On an ordinary August evening, seven fishing vessels leave Lusi harbour for nearby fishing grounds while articulated lorries cram the surrounding roads as they wait for the next catch to land.
The fishing grounds off the coast of Lusi, in Jiangsu province, eastern China, are a spawning ground for the large yellow croaker, a species of important commercial value. The stocks of yellow croaker were left exhausted by decades of overfishing and fishing grounds badly damaged, but in recent years their numbers have bounced back.
In late 2017, one man brought up a catch worth 400,000-500,000 yuan (US$60,000-$75,000) in a single haul, says local fisherman Pang Yuchang – such is the return of abundance.
“These days, lots of people come from Shanghai at the weekends to buy fresh fish,” he says. “You even have to book your hotel in advance.”
The resurgence of the fishing industry suggests that the management policies implemented by the Jiangsu provincial government have had some success. In 2017, it extended the two-month closed fishing season to three months to give juvenile yellow croaker more time to reach maturity.
The placement of artificial reefs – used since 2015 as part of a “marine ranching” approach (also known as sea farming or mariculture) – can also be credited with the species’ resurgence along the Chinese coastline.
The rise of marine ranching
Marine ranching was developed in the 1970s. It’s a type of aquaculture involving the cultivation of marine organisms for food and other products in open sea or in an enclosed section of ocean.
Early attempts involved sinking old boats and using manufactured reefs to change seabed currents and encourage algae to grow, which in turn attracted other marine species. Today the approach involves placing artificial reefs on the seabed, releasing juvenile fish, and encouraging the growth of kelp forests. There are more equipment-intensive approaches to marine ranching, which are used to raise high-value fish species, but these are less common in China.
Historically, China’s approach to the sustainable management of coastal fisheries has been to reduce capacity: cut the number of fishing boats, extend the closed season, and reduce fuel subsidies. But in the last few years, the pace has quickened on more production focused and technical approaches.
Profit to be made
China’s 200 existing marine ranches are also popular destinations for tourism and leisure fishing, attracting 16 million visitors per year. So while each ranch costs on average 5.6 billion yuan (US$820 million) to create, the industry can generate as much as 31.9 billion yuan (US$4.7 billion) in revenue each year, according to the national pilot plan.
The Ministry of Agriculture is planning to increase the number of national marine ranching pilot projects from 42 to 178, and the amount of sea area covered from 850 to 2,700 square kilometres, by 2025. To achieve this goal, 50 million cubic metres of artificial reefs will be created, generating 15 billion yuan (US$2.2 billion) a year in fishing and tourism revenues, according to “conservative estimates” from the Ministry of Agriculture.
The risks of overexpansion
But creating marine ranches is complicated and the risks of rapid overexpansion must be considered.
Dr Yang Hongsheng, deputy head of the Institute of Oceanology at the Chinese Academy of Sciences, told chinadialogue that problems can arise during the management, planning and construction of marine ranches. He says that the variety of marine environments along the north-south coastline makes the selection of locations a challenge. Examples of the environmental risks include damage to the seabed from marine infrastructure, disruption to the food chain, and pollution from intensive agriculture and tourism.
Ownership and management of the ranches is split between local government and aquaculture companies.
China’s marine ranches are currently concentrated in the Bohai and Yellow Sea and its surrounding area. There are only nine pilots in the South China Sea. There are none in the tropical regions.
China does not yet have any specific regulations on the construction of marine ranches. But according to guidelines from the United States’ Bureau of Safety and Environmental Enforcement, artificial reefs should not be created in a way that might damage natural habitats; and should not be placed on coral reefs or beds of aquatic grasses, microalgae or shellfish.
In China, locations should be chosen following a scientific survey of the seabed (under the purview of the Ministry of Agriculture and Rural Affairs), says Yang. They must also meet a minimum surface area – marine ranches of less than 10,000 hectares are of little environmental or economic benefit, he adds.
“The definition of a marine ranch used in China is too broad,” Yang told China Science Daily. “Placing artificial reefs, the release of juvenile fish and even the use of cages are all defined as marine ranching. There’s also confusion between coastal fish farming and marine ranching, leading to a proliferation of marine ranches.”
With 19.1 billion yuan of state investment planned, local governments and businesses are expected to be drawn to the sector – and possibly be willing to ignore expert advice for the sake of being awarded a national pilot project.
Marine ranches are relatively new in China. It is not yet known how these larger-scale human interventions will affect the marine environment. Deciding how to prevent and minimise these impacts is crucial. There is concern is that marine ranching is taking place without a full understanding of the impacts, says Xu Qiang, a professor at Hainan University and specialist on ranching in the South China Sea.
The majority of China’s marine ranches have been designed to increase the output of “economically-valuable” marine life. Disruption to marine ecosystems such as mangrove forests, kelp beds, and oyster and coral reefs are rarely taken into consideration, nor is the genetic diversity of wild fish populations.
Ranches designed solely to increase the population of a single species reduce the stability and sustainability of the ecosystem, says Yang. Meanwhile, the release of farmed juvenile fish affects the genetic structure and diversity of wild populations.
In some places, the release of juvenile fish, coupled with remediation and better protection, may be enough to restore ecosystems without the need for artificial reefs.
“If the environment is to be put first, the builders of marine ranches need to respect the oceans and nature,” says Xu. “The rapid transfer of marine environmental technologies and expertise will be crucial. Investment alone won’t ensure marine ranches are a success.”