CLINTON — The sound of labored breathing crackles over the radio aboard the fishing boat Rawdeal on an overcast morning in late May.

Anchored about 100 yards off the eastern coastline of Whidbey Island, within sight of the Clinton ferry landing, the crew on the 26-foot aluminum fishing boat is after geoduck. The giant clams, which grow wild in the Pacific Northwest, are pound for pound the most-valuable seafood being harvested from Puget Sound today.

“I just can’t equalize,” diver Jesus Madrigal, a member of the Tulalip Tribes, tells skipper Dennis Hegnes, the boat’s owner. In SCUBA speak, this means Madrigal’s ears aren’t adjusting to the change in pressure as he descends.

Madrigal is 30 feet below the surface, in murky water that is barely 50 degrees. He is connected to the boat by an air-supply hose and communication cable. The sharp pain in his ears is typically remedied by a trip back up, but that takes time — something the fishermen don’t have.

Time is money in all types of commercial fishing, but that’s particularly true in the geoduck fishery. One reason is the huge market demand in China for the big bivalves. The other is how the Tulalip Tribes manage their divers, restricting harvest to just a few hours at a time as part of a strategy to keep the fishery sustainable.

Twenty years ago, the commercial geoduck industry was something people at Tulalip had just begun to explore. Now, it’s a $2 million-a-year business for the tribes, who annually pull about 175,000 pounds of the giant clams out of muddy seabeds around Snohomish and Island counties.

Last season, 90 percent of wild geoducks harvested in Washington were sent to Asia in what amounted to a $74 million export industry for the state. With prices hinging on the clams’ health, packagers race to SeaTac with their freshly caught product. If all goes well, geoducks plucked by a Tulalip diver in the morning can be stowed in the cargo section of a passenger plane leaving the airport on a regularly scheduled flight to Asia around 10 p.m. As little as 24 hours later, they will already have been retanked, ready to be sold live in one of Hong Kong’s many bustling seafood markets.

“They’re number one,” Madrigal said.

On a top day, a diver can haul in thousands of pounds of wild geoducks, which usually sell at the dock for $7 to $15 a pound. If the market is really booming, that price could exceed $20 a pound. With top clams weighing in about 2.5 pounds, divers talk about how the fishery is sometimes like picking up $20 bills from the seafloor.

On that day in May, the Rawdeal was one of 11 boats commercially harvesting geoduck on a stretch known as a “tract.” The divers had two hours to work and not a minute more, closely monitored by a tribal fisheries patrol boat.

Madrigal decides to return to the surface just two minutes after the tract opens for fishing. Hegnes and deckhand Roy King hastily remove his oxygen mask and hand him a paper towel to blow his nose.

Eight minutes later, a little after 8 a.m., Madrigal is back in the water and making his way to a depth of between 40 and 60 feet where he’ll use a pressurized water hose to flush geoducks from beneath the seabed.

Depending on experience, a geoduck diver typically nets up to 70 percent of the money made from a boat’s total catch. Madrigal’s four seasons of experience give him 60 percent of the Rawdeal’s share.

Despite the rough start, in 90 minutes of digging, Madrigal unearthed more than 400 pounds of geoduck. They fetched $9 per pound at the dock.

“It stressed me out a lot,” Madrigal, 33, said. “I’ve never had that issue before (problems equalizing). My allergies are really bad this year.”

When he’s not diving, Madrigal works as a bookkeeper. His excursion off Whidbey Island earned him close to $2,300.

The clock hadn’t yet struck noon.

The word geoduck (pronounced gooey-duck) is derived from Lushootseed, the ancient language spoken by the Tulalips and many other Coast Salish tribes. The Lushootseed word is pronounced “guay,” like Paraguay, paired with “dugh,” the “g” delivered hard and from the throat.

Scientists call the geoduck species found in Puget Sound panopea generosa.

“They’re typically found in the 2-to-3 pound range,” although some specimens have been found at nearly 9 pounds, said Bob Sizemore, research scientist with the Washington Department of Fish and Wildlife.

Numbers vary from year to year, but Sizemore estimates that Washington’s waters are home to 185 million pounds of wild geoduck, which bury themselves into the seabed and typically are only visible underwater during summer months, when their long siphons are extended to feed on drifting phytoplankton. Geoducks are exceptionally long lived, known to reach 160 years in the U.S., and 168 years in Canadian waters.

State and tribal fisheries managers limit divers to areas where harvest is allowed.

“The idea is to have a focused harvest and then rotate to a new tract,” Sizemore said. “With species that are long-lived, you have to be very careful about harvest.”

Working together, state and tribal shellfish managers have calculated not only the rate of allowable harvest but also the stopping point. The rate of harvest is slow enough to allow for healthy reproduction. The tracts are closed once 35 percent of the original amount of geoducks remain. Once that mark is reached, a tract won’t reopen for at least another four decades. In other words, divers may only harvest a few tracts over the span of their lifetimes.

The Tulalips and other tribes across Washington had their treaty rights to harvest fish reaffirmed by the landmark 1974 Boldt decision. The case forced big changes as it recognized the tribes’ demands to co-manage fisheries alongside the state.

It wasn’t until 1994 that another federal judge ruled that the same treaty rights applied to shellfish.

Today, geoduck tracts are split up 50-50, with the state sharing annual harvest quotas with tribes who self-govern and regulate their own operations.

