Attending a World Aquaculture Society conference is the perfect opportunity to explore the aquaculture activities of the host country. In China, aquaculture is a vast and diverse sector, and Hainan — a tropical island of 34,000 km² — offers a fascinating glimpse into it.

Located off the southern coast of China, Hainan is home to 7.1 million inhabitants, mostly concentrated in Haikou, the capital, and in Sanya, a famous seaside resort. Thanks to its mild climate — with an average annual temperature of about 25 °C — the island attracts numerous tourists, especially in winter.

A Still Modest but Promising Production

Although aquaculture is now the island’s dominant economic activity, pearl farming remains relatively limited. Hainan mainly cultivates Pinctada martensii and, to a lesser extent, P. maxima. These oysters are either harvested from the wild or produced in hatcheries at Hainan University.

Reproduction of P. martensii can be induced year-round, but hatchery production is concentrated between February and May, then between September and December. The larvae are raised in concrete tanks, fed selected microalgae, and transferred to collectors after 24 days. The spat grow at sea until reaching 70 mm, after which they are grafted with two nuclei measuring 4.5 to 7.5 mm. After eleven additional months, the pearls are harvested. Survival rates average around 35% before grafting and 60% afterward.

The Linshui Experimental Farm

Hainan University’s farm, located in Linshui Bay, is built on a stilted structure from which mesh cages are suspended. Created in 1978, it initially produced pearls from P. martensii and P. maxima. After a period of interruption, P. maxima culture has recently resumed under the guidance of Professor Wang.

However, coexistence with other aquaculture activities — fish farming, lobster culture, seaweed farming — has led to conflicts and the disappearance of neighboring edible-oyster farms. Measures are now being taken to relocate pearl farms to more isolated areas.

Research and Innovation

Professor Wang is working on establishing a research institute in Sanya, equipped with a hatchery and a grow-out farm for P. maxima. His research focuses on producing polyploid P. martensii and improving pearl quality. Among the innovations is a coated nucleus containing an antibiotic and a cell stimulant, designed to reduce rejection rates and improve survival. The nuclei, initially lemon-yellow, lose their color after implantation and can be stored for up to twelve months.

Towards Advanced Genetic Selection

Fang Xuan Jun, from the Tropical Agricultural Resources Institute, is evaluating the growth, survival, and nacre color of natural and hybrid strains collected from Sanya, Beihai, and Daya Bay. Using random amplified polymorphic DNA techniques, he is attempting to isolate genetic markers for the most desirable traits and developing numerical analysis methods to optimize oyster selection.

This research could eventually transform Hainan’s pearl farming industry into a more profitable and technologically advanced sector, thereby strengthening China’s role in the global pearl market.