Eels are born in the Sargasso Sea in the North Atlantic Ocean and then swim thousands of miles across ocean currents to reach the freshwater of estuaries and coastlines.
There, they turn into small, transparent glass eels.
An eel mop – which looks just like a mop used to clean floors – mimics suitable habitat for the wriggly animals to swim inside for a safe haven from the open waters.
Best told BBC Radio Wiltshire: “We are really excited that we are supporting the European eel reintroduction on the Kennet by using citizen scientists to help monitor these mop sites.
“We are hoping to monitor six sites across the River Kennet, some in Wiltshire and some over the border in Berkshire, we are looking for volunteers who can help us with this.”