Can Aquaculture Make Seafood Sustainable?

The Midwest of the United States is famous for its farm-raised meat and dairy, from burgers to cheese curds and ice cream. But what about Wisconsin’s long-standing tradition of a Friday night fish fry? While we might imagine its source as a fisherman with a pole on a riverbank, could that fish too have come from a farm? For any seafood-eater (especially the environmentally-conscious) who can’t quite picture a farm full of fish, it may be worth it to understand what aquaculture—a form of farming plants and animals in a controlled aqueous environment—is all about.

Many of us might be confused whether to buy farmed or wild-caught seafood, even with the internet at our fingertips. The most-frequently consumed seafood products in the United States, for example, are shrimp and salmon. The high shrimp demand in the US accounts for a significant chunk of the over 53 percent of global seafood production that were farmed animals in 2016. Even though we likely eat farmed products, our understanding of them may be a bit vague. When we consider that 89 percent of global fisheries are exploited and overfished while consumer seafood demand continues to rise, the ins and outs of aquaculture deserve more attention.

In the media, it is common to see generalized statements about aquaculture that include phrases such as “farmed seafood with antimicrobial resistance.” These statements conflate farming seafood with antimicrobial resistance without exploring the diverse world of seafood farming. For example, the US daytime television show Dr. Oz claimed Chinese farmed tilapia are less healthy than wild-caught or domestically-raised fish due to less-stringent controls on antibiotic use and cage farming. However, from 2003 to 2013, antibiotic residues and contaminants were such a worry in the Chinese aquaculture industry that the Chinese government requested a mandate against antibiotic usage without regulation or a prescription from a veterinarian.

Around the world, farmed fish from Best Aquaculture Practice certified farms have endured strict regulations on production that proactively prohibit antimicrobials, medicated feeds, antibiotics, and other intoxicants that would affect human health negatively. Still, misleading reports perpetuate a negative social understanding about aquaculture seafood in the US. These reports draw their claims largely from older forms of aquaculture. Leaps and bounds are being made in the industry. There is a current effort to produce sustainable products through the usage of newer technologies and nutrition. The forward movement of aquaculture is a promising beginning to sustainable seafood.

Origins to Present

Farming seafood may seem new, but the practice of fish farming has been around for thousands of years. The beginning of aquacultural practices is often dated to around 4000 B.C., when some cultures began using a minimalist approach of trapping aquatic species, a practice which significantly improved fresh food availability. Romans began domesticating wild carp and, independently, the Chinese practiced similar forms of aquaculture around that same time. In Japan, seaweed production began around 1670 A.D. for the purpose of salt, iodine, colloid, and alginate extraction. In the 1960s, aquaculture began to notably advance on an international scale as global demand for freshwater and saltwater finfish, black tiger prawns, mollusks, oysters, and kelp took off.

Wild-caught tuna thawing out before the canning process. Image by author.

Now, the most common techniques used in aquaculture are inland and offshore. A typical inland system uses raceways, which redirect natural streams and treat wastewater. Offshore aquaculture, on the other hand, presents especially high environmental risk. Floating pens in open water or along shorelines utilize ocean tides to keep the pen water fresh. Fish regularly escape from the pens and impact local fish populations with disease and interbreeding. Nutrient pollution of the surrounding sea varies in severity depending on pen depth, flushing patterns in the tide, and other variables.

Emerging Technologies

Many scientists believe that aquaculture could be productive and well-managed on global coastal regions, but with the current state of the global fisheries stock, this is an uncertain idea. The most productive zones in the ocean exist along shorelines. Littering shorelines with fish pens will monopolize the space needed for fish populations to bounce back. At the same time, many previously-developed inland systems come accompanied with their own environmental risks. Thus, with the evolution of aquaculture technology, closed systems have been developed. In a closed system, which producers can place anywhere inland, a barrier controls the fish’s interaction with the external environment. It contains animal escapes and nutrient pollution to its enclosures.

