US police are mystified by the number of dolphins that have washed ashore along the northern Gulf Coast with bullet wounds.
The mammals also have missing jaws and fins hacked off, and federal officials said they are looking into the mysterious deaths.
The most recent case was of a dolphin found dead off the coast of Mississippi, its lower jaw missing.
Officials from the National Oceanic and Atmospheric Administration (NOAA) said they're asking everyone, from beachgoers to fishermen, to be on the lookout for injured or dead dolphins – and any unusual interaction between the mammals and people.
"It's very sad to think anyone could do that to any animal," said Erin Fougeres, a marine mammal scientist for NOAA in St Petersburg, Florida. "There have been some obviously intentional cases."
Ms Fougeres said five dolphins have been found shot. In Louisiana, two were shot in 2011 and one in 2012. And in Mississippi, three were found shot this year, the most recent one being found last week, which was first reported by the 'Sun-Herald' newspaper.
Besides the shootings, a dolphin in Alabama was found with a screwdriver stuck in its head over the summer. Another in Alabama had its tail cut off, and that animal survived. Still others were missing fins or had cuts to their bodies.
"I think it is outrageous," said Moby Solangi, the executive director of the Institute for Marine Mammal Studies in Gulfport, Mississippi. "These animals are very docile, very friendly and they're very curious. And their curiosity and friendship brings them so close that they become targets and that's the unfortunate thing."