Impacts of Aquaculture
Any activity that uses natural resources or interacts with the environment will potentially have issues relating to it. Aquaculture is no exception. Here are a few concerns about the practice:
Especially with intensive aquaculture farms, there is the issue of irresponsible waste (including uneaten food, body wastes and dead fish) discharge from the farms, which result in contamination of nearby water and soil. If chemicals, nutrients and foods dissolve in farm water, they cause eutrophication such waters come into contact with surrounding waters. This is known as nutrient. Organic residue that settles on the seabed may also cause alteration of seabed fauna and flora communities.
Here is an illustration of a basic open-net pen.
Notice how nutrients are added and how fish waste collects at the bottom?
Wild stock may face food and mating competition or predators if farmed species get into the wild, either by intentional release or accidental escape. They can spread diseases and just like the concerns of GMO seeds, they may mix up with wild species and soon we will not be able to differentiate between wild stock and farmed species. They my also interbreed with wild stock and endanger some native species, threatening the entire ecosystem.
One good example of habitat destruction is from the creation of ponds for culturing marine shrimps. Thousands of hectares of mangroves and coastlands, which serve as nursery ground for many aquatic organisms have been destroyed in places such as Thailand, Vietnam and the Philippines. Mangroves also support many marine and terrestrial species, and also protect coastlines from storms.
Chemicals used to Control Diseases
To control bacteria, fungal, viral and other pathogenic matter, drugs and chemicals may be used on fish farms (ponds and cages). There is always a chance that these dissolved chemicals may get into contact with other aquatic organisms nearby. Too mush use of such drugs can also have an effect on humans who eat the fish.