Bivalves are an important source of animal protein for humans, and major commercial fisheries for mussels, arks, oysters, scallops, cockles, venus clams, and razor clams have long existed worldwide. Humans have consumed bivalves for millennia, and the first documented record of bivalve aquacultureAquaculture:
The science of farming organisms that live in water, such as fish, shellfish, and algae dates from the 8th century in Japan. In 2003, the value of U.S. major commercial bivalve species (especially the Soft-Shelled Clam, Hard-Shelled Clam, Surfclam, Geoduck, Blue Mussel, Eastern Oyster, and Sea Scallop) exceeded 570 million U.S. dollars. Economically, the most important bivalves under aquaculture are Blue Mussels, with peak production of 500,000 annual metric tons in the late 1990s. The worldwide marine bivalve harvest (that is, the collection of wild populations, as opposed to those raised in aquaculture) in 2002 was more than 2 million metric tons.
Pearl production is an important industry, especially in Japan, China, Australia, French Polynesia, and Indonesia. Shells of freshwater pearl mussels, formerly important in the button industry, are now used to produce beads that are implanted into marine pearl oysters to initiate cultured pearl production. The shells of many bivalves are also commercially valuable as ornamental objects, jewelry, collectors’ items, and as mother-of-pearl for inlay.
Because they feed by filtering water, bivalves accumulate heavy metals, bacteria, viruses, and toxins that are in the water in which they live. With the expansion of aquaculture and subsequent increase in shellfish consumption, the risk of bivalve-derived diseases, more generally known as “shellfish poisoning,” is an increasing concern for public health management.
Under certain conditions (due to environmental factors or human activities), planktonic organisms called dinoflagellatesDinoflagellates:
Chiefly marine, planktonic, usually solitary phytoflagellates (which have many characteristics in common with algae) that include luminescent forms, forms important in marine food webs, and forms causing red tides. occasionally bloom in the oceans. Such an outbreak is called a "red tide," because the toxic waste products of the dinoflagellates can turn the water orange or red. During the course of normal feeding, bivalves concentrate these toxins, and if they are later eaten by humans, dangerous and sometimes deadly shellfish poisoning can occur. Local departments of health in areas near the shore constantly monitor the toxin levels in the ocean and periodically close areas to shellfish harvesting if the toxins reach a dangerous level. More information on shellfish poisoning can be found here.
Some marine and freshwater bivalves pose important economic threats.
The vast majority of negative ecological impacts by bivalves are caused by invasive species, spread either accidentally or intentionally.