Problems Inherent to Aquaculture

Workers wearing rain slickers feeding fish held in large tanks on an aquaculture farm.
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Monty Rakusen / Getty Images

Unless you live on the Gulf Coast, when you buy frozen shrimp at the grocery store, there's a good chance the crustaceans never spent a day in the ocean. They might have been bred and raised in a shrimp farm for the specific purpose of being sold for food. This process is just one of many that fall under the definition of aquaculture.

It can involve freshwater or saltwater fish, plants, or other life forms, and the reasons might be commercial—as in the example of the shrimp—or they might be environmental or research-based.

While there are a number of ways aquaculture benefits the environment, there also are several concerns regarding its use that are important to understand—especially if you are considering becoming involved in the industry.

The Environment

Like a giant aquarium, land-based fish farms live in tanks containing dirty water that must be changed. Depending on the set-up of the system, this can result in the discharge of significant amounts of wastewater containing feces, nutrients, and chemicals released into the environment. The release of this matter can result in algae blooms that eventually remove dissolved oxygen in the receiving waterway, or eutrophication. Zero oxygen content results in deadly fish kills.

Additionally, chemicals such as antibiotics and water treatment agents commonly used in the aquaculture industry can be released into waterways. Aquaculture systems need to be closed, or wastewater treated prior to discharge.

Disease Spread From Aquaculture Farms

Aquaculture operations can spread parasites and disease into the wild. Just like commercial chicken coops must be kept clean and are notorious for the spread of disease, farmed fish and shellfish are subject to the same circumstances. Also, farmed fish have an increased chance of getting parasites such as sea lice, as opposed to fish that live and breed in their natural environments.

Farmed fish are exposed to diseases through the use of unprocessed fish as a food source. Some farms will use the unprocessed food fish as opposed to the safer processed fish pellets.

Escapees

Aquaculture is one of the largest causes of the occurrence of foreign species introduction into new areas. This introduction can create an unhealthy spread of the invasive species under the right conditions. Farmed fish and other animals can escape from their pens, damaging both the environment and threatening native fish populations.

As a result, escaped farm fish can compete for food and habitat, displace indigenous species, and interfere with the life of wild species. They also can carry diseases and parasites that might kill native species. Additionally, escaped farm fish are able to breed with the wild stock which can dilute the natural gene pool and threaten the long-term survival and evolution of wild species.

Secondary Impacts

Because farmed fish need a food source, other wild species are at risk of being over-fished for the manufacture of fish food. Because most farmed fish are carnivorous, they are fed either whole fish or pellets made from fish. Species such as mackerel, herring, and whiting are threatened because of the need to create food for farmed species.

Effects of Construction

Both land-based and aquatic wildlife can lose their habitats through the building of aquaculture facilities if they are placed along the coastal property. Often the aquaculture businesses will locate near coastlines for the easy access to clean and natural water.

In one example as reported by The Ecologist, mangrove forests have been cleared to make space for shrimp farms. The 2010 government-sponsored project was aimed at reducing poverty in Malaysia. Instead, it destroyed the forest that the local population depended on for food and promised jobs were not forthcoming.