A day of fishing for Ken Apple is no lazy day on the riverbank, cool drink at hand, a radio lilting, perhaps.

Encased in a 7 mm-thick, sausage-tight wet suit, the 50-year-old Citrus Heights man picks his way down a rocky cliff, sometimes clutching a rope to ease his descent. If he's lucky, he'll find an ocean flattened like bathtub water. Otherwise, he heaves into 8-foot-high swells, holding his breath and plunging 20 feet into the murky depth to wrench loose a snail-like delicacy.

That's how it can go in the hunt for abalone, a marine mollusk that can fetch as much as $100 each. For Apple, who eats all his take, it's worth every minute.

"I work so I can dive," Apple said.

California Department of Fish and Game is looking to revamp the rules of the hunt for red abalone, which could mean new markets -- possibly putting it back on more restaurant tables -- and expanded fishing opportunities for thousands of people like Apple.

Commercial fishing could reopen for the first time since 1997, possibly by 2008, a welcome opportunity for some, but a dubious move to some recreational divers who fear a run on abalone.

Slow-growing abalone rapidly become depleted from over-zealous fishing, biologists have said, which is why commercial fishing was cut off a decade ago.

Scientists have noticed a troubling trend in Northern California, the only place for legal recreational abalone hunting in the state. Department biologists tracked a low number of immature abalone in locations like Van Damme State Park along the Mendocino coast or Fort Ross.

It could mean a dangerously diminished adult population in five or 10 years, which could force a reduction in the three-a-day, 24-a-year limit for recreational red abalone fishers.

"We don't foresee problems in the near future, but we do have some concerns," said Ian Taniguchi, a biologist with Fish and Game who specializes in abalone and sea urchin.

Abalone, treasured for its chewy but buttery taste, has had a storied history along the West Coast.

Sea otters once thrived on abalone, but after fur traders decimated the sea otters in the 1800s, abalone proliferated enough to support commercial fishing. After World War II, commercial fishers were pulling tons of red abalone off the Ventura County coast in the Channel Islands until 1997, when Fish and Game banned it and limited recreation fishing to north of San Francisco.

Now, Fish and Game sells between 35,000 to 41,000 "report cards" annually to recreational abalone fishers. Each card has 24 spaces to record each person's annual legal catch, which can be retrieved only by natural diving -- no breathing equipment.

Depleted by fishing and disease, red abalone appears to be making a comeback in the Channel Islands at San Miguel Island, Taniguchi said.

In 1997, less than 1 percent of the red abalone there fell within the legal size range. Now, nearly 70 percent of the population is within the 7-inch breadth limit for recreation fishing and 38 percent meet the commercial limit of 7 3/4 inches, Taniguchi said.

Fish and Game is considering allowing both commercial and recreation fishing at the island, but scientists still need to determine if the numbers are high enough and how to balance commercial and recreation limits.

A group of commercial divers, the California Abalone Association, supports the plan, said Chris Voss, who, like other members, has been harvesting sea urchin since the ban.

"We are concerned about sustainability first and foremost," he said.

With the commercial market virtually closed, the value of abalone has soared, giving rise to a huge black market, particularly for Asian restaurants.

In December, two San Francisco men driving down the coast were pulled over and arrested after police found 49 abalone in their car. Fish and Game wardens snagged 10 men last summer who were accused of illegally harvesting abalone off the North Coast and selling on the black market or to restaurants.

Some restaurants, rather than buying farmed abalone, which is also pricey, just keep it off the menu.

Abalone has shown up as a costly special offering maybe twice in the six years that Todd Torgerson has been head chef at Scott's Seafood in Sacramento, he said.

A reopened commercial market could lower the price, now going for $70 a pound commercially, he said, but it might not get down to the halibut price of $12 to $15 a pound.

If the price drops, it would be an easy sale, he said. "A lot of people enjoy it. It's an intriguing dish," he said.

A veteran abalone diver who works at Dolphin Scuba Diving Center in Sacramento questions opening a commercial fishery so soon.

"I want it to stay closed so the abalone can replenish on a widespread basis, so the whole area can open up, not just one island," said Jason Schmitz, who has been abalone-diving for 10 years.

Schmitz, 42, found marine gold when he pried open an abalone and discovered a rare pearl, which he had made into jewelry. Schmitz also is blessed by the sport in another way: He has access to a cabin on a private cove along the North Coast where he can reap his daily catch in 15 minutes, he said.

Apple, the other diver, isn't quite that lucky, but he does try to outreach the hordes by using an inflatable boat at times.

For a man who gets "frothy at the mouth" on the opening day of abalone season in April, Apple is concerned about any narrowing opportunities and supports conservation measures.

"I don't want to see it to the point where my grandchildren can't go out," he said.

• Sacramento Bee Story