Just as agriculture is often criticized for use of pesticides, genetic modification, and synthetic fertilizer, so too is fish farming, or aquaculture, under attack for its own controversial practices. In an age where food production strives to be environmentally sustainable, too often do farms jeopardize the state of local ecosystems with their interference.
The problems with fish farms are manyfold, and fixing them will likely take an industry-wide effort that may be difficult to adopt. Still, the opportunity to prevent further damage done to the environment justifies most counteractive measures.
While aquaculture is promoted for, among other things, its ability to prevent overfishing in the wild, some fisheries have actually contributed to this issue by using live game from the sea to feed farm-grown fish. This has led to problems not only for local fish populations, but for coastal towns that often rely on said fish for their primary source of food. Additionally, this practice raises questions on food security, particularly when disease can spread quickly amongst stock fish.
That said, overfishing is just a single facet of the problem. There is also a prolific debate over the best way to contain fish, with the most common and perhaps the most disruptive method known as mariculture, when stock is raised in penned-off sections of the ocean. Mariculture is problematic because of the waste introduced into the environment as well as the disruption of ecosystems to make room for enclosures. Non-native fish and diseases can breach containment and cause havoc in an environment that is not equipped to handle them. Even a few specimens of an invasive species can cause an irreversible problem, as seen with the lionfish outbreak in the Atlantic ocean.
Even if diseases are treated and only native fish are used, the waste produced by the masses of fish kept on farms is destructive enough on its own. This can lead to algal bloom, which can lead to widespread loss of marine life if left unchecked.
The situation seems pretty grim, especially with farms disrupting a multitude of ecosystems, lifestyles, and aquatic terrain. Yet, sustainable practices do exist, and through scientific advancement, it may be possible to minimize the environmental footprint left by aquaculture.
Plant-based feeds, particularly sourced from sustainable agriculture, are a good place to start. Fish meal and fish oil-based diets for stock fish should be eliminated, not only to prevent overfishing, but to reduce the food’s negative effect on fish protein.
Careful management of fish enclosures should also be considered. Scientists have worked on developing sustainable tank systems for use in containing non-native fish populations, preventing the spread of disease, and sequestering waste. One particularly innovative variety of tank system has a filtration system designed to efficiently recycle water and convert fish waste into a methane biofuel. Additionally, the team that designed the tank has addressed the problem of fish reproduction in captivity by distributing pellets meant to simulate reproductive hormones and ensure controlled breeding.
That said, such a system would be difficult to implement on a widespread scale. On a more practical level, bag nets or walled off sea pens may be a more cost-effective system for the time being, though non-native species should always be kept in tanks on land.
Further measures to be taken include building facilities that don’t affect local ecosystems or communities and only harvesting adult fish to allow for population resurgence. For a more thorough list of sustainable aquaculture practices, visit Greenpeace.org.
It may appear difficult to implement all of these measures at once, and to be certain, we have a long road ahead of us when it comes to aquacultural sustainability. However, we have worked toward better farming practices through technology; we are capable of doing the same on the seas as we have done in the fields.