Six gray seals have been killed on Cape Cod, Mass., beaches over the past five weeks, all of them shot and "suffering greatly," a federal official investigating the deaths said.
No arrests have been made in the killing of the seals, which are protected under federal law. The most recent dead gray seal was found shot in the head Friday, one day after federal officials said they were investigating the five previous killings.
"It's obviously very unsettling. This is tough for our team that is out there responding and trying to save these animals 24/7," said Michael Booth, the communications officer for the International Fund for Animal Welfare (IFAW).
Booth told ABC News that these shootings are "very unusual." In the past 12 years, they have had only six similar occurrences.
Gray seals are federally protected under the Marine Mammal Protection Act, which makes it illegal to kill them. If convicted, one can face a maximum of one year in prison and a $100,000 fine for each killing, according to the Cape Cod Times.
NOAA, the National Oceanic and Atmospheric Administration, is leading this investigation.
"These animals are suffering greatly. We are taking these crimes very seriously and are strongly encouraging anyone with information to call," NOAA Special Agent Todd Nickerson said in a press release.
According to the IFAW, each time a dead seal is identified, the animal is examined on scene for forensic evidence. After this initial investigation, CT scans and a dissection and removal of bullet fragments provide more accurate evidence.
While Booth said he cannot disclose the exact locations where the bodies have been discovered, he said they have been on the Nantucket Sound beaches somewhere between Dennis and Chatham.
Once an endangered species, the population of gray seals has been able to rebound.
However, the Boston Globe reports that attitudes about the seals are divided in the area. They report that tourists and residents enjoy seeing the sweet-faced gray seals, but some fishermen consider them a nuisance that pollute the water and act as competition for fish.
Booth said the investigation has not yet identified any motives in this case or whether the killings were all committed by the same person. As the investigation continues, more than 300 volunteers all over Cape Cod work to keep an eye out for the area's marine animals.
"This is very, very unfortunate and all we want is for this to stop," Booth said.