Footage shows a woman attempting to straddle a dolphin that had become stranded in the shallows.
Beachgoers attempted to release it back into the ocean unsuccessfully, before the decision to euthanize it was taken.
"Such a beauty," one viewer commented. "What a blessing. Such a treat to have the privilege to see him."
Satellite images suggest that Russia has deployed an army of dolphins to protect their naval base in the Black Sea.
The dolphin was found on a U.K beach by Rosie Woodroffe, who guessed its tail had either been bitten off or removed by a propeller.
The woman found the calf, which was only 24 to 48 hours old, and stayed with it until rescue teams arrived.
Based on the shape and size of the wound, investigators said the mammal was likely "impaled while in a begging position."
The attack took place during a show at the aquarium, with families watching on as the trainer struggled in the water.
Kylie the dolphin was recorded making porpoise vocalizations over a period of two years.
The last remaining freshwater dolphin on a stretch of the Mekong died after its injuries prevented it from hunting.
Clearwater Marine Aquarium said people should not attempt to free the dolphin as it can place additional stress on the mammal.
Winter was rescued along Florida's East Coast in December of 2005 when her tail was caught in a crab trap rope, causing it to be amputated.
Michael Sutton, who spotted the carcass, said the bite measured about 2 feet across.
"Groups from all over the Gulf South converged to help rescue the injured dolphin," according to a Facebook post from the Slidell Police Department.
The friendship between Gunner the Golden Retriever and Delta the dolphin has charmed social media users.
Research into the attacks, which took place in the Baltic Sea over three months in 2016, is still ongoing.
The video was filmed by Newport Coastal Adventure on May 16 during an afternoon trip off Laguna Beach.
"I've seen it all...but this excited me," said the fisherman who shot the video.
"With four out of eight dolphins dying inside of 16 months, the situation has reached critical mass," said a campaigner.
The study "highlights the magnitude of plastic pollution," a professor of conservation told Newsweek.
An animal rescue organization is offering a $5,000 reward for information.
A pod of dolphins helped protect a humpback whale calf in Australia.