WSU leading the charge on sonar

Occasionally, we get asked what Wild Steelheaders United is really doing to improve wild steelhead populations across their range.

 

We could start by mentioning that our habitat restoration and fish passage improvement projects are delivering big results in some of the last best wild steelhead strongholds in North America. In the past year alone, our work along California’s fabled Lost Coast between the Russian and Klamath Rivers (managed by TU’s North Coast Coho Project) has prevented over 58,500 cubic yards (~4,200 dump trucks’ worth) of sediment from being delivered into streams; installed some 725 pieces of large wood material in over 11.5 miles of stream to increase habitat complexity and pool scouring; improved or eliminated over 22 miles of old forest roads with potential to leak sediment into spawning and rearing streams; and removed or upgraded two major barriers to fish migration.

 

We are also helping to improve the science behind steelhead management. One small piece of this effort — with big potential to guide recovery of wild steelhead populations — is increasing the use of sonar to monitor adult anadromous fish runs. To date, WSU staff and volunteers have partnered with state and federal agencies, tribes and watershed councils to install Dual Frequency-Identification Sonar (DIDSON) units in wild steelhead rivers in Washington, Oregon, and soon, in California’s Eel River.

 

A weir directs fish into the beam of a sonar unit on Washington’s Elwha River

 

Sonar has been in use to monitor and count sockeye runs in Alaska and Canada for nearly two decades and has several advantages over traditional fish counting methods. One particular benefit of this technology is the confidence intervals around escapement estimates made with sonar are smaller than most other methods, with the exception being dam counts. Essentially, with sonar there is less error and run size or escapement estimates are more likely to be accurate. Additionally sonar can also be used in rivers with glacial, tannic or mud stained water which makes counting by other methods difficult.

 

Recently, we raised the funding for and purchased the latest iteration of this technology, known as an ARIS-1800 (for a demo watch this awesome this video). This device and the accompanying software makes reviewing data quickly and accurately a snap! Not only can you see fish movement, the system can provide very accurate measurements of fish. Another highlight of this technology is its portability — the units are small and can be used on numerous streams and projects.

 

On large rivers such as the Elwha weirs are often used in conjunction with sonar for more accurate counts

 

Our latest sonar purchase has been placed in a Coastal Oregon winter steelhead stream as part of a multi-year study. This particular watershed has received millions of dollars of restoration work in the form of placements of large wood and rock structures. These in-stream treatments provide high water refuge for juvenile steelhead and trap sediment, which increases spawning habitat and improves summer rearing conditions. Anglers who fish this system have experienced an increase in adult catches in recent years, but for many years no one has attempted to verify this response to the habitat improvements by counting the number of returning adult steelhead. WSU’s sonar units will go a long way, in this stream and others, to help fisheries managers determine which strategies are most effective at boosting wild steelhead returns.

 

Technology such as sonar is a great way for managers to get a better handle on the health and trends of wild steelhead populations. This investment in data collection will pay dividends by helping direct limited conservation and restoration dollars to where and how it can be most effective.