Today we tell the story of an important oyster member of China—the “Jinjiang” oyster. “Jinjiang” means close to the river in Chinese, and it is mostly found in rivers and estuaries with relative low salinities. Jinjiang oyster is widely distributed in China, ranging from the Lizijiang (oyster river) on the border with Korea to Beihai of Guangxi Province and even in Hainan Province. Jinjiang oyster reefs once dominated many big rivers and estuaries, ecologically and economically. It grows faster and is bigger size than the Pacific oyster, which is one major aquaculture species worldwide.
The shellfish research team from the Institute of Oceanology, Chinese Academy of Sciences (IOCAS) has been studying the classification, ecological distribution and the adaptive evolution of oysters in China for more than 10 years. The research team witnessed significant loss of wild Jinjiang oyster resources, and the situation is even worse in Northern China. For example, dramatic recent declines in natural oyster populations and oyster reefs occurred in the Bohai Sea area. And more than 99% of oyster reefs have been lost and reach the point of functional extinction. My personal research experience with Jinjiang oysters began two years ago.
In March 2017, I went to Binzhou, Shandong province for the first time with my colleagues Wei Wang and Rihao Cong. My original purpose for that trip was to collect Jinjiang oyster specimens for some basic research. However, barely any Jinjiang oysters were collected in the intertidal zone after searching all the river estuary of Binzhou. This situation was unexpected compared to that in 2005-2007 when my colleagues collected Jinjiang oysters in Binzhou easily. I was told the port construction and other economic activity to alter shorelines led to habitat loss and collapse of the Jinjiang oyster in that sea area. The general Jinjiang oyster resource decline was also mainly due to the overfishing together with other anthropogenic factors such as decreased freshwater inflows and pollution from land-based sources.
One month later we went back to Binzhou again and this time it was more efficient and we got 40 kgs of Jinjiang oysters from one local fisherman, Mr. Fu, who caught them in a “secret” place by diving in the subtidal zone. After we got his trust, we knew the exact collecting sites and had the chance to know more about the current status of the Jinjiang oysterpopulation in this region. The total area of this oyster population was estimated as 2-3 km2. We then set some substrates for the larval attachment to monitor seedling replenishment. Mr. Fu averagely collects more than 15, 000 kgs of Jinjiang oyster per month, working up to 8 months of the year.
The collected oysters are sent to the food market with a price of 4-5 Chinese yun per 500 grams. I do not know how many local fishman like Mr. Fu are living on this population, but I know this oyster population is not sustainable at the cost of the current harvest rate. The continued harvest is even a persistent phenomenon globally despite collapse of oyster populations and reefs. Measures must be taken to conserve this population!
Firstly, we drafted a letter to the government of Shandong Province, seeking the support to build a protection area and make corresponding protective policies. Secondly, with support from the Fund for Modern Agro-industry Technology Research system, we established techniques for the artificial seedling of Jinjiang oysters. Each year since 2017, more than 10,000,000 oyster spats were produced in the hatchery and put back into the site of origin to increase the resource amount. The efforts of Jinjiang oyster aquaculture is hoping to reduce harvests of wild stocks. It has not been a major aquaculture species yet in China.
The plans for rebuilding oyster populations are still rare in China. Luckily, this year a new project of mine supported by the Strategic Priority Research Program of the Chinese Academy of Sciences was initialized. In which, we attempted to restore the oyster population and rebuild oyster reefs in Laizhou and Bohai bay. The long-term goal of this project is not for oyster fisheries production, but for the recovery of associated critical ecosystem services the oyster reef provides, such as removing excess nutrients, increasing fishery biodiversity and improving water clarity. In addition, the efforts of Jinjiang oyster aquaculture is hoping to reduce harvests of wild stocks. For new thinking and approaches for oyster population and oyster reef conservation and restoration, an international forum themed on ecological function and the protection of the oyster reef was hosted by the shellfish research team in 2017.
In general, the conservation, restoration, and management of the Jinjiang oyster needs the participation and close cooperation of the government, the public and the scientific community.