A fisherman from Quang Ngai Province died Sunday when his oxygen pipe broke while he was diving for holothurians.
Le Van Co, 23, was the second holothurian fisherman from the Ly Son Island of the province to be killed in the past six months.
Co was sailing with 13 others on a boat captained by Duong Van Giau.
Ly Son fishermen said a kilo of holothurian sells for VND500,000-700,000 (US$26-37) and a kilo soaked in wine can bring more than a million dong, so many young men from the island are drawn to the job.
Vo Xuan Huyen, chairman of the district, said the district has around 1,000 people working on 200 boats diving for holothurians around Hoang Sa (Paracel) and Truong Sa (Spratly) Islands.
Each boat can fetch up to 400-500 kilos of holothurians each trip and one diver would receive a share of more than VND10 million, Huyen said.
"But as holothurians are disappearing, the fishermen have to go farther offshore and dive deeper, meanwhile facing more risks," he was quoted by Vnexpress as saying Tuesday.
Statistics from Ly Son District showed that around ten people from the district were killed or paralyzed from diving too deep for holothurians.
Holothurians are highly valued in Malaysia, China, Japan, Indonesia and Vietnam as people believe they have medicinal qualities.