For more than a decade scientists and environmentalists have been warning of a mass slaughter of dolphins around Peru.
Hundreds of fishing boats have been accused of killing the animals and using their fatty bodies as bait to catch sharks.
The killings, two or three per hunt, by hundreds of fishing boats around the country, add up each year to make it the biggest illegal slaughter of dolphins in the world, according to environmentalists.
ITV News has obtained footage that shows fishermen harpooning dolphins for bait. It's the first time this secret hunting has been filmed.
Science Editor Lawrence McGinty's report contains images you may find disturbing.
The footage, shot undercover by British journalist Jim Wickens, shows the hunting taking place, hundreds of miles off the coast of Peru.