After the last of the Youth Fisheries Academy day camps, Claire, Tree and I transitioned to working on various field projects. It has been great fun to get outside and help with a large variety of projects--electrofishing, installation of the Elwha River fish weir, and river surveys for freshwater mussels just to name a few. We have been mostly helping with a freshwater mussel survey project led by Teal Waterstrat, another STEP student, so I will tell you a little bit more about why we’re looking for these invertebrates and our experiences in the field!
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| Looking for freshwater mussels |
Freshwater mussels are very elusive creatures that live in the bottom of healthy river and lake systems. They are not very mobile, so their life cycle includes a larval stage that requires a host fish as a means of dispersal. The Western Pearlshell mussel, for example, has larvae that cling to trout and salmon for transport. Another interesting fact about the Western Pearlshell mussel is that its lifespan can exceed 100 years in healthy rivers! Wherever they occur, freshwater mussels play very important roles--they help cycle nutrients, maintain water clarity, and are a food source for several animals (river otters, muskrats, skunks, raccoons, etc). There are close to 300 species of freshwater mussels in all of North America and most (about three quarters) are in major decline due to pollution and habitat disturbances.
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| Snorkel survey in the Chehalis River |
We waded and snorkeled streams in the Chehalis River watershed with the hopes of getting a general idea of if--and where--mussels are living and what types of mussels are present. Discovering the numbers and locations of freshwater mussels is an important goal for a couple of reasons. Firstly, freshwater mussels are an indicator species. This means that their presence or absence can tell us a lot about the long-term health of a river because they are unable to survive or flourish in systems that are heavily disrupted or polluted. Secondly, we’re conducting these surveys because the mussel population is not well documented in the Chehalis River basin. Teal has done a lot of research and discovered where freshwater mussels have been found in the past and then coordinated surveys of those areas.
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| Still looking . . . |
This has been exciting work since I had never seen a freshwater mussel before taking part in these surveys. After completing the training and practice, this now makes perfect sense--freshwater mussels look just like rocks! So taking that into consideration, we developed a few strategies for increasing our chances of seeing freshwater mussels during the surveys including using polarized sunglasses, sub-surface viewing tools called aquascopes, and training in areas with healthy mussel populations in order to develop a clear search image. Claire, Tree, and I have been mostly wading in rivers and using aquascopes to look for mussels. While not terribly fruitful, it has been quite enjoyable!
As this project continues and expands, we will be able to form an idea of the health of the rivers we are surveying based on what we find (or don’t find). These findings will, in turn, give us very important information about what sort of management, conservation, and restoration practices would be most beneficial for the Chehalis River basin.
--Mara Healy, STEP Fisheries Technician
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