In 2006 researchers dredged up an ocean quahog clam (Articus icelandius) from the chilly waters around Iceland. They called her Hafrun. Her life was cut short when a graduate student flash-froze her little body in liquid nitrogen and neatly sliced her shell, whose growth rings held a fabulous secret: Hafrun had settled out of the plankton to begin her modest but tenacious existence in the year of Our Lord 1499. Think of her next time you tuck into a clam chowder. Not all shellfish grow so old or so slowly, nor, thank goodness, is there a convention to give each of them names. A lot of bivalves actually grow surprisingly fast. A king scallop (Pecten maximus) reaches 'commercial' size in about 4-5 years, and the same is roughly true for oysters. Mussels can grow even faster - from spat (the miniature version of themselves that leaves the plankton to adhere to surfaces) to parsley, onion, muscadet and optional dash of cream in fifteen short months. Fortunately, many of our most appetising bivalves are fast-growing. Furthermore they eat plankton, which keeps feed costs remarkably low; in fact, zero. There is some shellfish farming. But why is there not more? Perhaps because the question is not as simple as it might at first appear.
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