Cornelius' Corner:

"Fish & Filtering Friends"

Cornelius’ Corner: “Fish & Filtering Friends”

Electrofishing in the creek.

Electrofishing in the creek.

Hello everybody!

Earlier in the summer, my coworkers got to work with scientists from the Pennsylvania Fish & Boat Commission to conduct fish and freshwater mussel surveys in the park! While a lot of people come to the park for hiking, picnicking, and enjoying the historic buildings, many don’t realize that we work really hard to understand the biological systems in the park. The more we know, the better the care we are able to give them!

Brown Bullhead – a new species for the park!

These surveys were a follow-up to fish surveys conducted in 2016 by our intern Ben Staud. While Ben used a big seine net to sample fish in the creek below the dam, this effort focused on the stretch of Concord Creek at the far upstream end of the park. Instead of a seine, the scientists used electrofishing. With this technique, an electrode is used to introduce an electrical field to the creek which temporarily stuns fish nearby. Once they are stunned, they can be easily caught for identification then released back into the creek.

Through the fish survey, the scientists identified 9 different species of fish inhabiting the shallow riffles and calm stretches at the top of the park. These include American Eels, Largemouth Bass, Pumpkinseed Sunfish, and Fallfish. The most exciting find was a Brown Bullhead, which had not been officially documented in the park’s waterways before!

Using Bathyscopes to look for mussels.

While looking for fish, the group also used visual inspection to search for freshwater mussels! While mussels aren’t typically considered a visually exciting animal, they are very important because they clean the water around themselves while feeding. A single adult mussel can filter 10 gallons of water per day. This makes mussels very sensitive to pollution, so finding freshwater mussels in the park is a sign that water quality is good!

Eastern Elliptio mussel.

The surveys found over 100 Eastern Elliptio mussels between Chester Creek and the millrace. These mussels are oval-shaped and get to be between 4 and 5 inches long. Despite their size, the brown to green coloring of the shells makes them very hard to see. During the mussel surveys, the scientists used bathyscopes and snorkeling to get good looks beneath the water surface to spot the well-hidden shells!

Now that we have a good idea of how where in the park to find mussels and what species are present, my coworkers will be able to pay close attention to their populations during silt removal and stream restoration projects over the coming year.

Have you seen any fish in the park lately? Stop by the Visitor Center and tell me all about them!

– Cornelius

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