GRAND ISLE, La. — Standing near a ruined marina on this tiny island where Hurricane Katrina made landfall, Wayne Estay is surrounded by the rubble of America's costliest natural disaster and the mangled debris of what may be a dying slice of American life.

The commercial fishing boats — too many to count — have been battered beyond repair, overturned or sunk.

The teeming docks where millions of tons of seafood — shrimp, oysters, blue crabs and fish — have been unloaded over the decades no longer exist.

The factory that produces the ice needed by every waterman within 30 miles storing fresh seafood is gone.

And the rich fishing grounds seem profoundly toxic anyway, with dead fish floating on the surface and a nauseating stench rising from thick, inky waters.

The Louisiana seafood industry — a dynamic economic machine that produces an estimated 35 percent of North America's oysters, 46 percent of its shrimp and 28 percent of its blue crabs — was struggling well before Katrina barreled into the Gulf Coast three weeks ago. Aggressive foreign fishing competition was taking a heavy toll, market prices had been in the doldrums for years, skyrocketing fuel prices were eating into already small profit margins, and coastal erosion had consumed roughly half of the marshes that existed in the 1900s.

But Katrina dealt a blow to these sheltered, salty bayous that goes far beyond dollar signs.

Those who for generations have hauled much of America's seafood — people who have worked the waters and ropes until their hands were rubbed so smooth they no longer bear fingerprints — are virtually out of business for the foreseeable future. Even if their boats were not lost, they have been prohibited from fishing until federal biologists can determine whether the filthy water has contaminated the seafood. And most troubling of all, virtually every link in the fishing infrastructure has been wiped out — there are no dockside fuel pumps, no seafood processing sheds, few operational marinas.

An estimated 4,800 commercial fishing people in Louisiana have become long-term victims of Katrina. These are families who subsist on shrimp gumbo four days a week, who still speak with a Cajun accent difficult for outsiders to understand, who are often working the water by the time they are 5 or 6. Interviews revealed that most lack insurance for their boats, vessels that can cost well over $250,000 apiece.

Sitting on a damaged trawler last week, Herman Helmer Sr., 78, who spent his first full day shrimping with his daddy 72 years ago, looked out at an empty bayou that would normally be dotted with fishing vessels this time a year, the height of shrimping season.

"I'd rather die than not be on the water," he said quietly. "And this might kill me."

Katrina has from the beginning been a storm that awes by numbers — numbers of dead, numbers of homes and businesses lost, numbers of towns destroyed. An examination of the effect on the seafood industry is equally staggering.

Seafood is a nearly $3 billion industry here, in a state with an $18.7 billion budget. But nearly 99 percent of the state's oyster population was destroyed when Katrina roiled the bayous' waters so much that oyster beds were left beneath several feet of mud, starving the bivalves of oxygen and destroying harvests for several years to come.

The loss of this year's shrimp season — which goes from now through November — is predicted to cost some $540 million. The lost oyster crops will result in some $150 million in revenue shortfalls per year for as many as three years. The state's Department of Wildlife and Fisheries has estimated that the total cost of Katrina to the industry — including infrastructure damages and the loss to seafood distributors and retailers — will run upwards of $1.1 billion next year alone.

At the core of many of the industry's current problems is this: Like in the sea itself, where everything is connected, the fishing industry here is so interrelated that one part of it cannot revive without the others — and all have been destroyed.

One of the keys to the seafood industry's recovery will be the results of a National Oceanic and Atmospheric Administration test of the region's fishing waters. Results aren't in yet.

Although so much has been debated about what the loss of New Orleans and its vibrant culture would mean for the United States, what would the loss of the centuries-old bayou fishing culture mean?

"Everyone loses a piece of America if we die off," said Floyd Lusseign, whose 17-year-old son just bought his first shrimping boat and was to be his family's fifth generation to work the waters near Grand Isle.