Freshwater Mussel Research

Survey at Norwood Island - Over the past 16 years, our staff have taken a keen interest in freshwater mussels. This species is pretty amazing, a native mussel that filters water and can live to be over 100 years old in the right conditions. WR has had concerns about their health in the Willamette River system for years. 

In 2002 we identified a massive bed of this native species along a side channel at Norwood Island. In the summer of 2017 WR launched a major project to study this population to determine its size, population and whether it was reproducing. Further, we sought to look at a large stretch of river to determine where mussel beds exist. Our work took us snorkeling over 120 miles with staff and volunteers. 

Mussels temporarily removed from river bed to measure during survey. 

Mussels temporarily removed from river bed to measure during survey. 

Team measures and catalogs mussels - Summer 2017. 

Team measures and catalogs mussels - Summer 2017

Our work revealed some alarming findings. The mussel bed at Norwood Island is not reproducing. While there are thousands upon thousands of live mussels in the channel, our careful study indicates the presence of no juvenile mussels. The vast majority of mussels are quite old. In most mussel beds there is a mix of ages that can be identified The reasons for this lack of reproduction could involved a number of factors:

 - Pollution, from pesticides to ammonia. 

-  Alteration of habitat and natural river flows. 

 - Lack of presence of host fish during critical times - such as Spring Chinook, Winter Steelhead, and Cutthroat trout. 

Over the coming months, Willamette Riverkeeper will continue this work, and will study some of the other mussel beds we identified during our snorkel survey this past summer.

Quadrat on the river bottom. Mussels within this area are counted.

Quadrat on the river bottom. Mussels within this area are counted.

In our view, this work is critical to the health of the overall river system and may indicate necessary steps that must be taken to further improve water quality and reduce toxics in our river. 

 

Mussel Survey from Eugene to Salem