Controlling Clams

While the Asian clam is a monstrous invasive species, it is not completely infallible.

A temporary barge in Emerald Bay, Lake Tahoe. Researchers use this as home-base when applying clam controls. Source

Predation

Fish predation can drastically limit the abundance of C. fluminea, at least limiting the densities that they may attain in certain ecosystems (5). In some ecosystems the Asian clam has trouble coping with a mix of resident fish communities (5). Carp, bluegill, striped bass, blue catfish, and other fish were found in Robinson et. Al to consume Asian clam, but none of those species are present in Lake Tahoe. As is often the case with most invasive species, careful prevention remains the optimal means of control.

Current Work: Removal

The Tahoe Environmental Research Center is studying various mechanisms to remove Asian clam from the Tahoe lakebed, but it seems unlikely that they will ever be completely eradicated (1). Wittmann et. Al developed a method of creating “benthic bottom barriers” of ethylene propylene diene monomer sheets (EPDM) to physically cover the clams and prevent oxygen from reaching them, thereby causing their eventual death (Wittmann et. Al). The method is effective, causing 98% mortality when the EPDM sheets were left secured for 120 days on the lake floor (Wittmann et. Al). One year after the barrier removal median shell length was roughly 65% of what it was the year before, with Asian clam population number sharply lower (Wittmann et. Al). At least on small scales, this is an effective treatment for C. fluminea. 


Peter Fimrite detailed scientist's efforts of placing 238 rubber mats over 5 acres of infested lake bottom to cause a hypoxic environment (7). This would suffocate the clams within 60 to 90 days in the winter and 30 days in the summer (7). The work done in Lake Tahoe is the world’s first attempt at smothering Asian clam (7). This work is being done by the Lahontan Regional Water Quality Control Board and the Tahoe Regional Planning Agency, called the Lake Tahoe Aquatic Invasive Species Program (7). The Tahoe Regional Planning Agency has since implemented an intensive boat inspection program to prevent the further introduction of invasive shellfish, particularly the quagga mussels. (7)

TERC researchers installing EPDM mats. Source

Pesticides?

The best way to get rid of pests is to chemically treat them, right? Depending on the environment, pesticides may or may not be applied. While pesticides are certainly capable of killing the Asian clam, some environments such as Lake Tahoe are extremely sensitive. They are very difficult to control, particularly in water, and would likely negatively impact other native species.