- Acoustic barriers replace nets in yellow croaker farming
- Zhejiang is betting on smart marine agriculture
Chinese researchers and fishery operators have deployed what they claimed as the world’s first “net-free sonic marine ranch,” using underwater acoustic barriers to contain tens of thousands of fish without physical cages off the coast of eastern Zhejiang province.
Ten bright orange floating buoys were recently installed near Luxi Island in Wenzhou’s Dongtou district, creating an invisible sound-based enclosure across roughly 160 mu, or about 26 acres, of sea area for 30,000 large yellow croakers, according to local media reports on May 22.
The system was jointly developed over six years by Wenzhou-based Huangyudao Marine Fishery Group Co., Ltd. and the Institute of Acoustics, Chinese Academy of Sciences, with total investment exceeding 20 million yuan ($2.94 million).
The technology works by exploiting the sensitivity of large yellow croakers to specific sound frequencies. Floating sonic devices emit acoustic signals that fish detect from dozens of meters away, prompting them to turn back before crossing the boundary.
Hemming in yellow croakers only
Unlike traditional net pens, the system does not physically restrict the fish or interfere with growth, developers said.
The acoustic barrier mainly affects croaker species, while other fish and shrimp can move freely through the area, allowing a more natural marine ecosystem to form.
Stocking density has been reduced to about 0.2 fish per cubic meter, equivalent to roughly two fish in every 10 cubic meters of water, compared with 12 to 14 fish per cubic meter in conventional net-cage farming.
The lower density is aimed less at maximizing output than at producing near-wild quality fish with significantly larger living space.
“Yellow croakers raised this way develop slender bodies, thicker backs and firmer, more delicate meat that closely resembles wild fish,” said Shi Fuming, chairman of Huangyudao Marine Fishery Group.
Operators can remotely monitor buoy conditions, water quality and fish activity in real time through mobile devices from as far as 25 kilometers away.
The “high-efficiency sonic net-free enclosure technology for large yellow croaker farming” was included in a 2025 agricultural technology cultivation list issued by China’s Ministry of Agriculture and Rural Affairs.
Large yellow croaker is one of China’s four major commercial seafood species — the other three being hairtail, small yellow croaker and cuttlefish — and remains especially popular in Zhejiang cuisine.
First provincial-level policy
Wenzhou produced 22,000 tons of large yellow croaker in 2025, ranking first in Zhejiang province by both output and industry value, which exceeded 1.9 billion yuan.
The province’s total yellow croaker industry was valued at about 12 billion yuan in 2025, accounting for more than 10% of Zhejiang’s marine fishery output value.
Zhejiang has also rolled out China’s first province-level support policy dedicated to the yellow croaker supply chain, targeting output of 80,000 tons and industry value of 24 billion yuan by 2030, double the 2025 levels.
