MELBOURNE, Fla. -- James Smith held his breath and dived in the chilly waters of the Indian River beneath the Melbourne Causeway on a recent weekday morning, emerging a few seconds later holding a stone crab by both claws in his gloved hands.

“A fatty!” the 27-year-old Satellite Beach man said happily. “And there’s more down there.”

Smith and longtime friend and diving companion Chris Drake, 27, submerged once again and brought up two more crabs — both larger than the first.

“Getting pretty close to a limit,” Smith said, patting a mesh bag tied to his weight belt.

The two had planned to try the nearby Eau Gallie Causeway if they had no luck on their first stop. But in only about two hours of free diving beneath the U.S. 192 bridge, they collected their limit of a gallon of claws apiece — enough to feed themselves and their parents.

“Quiche, crab cakes, or just dip them in butter,” Drake said nonchalantly.

Smith and Drake have been diving for stone crabs since they were pre-teens — taught by Smith’s dad Rodney, a former light-tackle fishing guide and founder of Coastal Angler magazine. Both confessed to being scared the first few times they dived underwater and grabbed the pugnacious creatures by their claws. And both have been pinched a couple times between the crusher and pincer, narrowly escaping serious injury.

Stone crabs are said to exert up to 19,000 pounds per square inch of gripping power with their appendages, but according to Smith, they don’t always stand and fight.

“Some pinch, some hide and some run,” he said, echoing a phrase used in his PureOceanTv.com how-to video posted on YouTube.

As teens, Smith and Drake were very secretive about their stone crab diving success, only sharing their knowledge with a few friends. But these days, they’ll give tips and advice to anyone who asks — both to highlight the importance of the marine ecosystem in the vast Indian River Lagoon and because they have no apparent competition.

“I see a million lobster free divers, not one stone crab diver,” Drake said.

Added Smith: “We’re the only ones who kept doing it. We want to get people to know about the water quality of the lagoon and get more enthused about it and be able to save the lagoon.”

The lagoon system, which stretches more than 150 miles from Jupiter Inlet to Ponce Inlet, has come under hard times in recent years with heavy fresh water discharges, polluted run-off from farms and lawns, and other factors causing large algae blooms and sea grass die-offs. Its brackish waters aren’t nearly as transparent as in decades past, but the two dedicated stone crab divers still manage to find their bounty in most of their usual hot spots, which extend from Sebastian Inlet to Port Canaveral.

“It’s just as easy, if not easier, because we know where to look,” Drake said.

Their hunting grounds include bridges, fishing piers and docks where they locate stone crab burrows amid a telltale pile of mollusk shells between sand and rock.

“You’ll see a piece of a claw in the hole,” Drake said. “You have to commit to the crab — you pull one claw out and quickly grab the other claw. If you try to grab them from the front, you will get pinched.”

Smith carries a marked clothes pin as a measuring device to make sure each claw meets the legal minimum size of 2¾ inches from the elbow joint to the tip of the immovable point. For the first few crabs he caught under the Melbourne Causeway, he took both legal-sized claws. But as the water got clearer and he saw more and more “fatties,” he took only one. Stone crabs can regenerate missing claws in about a year, but being clawless makes scavenging for food more difficult.

Smith and Drake said they are very careful about breaking off the claw cleanly because doing it wrong can kill the animal instantly. A 2010 study by the Florida Fish and Wildlife Research Institute in St. Petersburg showed 20 percent of the claws measured at commercial fish houses were regenerated, so crabs can survive being de-clawed. The inside of the claw has whorls like a fingerprint which, if unbroken, indicate the original claw. But if there are dots and dashes, that means a new claw.

From time to time, the two men said, they have considered becoming commercial trappers. The profession can be lucrative, with colossal claws selling for as much as $55 per pound. But they never went through with it.

“It’s more fun to free dive, and it shows more respect than baiting a trap,” Drake said. “And it’s sustainable. We welcome anybody to do it by hand. If they can do that, we’re stoked.”