Mr. Jurisich, 56, was steering his 26-foot skiff on Adams Bay, between the west bank of the Mississippi and the Gulf, where his family owns the leases on oyster beds. Mr. Jurisich estimates that he lost 90 percent of his oysters on some leases, 30 percent elsewhere. He knew early on this year that the oysters were in danger, because he couldn’t taste any salt in the water.
“Every day, you could drink it,” he said. “No salt in the water. That’s when you have issues.” (The oysters are also threatened by river diversions, meant to rebuild the eroding coastline, that dump sediment in coastal waters.)
The Eastern oyster found in the Gulf of Mexico is the same species, Crassostrea virginica, found on the Atlantic coast. But oysters grow larger and fleshier in the Gulf’s warmer waters, making them well-suited to cooking. The thick paste of greens, herbs and butter on oysters Rockefeller, invented at Antoine’s restaurant in 1899, would overwhelm a delicate Malpeque or Olympia oyster.
The depleted harvest isn’t nearly as noticeable in other parts of the country, where Gulf oysters are less available and less likely to show up on menus. Diners accustomed to East and West Coast oysters often find Gulf oysters unwieldy and bland.
Shortages have forced some Gulf Coast raw bars to replace local oysters with ones from other regions, but many are reluctant to do so, for reasons of economics, taste and regional pride.
“I have nothing against those other oysters,” Mr. Pettus said, “but they’re not ours.”
Still, the Gulf Coast oyster market has started to reflect changing tastes.
Start-up companies like Murder Point Oysters, in Alabama, have introduced a new kind of Gulf oyster. Raised in submerged cages, the farmed oysters, often referred to as off-bottom oysters because they’re not raised on reefs at the water bottom, are similar in size, saltiness and price to varieties from other regions.