Officials in Ecuador said they discovered 357 dead sharks from a boat in the protected waters off the Galapagos Islands national park.
They were hunted and fished illegally.
The Quito government said it will file criminal charges against the crew of the Ecuadorean boat (comprising some 30 fishermen), which was detained near the Genovesa Island inside the marine reserve.
The shark species found included 286 bigeye threshers, 22 blue sharks, 40 Galapagos sharks, six hammerhead sharks, two tiger sharks, and one mako shark.
Reportedly, the sharks are hunted to feed the huge demand for shark fin soup in Asia.
Since 1979, the Galapagos region has been declared a “natural heritage site” by the United Nations due to its extraordinary land and marine species. As such, fishing for sharks in the area is forbidden.
John Bruno, a University of North Carolina marine biologist who teaches at the Galapagos Science Center, wrote in a blog that park officials said it was the biggest shark seizure in its history.
"As sad as it is," he wrote, "I am really encouraged that the park now has the capacity to detect and apprehend illegal fishers in the marine reserve."
He added: “Surprisingly, whole (but gutted) bodies of the sharks were on board, ie, they were not finned at sea.”