Industrial interest in aquaculture has exploded in recent years, becoming widely adopted in America and Europe and providing a huge number of jobs and value to the economy. At the beginning of the 1980s less than 10 per cent of the fish used for food products came from aquaculture, but this figure has now risen to 50 per cent. Scotland’s foray into salmon aquaculture has led to the fish becoming the country’s largest food export, providing employment for upwards of 8,000 people in rural communities and creating produce with an annual retail value of £1 billion.
This is alongside a massive increase in demand for fresh fish from consumers, with a study by the UN Food and Agriculture Organisation arguing that sustainable aquaculture is the only means by which this demand can safely be met. Indeed, overfishing of natural populations leads to damaging reductions of fishing stock, which harms the balance of the local ecosystem and threatens knock-on effects all along the food chain. Is aquaculture sustainable enough to ameliorate these problems? What would a sustainable aquaculture look like?
Is Aquaculture Sustainable?
When practised in unsustainable ways, aquaculture can be just as damaging as traditional overfishing. Examples of issues include the increased removal from their natural habitats of certain fish species, in particular juveniles, which are essential for the future growth of marine populations. This is done when aquaculture businesses are first setting up, but can happen at the beginning of every growth cycle.
At the end of the growth cycle, when growth tanks are cleaned out, organic waste and toxic effluents can be released into the ocean, leading to problems such as harmful expansion of algae growth. What is more, the fish being farmed require food themselves. Fishmeal and less valuable fish are used to produce this feed, but in developing countries this often constitutes the main food source of the local people. This can lead to the displacement of entire communities.
It is important to note, however, that the aquaculture practised in most western countries, including the UK, is a highly regulated industry like any other and is subject to an array of environmental and trading laws. Does this guarantee sustainability, though?
What Would a Sustainable Aquaculture Look Like?
No particular species of fish is sustainable – sustainability depends on the operation of the farm, the type of aquaculture equipment used and the lifestyle habits and feeding of the species. Ideally, farmed fish should be herbivores capable of breeding in captivity. The plant-based feeds used should originate from sustainable agricultural operations. The use of wild-caught juveniles harms sustainability further.
Sustainable fish farms should seek to minimise negative environmental impacts of their operations by avoiding discharging effluents into the local area – instead opting for storage tanks and safe disposal. Any non-native species being farmed should be restricted to tanks based on land to minimise the risk of disease and cross-contamination of local wild populations. Excessive stocking densities in farming tanks should also be avoided to prevent disease outbreaks.
The local human population should also be protected from harm, such as the depletion of drinking water supplies and local fishing stocks. Fish farming businesses should seek to support and develop the long-term social and economic well-being of these communities. Taking such steps will ensure that the environment, local communities, natural fishing stocks and aquaculture businesses can all enjoy a profitable and mutually beneficial relationship together.