Sink or Swim

But after measures to protect and restore large yellow croaker resources, in particular artificial breeding technologies, large yellow croaker aquaculture has become an important industry. The output of farmed large yellow croaker has increased, reducing the pressure on wild resources.　

According to the China Fishery Statistical Yearbook, the national aquaculture production of large yellow croaker exceeded 150,000 tons in 2016, 200,000 tons in 2019 and 250,000 tons in 2020.　

In the past five years, developing deep-sea aquaculture – fish farming that takes place in offshore areas further away from coastlines – has received more attention from authorities, both local and national.　

These efforts are targeting the quality and yield of species like the yellow croaker, with facilities to breed them constructed in sea areas off the coasts of eastern and southern Chinese provinces like Zhejiang, Fujian and Guangdong.　

Professor Wang Zhiyong at the Fisheries College of Jimei University, an expert in aquatic genetic breeding and aquatic biotechnology, told NewsChina that the Zhenyu 1 platform, the first deep-sea truss-type large cage in Lianjiang County, Fujian Province, started operating in 2019.　

In 2022, China’s pioneering aquaculture vessel the Guoxin 1 started production, also targeting the yellow croaker, and it marked the beginning of an upgraded new deep sea aquaculture model to culture this species.

Breeding high-value fish varieties such as salmon is hard. The Deep Blue Series (Deep Blue 1 and Deep Blue 2), and Marine Granary Series (Marine Granary 1 and Marine Granary 2) in China’s Yellow Sea area are deep-sea smart aquaculture cages for salmon. Cultivating salmon fry is still a problem, so these salmon breeding facilities still rely on imported fry.　

For now, China uses a “land-sea relay” model for salmon farming. Fish fry are bred and grow in freshwater, which provides appropriate water quality, temperature and food sources. When they reach a suitable size, they are acclimatized to saltwater, and transferred to a seawater environment which offers more natural food resources and larger living spaces. “It takes about three years for a salmon fry to grow to a marketable size. However, for every extra day of cultivation at sea, the risks increase exponentially,” Guo Genxi, chief scientist of fishery equipment engineering technology at the Chinese Academy of Fishery Sciences, told NewsChina. These risks to fish farmers and their investors include losing the fish to poor weather and disease.　

As a result, some experts told NewsChina that instead of culturing rare, special and expensive fish in a deep-sea environment, the emphasis should be on common indigenous fish species with large potential markets.　

China’s deep-sea aquaculture is still in its infancy, and has not developed a dominant species as Norway did. Marine expert Hu Zhenyu, deputy director of the Qianhai Branch of the China Development Institute (Shenzhen), told NewsChina that the industry in China does not yet have a proper development plan.　

“No one is really sure which fish species should be selected, who the target customers are, or how the market is likely to accept certain species,” Hu told NewsChina in March 2024.

Addressing the present development stage and obstacles to deep-sea aquaculture, Professor Wang said facilities need to be constructed to better withstand typhoons and other extreme conditions. Issues involving aquaculture techniques need to be improved – these include how to clean large deep-water cages and how to feed the fish in deep-sea environmental conditions. The feed may need adjusting since the salinity of water differs between inshore and offshore areas, thus feeds with different formulas may be required.　

From the perspective of breeding, cultivating a variety of large yellow croaker that can adapt to a deep-water environment with strong currents is especially challenging. “This is because large yellow croakers can’t resist currents well, their scales are easily shed in water with strong currents. If you’ve ever handled large yellow croakers, you’d know how easily the scales can be scraped off,” Wang said.　

“The current causes them to jostle each other or scrape the net, and their scales fall off. Their skin gets damaged, and then bacteria can infect them, causing disease. So it’s necessary to enhance their adaptability to strong currents,” he added.　

Other factors including complex water flows and high pressure in the deep sea causes large yellow croakers to use too much energy, requiring a higher food intake, and this increases costs and production time, characteristics that Wang aims to fix through breeding stronger individuals that require less fish feed and less fish meal.　

“If you want to achieve development and obtain aquaculture benefits in deep-sea and offshore areas, you have to improve the germplasm (genetic resources) and cultivate varieties adapted to deep-sea and offshore aquaculture. It’s the only way to improve the outcome,” Wang said.　

Professor Ke Caihuan from the Department of Oceanography and State Key Laboratory of Marine Environmental Science at Xiamen University also emphasized the importance of deep-sea current-resistance. Ke has made some progress in the field of abalone artificial breeding, spending 11 years developing a new national certified variety called “Lüpan abalone” which has higher heat resistance than previously cultured varieties and a much higher growth rate.　

“Through enhancing the current resistance ability or through proper design of the cages, this variety can become suitable for deep-sea aquaculture and it has enormous market potential,” Ke told NewsChina.

Many varieties of grouper are suitable for deep-sea aquaculture. They have high economic value, tender meat and provide rich nutrition.　

The first hybrid grouper to be approved by Chinese agriculture authorities in 2017 was the Hulong hybrid grouper, or tiger dragon grouper. It was a collaboration of more than 10 years between a research center, two universities and an aquaculture company, Professor Luo said.　

