Problems Inherent to Aquaculture
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.
Like a giant aquarium, land-based fish farms live in tanks containing dirty water that must be changed. Depending on the system's set-up, 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 which eventually remove dissolved oxygen in the receiving waterway, or eutrophication. A zero oxygen content results in deadly fish kills.
Additionally, chemicals such as antibiotics and water treatment agents commonly are used in the aquaculture industry, and aquaculture systems need to be closed, or wastewater treated prior to discharge.
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 also are exposed to disease through the use of unprocessed fish used as a food source, as opposed to safer processed fish pellets.
Aquaculture is one of the largest causes for the occurrence of foreign species introduced into new areas, which creates invasive species under the right conditions. Farmed fish 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.
Because farmed fish need a food source, other wild species are at risk for 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.
Affects of Construction
Both land-based and aquatic wildlife can lose their habitats through the building of aquaculture facilities along coastal property, where clean and natural water can be accessed for its processes. In one famous example, in Asia and Latin America, mangrove forests have been cleared to make space for shrimp farms.