Aquaculture is often championed as the sustainable solution to the overfishing and overexploitation of the oceans, including the South China Sea (SCS). In theory, aquaculture could safeguard food security and promote economic development while reducing marine catch intensity and contribute to preventing of fishing disputes. A recent study finds that marine aquaculture presents an opportunity for increasing seafood production in the face of growing demand for marine protein and limited scope for expanding wild catch production — the current total landings of all wild-capture fisheries could be produced using less than 0.015 percent of the ocean area of the planet.
In Asia, in recognition of the potential effects of diminishing marine-capture fisheries, many countries have turned to aquaculture as a means to reduce overfishing while increasing fish supply, providing employment, and generating foreign income. Currently, Asian countries account for the nearly 90 percent of global aquaculture production. In 2016, China produced 51.4 million tonnes of farmed fish, accounting for more than 60 percent of global fish production from aquaculture. Vietnam, Indonesia, and the Philippines are major farmed-fish producers as well. Owing to growing concerns over the safety of the farmed fishery products and environmental impacts of the intensive freshwater and coastal aquaculture, China has made expanding mariculture a priority of the government’s 13th Five-Year Fisheries Development Plan.
In the context of the SCS disputes, immediately after the reconciliation between China and Philippines under the Duterte administration, the two countries began to embark on aquaculture and other joint projects in the SCS. In November 2016, the assistant director of China’s Department of Fisheries, Liu Xinzhong visited the fishermen of Zambales in the Philippines, and offered aquaculture training to the Filipino fishermen in China. Shortly after, in January 2017, China hosted a 17-person delegation of Filipino fishermen, officials, and seafood executives, who received training in deep-sea cage-fish farming, feed and nutrition, and seedling preparation. Also in January 2017, the China-based Fangyuan Shipbuilding Co made plans to invest 3 billion renminbi ($437 million) in an aquaculture and processing project in the Philippines. Similarly, China offered to cooperate with other SCS countries including Malaysia, Vietnam, and Brunei to develop aquaculture.
Yet in spite of all the optimism and ongoing aquaculture development projects led by China, aquaculture in its current form might not be a promising solution to the overfishing problem and worsening fishery conflicts in the SCS.
First and foremost, the impact of aquaculture on wild fish stocks remains contentious. While higher aquaculture production might relieve pressure on wild fish stocks, the sector’s overdependence on fishmeal and trash fish for feed opens it to ecological risks. With aquaculture providing more than half of all fish consumed globally, another major transition is also underway: Aquaculture’s share of global fishmeal and fish oil consumption has expanded phenomenally over the past decades. Certainly, for the aquaculture sector as a whole, the ratio of wild fish-in to farmed fish-out (FIFO) based on feed ingredients has fallen well below one. However, aquaculture’s share of global fishmeal and fish oil consumption still increased substantially due to greater amounts of fishmeal fed to carnivorous species, and high levels of fish oil used to provide long-chain omega-3 oils in farmed fish. As small-scale nonindustrial aquaculture is being increasingly replaced by large-scale industrialized aquaculture, the industry’s demand for fishmeal and fish oil is poised to grow. Due to the high levels of fish meal and fish oil in aquaculture feeds, many species require more fish biomass as inputs than the farmed fish produced. As a result, there has been a gradual shift in the wild fish capture from large and value carnivorous species, to smaller, less valuable species that feed at lower trophic levels.
Given the finite nature of global marine resources, aquaculture’s increasing share of fishmeal and fish oil consumption gives rise to many problems. Among the problems, a key issue is that fishmeal and fish oil demand by aquaculture is less responsive to prices than the demand by the livestock industry due to the challenges in finding suitable substitutes. Therefore, growth in the aquaculture sector is likely to increase prices for the relatively fixed level of fishmeal and fish oil production. Higher commodity prices can create incentives for overfishing in poorly regulated fishing regions (such as the South China Sea) and economically marginal fisheries. In this sense, unless appropriate substitutes are found, aquaculture stops being a solution to overfishing and starts contributing to it, turning it into a risk for natural marine ecosystems.
