Lawmakers have passed a landmark shark conservation bill, closing loopholes that had allowed the lucrative shark fin trade to continue thriving off the West Coast.

The measure - which the Senate passed Monday and the House passed Tuesday morning - requires any vessel to land sharks with their fins attached, and prevents non-fishing vessels from transporting fins without their carcasses. The practice of shark finning, which is now banned off the Atlantic Coast and the Gulf of Mexico but not the Pacific, has expanded worldwide due to rising demand for shark's fin soup in Asia.

"Shark finning has fueled massive population declines and irreversible disruption of our oceans," said Sen. John F. Kerry (D-Mass.), the bill's author, in a statement. "Finally we've come through with a tough approach to tackle this serious threat to our marine life."

Both Del. Madeleine Z. Bordallo (D-Guam), who sponsored the House version, and Rep. Doc Hastings (R-Fla.), spoke in favor of the bill Tuesday before it was adopted under suspension of the rules. It now awaits President Obama's signature.

"Some things are just worth waiting for," said Michael Hirshfield, chief scientist for the advocacy group Oceana. "Now we can all be a little less afraid for sharks."

Although Congress passed legislation aimed at protecting sharks a decade ago, shark finning has continued because the fins fetch a far higher price than the meat. According to the National Oceanic and Atmospheric Administration's Fisheries Service, 1.2 million pounds of sharks were caught last year in the Pacific, although it does not say what portion of those landings were fins.

The bill also allows federal authorities to identify and list which fishing vessels hail from nations that do not have the same shark conservation rules as the United States.

Although the legislation enjoyed bipartisan support, Sen. Tom Coburn (R-Okla.) blocked it Sept. 29 on the grounds that implementing it would cost taxpayers money. The bill sponsors offset the measure's five-year, $5 million cost by cutting that amount from a federal fisheries grant program over the next two years.

"The bill was snatched from the jaws of defeat," said Matt Rand, who directs global shark conservation at the Pew Environment Group, adding that it would help federal officials when they negotiate for stricter global catch limits. "It gives the U.S. a further leadership role and mandate to push for shark conservation from other countries."

The Obama administration has pushed for cuts in global shark-fishing quotas, with mixed results. In November, international authorities banned the catching of oceanic whitetip and several types of hammerhead sharks in the Atlantic, but international negotiators declined to impose trade restrictions last spring.

Nancy Perry, vice president for government affairs at the Humane Society for the United States, said the measure would both spare individual sharks "the unspeakable cruelty" of finning and could help broader shark populations recover off the United States' coasts.

The bill does include one exemption from the shark finning ban, for the smooth dogfish shark fishery off the North Carolina coast, to win the support of Sen. Richard Burr (R-N.C.).

But activists such as Rand said they were confident the measure would curb shark catches in U.S. waters. After the 2000 Shark Finning Prohibition Act passed, he said, the average annual landings of sharks off the United States between 2001 and 2006 declined 93 percent.