Lack of cooperation between nations which have competing claims to the sea is also contributing to the depletion, they said.
A number of countries claim the waters, including their reefs and rocky outcrops.
A study shows the number of some species at about five percent of 1950s levels.
Several of them, such as coral groupers and Napoleon Wrasse, have declined by 80 percent in the past eight years alone, it said.
“The South China Sea is… under threat from various sources. We need to do something,” said Rashid Sumaila, director of the Fisheries Economics Research Unit of the University of British Columbia.
“The most scary thing is the level of decline we have seen over the years. Some species (are facing) technically extinction or depletion,” Sumaila, who headed the study, told a press conference in Hong Kong.
Read more: http://www.interaksyon.com/article/119689/some-south-china-sea-fish-close-to-extinction