Luo said this variety combines the excellent growth characteristics of its parent species, with a fast growth rate as the trait of its female parent, and a large body size as the trait of its male parent. The Hulong hybrid grouper is widely cultured off the southern Chinese coast, and accounts for around 70 percent of the grouper market in China. The total annual production of groupers in China is about 250,000 tons, with the Hulong hybrid grouper yields of 200,000 tons, ranking third in total output after the golden pompano, the large yellow croaker.　

The Hulong hybrid grouper’s output and stable price creates a stable market. “The farm gate price for this variety hovers around 60 yuan (US$8) per kilogram, allowing fish farmers to make around 20 percent profit, and it’s popular with consumers across the country,” Luo said.　

Another high-value grouper variety, the leopard coral grouper, is favored by fish culture farms due to its high market price in parts of China. This variety is mainly distributed in tropical and subtropical waters of the Indo-Pacific region and they like to live in coral reef areas. Cultivating this variety is more difficult and costs more to farm than a hybrid grouper, with stricter requirements for water temperature and quality. The farm gate price for this variety is around 300 yuan (US$41) per kilogram so fish farmers get more profits, Luo said. But so far it is only cultivated around Hainan Province, with an annual yield of 20,000 tons.　

Luo cautioned that while deep-sea aquaculture for grouper species is viable, due to its relatively weak resistance to wind and waves, it is not suited to deep-sea and offshore cages. “But it can be a suitable breed for aquaculture vessels operating in deep-sea areas,” he said.　

Research is ongoing in Fujian and Guangdong on cultivating two new hybrid grouper varieties, the Yunlong hybrid grouper and Qinglong hybrid grouper. Luo said both could potentially be cultivated in deep-sea aquaculture vessels, which contain breeding tanks and are considered safer than cages.　

An example of recent success in deep-sea aquaculture is the golden pompano, which is gaining popularity, Luo said. It has strong swimming ability, allowing it to better adapt to powerful deep-sea currents, and is well-suited for freezing and processing. It is one of the main deep-sea cage culture varieties in southern coastal regions of China. In 2023, the annual output of golden pompano was 292,300 tons, exceeding that of the large yellow croaker and ranking first among marine fish culture varieties in China.　

The golden pompano has a relatively fast growth rate in deep-sea aquaculture. Under appropriate breeding conditions, it can reach marketable size in a relatively short time, ranging from six months to up to one year, which helps improve culture efficiency and economic benefits.　

Yet as more investors were attracted, fish farmers shifted to culturing golden pompano without securing sufficient markets for the species, leading to oversupply in 2024. Luo said that as there is not yet a stable large market and acceptance for domestic consumers, there were significant price fluctuations, and some aquaculture companies were overextended and went bust.　

For years, Luo and his team have been researching and cultivating deep-sea aquaculture species that fit a mid-tier market price. The greater amberjack, also known as rock salmon, comes from the same family as the golden pompano. According to Luo, it has a substantial mouthfeel, yet remains tender and easy to chew. It is suitable for sashimi and can be grilled, baked or fried. “This variety, already popular in Japan for sashimi, isn’t really known in China,” Luo said, who believes cultivation should be encouraged for domestic consumers. “We need to ensure a good living environment, quality control, refrigerated transportation and make sure that chefs know how to cook it, so we’ll be fully prepared to embrace this emerging variety.”

According to Wang Zhiyong, continued consumption of small fish as a crucial protein source in aquaculture feed is destructive to sustainable marine ecology, thus most countries have started to manage fish resources, so aquaculture companies are seeking alternative protein sources.　

“For instance, we can use alternative proteins and oils derived from insects, algae and an array of other more sustainable substitute sources to formulate feed. By adopting such measures, we can alleviate the pressure on wild fishery resources,” Professor Cao Ling from Xiamen University’s State Key Laboratory of Marine Environmental Science told NewsChina.　

In the fish breeding sector, some domestic experts and companies are already working on artificial breeding for varieties with higher feed conversion efficiency.　

Due to its delicious meat, the Napoleon wrasse has been heavily fished and illegally caught, especially in Asia. It is listed as endangered by the International Union for Conservation of Nature (IUCN). The artificial breeding of the species is a significant yet challenging endeavor due to its low fertility rate and the time it takes to reach sexual maturity, up to seven years. Luo said attempts to artificially breed the Napoleon wrasse started in 2006 in China, but there was only initial success in 2014. “However, the successfully bred fish stocks were lost due to typhoons, while the lack of sustained funding to purchase parent stocks of Napoleon wrasse hindered the attempts to breed it,” Luo said, adding there is still a long way to go to achieve commercial artificial breeding of this endangered fish for deep-sea aquaculture.　

“To attain sustainable marine resource utilization, we should strengthen the synergy between deep-sea aquaculture and capture fisheries in the long term,” Cao Ling said. “For example, some species that have been overfished may now be vulnerable or endangered. Through deep-sea aquaculture, we can help rebuild wild populations through artificial breeding, stock enhancement and release activities.” She noted that if developed properly, deep-sea aquaculture could provide alternatives to traditional captive fisheries and effectively way to supplement wild resources.