COLUMN ONE : ‘Jaws V’--A Shortage of Sharks? : Overfishing depletes their populations, giving them a new image as a vital part of the food chain that should be protected.

After he received his master’s degree in business from Yale, Marc Agger did a stint as a mergers-and-acquisitions specialist on Wall Street.

That was in the early 1980s. Today, he’s into shark fins. In a smelly warehouse in the old Brooklyn Navy Yard, the 32-year-old president of Agger Trading Co. buys, dries, and sells more than 100,000 pounds a year of dorsal and pectoral fins and lower lobes from more than a dozen species of sharks--makos, blues, lemons, tigers, blacktips, and duskies. Cured, they fetch $10 to $30 a pound--not quite as lucrative as mergers and acquisitions, but better than frozen pork bellies.

On sunny days, Agger’s shark parts lie on racks out on the docks, withering in the sun. In foul weather, they dry under whirring industrial fans in the cavernous building that once housed clanging repair shops, when the shipyard was in its heyday. When Agger deems them ready, they are shipped around the world, to be used in shark’s-fin soup in upscale Oriental restaurants from Manhattan to Beverly Hills, and from Tokyo to Hong Kong.

But not everyone views an Agger dorsal as a morsel. Among marine conservationists, Agger and his fellow entrepreneurs in the fin trade are viewed as a major factor in the increasingly alarming decline in the number of sharks in the Atlantic.

There’s no dispute that the trend is a clear one. Having survived 400 million years and earned a modern-day reputation as mindless, insatiable, indestructible killing machines, sharks have now come under serious attack by a superior predator. And they have been caught at an unsustainable rate throughout the ‘80s, experts agree.

With the market for shark fins booming--and shark filet fast becoming haute cuisine in the United States--the business has exploded from 500 tons in 1980, when shark fishing was being officially encouraged, to 7,500 tons in 1989. When the catches of recreational fishermen are counted--along with the sharks that are killed and thrown back into the sea--the National Marine Fisheries Service calculates that total shark take last year was almost 25,000 tons.

Even more ominous, American shark catches are only the tip of the problem. Five years ago, the United Nations’ Food and Agricultural Organization estimated the worldwide catch of cartilaginous fishes totaled 1.3 billion pounds--enough to circle the earth with sharks four times, according to Samuel H. Gruber and Charles Manire of the University of Miami.

Harry Upton, fisheries program director at the Center for Marine Conservation in Washington, says the dramatic growth of shark fishing in the United States means that the Atlantic populations of mako, hammerhead, blacktip and thresher all are facing “imminent collapse.”

Miami’s Gruber, considered one of the nation’s top authorities on sharks, agrees. Unless there is a dramatic turnaround, he warns, many species will be pushed to the brink of extinction within 20 to 30 years.

Some already have been.

Commercial volumes of the soupfin shark were wiped out in the 1940s. Overfishing reduced the Scottish and Norwegian stock of spiny dogfish to levels where they could no longer be caught in profitable numbers--a situation that experts describe as “commercial extinction.” And in the 1960s, fishing fleets nearly eradicated the porbeagle shark in the Atlantic.

Off California, makos and threshers--the most prized of food sharks--have been depleted.

Commercial shark fishing developed in earlier times because shark livers were a rich source of Vitamin A. Scientists long ago developed synthetic vitamins, but the exploitation of sharks has been propelled faster by new forces.

Signs of Warning

The warning signs are dramatic:

Around the Florida Keys, only a few years ago, lemon sharks could be found by the hundreds. Now they are hard to find at all. Most have been slaughtered for crab bait.

Around Costa Rica’s Cocos Island, hammerhead sharks--which feed on coral--have been decimated for their fins.

In the past several years, the widening market for fins of nearly any species has produced an upsurge in “finning”--a practice in which the fisherman catches the sharks, slices off their valuable fins and throws them back into the ocean to die.

By Gruber’s estimates, the take of shark fins in waters around Florida has skyrocketed--from a mere 1.5 tons in 1986 to 40 tons just two years later. “This works out to over 100,000 individual animals,” Gruber reported late last year, “and in many cases only the fins are saved. In some grotesque cases, the shark is returned to the ocean alive without fins, to starve to death.”

Even Agger, who buys fins from 300 boats ranging over the east, west, and south Atlantic, says it is time for regulation. “Fishing right now is like the Wild West,” Agger said. “It’s like, ‘Let’s go out and shoot a buffalo for dinner.’ ”

In fact, federal protection for sharks is on the way.

Last October, the National Oceanic and Atmospheric Administration produced a draft management plan that for the first time would impose limits on both commercial and recreational catches of 38 species that are found in the Atlantic. It would require both shark fishermen and dealers in shark meat to obtain permits. And it would seek to control finning by limiting the buying and selling of fins to a proportion of the number of carcasses.

The initial proposal would set an overall annual limit of 16,250 tons and would create a federal oversight team to monitor compliance by fishermen and dealers.

