How to Shop for Shellfish at a Market

Shopping for shellfish at a British market is one of the great small pleasures of coastal life. A good fishmonger's stall smells of the sea, not of the dockside skip, and the difference between a memorable plate of scallops and a disappointing one is usually decided at the counter, not in the kitchen. Here is how to buy shellfish with the confidence of someone who has done it a hundred times.

Start with the Stall, Not the Price

Take a walk past the whole market before you spend a penny. A stall worth buying from will have shellfish kept on ice or in a chilled cabinet, not sitting out in a tray on a sunny morning. Look at the display as a whole: is there a visible cold chain, are cooked and raw shellfish separated, and are there signs of stock turning over quickly rather than shellfish that has clearly been sitting there for days?

On a traditional fishmonger's slab, you want to see shellfish on a bed of ice with the ice draining away, never swimming in a pool of water. Cooked items should be kept well away from raw ones. If the stall looks tidy, the staff are interested, and the shellfish is cold and glossy, stay. If everything is a bit warm and vague, walk on.

Ask Three Questions

A good stallholder will enjoy being asked, and you will learn a great deal from the answers.

• When was it caught? For anything landed locally, "this morning" or "yesterday" is ideal. Anything over three days old had better be a live crab, a live lobster or an oyster still in its shell.
• Where is it from? A market in Whitby should be able to tell you that the crab came from up the coast. A market in Cornwall should know its mussels. Long-distance shellfish can be excellent, but you want the stall to know.
• Is it cooked or raw? Cooked prawns, cooked crab and dressed crab should be eaten within a day or two. Live shellfish should be cooked within 24 hours of getting it home.

Ask about price by the kilo too, and check that you are not paying for ice, water or heavy packaging.

Reading the Shell

The shells tell you almost everything. Reject anything with a broken or cracked shell, since it will not keep and may already be spoiling. Beyond that, look for the signs of life:

• Mussels and clams: shells should be tightly closed, or close promptly when you tap them. A gaping mussel that will not shut is a dead one.
• Oysters: buy them with the shells closed and heavy for their size. An open oyster is finished.
• Scallops: the shell should be closed or close when handled; the muscle should be creamy white and the roe, if present, a bright coral or orange.
• Crabs and lobsters: buy them alive and lively if you can. The tail of a lobster should curl under firmly when you straighten it; if it flops, it is dead or dying. Crabs should feel heavy for their size, with no black spots or soft patches under the shell.
• Cooked prawns: firm, brightly coloured and not slimy. A little blackening at the tail is normal, but avoid prawns that are mushy or have lost their colour.

The Smell Test and the Chill Chain

Fresh shellfish smells of clean seawater and cucumber rind. That is the smell you want. Walk away from anything that smells of ammonia, of bleach, of drains, or simply of strong fishiness. Oysters and mussels should smell of the shore they came from.

Ask to feel it. Shellfish should be properly cold, not cool. If the stallholder is handling it with bare hands on a hot day, or if there is no ice under the display, that is your answer. Once you have bought it, get it out of the sun and into a cool bag with ice packs as quickly as possible.

Know What Is in Season

A little seasonal knowledge will steer you towards the best value and flavour.

• Native oysters are traditionally eaten in months with an r in them, from September to April. The rest of the year is for breeding and resting.
• Mussels are at their sweetest in the colder months, though farmed mussels are good all year.
• Crab is fullest and sweetest from late spring through to autumn, when the meat fills the shell.
• Scallops vary by area; along many coasts, the cold months are best.
• Whelks and cockles are classic winter market fare, particularly in the north and around the Thames and Welsh estuaries.
• Langoustines from Scottish west coast waters are a summer treat worth the money.

Getting It Home and Keeping It Well

Transport shellfish in a cool bag, with the cooked and raw items in separate sealed containers. At home, live mussels, clams, oysters and crabs should go into the fridge, covered with a damp cloth, in a bowl so they do not drip onto anything else. Never soak live shellfish in fresh water; it will kill them. Cooked shellfish should be tightly covered and eaten within a day or two.

Give live shellfish a sniff again before cooking and discard anything that has died, that will not close when tapped, or that smells wrong. A cracked shell or an odd smell is not a bargain at any price, and a good market stallholder will always agree with you.