Tuesday, August 23, 2011

Looking for Freshwater Mussels in the Chehalis River Watershed

We are initiating an exciting new project to learn the distribution of freshwater mussels in the Chehalis River watershed. Western Washington is home to three types of freshwater mussels--the Western Pearlshell, Western Ridged, and a diverse group of mussels called Floaters. Pearlshells and Western Ridged mussels typically inhabit streams and rivers while Floaters typically live in slow-moving water or lakes and ponds.

Western Pearlshell mussels
Freshwater mussels are useful as indicators of water quality and healthy fish communities. Mussels cannot move like fish so they flourish or perish with changes in environmental conditions. They keep records of change in their shell’s growth and accumulate compounds in their tissue. Some mussels are thought to live in the same place for over a hundred years! That is a lot of time and change in one spot. Mussels need a healthy fish community in order to reproduce. As young, they hitch a ride on the gills of fish and ride around the stream until they drop off and settle into the substrate where they will likely stay the rest of their lives. Don’t worry if you don’t see mussels, though--they are hard to spot and don’t live in every stream.

Snorkel survey in the Satsop River
Right now we are snorkeling and wading several Chehalis tributaries in Grays Harbor and Mason Counties and are finding Pearlshells as individuals and in large beds. We have also found a number of Floater shells, but no live mussels. This is not surprising, though, given the quick-moving streams we are targeting now. For the rest of the summer, we will be snorkeling and wading more streams, as well as working with biologists from Washington State agencies, forest resource agencies, and private firms to track down promising mussel locations. Knowing the type and location of the mussels will help us track their populations through time, providing us with important information about the health of the Chehalis River watershed and a better understanding of the role of mussels in the rich and diverse waters of the Pacific Northwest.

If you are interested in learning more about freshwater mussels, please visit the Xerces Society’s webpage where they have a free online field guide to Mussels of the Pacific Northwest.

A word of warning--Although you might be tempted to collect some mussels for yourself, it is illegal to eat or collect live mussels in Washington State. Besides, I've been told they are not the most appetizing creatures in the water anyway.