Seafood is a common source of protein and ensures food security in many coastal regions across the world. The seafood industry also has economic importance- serving consumers and exporting delicacies and popular varieties of fish, crab, shellfish, etc. However, overfishing and certain aquaculture practices have raised environmental concerns.
Is seafood sustainable? Does the seafood industry cause environmental problems? And is seafood better than other types of meat? These are some questions that will be answered subsequently.
Aquaculture is the process of cultivating aquatic life for our consumption. This happens in natural marine habitats or in controlled environments that replicate marine habitats. There are many stages in aquaculture. The first stage is the hatchery (collecting eggs, breeding of fish). The fish are then transferred to the farm where they are grown to their full size. Then they are harvested, processed, packaged and transported to stores and markets (Global Seafood Alliance, 2019).
Environmental impacts of aquaculture
Certain species like salmon consume wild fish as their food. So, it takes more than one kilogram of wild fish to produce one kilogram of salmon (Greenberg, 2014). This leads to overfishing to meet the dietary needs of the species being cultivated.
Aquaculture also generates waste through fecal matter and unused feed. The waste is nitrogen-rich and causes oxygen depletion if they are discarded in marine environments. This would choke aquatic organisms in the ocean. The use of pesticides and antibiotics in aquaculture produces chemical waste that pollutes ocean water.
Shrimp farming mostly occurs in tropical and subtropical ponds, within mangrove forests. When pollutants accumulate in shrimp farming ponds, the ponds are abandoned and cultivation is continued in a new pond. This results in the destruction of mangroves, which also host other species of fish and offer coastal protection against cyclones. Therefore, organic aquaculture has started gaining importance, to protect mangroves and sustain people’s livelihood (Greenberg, 2014).
The fishing industry also removes reproductively mature fish from their natural environment, which leads to population decline of fish. Overfishing can slow down the growth of fish population and disrupt the marine food chain. It threatens the livelihood of small fishermen who depend on the daily catch for food and income (Pariona, 2017).
Harmful fishing techniques
These are two ecologically damaging fishing techniques, that are now being banned by many countries due to the problems they cause.
- Bottom trawling – Fishermen drag a net along the seabed. This disturbs the sediments that had settled at the bottom. The sediments are carried to other parts of the ocean by the currents. Accumulation of sediment creates murky water, which blocks the sunlight from reaching underwater plants, creating oxygen-deficient regions. Pollutants that had settled at the seabed are stirred up and enter the food chain, poisoning marine life.
- Blast fishing – Explosives are used to kill large numbers of fish at once. This destroys coral reefs and causes oceanic noise pollution (Greenberg, 2014).
Waste generated by aquaculture
Fodder waste and chemical pollutants not only pollute the local ocean water, but can be transported throughout the ocean, affecting different levels of the food chain. It could affect the growth of plankton, and subsequently reduce biodiversity.
Aquaculture waste, once treated, has many uses and economic potential. Fodder waste can be converted to biogas or as fertilizers for soil.
Chitin, obtained from the exoskeleton of crustaceans (crabs, lobsters, shrimp), is used as an additive in fish food. Chitin also has other applications in the medical field.
The process of obtaining chitin also recovers carotenoids. Shrimp waste has economic potential due to the presence of carotenoids. Carotenoids are responsible for the color in shrimp and shellfish. Once extracted and processed, they are used in the food industry and the cosmetic industry.
Compounds like enzymes and proteins could be used in the pharmaceutical industry, and the methods to extract these from seafood waste are being researched (Arvanitoyannis & Kassaveti, 2008).
Seafood production and climate change
The rising temperature of ocean waters due to global warming has reduced fish productivity and changed the distribution of fish population. This hurts seafood production, especially in the tropical countries who are most dependent on seafood for food and money.
Warmer water increases the risk of algal blooms, which will hamper aquaculture. Aquaculture farms will shift their location depending on the condition of the water and marine productivity (Palardy, 2022).
Yet, seafood has the potential to become one of the most sustainable ways of achieving food security for the future.
Seafood can be sustainable
Currently, the seafood industry is criticized for causing overfishing, water pollution and marine degradation. In spite of these environmental impacts, it has the potential to become sustainable if managed efficiently, with proper waste recycling and treatment, and policy measures to ban hazardous fishing methods and overfishing.
Seafood has higher protein retention compared to other types of meat like pork, chicken and beef. Aquaculture is more resource efficient; it has lower greenhouse gas emissions, water demand and land requirement than land-based meat production (Greenberg, 2014).
Some varieties of seafood have lower environmental impact than other varieties. For example, farmed shellfish, mollusks, sardines, mackerel and herring have low environmental impact compared to catfish aquaculture and shrimp. This is because more energy is used for water circulation in the latter.
Mollusk aquaculture (oysters, mussels, scallops) has a positive impact on marine environment because mollusks absorb excess nutrients from water, that would otherwise harm the ecosystem. Capture fisheries do not use fertilizers and thus generate less pollution compared to intensive fish farming (Ma, 2018).
Therefore, consumers also play an important role in the sustainability of seafood by choosing species that have low environmental impact for cultivation and sourcing their seafood from fisheries that follow sustainable practices.
Arvanitoyannis, I., & Kassaveti, A. (2008). Fish industry waste: treatments, environmental impacts, current and potential uses. International Journal Of Food Science &Amp; Technology, 43(4), 726-745. https://doi.org/10.1111/j.1365-2621.2006.01513.x
Greenberg, P. (2014). Environmental Problems of Aquaculture. Earth Journalism Network. Retrieved 17 June 2022, from https://earthjournalism.net/resources/environmental-problems-of-aquaculture.
Ma, M. (2018). Choice matters: The environmental costs of producing meat, seafood. UW News. Retrieved 17 June 2022, from https://www.washington.edu/news/2018/06/11/choice-matters-the-environmental-costs-of-producing-meat-seafood/.
Palardy, J. (2022). Seafood Production Suffers Under Climate Change, but Sustainable Reforms Can Help Maintain Harvests. Pew. Retrieved 17 June 2022, from https://www.pewtrusts.org/en/research-and-analysis/articles/2022/05/11/seafood-production-suffers-under-climate-change-but-sustainable-reforms-can-help-maintain-harvests.
Pariona, A. (2017). What Is The Environmental Impact Of The Fishing Industry?. WorldAtlas. Retrieved 17 June 2022, from https://www.worldatlas.com/articles/what-is-the-environmental-impact-of-the-fishing-industry.html.
What is Aquaculture, and Why Do We Need It?. Global Seafood Alliance. (2019). Retrieved 17 June 2022, from https://www.globalseafood.org/blog/what-is-aquaculture-why-do-we-need-it/.