As health and fitness trends gain increasing importance in modern life, demand for high-protein foods has surged dramatically, and consumption of traditional meat has reached record highs. Per-capita consumption of seafood — an excellent source of quality protein — is set to continue rising. Yet rampant overfishing is hardly new news. Faced with escalating demand, farmed fish are shifting from a supporting role to center stage, bringing with them both new opportunities and a fresh set of problems. Can fish farming be a savior for both humanity and the environment?
Aquaculture as a Lifeline for Fisheries — Yet Bringing New Ecological Pressures
According to the Agricultural Outlook 2025–2034 report published jointly by the Organisation for Economic Co-operation and Development (OECD) and the Food and Agriculture Organization of the United Nations (FAO) in 2025, global consumption of aquatic animal food is projected to grow, with Asia accounting for 75% of that growth. Although the growth rate over the next 10 years is slower compared to the previous decade, it still stands at 11%; demand for seafood for food purposes is also expected to grow by 13%, with total projected demand reaching 192 million tonnes by 2034.
With demand skyrocketing, production must inevitably increase. However, a 2021 FAO report estimated that 37.7% of the world's fish stocks are already overexploited — being harvested faster than they can naturally reproduce — a problem that peaked in the 1990s. Countries subsequently began seeking other effective aquatic food sources, providing substantial subsidies and training. This spurred decades of rapid development in aquaculture, which in 2022 officially surpassed wild-catch fisheries in supply chain share, accounting for 51% of the world's total supply. By 2024, output was more than four times what it was 30 years ago.
Yet while aquaculture has bought time for increasingly depleted ocean resources and provided an alternative supply, traditional farming methods can damage surrounding aquatic environments. When not handled properly, nutrients discharged from fish farms — such as feed residue and excrement — can affect the survival of native flora and fauna, potentially causing algal blooms, oxygen depletion, and fish die-offs. Additionally, choosing the right species and designing suitable farming environments are critical challenges, all of which are closely tied to building a sustainable food supply.
From Fish Meal Feed to Eutrophication Wastewater — How Fish Farms Impact Marine Ecosystems
Setting aside species selection and environment design for a moment, one of the greatest problems in modern aquaculture is that the most commercially valuable species — such as salmon, trout, and shrimp — are carnivorous. Raising them requires feeding them wild-caught fish (typically anchovies, sardines, and the like), a practice known as "fed aquaculture." Many of the fish used for this purpose come from West Africa, where they could otherwise serve as food for local communities; instead, they are sold to fishmeal factories and processed for export to Europe and North America. This demand not only harms the livelihoods of some of the world's poorest people, but also disrupts complex marine food webs.
The FAO report notes that prior to 2024, of the approximately 91 million tonnes of wild-caught fish harvested each year, around 17 million tonnes went toward aquaculture. Producing just 1 kg of salmon can require as many as 6.24 kg of wild-caught fish. This farming model does nothing to reduce the pressure on wild fish populations.
In recent years, the amount of wild-caught fish needed to produce one unit of farmed fish has fallen from 1.9 — recorded during the initial boom of aquaculture in 1997 — to 0.28 in 2017. However, Jennifer Jacquet, a professor of Atmospheric and Earth Sciences at the University of Miami, explains that any fishmeal removed from fish feed must still be replaced with land-based alternatives, a situation analogous to clearing forests to raise land animals.
On another front, poorly sited fish farms carry significant pollution risks. In recent years, negative impacts from such farms have been documented in parts of Norway and Scotland. Norway, the world's largest producer of farmed salmon, has been particularly hard hit: the Sognefjord — its longest coastline fjord — has seen oxygen consumption rise by roughly two-thirds due to excess nutrient runoff, with rising water temperatures caused by climate change contributing an additional one-third increase in oxygen consumption. The fjord's ecosystem is under serious threat as a result.
A research report from the Sunstone Institute found that Norway's aquaculture industry discharged 75,000 tonnes of nitrogen, 13,000 tonnes of phosphorus, and 360,000 tonnes of organic carbon in 2025. These nutrients are equivalent to the nitrogen found in the untreated sewage of 17.2 million people, the phosphorus from 20 million people's untreated sewage, and the organic carbon from 30 million people's untreated sewage. For a small country with a population of only 5.5 million, the pollution load from just these three nutrients alone is already 3 to 5 times its own population.
