NEW YORK – The armed agents stroll into the frigid market, where the pungent stink of seafood assaults them. The smell pervades their clothes and the scaly, gooey water clings to their boots.

They pass burly men slinging slabs of fish with gleaming hooks and table saws ripping through frozen chunks of swordfish and tuna. Tempers flare as forklifts dart around the cavernous building known as the Fulton Fish Market.

Agents Chris Schoppmeyer and Scott Doyle barely notice any of this. They’re only interested in clams today. They want to know which of the wholesalers have unknowingly bought the shellfish from a company involved in a smuggling operation.

They stop at a fish stand. Schoppmeyer recognizes the name. He’s got a bite. “They were definitely sold here,” Schoppmeyer says.

Such fishing expeditions play out on a regular basis for agents of the National Oceanic and Atmospheric Administration’s little-known law enforcement office.

The agents’ mission has taken on greater urgency in recent years as more and more illegally harvested seafood gets pulled from the water and makes it way onto the nation’s dinner plates.

Agency data show that in the 2006 budget year, about 750 investigations were opened in the Northeast region, which includes many of the nation’s biggest commercial ports like Cape May, N.J., and Gloucester and New Bedford, Mass. That represents a nearly 108 percent increase from five years earlier.

Many of these busts have focused on a black market for seafood that stretches across the world.

Last year, a corporation from Uruguay and one of its executives pleaded guilty to trying to import and sell $3.5 million worth of Chilean sea bass, also known as “white gold” because it is so expensive. Chilean sea bass is a main target of illegal operations because of the huge market for the rare fish, resulting in tight fishing restrictions.

NOAA agents also helped uncover a South African corporation that was illegally harvesting massive quantities of rock lobster, devastating the species.

“That was the worse case I’ve seen and greed was the major catalyst for the over harvesting,” agent Jeffrey Ray said.

NOAA’s primary mission is to predict environmental changes, and provide industry and government decision-makers with a reliable base of scientific information. Within NOAA is the National Marine Fisheries Service, providing the checks and balances that govern fragile, watery ecosystems that are imperiled.

Studies warn of dire consequences to the global ecosystem because of illegal harvests, including one that suggests the world’s oceans will run out of fish by 2048.

Officials say the United States provides ample opportunity for overfishing; more than one-fifth of the world’s most productive marine areas lie within the nation’s territorial waters.

Authorities say plenty of illegal fish is destined for restaurants and retail outlets in places like New York City, with its 8.2 million residents who eat an average of about 17 pounds of seafood a year.

Every year, commercial fishermen in the U.S. land nearly 10 billion pounds of fish and shellfish valued at about $3.5 billion. The fishing industry employs 28 million people, and NOAA says the value of the ocean economy to the U.S. is more than $115 billion.

But the agency, a part of the U.S. Department of Commerce, does this crucial enforcement task on a shoestring budget with only about 225 employees.

Recognition for the federal agents is scant.

“Yeah, sure it’s daunting,” says Doyle. “But our little victories become big victories. When we catch a guy it reverberates throughout the industry.”

The agents use informants, tips and accounting. Fishermen and wholesale dealers keep meticulous records, and evidence of crimes often turns up in the bills of sale. They can also track fishing boats using global positioning systems.

Often, agents end up in New York City, whose Fulton Fish Market is one of the biggest seafood markets in the world. Because the Bronx market is so sprawling, it provides an enticing way for companies to launder illegal seafood. Years ago, the mob controlled the market but have since been pushed out.

With 37 fish wholesalers, the market processed a staggering 248.7 million pounds of seafood last year.

Walking through Fulton with Doyle, a former high school science teacher and New Jersey game warden who joined NOAA nearly 20 years ago, is like peering into his case files. Many people know him, respect him and probably fear him.