LIMA, Peru (AP) — Authorities in Peru say they've detained a ship carrying 12.3 million dried seahorses with a $6 million export value in an unprecedented operation.

Peruvian marines followed the Adonay ship for several days before intercepting it about 200 miles (322 kilometers) off the Pacific coast.

On board, authorities found 55 boxes filled with seahorses in what Peruvians say is the largest such capture on record.

Four crew members were also detained and face up to five years in prison each.

Throughout the years, the sea creature has been illegally bought for use in Chinese medicine.

But concerns about declining populations have led many countries to implement export bans.

Authorities announced the latest operation Tuesday and say the seahorses will be donated to investigative centers and local universities for research.