Lookout Point, Cougar and Big Cliff dams. We’ve changed operations at these dams to help with downstream fish passage – or that’s the goal. These traps will give us insight into how well we’re doing.

Corps contractors monitor screw traps downstream of Cougar Dam, May 28, 2021.

The water flow turns a large screw creating hydraulics, which keeps small fish from escaping the trap. 

These traps are collecting juvenile salmon after they pass through Lookout Point, Cougar and Big Cliff dams.

We’ve changed operations at these dams to help with downstream fish passage – or that’s the goal. These traps will give us insight into how well we’re doing.

Corps contractors monitor screw traps downstream of Cougar Dam, May 28, 2021. The water flow turns a large screw creating hydraulics, which keeps small fish from escaping the trap. These traps are collecting juvenile salmon after they pass through Lookout Point, Cougar and Big Cliff dams. We’ve changed operations at these dams to help with downstream fish passage – or that’s the goal. These traps will give us insight into how well we’re doing.

Corps contractors monitor screw traps downstream of Cougar Dam, May 28, 2021.

The water flow turns a large screw creating hydraulics, which keeps small fish from escaping the trap. 

These traps are collecting juvenile salmon after they pass through Lookout Point, Cougar and Big Cliff dams.

We’ve changed operations at these dams to help with downstream fish passage – or that’s the goal. These traps will give us insight into how well we’re doing.

Corps contractors monitor screw traps downstream of Cougar Dam, May 28, 2021. The water flow turns a large screw creating hydraulics, which keeps small fish from escaping the trap. These traps are collecting juvenile salmon after they pass through Lookout Point, Cougar and Big Cliff dams. We’ve changed operations at these dams to help with downstream fish passage – or that’s the goal. These traps will give us insight into how well we’re doing.

PORTLAND, Ore. - The bulky contraptions float listlessly downstream of three dams in Oregon’s Willamette Valley. The buoyant, metal devices hold large screws that the water flow turns. This twist of the screw – creating a creaking, rasping, scraping sound – generates enough hydraulics to keep small fish from escaping the slowly spinning, cone-shaped collectors – or, screw traps.

              “They funnel fish from the upstream end of the cone where they come in at, back into a live box at the rear end and that allows you to collect the fish for sampling,” explained David Trachtenbarg, Portland District, U.S. Army Corps of Engineers fish biologist.

              The Corps placed these traps below Cougar, Lookout Point and Big Cliff dams this year to help fish biologists collect data about fish passage at these tall dams. Downstream fish passage is difficult because dam height, combined with reservoir-level fluctuation, makes downstream fish passage difficult – an issue the Corps is working to fix.

              “Operating the screw traps will allow us to get an indication of whether the operation that we are doing at a given project is providing that benefit,” said Brad Eppard, Fish Passage Section chief. “Is it getting fish past the dam.”

              Screw traps are rudimentary tools that give Corps biologists basic data about the fish and the Corps will use them for the next couple years. The data is partially influenced by other factors, including traps only spans a small portion of any water body and they are designed to primarily capture smaller fish that cannot swim out of the device.

              “It’s a way to look at and to evaluate migration timing,” said Eppard. “From a big picture perspective, it’s to look at things like run-timing, to examine fish condition and to collect what species of fish are out there.”

              Fish biologists check the screw traps daily to examine, categorize, measure and release any fish caught in the traps and they are especially keen on Chinook and steelhead salmonoids. Even though the screw traps are basic tools, they do provide useful insight. They allow for Corps staff to estimate how operations at these dams are impacting fish passage and what changes the Corps can make with the goal of increasing passage success.

Corps biologists plan on using screw traps through at least 2022 to evaluate fish migration and may also use more refined methods, such as active tag studies to help give more precise data on fish passage, depending on funding.


How to Subscribe to RSS

Use Edge Browser
How to follow feeds in Microsoft Edge

  1. Visit the Microsoft Edge Add-on store: https://microsoftedge.microsoft.com/addons/Microsoft-Edge-Extensions-Home. ...
  2. Search for “rss feed reader”: ...
  3. Click “Get” Next to “Feeder – RSS Feed Reader”, then Confirm by clicking “Add Extension”
  4. ​ Setup your feeds: Search for feeds one-by-one, browse the library of sites or import feeds with OP
    Use Outlook
 
  1. In Outlook, right-click the RSS Feeds folder and choose Add a New RSS Feed.

  2. In the New RSS Feed dialog box, enter the URL of the RSS Feed.

    Enter the URL for the RSS Feed

    Tip: If you need help finding the RSS feed URL on a website, look for an RSS icon.
     Button image Right-click that icon, and then copy the shortcut to the Clipboard.
    Press Ctrl+V to paste the information from the Clipboard into the RSS Feed location box.

    Choose Add > OK.                                                                

    Additional Subscription Information: Microsoft How to Subscribe to RSS feed in Outlook

Use Internet Explorer

Open Internet explorer and open any USACE website. Look for the small RSS icon and click on that icon as show in this image:

Once it opens in Internet Explorer, it will have an option at the top to subscribe to this RSS feed as show here:

 

 

 

 

 

 

Use Google Chrome
Chrome Extension allows RSS Feed Subscriptions

Free RSS Feed Readerhttps://feeder.co