California authorities are on the hunt for the person or persons responsible for fatally shooting three sea otters last year. Conservationists and animal rights activists from several private and public groups are offering a $21,000 reward for information that could lead to the culprits’ arrest.

The three sea otters, an endangered species that was hunted nearly to extinction during the early 20th century, were found dead last fall on a Monterey Peninsula beach, according to federal wildlife authorities who announced the reward on Friday.

“We want to bring things full circle and find the people responsible for this act,” Rebecca Roca, U.S. Fish and Wildlife Service Resident Agent, who is directing the criminal investigation into the shootings, said in a statement, according to the Los Angeles Times.

Wildlife authorities say that two of the otters were shot in the head, while the third was shot in the back. The shootings occurred sometime between Sept. 1 and Sept. 5, 2013. Authorities removed coated lead bullets from all three of the animals.

“These baseless killings are nothing short of acts of barbarism,” Kim Delfino, director of California programs for Defenders of Wildlife, said in a statement, according to KSBW. “Moreover, shooting endangered species like the southern sea otter is illegal, and the criminals responsible should be punished to the highest extent of the law. Southern sea otters are one of the charismatic species that make our country such a special place, and we must do all that we can to protect and champion these imperiled animals.”

California’s sea otters were nearly killed off in the late 19th and early 20th centuries by fur traders who hunted them for their pelts. The marine mammal, which is native to the coasts of the northern and eastern Pacific Ocean and once inhabited the waters stretching from Oregon to Baja California, numbered in the tens of thousands. Over time, their population plummeted to just a few thousand individuals.

According to the U.S. Geological Survey’s Western Ecological Research Center, today there are about 2,900 of them in the wild.

"With all of the natural threats and human-caused problems facing sea otters, it's especially tragic that a person would set out to intentionally kill these sea otters," said Andrew Johnson, Sea Otter Research and Conservation Program Manager for the Monterey Bay Aquarium.

Anyone with information that could lead to an arrest is encouraged to contact the U.S. Fish and Wildlife Service at 650-876-9078. You can also make an anonymous report by calling the U.S. Fish and Wildlife contact line at 703-358-1949.

If caught, the person or persons responsible for the killings could face fines up to $100,000 and even jail time.

The unwarranted killing of the three California sea otters is reminiscent of an October 2013 incident in which authorities discovered four dead sea lions in Malibu, each with gunshot wounds. It was unclear whether or not the animals were shot after they were already dead.

According to the Los Angeles Times, during California’s annual fishing season, wildlife officials receive more animals with gunshot wounds than any other time of the year. Authorities suspect fisherman who are trying to deter sea lions from damaging their catch and gear, but investigations into who pulled the trigger are often unfruitful.