Tulalip has adopted what it calls “derby style” harvest, tribal shellfish program manager Mike McHugh said.

“We started at 8 to 10 hours on restrictions 15 years ago and slowly reduced to two to three hours,” McHugh said.

While other tribes may open a tract for a few days harvest and monitor quotas by weight, Tulalip allows its divers to haul in as many pounds of geoduck as they can within a two- or three-hour window, depending on the area.

“We’re forced to dig fast,” said Hegnes, owner of the Rawdeal.

For divers, the time constraints make for a steep learning curve.

“It was really hard for me at first” Madrigal said, “A lot of people get licensed, dive once, and say ‘This isn’t for me.’”

This gap in skill and experience is evident at the dock after harvest.

On May 27, the same day Madrigal had trouble equalizing, the 11 boats from Tulalip brought in anywhere from just a few hundred pounds to almost 1,500 pounds apiece.

“There’s only a handful of guys that are really big diggers,” says Shane Baker, a veteran Tulalip fisherman and boat owner. He’s been diving both commercially and recreationally for 17 years.

With strong currents and visibility often limited to a few feet, Baker says intuition often is what makes a top-notch diver.

“Some guys pick it up fast and some guys just don’t,” Baker said.

Mental strength also is important.

“In my head I prepare a couple days in advance and get psyched up,” Baker said.

This is exactly the mentality towards commercial diving that the Tulalips want to encourage, McHugh said.

“We like to keep it competitive,” he said. The policies forcing fishermen to work quickly help prevent problems, he said, such as divers only harvesting the highest quality specimens and tossing the rest. That practice could harm geoduck populations over time.

The high-speed derby method comes at a cost.

Adam Peterson is a geoduck buyer who works as an independent contractor for packaging companies. Heading to the dock to buy geoduck from Tulalip divers can be a gamble, he said.

The quick harvest means divers don’t always bring in the highest grade geoduck.

As a result, Peterson has started asking divers to text him photos of the catch before he makes a trip up to the reservation.

Prices at the dock are adjusted accordingly.

“We know we’re 20 to 25 percent below the price” paid other tribal divers, McHugh said. “It’s the philosophy of the management here. Being fair is more important than grabbing the high price.”

As a non-Indian involved in the geoduck trade, Peterson has a unique perspective on the industry.

Originally from Port Angeles, he grew up, as he puts it, “just a mile off from the best wild ‘ducks you can get in the world,” near Dungeness Spit.

His uncle married a woman from the Lower Elwha Klallam tribe. That gave Peterson, 30, an opportunity to learn the commercial geoduck trade. It is a business that can be lucrative and deadly. He knew a Skokomish tribal diver who died from an embolism while working in Hood Canal in 2011. He had planned on buying the man’s catch that day.

Peterson operates under the name Rain Seafood Inc., and typically purchases between 1,000 and 3,000 pounds of geoducks a day from reservations around western Washington.

Once loaded into his refrigerated truck, the haul is taken to L &C Seafood in Tukwila, where workers rush to sort the clams by grade.

High-grade geoduck is typically between 1 pound and 2.5 pounds, with a light tan color and thick neck.

“When it comes to geoduck, the most important thing is health,” Peterson said.

Some Chinese customers believe eating geoduck boosts testosterone. To fetch top-dollar in Asia, the clams must remain healthy enough during transport to be sold live.

After arriving at L &C Seafood with a truckload of geoduck, Peterson’s product is moved quickly into a small temperature-controlled room.

Ideally, geoducks will go through this packaging process in the afternoon and be on their way to Asia aboard a jet by that evening. Each of the clams is held shut by a rubber band and kept at around 45 degrees with ice gel inserts in a cooler.

Retail prices in China are currently closer to the $20 a pound mark, Peterson said. In years past, there were reports of prices climbing to $100 a pound or more during peak demand times such as Chinese New Year.

Profits from Washington geoduck exports have jumped 63 percent since 2004, according to the state Department of Agriculture.

McHugh, the Tulalip shellfish program manager, attributes that to China’s middle class growing, making geoduck a more affordable splurge.

“It’s turned into ‘roast beef’ for the middle class,” he said.

Between 2006 and 2009, McHugh started noticing more buyers looking for smaller geoducks. It represents a shift in the industry from the 1970s and 1980s, when geoduck first took off as a party food for upper class people in China and Japan looking for huge “jumbo” clams to display at social gatherings.

With more geoducks than ever being shipped from Washington’s shores, officials are keeping a close eye on contaminants. One concern is Paralytic Shellfish Poisoning (PSP), or “Red Tide” as it’s more commonly known. Geoducks, like all filter feeders, can ingest the neurotoxin. In high doses, it can cause paralysis in humans.

A year ago, China lifted what had been a five-month ban on live shellfish imports after reportedly finding high levels of contaminants, including arsenic and PSP in shellfish harvested in the Pacific Northwest.

State fisheries research scientist Bob Sizemore and his divers continue to monitor the health of Washington’s giant clams.

“Our current estimates are that our geoduck population is in very good shape,” he said.

For divers, like Jesus Madrigal, that’s comforting news. Since getting his license in 2001, he’s watched Tulalip’s fleet triple in size.

He’s not worried about competition. Geoduck diving will always be a business for the strong.

“I just really go for it,” he said. “People that work harder get more.”