Environment DEC
From the April 2003 issue
Raritan Bay Shellfish Transplant Program Cancelled
DEC has cancelled the Raritan Bay Shellfish Transplant Program for 2003 due to the presence of the parasitic disease Quahog Parasite Unknown (QPX) in wild hard clam populations in Raritan Bay off Staten Island, New York. This marks the first time that the disease has been found in hard clams in New York waters.
Cleansing the Clams
The Raritan Bay Shellfish Transplant Program moves hard clams harvested from uncertified (polluted) waters to certified (clean) waters, where the clams cleanse themselves over a minimum 21-day period. This cleansing time prepares the clams for eventual marketing as food. Shellfish transplanting normally takes place from April through October, when water temperatures support the cleansing process. The program has been in operation since 1987.
After getting reports of dead and dying clams in the harvest transplant area in Raritan Bay last summer, DEC collected specimens for analysis. Heavy infestation of QPX was confirmed in tests performed by two laboratories. Monitoring and lab tests continued throughout the fall. The subsequent analysis represents the first documentation of a widespread occurrence of QPX in subtidal populations of wild clams in New York.
DEC is working with the Marine Animal Diagnostic Laboratory at SUNY Stony Brook, Cornell University and other groups to develop strategies, monitoring programs to determine the prevalence of QPX in Raritan Bay and other areas of the state, and mitigation measures to reduce the intensity of the disease in infected clam beds.
Disease Effects and History
QPX causes inflammation in the gills and mantle that prevents clams from closing their shells. The clams are then unable to move food and oxygen-bearing water to their internal organs.
The disease, which is caused by a protozoan parasite, was first reported in wild clams during the 1960s and in hatchery-reared clams during the 1980s, both in Canada. It has also been documented in New Jersey, Massachusetts and Virginia. QPX does not harm humans and does not represent a public health concern. It is, however, fatal to hard clams and causes significant mortalities in infected clam beds. There is no known treatment or cure for QPX in hard clams.