Although the final plan was to have been published last February and put into effect in June, it is yet to be completed--because officials have not been able to agree on what the limits ought to be.

As an interim step, conservationists have asked Commerce Secretary Robert A. Mosbacher to take emergency steps while the protection plan is being completed. In a letter last week, the Washington-based Center for Marine Conservation called on Mosbacher to put the recommendations on regulating finning into effect immediately and to limit recreational shark catches to one per vessel.

Similar pleas came from the University of Miami’s Rosenstiel School of Marine and Atmospheric Sciences and the National Wildlife Federation. “This is a typical case of federal and state governments responding after a fire is out of control,” said George Burgess, senior biologist at the Florida Museum of Natural History.

“If we wait for hard data to come in, the sharks will be gone,” Burgess says. “Decades, not years, would be required for them to recover. My personal opinion is that if we impose stringent limits now, the populations could recover in a reasonable amount of time. But if we wait another year, the crash will have occurred.”

The problem is more acute in the Atlantic than in the Pacific. The water off the East Coast is warmer and the continental shelf is wider, so there’s room for more species to exist and be at risk. The Atlantic is also the fishing ground of the long-line tuna and swordfish boats, which account for much of the shark catch.

What makes the threat of the population collapse so critical is the fact that unlike other fish, sharks reproduce slowly. They have long gestation periods and give birth to relatively few young. In some cases, they take years to reach sexual maturity.

Even after years of research there are vast gaps in the knowledge of their reproduction, feeding, and migration habits.

Over the past quarter-century, Jack Casey of the National Marine Fisheries Service has tagged 90,000 sharks of some 30-odd species, seeing thousands of them caught again--some more than 25 years after their release.

Casey’s work has shown that species such as blues migrate across entire oceans, using the continental shelf off the United States as a breeding ground and then crossing the Atlantic to give birth to their young off Portugal, Spain, the Canary Islands, and the coast of Africa. Sand sharks travel with the withdrawing summer, leaving New York and moving down the Eastern Seaboard into the Gulf of Mexico to the Yucatan Peninsula. But, except for their concern that some species are flirting with population collapse, scientists would like to know much more before they make any long-range decisions on how far to go in protecting sharks.

“We have not been studying sharks in the way to produce the kind of data we need,” George Burgess says. “By the time we have the data, it could be too late. We have to put a management plan in place based on the unsatisfactory situation where we are saying to people, ‘Trust us.’ ” In fact, there is more at stake here than protecting creatures merely for their intrinsic worth.

Top Predators

Sharks reign at the apex of the marine predatory system--350 species of them, from 35-foot whale sharks and the fearsome great white sharks of the movie “Jaws” down to 8-inch cigar sharks. If their population were to collapse catastrophically, it could spark a population explosion among the predators beneath them in the chain, setting off a ripple effect that could reach major consequences.

There also is a lot to be learned from laboratory studies of shark physiology.

“Without access to research specimens,” says Gruber, “we may never fully understand why sharks are so resistant to cancer, how a serious wound heals in less than 24 hours, or why a lacerated cornea, which in any other creature would permanently cloud over, remains clear, functional, and rapidly heals.”

Although the problem in the Pacific is less acute than the Atlantic, some conservationists, such as Gruber, contend that the Pacific needs a federal protection plan similar to that being drafted for the Atlantic.

During the 1980s, thresher sharks were taken off the California coast by commercial net fishermen, who mixed shark fishing with their quest for swordfish. The California Fish and Game Commission shortened the season for threshers, but the population continued to decline.

Last year, authorities issued no commercial thresher permits, though fishermen may still take sharks as part of their swordfish operations. Mako sharks can also be taken in nets, as long as the catches are incidental.

The state is, however, permitting a small experimental long-lines shark fishery, and is licensing six boats to operate from San Pedro and Ventura. In the Santa Barbara area, meanwhile, California halibut fishermen have begun taking angel shark, which is being marketed to restaurants and food stores.

Still, most of the shark filets now found in California restaurants and food stores are imported from Mexico or from the Atlantic.

It was not until the 1980s that commercial shark catches in the Atlantic surpassed the volume of sport fishing.

Over the years, shark has been a sort of blue-collar sports fish. Because sharks swim so close to shore, fishermen don’t need the kinds of expensive fishing boats that are required to reach the deep-water territory of big-game fish.

Moreover, for many a man, the challenge of prevailing over a massive, fighting shark provides a thrill that surpasses catching the ordinary game fish. “There is a Jaws-image motivation,” George Burgess says.

Indeed, the 1970s movie in which an Eastern summer resort was terrorized by a man-eating great white produced a new wave of revulsion and fear of sharks. But the final result “was an educational backlash,” Jack Casey says. “There was an advance in general public understanding after the horror cooled down.”

“The shark’s image is changing,” says Steve Moyer of the National Wildlife Federation. “People are learning that they are top-of-the-line predators in a very intricate marine food web, and that they ought to be there.”

Times staff writer Tien Lee in New York contributed to this article.