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Friday, May 09, 2003

Check the water
before digging clams

A reader recently wrote me that in the 1940s people dug for clams in the Ala Wai Canal. It's not safe to eat anything caught in that polluted waterway anymore, but he wondered about other places.

"I bet there are pristine locations on the neighbor islands where clams can be harvested. Those who know probably don't want to share this information."

The clams of which my reader writes are not native to Hawaii. In the 1920s several species of clams and oysters were introduced from Japan and North America to Hawaiian waters as a food source. Among these was the Japanese littleneck clam, also known as the Manila clam.

Gathering these clams on the mud flats of Kaneohe Bay was a popular activity until 1969, when silt and overharvesting mostly wiped out the beds. Today some of those introduced edible species still live in sheltered, shallow areas such as Pearl Harbor, Maunalua Bay and Kaneohe Bay. If they thrive and are harvested anywhere else in Hawaii, I don't know where.

Clams, whether native or imported, are scarce in Hawaii, but in other parts of the world, they're practically a lifestyle. In New England, people hold parties called clambakes during which they steam clams, lobsters, corn on the cob and potatoes over coals in large pits.

The Pacific Northwest's beaches often are littered with clamshells, and you can get steamed clams just about anywhere on the West Coast. One of my favorite Seattle restaurants has a sign at the entryway that says, "KEEP CLAM."

In the biology world, clams are part of a large class of animals called bivalves. These animals, which include mussels, oysters, scallops and other lesser-known types, all have two hinged shells that usually enclose the animal's entire body.

The most famous clams in the world are the giant clams of the Indo-Pacific. But not all giant clams are big. Six species fall into this category, the smallest being only about 4 inches across. The largest, however, lives up to its name. It can grow to more than 4 feet wide and weigh around 700 pounds.

Giant clams grow hinge down, with their two shells gaping open. Contrary to the scary stories, giant clams do not clamp onto swimmers and divers and hang on. If startled, the clam will partially close its shells, but it can't close them completely.

All bivalves have a muscular foot. In some species the foot is efficient at digging, allowing the creature to burrow deep into sand or mud. The foot is also the part of clams and other bivalves that people like to eat, although we swallow the animals' guts, gills and gonads right along with the feet.

People who grew up eating clams think they're the food of the gods. Others of us, however, never quite warm up to the idea of steaming an animal alive and then eating it, guts and all, often including grains of sand.

Clams and their cousins are filter feeders, meaning they sift food from the surrounding water. During this feeding they can collect pathogens such as those that cause red tide, hepatitis and other diseases. Clean water, therefore, is crucial when it comes to harvesting clams.

I don't expect anyone to divulge their secret clamming spots to me. But if anyone is clamming in Hawaii today, please make sure the location is pristine.



Marine biologist Susan Scott writes the newspaper column, "Ocean Watch",
for the Honolulu Star-Bulletin,