China’s Deep Blue 1 offshore fish farm, which floats in the middle of the Yellow Sea , can hold up to 300,000 Atlantic salmon. A support ship houses the farm’s workers and is used to process the fish ready for market. (Illustration: Ricardo Macía Lalinde / China Dialogue Ocean)

CN - China’s offshore fish farming grows amid environmental concerns

The country is expanding its aquaculture in deeper waters as a more sustainable solution, but the environmental impacts are concerning scientists

China's offshore aquaculture unit, Deep Blue Number-1The submersible design allows China to produce Atlantic salmon in warm water

Over 100 nautical miles off the coast of China in the Yellow Sea, a huge octagonal structure rests in the water. This is no new-look oil rig. It’s Deep Blue 1, China’s first offshore aquaculture base for farming salmon.

At its corners, the yellow octagon has steel columns extending 30 metres into the water. Enclosed by black mesh, they form a cage with a volume of 50,000 cubic metres, and room for 300,000 salmon. The yield is nearly 1,500 tonnes of fish per year.

Deep Blue 1 is merely a taster for future developments in Chinese offshore aquaculture. The Guoxin 1 aquaculture vessel is designed to produce 3,700 tonnes of fish annually. The ship cruises between the Yellow and South China seas, avoiding typhoons and “red tide” algal blooms, and keeping to waters in the 22C to 26C range suitable for the fish. This factory-type aquaculture vessel contains 15 tanks with a total volume of nearly 90,000 cubic metres. Stock density is four to six times that of traditional net pens.

Illustration of Guoxin 1
The Guoxin 1 is a floating fish farm the size of an aircraft carrier. It has 15 fish tanks in its hold and aims to produce 3,700 tonnes of fish annually. In its first trial phase, the vessel produced more than 1,200 tonnes of large yellow croaker. (Illustration: Ricardo Macía Lalinde / China Dialogue Ocean

Following successful trials of the initial project, upgraded versions of the vessel, in the form of Guoxin 2 and Guoxin 3 are due for delivery in March 2024.

China is developing various forms of offshore aquaculture. According to data released in June by the Ministry of Agriculture and Rural Affairs, coastal provinces have already brought into use more than 20,000 “gravity cages” – each formed of a net and a floating collar – 40 steel-framed sea cages, like Deep Blue 1, and four aquaculture vessels. China’s offshore aquaculture currently spans nearly 44 million cubic metres of water, yielding almost 400,000 tonnes of seafood – more than 20% of national mariculture, or marine farming, output.

The ministry says: “With another five years, we aim to increase the scale of offshore aquaculture nationally by 16 million cubic metres, to more than 60 million cubic metres, and achieve annual offshore aquaculture output of more than 600,000 tonnes – more than 25% of sea-farmed fish products.”

Offshore aquaculture: known for its large scale

In the policy paper “The opinions on accelerating the development of offshore aquaculture”, jointly released in June by the Ministry of Agriculture and Rural Affairs and eight other Chinese government departments, offshore aquaculture is defined in a way that stresses the use of large-scale installations such as gravity cages, steel-framed cages, aquaculture platforms and aquaculture vessels, supported with mechanisation, automation and smart technology. They should all enable aquaculture to be undertaken at scale and efficiently in deep offshore waters, the paper states.

illustration of the Blue Diamond 1
Another of China’s large-scale offshore fish farms is the Blue Diamond 1. Positioned 10km off the coast of Shandong province’s Laizhou Bay, this fenced sea-cage boasts a volume of 160,000 cubic metres, and is currently farming spotted knifejaw (Oplegnathus punctatus), a high-value sushi-grade species. The facility was built to withstand typhoon-strength winds and nine-metre waves. (Illustration: Ricardo Macía Lalinde / China Dialogue Ocean)

Offshore aquaculture operations are often large-scale in order to achieve cost reductions. This is necessary because they are situated far from land supplies, meaning it costs a lot to deliver feed, supply energy and transport catches. Increases in production capacity and centralising of operations are also needed to reduce costs.

Lin Ming, of the Chinese Academy of Engineering (CAE), explains in a paper that the greater the volume of a sea cage, the lower its per-unit operating costs and the higher its cost-effectiveness. Larger volumes of water also create conditions more like those in which wild fish grow, and generate a higher-quality yield. Cui Mingchao, an associate researcher at China’s Fishery Machinery and Instrument Research Institute (FMIRI), sums up the thinking behind the Guoxin 1 design as “big in capacity, with costs spread out”.

Similarly, experts advise selecting large fish species for farming. Guan Changtao points out that the scale of offshore aquaculture farms means they have high per-cage yields, with centralised harvesting and delivery to market. So, it is necessary to ensure that there is a market for the fully grown fish. Guan wants the industry to reach a consensus on jointly developing a setup based around five staple species: large yellow croaker, golden pompano, grouper, sea bass and flounder, along with fish such as cobia, brown croaker, seabream, and amberjack.

The Guoxin 1 is a floating fish farm the size of an aircraft carrier. It has 15 fish tanks in its hold and aims to produce 3,700 tonnes of fish annually. In its first trial phase, the vessel produced more than 1,200 tonnes of large yellow croaker.

It is difficult to gauge market response as offshore fish farming is still being trialled. To date, only limited quantities of fish have been harvested and brought into the distribution chain. A senior figure in the fisheries media, who wishes to remain anonymous, tells China Dialogue that compared to catches of wild fish, yields from offshore aquaculture are currently more stable, and the model is more sustainable. Moreover, the quality of fish farmed far offshore is better than that of fish from near-shore operations, due to an obvious difference in water quality.

Offshore aquaculture products largely sit in the upper-middle price range. In the case of salmon, for example, the domestically produced offshore aquaculture product beats imports in terms of price and freshness.


Read also

Chinese aquaculture vessel Guoxin 1 trumpets first yellow croaker harvest, Undercurrent News, October 5, 2022


Zhao Xiaoxia, deputy chief engineer of Guoxin 1, said in an interview that the vessel’s large yellow croaker currently sell for around twice the price of fish farmed inshore. Being quasi-wild is a distinct quality advantage, too, given that a wild individual could easily be sold for more than 1,000 yuan. As the industry develops and upgrades, it can be expected that there will more affordable, good-quality fish on the market, he added.

An urgent need for sustainable blue transformation

Rich in micronutrients and high-quality protein, aquatic products are becoming increasingly popular as a sustainable and healthy dietary choice. A report by the UN Food and Agriculture Organization (FAO) on the state of world fisheries indicates that global seafood consumption is now more than five times what it was 60 years ago, and as world population and income rise, the consumption of seafood will continue to grow.

Overfishing has long been a source of concern, so the spread of sustainable fisheries in recent years is a positive development. However, the FAO report states that the proportion of fish stocks at biologically sustainable levels decreased from 90% in 1974 to 64.6% in 2019, meaning that overfishing persists. Aside from the impact on biodiversity and ecosystems, this threatens fishery yields.

Overreliance on near-shore aquaculture is also problematic. China is the world’s largest producer and processor of aquatic products, with fish farms dotted all along its coastline. Previously dominant and cruder forms of fish farming have left a legacy of environmental pollution and ecological problems in the country’s near-shore waters. Direct discharge of fish farm effluents, accumulations of faecal matter and the uncontrolled use of fishery drugs – in particular, antibiotics – have all contributed to the degradation of coastal mangroves and the increasing occurrence of red tides. Research has shown that the increase in red tides correlates with the increase in shrimp farming.

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