At The Oceanaire, chef Kevin Davis serves white salmon whenever he can get the rare fish. His Ivory King Salmon With Chanterelle Mushrooms shows off the salmon's unique, delicate flavor.

YESTERDAY'S TRASH fish is today's sought-after delicacy.

White king salmon — or ivory king — is now found on menus in top restaurants from Seattle to New York City. But the rare, pale-fleshed fish used to be cast aside as undesirable. In years past, says Professor Don Kramer of the University of Alaska, white king was cheaper than red king; today, it's more expensive.

A white-king salmon is, after all, quite an oddity. No one is sure why about only one in 100 wild kings is white. One theory is that they eat a different diet. The bright-red color of wild salmon comes from a diet of shrimp, krill and crabs that contain carotenoids, natural pigments found in plants and animals. Beta-carotene, which makes carrots orange, is probably the most familiar one. Some scientists believe that white salmon eat mostly squid and fish, which have fewer carotenoids. (Farm-raised fish are fed a diet supplemented with carotenoids to produce the familiar reddish-orange flesh.)

However, many scientists point to genetics instead. Since both white and red kings live in the same waters, it's likely they would consume the same thing. "There must be some genetic reason that these fish don't deposit the colored pigment in their flesh," Kramer says. "But I don't know of any studies that have been done to prove it."

Whether due to diet or genes, the fairer the rarer, and people will pay a premium to eat it. At first glance, you might think you're eating halibut, but the texture and taste are similar to regular king salmon. Dale Erickson, owner of University Seafood in Seattle, says because the fish are scarce, they always sell out right away from his store. White salmon goes for about $6.98 to $12.98 a pound, depending on the season and origin of the fish. While fresh is hard to come by, he does regularly carry a smoked version. "Ivory king has its own flavor and texture, with high oil content," Erickson says. "My wife, Jeanette, won't eat any other kind of salmon."

Erickson is in daily contact with suppliers in Alaska and Canada to learn how many white kings are available. The fish look the same from the outside, so only when they are cleaned is it obvious which are white. King salmon can be caught from Alaska down to Oregon and California, with different areas producing different flavored fish. Although both colors of kings are found in rivers, Erickson's favorite is ocean troll-caught from southeast Alaska.

The Oceanaire Seafood Room chef Kevin Davis eats wild king about three or four times a week in the summer. He loves white salmon, which he describes as milder than red with a distinct flavor all its own. "If it doesn't all get sold to New York, you can get it. If it can be had, I'm going to have it," he says. "I treat the fish with very high respect."

At The Oceanaire, Davis offers a thick, 10-ounce filet of ivory king simply grilled or broiled with olive oil and gray salt for $25.95. Occasionally he also serves the fish grilled with port-soaked cherries, rosemary, smoked almonds and orange zest. "People find ivory king appealing on the menu," he says. "It's a nice alternative to red king."

If you buy the fish yourself, Davis cautions, make sure it is high-quality and fresh. "Don't buy it just for the color," he says. "Make sure you get good fish. It's expensive, but it's worth it."

Catherine M. Allchin is a Seattle free-lance writer. Barry Wong is a Pacific Northwest magazine staff photographer.