Conservationists are urging anglers to remove the heads of northern snakehead fish, an invasive species first identified in the U.S. in 2002. These air-breathing fish, which can survive out of water, pose a threat to native species and can compete for resources. It’s illegal to transport or possess them under the Lacey Act, and anglers are encouraged to report sightings to conservation authorities after killing the fish by following specific disposal methods.