Discovering Invasive Asiatic Clams on the Verde River in Cottonwood AZ

Asiatic Clams

As we walked along the banks of the Verde River near Cottonwood, AZ we were astonished to find clam shells! Not something one would expect to see in the Verde Valley and the Black Hills of north - central Arizona. Apparently these are the Asiatic clam (Corbicula fluminea), an invasive species, first noted in the 1950s. Clam-digging is a favorite tasty pastime of the local Cambodian and Vietnamese population, particularly on weekend family picnic outings.

They are small, typically less than an inch, with a light-colored or dark olive green to black shell ornamented by distinct, concentric ridges or striations. The particular shells we found had been bleached white as they dried in the sun.

We also found an interesting conglomerate stone consisting of agate, quartz, sandstone, and calcium carbonate (limestone).