HOUMA, La. — Loulan Pitre Sr. was born on the Gulf Coast in 1921, the son of an oysterman. Nearly all his life, he worked on the water, abiding by the widely shared faith that the resources of the Gulf of Mexico were limitless.

As a young Marine staff sergeant, back home after fighting in the South Pacific, he stood on barges in the gulf and watched as surplus mines, bombs and ammunition were pushed over the side.

He helped build the gulf’s very first offshore oil drilling platforms in the late 1940s, installing bolts on perilously high perches over the water. He worked on a shrimp boat, and later as the captain of a service boat for drilling platforms.

The gulf has changed, Mr. Pitre said: “I think it’s too far gone to salvage.”

The BP oil spill has sent millions of barrels gushing into the Gulf of Mexico, focusing international attention on America’s third coast and prompting questions about whether it will ever fully recover from the spill.