So as not to jeopardize their case or encourage copycats, the Fish and Wildlife Service did not disclose the shipment’s country of origin, destination, what it was labeled as, and what else it contained.

The U.S. isn’t a significant producer or consumer of shark parts, but as a facilitator in the global shark fin market, it’s a transportation “powerhouse,” says David Jacoby, a research fellow at the Zoological Society of London. “The fins, whether legally or illegally obtained, have a fast route to their ultimate destination, which is often far East Asia,” he says. Americans “have some of the largest airports in the world, that have some of the highest numbers of flights and carriers, that enable things to move very quickly from one place to another.” ( Read more about the U.S.'s role in the shark fin trade .)

The fish are coveted for their fins , used in shark fin soup, a traditional Asian dish that Lara says can sell for up to $600 a bowl. Their meat, however, has little value, which means that some fishermen engage in finning—slicing the fins off live sharks and tossing the wounded animals overboard, where they sink to the bottom and drown, die of blood loss, or get eaten by other predators. This practice has been illegal in U.S. waters since 2000; various countries and international agreements also restrict shark finning.

In the context of the illegal shark fin trade, says Arthur Florence Jr., branch chief of Agriculture Air Cargo Operations for U.S. Customs and Border Protection, the Miami airport haul was a “drop in the bucket.” From 2000 to 2011, countries legally imported an average of nearly 17,000 tons of shark fins a year, according to conservative estimates from the Food and Agriculture Organization of the United Nations. Each year, scientists estimate , tens of millions of sharks are killed in both the legal and illegal shark fin trade—a troubling number, given “the lower productivity of … species common in the fin trade,” according to a 2006 study estimating the scale of shark catches worldwide.

Shark fin pathway

In the United States, 13 states and three territories have banned the sale of shark fins. But the country’s location along trafficking trade routes—between shark fishing countries in South and Central America and shark fin markets in Asia—means that significant illegal shipments transit the U.S. by land, air, and sea, according to a 2019 report on the U.S.’s role in the shark fin trade by the Natural Resources Defense Council (NRDC), a conservation nonprofit.

Hundreds of tons of shark fins pass through multiple U.S. ports. U.S cities with ports found transiting shark fins, 2010–2017 100 50 10 metric tons Seattle New York Oakland Newark UNITED STATES Long Beach Dallas/ Fort Worth Atlanta (354) Los Angeles Miami 274 Honolulu 859 metric tons Declared shark fins passing through U.S. to Hong Kong, 2010–2017 SOURCE: NATURAL RESOURCES DEFENSE COUNCIL

The NRDC report says that during the seven years from 2010 to 2017, between 591 and 859 metric tons of shark fins—from some 900,000 sharks—passed through U.S. ports. Yet those numbers are likely conservative estimates. That’s because the researchers focused only on Hong Kong as a destination, based their numbers on a single global shipping database, and tallied shipping records that explicitly declared the cargo to be shark fins. It’s common for shark fin to be incorrectly labeled as “frozen seafood” or “dried seafood”—or even as something completely unrelated like “tennis shoes,” if it’s “full-on smuggling,” says Elizabeth Murdock, director of the Pacific Ocean Initiative for the NRDC and lead author of the report.

The U.S. is obligated by both the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the treaty aimed at ensuring that cross-border trade doesn’t threaten species’ survival, and the U.S. Code of Federal Regulations to monitor in-transit wildlife shipments. Shark fins that are imported and then re-exported must be processed and may need CITES and U.S. permits. Shipments that simply pass through ports should be monitored but often aren’t, Murdock says, adding that if cargo transferred from one plane or ship to another stays under the control of the same shipping company, it likely won’t be inspected.

According to Florence, the inspection in Miami airport was a combination of intel and luck. The Fish and Wildlife Service had tipped customs off that a shark fin shipment was coming, but since the Agriculture Air Cargo Operations department processes more than a hundred in-transit flights daily at Miami airport, catching every illegal shark fin simply isn’t possible. “It’s kind of like finding that needle in the haystack.”

Michelle Zetwo, special agent with the National Oceanic and Atmospheric Administration, says she knew there must be occasions when shark fins transited through U.S. ports, but she was surprised at the numbers reported by the NRDC.

In 2017, Zetwo was part of a shark fin bust at the Port of Oakland. The shipment of more than 52,000 pounds of shark fins, labeled as cucumbers and gherkins, was discovered during a routine inspection of a container vessel traveling from Panama to Hong Kong.

As with the 2020 Miami seizure, the discovery largely came down to luck, Zetwo says. “We didn’t know until we did the inspection, and it was just happenstance.”

View Images Between 591 and 859 metric tons of shark fins passed through U.S. ports from 2010 to 2017, according to a report by the Natural Resources Defense Council. The report’s lead author says that's likely just the “tip of the iceberg.” Photograph by Johannes Eisele, AFP/Getty

The NRDC report also notes that many exporting countries in Latin America are “major players” in the international shark fin trade and that nations such as Panama and Costa Rica ship as much as one-third to half of their shark fin exports through the U.S.