Farmers release crab seedlings into ponds in Gaochun district, Nanjing

Along the shores of Gucheng Lake in Gaochun district, Nanjing, east China's Jiangsu Province, crab farmers are out in their boats, releasing coin-sized seedlings into the ponds.

Crab farming is a specialty industry in Gaochun, involving over 100,000 farmers and generating more than 10 billion yuan (about $1.38 billion) annually in output value.

Crab farmers release crab seedlings into the ponds in Gaochun district, Nanjing, east China's Jiangsu Province. (Photo/Wei Hongwei)

On Feb. 24, Liu Shidian, technical director of a shrimp and crab seedling cooperative in Gaochun, took a call from crab farmer Zhou Husheng and immediately had workers collect crab seedlings from the pond. By the time Zhou arrived, 500 kilograms of crab seedlings were neatly prepared.

"The 15,000 kg of crab seedlings cultivated by us were fully booked before the Spring Festival. Once the water temperature reaches 5 degrees Celsius, it's time to release the crab seedlings into the ponds," Liu said.

Photo shows an energetic crab. (Photo/Wei Hongwei)

"Crab farmers in Gaochun focus on the premium crab market, so high-quality seedlings sell fast," said Zhao Huailiang, sales director at Jiangsu Huahai Seedling Technology Co., Ltd.

Last year, the company introduced "Jinnong No.1," a crab variety that contains 8 to 10 percent more edible meat than average varieties and also boasts 25 percent lower feeding costs, quickly becoming a favorite among local farmers.

In 2013, the company's team identified the shortage of high-quality crab seedlings as a major obstacle. Traditionally, farmers relied on their experience to select and breed crabs, resulting in inbreeding and genetic deterioration. To address this issue, the company collaborated with Nanjing Agricultural University and successfully created "Jinnong No.1."

In 2023, "Jinnong No.1" was officially approved as a new river crab breed by China's Ministry of Agriculture and Rural Affairs.

Aerial photo shows a crab farming area in Gaochun district, Nanjing, east China's Jiangsu Province. (Photo courtesy of the convergence media center of Gaochun district)

"Crab farming used to rely purely on experience—you had to watch the ponds constantly," said Xing Bangjian, head of an aquatic cooperative who manages 200 mu (13.33 hectares) of crab ponds.

Since 2022, Gaochun has promoted smart crab farming, and Xing was one of the first to adopt it. The smart aquaculture system tracks crab growth and monitors key water parameters like oxygen levels, temperature, and pH value.

"Last year, I introduced crab-perch co-culture in my 30-mu pond, and the perch alone brought in nearly 260,000 yuan," said crab farmer Tan Fengya.

Currently, more than 2,000 mu of ponds in Gaochun have embraced the crab-perch co-culture approach, boosting profits per mu by over 5,000 yuan. Gaochun led the way in China by introducing digital and smart aquaculture practices, with over 75 percent of its 224,900-mu crab ponds now utilizing smart farming systems.