The catch in the States primarily comes from Southern California, where they are known among fishermen as "the poor man's abalone." That may sound like an insult, but anyone who has had the good fortune to feast on abalone - whether pounded tender and quickly pan-fried or tenderized with a long slow cook into a stew or chowder - knows that any such comparison can only be seen as the highest of compliments.
Whelks are fairly large, quite a bit larger than the related but quite small sea snails commonly called periwinkles. Whereas periwinkles are usually served simply cooked with small picks to pull the tiny bites from their shells, whelks are more frequently served already removed from their shell. In Britain fried whelks are common; in Japan whelks are often used in sushi or grilled on skewers; in the West Indies they are chopped up and made into fritters.
The Kelletia kelletii species, usually called Kellet's whelk, is found along the Southern California coast, from Baja up to Monterey. It is a large, slow-growing snail that is being fished more regularly and intensively in recent years. It is a predatory scavenger that lives in the kelp forests and coral reefs that run along the coast. Most of the Kellet's whelk fishery is, in fact, by-catch from traps set for spiny lobsters and Dungeness crabs, since the mollusks, as scavengers, are attracted to the dead fish used to the bait the pots just as much as a crabs and lobsters are.