Meanwhile, as consumer demand for seafood diversifies, the market for specialty seafood such as octopus has been growing year by year, sparking discussions about octopus farming. However, farming octopus may overlook the habitat and hunting environment needs of wild octopus, as well as potential animal welfare concerns arising from keeping what are considered highly intelligent animals in captivity.
Making Aquaculture a Nature-Based Solution — Scaling Up Still Requires Policy and Funding
Of course, with careful planning and the right choice of farming species, fish farms can still have a positive impact on the environment. The oyster farming initiative in Fiji is a prime example.
Most aquaculture operations affect the environment through feed, antibiotics, and wastewater discharge. Oyster farming is the polar opposite: it requires no feed, no antibiotics, and no pesticides — only three things: clean water, a suitable temperature range, and naturally occurring microalgae and plankton in the water to feed on. Oysters also offer many environmental benefits, including filtering and purifying water, sequestering carbon within their shells, and forming reef structures that provide shelter for other marine life. Compared to land-based protein sources, producing one kilogram of protein through oyster farming also carries a lower carbon footprint.
In Fiji, a Pacific Island nation, the AQUA-Pearl project — supported by the International Institute for Sustainable Development (IISD), the Wildlife Conservation Society (WCS), the Pacific Community (SPC), and local pearl industry partners — works together with local fishing communities, regional governments, and the private sector. Its aim is to strengthen self-sufficiency in the face of climate change through natural farming methods and sustainable aquaculture, while protecting biodiversity and addressing local poverty. The pilot project selected for this purpose is oyster farming.
As a nature-based solution, the project recognizes that oysters can improve water quality, and that the farming lines can attract marine life and promote biodiversity. WCS Fiji will continue to monitor fish biomass and coral health near the oyster farming lines, while collaborating with communities to restore upstream watershed environments, improve water quality over the long term, and maintain thriving ecosystems through watershed planning and management — all while ensuring the food safety of oysters as an alternative protein source.
AQUA-Pearl is itself part of "Nature-based Climate Solutions in Aquaculture Food Systems in Asia-Pacific" (AQUADAPT), co-funded by the International Development Research Centre (IDRC) and the Government of Canada. Since its launch in 2023, AQUADAPT has implemented multiple experimental aquaculture projects across Southeast Asia and the Pacific region, developing more sustainable approaches to aquatic animal farming.
Nevertheless, IISD also emphasizes that scaling up this type of farming model requires innovation and investment. The AQUA-Pearl project spans a wide range of intersecting issues — including biodiversity, climate change adaptation, gender equality, food and livelihood security, and economic development — and no single actor can succeed alone. If humanity is serious about achieving a more sustainable aquaculture environment, coordination across all stakeholders remains essential.
The transition from wild-catch fisheries to aquaculture should have been a milestone on humanity's path toward sustainability. But if we continue to operate under the traditional mindset of "taking from nature," aquaculture risks repeating the same mistakes as land-based livestock farming — destroying forests and ecosystems in the process. Fiji's oyster farming project demonstrates an alternative path of "coexisting with nature," proving that aquaculture can transform from an ecological disruptor into an ecological restorer. The second half of aquaculture's story is an endurance race — one of policy foresight and financial commitment. Humanity must accelerate this transformation; only then can aquaculture truly become a solution that balances human food security with ocean sustainability.
References
- OECD, OECD-FAO Agricultural Outlook 2025-2034
- IISD, What One Pearl Oyster Farm in Fiji Can Teach Us About Climate Resilience
- IISD, AQUA-Pearl
- IDRC-CRDI, Nature-based Climate Solutions in Aquaculture Food Systems in Asia-Pacific (AQUADAPT)
- Vox, The race to stop octopus farming before it starts
- Global Seafood Alliance, Octopus aquaculture – unethical or the next Big Thing?
- DTU, Farmed fish on the menu—how we ensure sustainable seafood
- Eurasia Review, The Environmental And Social Impacts Of Fish Farming And Industrial Aquaculture – Analysis
- Business First, How oysters are farmed, and why they might be the most sustainable seafood you can eat
- The Guardian, Norwegian fish farms polluting fjords with waste likened to 'raw sewage of millions of people'
- The Guardian, Fish farms and pollution in Scotland
※ This article is reproduced from the Delta Electronics Foundation's Low Carbon Life Blog: 〈Can Aquaculture Relieve Pressure on Wild Fish Populations? Ecological Costs and the Hope for Transformation〉, co-produced with BlueTrend.