Raceways and recirculation systems (a.k.a. RAS or Recirculating Aquaculture System) are the most commonly used closed systems. Their benefits include minimal water requirements, control of water conditions, stable output production, high fish escape control, control of sanitary conditions, and low wastewater discharge. One of their biggest disadvantages is the high level of capital necessary to start a recirculating system, making them less accessible. Some businesses are focusing on creating a carbon-neutral closed aquaculture system by creating uses for organic byproducts and wastewater. For example, polyculture systems could grow seaweed from nutrients produced by fish and biosolids could be composted. If closed-systems became more popular, creation of an accessible infrastructure for composting would be a key piece of the sustainable aquaculture puzzle.

Using these emerging technologies in conjunction with high-quality fish feed will make for farmed fish that are a healthy food source by reducing issues of disease and, hopefully, eradicating antibiotic usage. Antibiotic residues in the meat of farm-raised animals has sparked food safety concerns in many industries, including farmed fish. Antibiotics are used to increase growth rates and keep the animals disease-free while living in densely populated ponds. To instead proactively keep animals healthy, farmers can opt to use high-quality fish feed made of insect and plant-based proteins as opposed to fishmeal or similar diets. As research continues to better understand fish health and different measures of fish welfare, regulations continue to change to improve the standards. Research on different nutritional needs of seafood are helping determine which diets both keep the fish healthy and provide a nutritious protein source for human consumption.

The Ripple Effect of Aquaculture

But what does aquaculture mean for the farmer? Combined (or polyculture) farming systems in the Mekong Delta demonstrate how aquaculture can utilize plants to reduce the nitrogenous waste produced by the seafood animals while also providing extra earnings for small-scale producers. Farming shrimp in between flooded rice field rows offers farmers two products from one area of land, combining for a larger profit. Farmers able to combine agriculture and aquaculture are likely to see appreciable output-to-input ratio increases even at the family scale. Smallholder farmers could use aquaculture as a tool to improve their socioeconomic status and alleviate poverty.

A local worker about to throw a cast net at a shrimp farm in Pedernales, Ecuador. Image by author.

Smallholders are not the only disadvantaged group who might benefit from closed-system aquaculture. The fishing industry is an extremely male dominated industry, while women play key roles in smallholder agriculture. By bringing the fish to the farm, inland aquaculture can empower rural women, providing them with economic and leadership opportunities within their communities. The Food and Agriculture Organization of the United Nations produced a small-scale fish operation study of a rural community in Bangladesh, displaying positive impacts of both women’s involvement and decreased offshore fishing activity. There was a 10 to 20 percent increase in fish production as well as improvements in socioeconomic status, child education, access to healthcare, and purchasing power with their earnings. Incorporating subsistence aquaculture at a grassroots level could attenuate many damaging cycles of unequal opportunity, while directly impacting the global hunger crisis.

Inland fish farms present an alternative to fishing far-removed oceans of their catch. Local, small-scale aquaculture systems could eliminate supply chain issues in urban communities and reduce food mislabeling and fraud, while also potentially significantly reducing labor abuses on fishing vessels. The industry of wild-caught fish and seafood currently depends on exploitative labor practices, which some researchers have described as “modern slavery” using the Global Slavery Index. Ethical aquaculture practices could form part of a solution to these embedded issues of social justice and labor abuse.

Bringing Fish on Land

For those interested in learning more about aquaculture and its effects, there are many options. Seafood advisory lists from the US Food & Drug Administration or Seafood Watch are accessible as applications on smartphones, and many of these lists include recommendations for farm-raised fish and crustaceans. Organizations like the Best Aquaculture Practices and the Aquaculture Stewardship Council offer certifications and product labels that help consumers know whether farmed seafood has been produced with sustainable methods. Although many might still reach for a fish stick without thinking about the source, maybe fish from the farm also has a place on the conscious eater’s plate.

Featured image: Recirculating Aquaculture System (RAS) tanks. Image by Narek Avetisyan, 2016.

Samantha N. Thammahong is a recent graduate from the University of Wisconsin–Madison. She received her Master’s Degree in Comparative Biomedical Sciences within the School of Veterinary Medicine, where she studied a rampant bacterial disease in cultured Pacific White Shrimp. She aspires to continue with her path in sustainable aquaculture practice. Contact.