Federal authorities are investigating a group of swimmers who were caught on camera allegedly harassing a pod of dolphins Sunday in violation of federal law, authorities announced this week.

Drone video deployed by Hawaii Department of Land and Natural Resources officials captured the 33 swimmers allegedly «aggressively chasing, cornering and harassing the pod» in Hōnaunau Bay on Sunday morning, authorities said. Announced Tuesday.

The agency’s 39-second clip posted online it appears to show more than a dozen swimmers chasing 11 dolphins. The dolphins eventually split up in two directions in the waters, and some of the swimmers turn around and appear to stop chasing some of the dolphins.

The allegations could put the swimmers in violation of the Law for the Protection of Marine Mammalsa law enacted in 1972 that makes it illegal harass wild marine mammals including dolphins, whales, seals, and sea lions.

The law stipulates two levels of harassment, according to the National Oceanic and Atmospheric Administration: one that refers to «any act of persecution, torment or annoyance» that could injure a marine mammal, and another that refers to «acts that have the potential to disturb (but not injure) a marine mammal» by disrupting their breeding, feeding, and other routines.

He spinner dolphins involved in the incident on Sunday are also protected by a standard published in 2021. It prohibits swimmers and boats from coming within 150 feet of the dolphins within two miles of the Hawaiian coast, according to Katie Wagner, a NOAA spokeswoman.

Spinner dolphins, smaller members of the species known for jumping and spinning out of the water, can be sleeping even when they appear to be awake and moving through the water. the Associated Press reported. That’s because half of their brains stay «awake» while they swim, helping them breathe and stay on the surface of the water.

NOAA warns that disturbing spinner dolphins could disrupt their daytime rest, negatively affecting their health and reproduction and leading them to become aggressive or evasive.

Officials from the Hawaii agency’s Division of Conservation and Resource Control, who were conducting what officials described as a «routine patrol» in the area, deployed the drone after spotting the swimmers from the ground on Sunday, said Dan Dennison, senior communications manager for the Hawaii DLNR.

Officers alerted the swimmers to the alleged violation while they were still in the water and later found them on land, where they launched a joint investigation with NOAA’s Office of Law Enforcement, according to the news release.

The swimmers have not been publicly identified.

It was not immediately clear what kind of penalties the swimmers could face, although NOAA guidelines say people prosecuted in violation of the Marine Mammal Protection Act could face civil penalties of up to $11,000 and up to a year in prison.

Authorities urge people to observe wild dolphins from a distance of at least 150 feet on land or sea and to avoid circling, catching or swimming with them, per NOAA guidelines.