Being the leading farmed-fish producer in the world, the development of China’s aquaculture sector offers striking evidence that aquaculture in its current form has not only failed to restore fish stocks domestically but also emerged as contributor to diminishing wild fish stocks worldwide, including the SCS. Ever since the 1980s, rapid depletion of fish stocks in its coastal and inshore waters has led China to promote inland and marine fish farming. Aquaculture now accounts for roughly three-quarters of China’s fish supplies. With scarce land, water, and coastal zone resources, China’s aquaculture systems are intensifying as producers seek higher returns. Intensification is reflected in higher stocking densities, more commercial feeds, and more frequent water exchange and aeration. Consequently, China has become the biggest consumer of fishmeal and trash fish.
According to a report published by Greenpeace in July 2017, 76 percent of China’s aquaculture species require trash fish as feed, and in 2014, aquaculture demanded at least 7.17 million tonnes of China domestic marine fishery resources, accounting for over 55 percent of the country’s total marine catch production. In natural systems, forage fish play an important role in converting plankton into food for higher trophic-level species including humans, larger fish, marine mammals, and seabirds. Overexploitation of forage fisheries can lead to local stress on these higher trophic species. Consequently, harvesting juveniles and the trash fish perhaps poses a bigger threat to marine ecosystem. Apart from extracting trash fish and fishmeal from its own waters and recycling fish-processing wastes as feeds, China, as the world’s largest importer of fishmeal, imports about one-third of the global fishmeal trade in any given year. Hence, it is not surprising that wild fish stocks failed to recover in Chinese waters despite the massive expansion of China’s aquaculture sector.
Second, the negative impacts of aquaculture on wild catch go beyond the use of wild fish to feed farmed fish, thus further straining fisheries resources. It also indirectly diminishes wild fisheries through habitat modification, wild seedstock collection, food web-interaction, nutrient pollution, and the introduction of exotic species and pathogens that harm wild fish population. As small-scale traditional aquaculture is replaced by large-scale industrialized aquaculture, the ecological risks of intensive and semi-intensive aquaculture can be quite severe. Parasites such as sea lice endanger farmed and wild species. Farm effluent also creates significant amounts of pollution. To make the matter worse, given the fact that millions of tonnes of fishmeal are used in fish farms annually and much of it sinking uneaten to the ocean floor, genes for antibiotic resistance are getting into ocean sediments through fishmeal, contributing to food-borne illnesses worldwide.
Third, even aquaculture’s contribution to food security needs to be revisited. From 1950 to 2010, 27 percent of commercial marine landings were diverted to uses other than direct human consumption. Serious doubts regarding food security emerged as 90 percent of diverted fish were classified as food-grade or prime food-grade. Out of the grand total, 18 million tons of fish were used specifically in the production of fishmeal and fish oil, which are commonly fed to aquaculture and livestock species. It was also discovered that there is an increase in the variety of fish being used for nondirect human consumption. This trend is mostly fueled by the growth of fed aquaculture in China and Southeast Asian countries and the depletion of overfished stocks of former target species.
While fishery products are vital sources of micronutrients and are often found in highly bioavailable forms, farmed fish may have lower nutritional value. Fish contains lipids, micronutrients (fatty acid and vitamins A, B, and D) and minerals (calcium, phosphorus, iodine, zinc, iron, and selenium), crucial for combating malnutrition in China and Southeast Asian countries. Aquaculture species that are most affordable, such as carp, are often not as rich in omega-3 fatty acids as the wild species of sardines and mackerels, which are accessible to impoverished communities. Soybeans, distiller’s dried grains with solubles (DDGS), and other plant-based feeds are increasingly used as alternatives to fishmeal. One potential consequence is the further alteration of nutritional composition of farmed fish. Aquaculture generally focuses on fewer species than those caught from the wild. A global fish supply dominated by aquaculture, as it is currently practiced, would reduce the diversity and nutritional value of many diets, thus undermining nutritional security.
The demand for fishery products from the SCS region is skyrocketing, and will continue to rise in the future. Given the status of fish stocks, the only way to meet this rising demand will be through aquaculture. While aquaculture will remain a key part of the solution to the mounting fishery challenges in the SCS, serious effort is needed to reduce the impacts of the region’s aquaculture and use of aqua feed on wild fisheries. Considering the fact that aquaculture in the South China Sea region is becoming increasingly intensified, sustainable fish farming in other regions such as United States, Africa, and Latin America, should be promoted to increase the global fish supply.
Zhang Hongzhou is Research Fellow at the China Program, S. Rajaratnam School of International Studies, Nanyang Technological University, Singapore.