Not a single shipment of shark fins moved through the Port of Baltimore last year, according to the National Oceanic and Atmospheric Administration. But Maryland still may ban the sale and trade of the Asian delicacy, much to the ire of some fishermen and restaurant owners.

Moves to restrict the shark fin trade — which is now illegal in four states and has prompted legislation in at least six others — has stirred a noisy public debate about how best to protect a top ocean predator whose numbers are shrinking. While the United States boasts some of the world’s toughest restrictions on shark fishing, requiring sharks be brought in with their fins attached, proponents of the measure argue that more needs to be done to stem the decline of sharks.

“This is everyone’s problem,” said Maryland Del. Eric Luedtke (D-Montgomery), who wrote the House bill partly out of his concern for the Chesapeake Bay. He noted that the number of large sharks off the East Coast has declined by 90 percent compared with historic levels, which led to an explosion in the Bay’s cownose ray population, and that in turn wiped out some oyster beds. “The reality is sharks don’t recognize state boundaries; they don’t recognize international boundaries. What’s bad for oceans elsewhere is bad for oceans here.”

But some Asian American businesses that serve shark’s fin soup, as well as fishing operators who catch sharks legally, oppose the bans, which went into effect in Hawaii in 2010 and in California, Washington and Oregon last year after receiving wide bipartisan support.

A group representing Asian American shark fin dealers, restaurateurs and grocers will argue in the California Superior Court in San Francisco next month that the ban is unconstitutional because the federal government has ultimate authority over interstate commerce and the state is not compensating them for the economic loss.

The fin trade is the top intentional driver of shark deaths worldwide — killing between 26 million and 73 million sharks annually — because their cartilage is used to make noodles for a soup served at weddings and business meals. Millions of sharks also die each year when they are caught accidentally in gear targeting other species.

In many ways, the push to target shark fins is modeled on the successful effort to outlaw raw ivory imports into the United States in 1989, a year ahead of a global ban on African elephant ivory. In both cases, according to Beth Lowell, campaign director at the international group Oceana, “It’s the product which is driving the unsustainable trade of a species. If we can impact the trade of the product, we can have a difference outside the U.S. as well.”

Although the United States was a major importer of elephant ivory, it accounts for less than 1 percent of the global shark fin trade.

Maryland’s secretary of natural resources, John R. Griffin, has joined a group of Ocean City business groups — including fishing operations, restaurants and hotels — in opposing the Maryland measure out of concern that it will restrict the local shark catch. The bill passed the Senate 42-2 last week and will have a hearing in the House on Wednesday. If it doesn’t pass before the chamber adjourns on April 9, it would have to be reintroduced next year.

Between 16 and 20 boats target five species of sharks off Ocean City primarily for meat but sometimes sell the fins separately. The amended Senate bill will allow these operations to sell only whole sharks.

In a statement, Griffin said that while the administration of Gov. Martin O’Malley (D) shares the sponsors’ goals, “We feel that the bill in its current state will hurt the honest Maryland commercial fisherman who already abides by the law and humanely lands sharks whole. As the bill stands, watermen will still be allowed to land sharks, but the fins will have to be wastefully discarded later in the process.”

Merrill Campbell, a commercial fisherman based in Ocean City, said he and his colleagues already abide by both state and federal fishing restrictions. “This is a back-door effort to eliminate commercial fishing. They’re eating legal shark fins in Montgomery County. I guess those rich folks up there think that’s a travesty.”

At least two Maryland establishments, Rockville’s Tysons Buffet & Restaurant and Silver Spring’s Wong Gee Asian Restaurant, sell shark’s fin soup. According to the Animal Welfare Institute, at least nine restaurants offered it in recent years.

Rebecca Regnery, deputy director of wildlife for the Humane Society International, said her group and others are targeting the shark fin trade in states with major ports and with large Asian American populations, not the overall practice of shark fishing. A bill is pending in the New York legislature, she said, and activists are concerned that more shark fins could flow into other states if it passes.

“We think that closing down the big ports and places with large Asian populations will end U.S. involvement in the fin trade, to a large extent,” Regnery said.

Legislators have tried to enact bans in Virginia and Florida but failed largely because of opposition from fishermen. Similar bills are pending in New Jersey and Illinois. Advocates are also eyeing Delaware, Nevada and Texas.

The shark ban lobby represents an eclectic coalition and varies depending on the state: Distance ocean paddler Margo Pellegrino has joined the advocacy group Shark Stewards in New Jersey, while the National Aquarium in Baltimore is one of the major proponents of the Maryland bill.

Peter How, president of the Asian American Restaurant Association, estimated shark’s fin soup constitutes between 2 and 3 percent of his members’ sales.

“Nevertheless, the shark’s fin soup can be replaced by dishes with other ingredients or substitutes out of environmental concern,” How wrote in an e-mail. “It is just a matter of time for a full transition. After all, our culture has been changing along with the history for social needs.”

Robert Hueter, who directs the Mote Marine Laboratory’s Center for Shark Research, said people need to keep in mind that banning U.S. fin imports will not address all the threats sharks face, especially since the bulk of the demand is in Asia.

“In and of itself, shark’s fin soup is not the enemy,” Hueter said. “If we could wave a wand tomorrow and end the fin trade, it would reduce the worldwide shark mortality. The more important question is, would it reduce it enough?”

While it remains unclear whether Maryland’s proposal will become law, the flurry of activity may prompt federal lawmakers to take action.

“The wildlife trade is a place where national leadership matters,” said Monterey Bay Aquarium Vice President Michael Sutton, whose group co-sponsored the California shark fin ban.

Rep. Sam Farr (D-Calif.), who also backed the state ban, said the movement reflects a growing awareness of the role sharks play in the ocean.

“This is a new frontier, the ocean,” said Farr, adding that he’s been impressed that some of his own constituents who go surfing off the central California coast back shark conservation even though they might encounter a lethal great white while at sea. “They’d rather bear that risk than have the ocean depleted of animals that rightfully belong there.”