Humanity has entered a brave new world of fishing. Sure, the fish on your table may look and taste the same as it always has, but its journey from ocean to hearth has undergone a fundamental shift. Where the question, “Was this fish wild?” once was rhetorical, aquaculture has muddied the waters of late. Originally only associated with the production of shellfish, the industry of aquaculture has grown and diversified in the last 50 years to become a major source of aquatic protein globally (Bostock). By raising fish and shellfish from birth until death and delivering them to the table, this process completely alters the route from net to plate.

 

In order to understand aquaculture and its ramifications, it is necessary to understand the relationship between what nourishes fish and what nourishes us. Fish are a mainstay of the human diet, available in thousands of varieties to appease any taste. For many, especially in developing countries, fish offers a relatively inexpensive and environmentally friendly choice for protein. Know a pescatarian? If you have ever eaten fish or shellfish, chances are you ate farmed fish. Producers have turned to aquaculture to keep up with the rising demand for fish and to compensate for declining wild fish stocks. Today, aquaculture produces 43% of aquatic animal food including fish, crustaceans and mollusks meant for human consumption (De Silva). It is hard to visualize a fish farm and finding the proper conditions for growth is a difficult process that is at the heart of aquaculture.

 

Aquaculture has the potential to feed the world. Unfortunately, the demand for fish may have pushed aquaculture to fix problems with short term solutions. The process as practiced causes more harm than good. To realize its true potential, it must become more palatable. Industrial aquaculture practices must break the mold of the monoculture to improve yields and become ecologically sound.

 

Fundamentals of Aquaculture

 

Farming fish is much like farming any other livestock: you need a pen to raise the fish, food to feed the fish, and proper environmental conditions for the particular type of fish. Aquaculture has a negative environmental impact when industrialization causes these interests of the fish farm to conflict with those of the local environment.

 

Locating a fish farm to optimize conditions for growth can be problematic. The right place, for example, might be in an area which already contains another productive ecosystem. For instance, fish farmers have cleared thousands of acres of mangroves for shrimp ponds in Thailand (Rosamond). Those mangroves provided a sanctuary for many of the wild fish caught in Thailand and by removing the mangroves, a net loss in fish production was inevitable (Rosamond). Another concern is whether the newly introduced fish may escape into the surrounding environment. Once there, this invasive fish may outcompete native fish or interbreed with similar fish (as in the case of salmon) resulting in less competitive hybrids with reduced vitality (De Silva).

 

Perhaps the biggest environmental impact in the industry comes from feeding the fish. The higher up the fish is in the trophic system, the more costly it becomes to the environment and to the farmer to raise and feed. Here, we see a fundamental difference between the various types of farmed fish. A mollusk culture requires no external feed inputs because they feed on ambient algae (Bostock). But for those farmers raising crustaceans and other intensive fish such as salmon, the feed is a combination of grain and other fish. Where do those fish in the feed come from? The answer is wild fish stocks. In 2008, aquaculture practices consumed 90% of the global fish oil supply and 71% of global fish meal (Bostock). Overall this comes out to about 1.9kg of wild fish feed for every 1 kg of the most commonly farmed fish (Rosamond). This increased demand on lower trophic level wild fish further strains already depleted fish stocks and could be remedied by diversifying the farmed fish. Based on this principle, fish with more vegetarian diets are generally more “green” when compared to their carnivorous counterparts because they put less strain on wild fish stocks. This generally environmentally friendly category includes “carp, catfish, tilapia and milkfish – as well as scallops, oysters and other filter feeders.” (Highfield)

 

Lastly, the monoculture nature of carnivorous fish production often results in a high incidence of disease (De Silva). To combat this threat, farmed fish require the application of large amounts of antibiotics (De Silva). These less healthy fish can be harmful to the consumer and lead to lower levels of productivity.

 

The Taste Test

Farming fish with the flavors associated with their wild counterparts is key to producing a viable product that consumers will buy. Surprisingly, producing the right flavor in aquaculture is a science and a major factor behind aquaculture economics. If the farmed fish differs from its wild counterpart, then it is categorized as “off-flavor.” (Rimando)

 

The source of this discrepancy can be traced back to the diet of the fish and the environment in which the fish was raised (Rimando).

 

The old adage goes “You are what you eat.” In the case of fish, this conventional wisdom proves true. Producers don’t perfectly reproduce the exact diet of wild fish even though the feed for fish often comprises the greatest expense in aquaculture. Farmers reach a compromise between a natural diet and high feed costs through a standard fish and grain feed. 

 

The higher up the trophic level the fish is, the more difficult the task is to perfectly match the natural environment’s nutritional requirements. Salmon are a case in point for discussing the difficulty in meeting consumer expectations while successfully raising high trophic level fish. When people search for suitable salmon, they associate quality with the pink-red color of the salmon (Alfnes). The cause of this characteristic color is astaxanthin located in the Salmon’s muscles (Alfnes). Although wild salmon acquire this color naturally from crustaceans, farmed salmon can’t find this compound naturally in the grain and fish feed that they consume (Alfnes). Suppliers compensate by feeding their farmed salmon synthetic astaxanthin with contributes little nutritional value, but comprises around 15% of feed costs (Alfnes).

 

Looking Towards the Future

Despite the daunting nature of many of these problems, farmed fish are destined to become an even more common occurrence on our plate. For the time being, the most environmentally appealing aquaculture is the most boring one—the farming of lower trophic level fish—and the industry’s biggest concern is its reliance on wild fish stocks for feed. This industry has problems in scaling due to its reliance on monoculture practices that emphasize quantity over quality. Yet, the link between the fish farm and its surrounding aquatic environment will force the fish farmer to explore more green practices.

 

 

 

Works Cited

 

Alfnes, F., Rora M., & Steine, G.The effect of color on consumer WTP for farmed salmon. (2005). Marine Resource Economics, 20(2)

 

Bostock, J., Gatward, I., Corner, R., McAndrew, B., Richards, R., Jauncey, K., & Handisyde, N. (2010). Aquaculture: Global status and trends. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 365(1554), 2897-2912.

 

De Silva, S. S., Nguyen, T. T. T., Turchini, G. M., Amarasinghe, U. S., & Abery, N. W. (2009). Alien species in aquaculture and biodiversity: A paradox in food production. Ambio, 38(1), 24-28.

 

Highfield, R. (2000). Fish farms are `robbing oceans': Wild fish used in processed foods to feed `aquaculture' shrimp, salmon: Final edition. The Gazette, pp. D.14.

 

Rimando, A., & Schrader, K. (2003). Off-flavors in aquaculture. Washington: American Chemical Society.

 

Rosamond, N. (2000) .Effect of aquaculture on world fish supplies. Nature, 405(6790), 1017-1024.