I said it is legal.
I am corrected. Bill Clinton signed a law banning it. However there is a list of restaurants still selling it.
Bill Clinton signed the Shark Finning Prohibition Act of 2000 (SFPA), which banned finning on any fishing vessel within United States territorial waters, and on all U.S.-flagged fishing vessels in international waters. Additionally, shark fins could not be imported into the United States without the associated carcass. In 1991, the percentage of sharks killed by U.S. longline fisheries in the Pacific Ocean for finning was approximately 3%. By 1998, that percentage had grown to 60%. Between 1991 and 1998, the number of sharks retained by the Hawaii-based swordfish and tuna longline fishery had increased from 2,289 to 60,857 annually, and by 1998, an estimated 98% of these sharks were killed for their fins.
I also note it says one must also bring in the carcass and of course done like that, it is not banned.
I suspect cats like shark even when humans don't like the taste.