Aquaculture: Environmental Issues

Alyssa Cross
Professor Kathleen Robinson
Analytic Writing
11/12/2007
Aquaculture: Environmental Issues
The human population, as it continually grows, causes increasing stress on the environment with high demands of food, space and other natural resources. Human needs are continually on the rise. That being so, it appears humans are consuming the entire world’s natural resources. Coal, oil and natural gases are all examples of overused energy resources, causing added stress on the environment due to pollution. Another example of the human need to consume is found in the following quotation, “more land has been converted to cropland since 1945 than in the eighteenth and nineteenth century combined” (“Troubling Environmental Trends” para. 1). Today, an additional stress on the environment is the issue of overfishing. The world’s fish population is dramatically decreasing as demands for fish rise. Due to the issue of overfishing, currently thirty percent of the world’s seafood comes from aquaculture (“Something Fishy” para. 2). Aquaculture is defined by the U.S National Oceanic and Atmospheric Administration as, “the propagation and rearing of aquatic organisms in controlled or selected environments” (“Something Fishy” para. 2). Aquaculture is agriculture, but using water versus land. Originally, aquaculture appeared to be the solution for overfishing. But there are several issues which are harmful to the environment caused by aquaculture. Aquaculture produces mass amounts of waste, high feed demands for growing fish, antibiotics, and the chance that farmed fish will escape. Due of these facts, aquaculture should not be viewed as the solution for overfishing. When all the facts are analyzed, aquaculture harms the environment more than it helps.
Presently, diseases and parasites create problems in aquaculture. Growing fish in tanks is not considered a natural process. Therefore, farmed fish are at more risk of contracting diseases or parasites then wild fish. When any set of animals, including humans, are placed in an enclosed area with a high population density, disease and parasites will spread rapidly. For example, if a college student gets sick, it is more likely their roommate or fellow boarders will also get sick. College students live close together in a smaller proximity to one another, breathe the same air, eat the same food, and share the same drinks, making it easy for bacteria to spread. Similarly, the same concept applies to farmed fish. Farmed fish are grown in high populations in small cages to ensure mass production and profit. The close quarters of the farmed fish allow disease, such as Molluscs in oysters or Crustaceain in cray fish, to spread with ease (Black 129). Diseased farmed fish can also find their way into waterways, contaminating local populations with a disease the local fish have never been exposed to (“Something Fishy” para. 4). If local fish populations contract a disease which they have never been exposed to, the results may be devastating, stressing the environmental ecosystem. Some farms have been abandoned because the disease or parasites could not be controlled; meaning all the land used for the farm is wasted. Closed farms create wasted space and destroy surrounding ecosystems. Diseases and parasites cause the contamination of local populations or the closing down of farms. All in all, diseases and parasites spread throughout fish farms and, overtime, add stress to the environment.
After awhile, farmers turned to the solution of antibiotics and vaccinations to fight the diseases and parasites. There are two main problems that have risen with the use of antibiotics and vaccinations. The two problems that occurred with the use of antibiotics and vaccinations are that the process proves to the wasteful and diseases build up immunities. Firstly, antibiotics are fed or poured into the fish cages. The concept of feeding the fish antibiotics has two drawbacks; it can prove to be very wasteful and unreliable. Feeding or pouring antibiotics does not guarantee a fish will receive the medication. The antibiotics that are not eaten by the fish run off into local waterways polluting them. Antibiotics can wreak havoc if they make it into the oceans (“Something Fishy” para. 4). Secondly, over time, bacteria and parasites build up immunity to the antibiotics. Once the parasite becomes unaffected by the antibiotic, farmers are forced to increase the dosage or change the antibiotic. Fighting diseases then becomes an ongoing cycle of immunity to antibiotics by the disease leading to the increase of dosage which in turn leads to the increase of pollution emitted by farm. Antibiotics and diseases are of the many drawbacks to aquaculture.
To ensure the best quality meat, farmed fish are genetically engineered. Genetic engineering is when two fish with desired traits are bred, to hopefully produce a fish with both desired traits (Black 129). Genetic engineering creates fish with different gene pools from those in the wild. Examples of desired traits are immunity to certain diseases, meat quality, size, and speed of growth. If a genetically enhanced fish escapes from the pen, it can breed or compete with local fish populations (“New Coalition Hopes to Sink Plan” para. 2). If a farmed fish breeds with local fish, the original gene pool could be diluted or lost forever (Black 130). Genetic enhancement of farmed fish can prove to be harmful to the environment if farmed fish escape (Davenport and Black 65). The purpose of aquaculture is to take the stress of fishing off endangered species. But by diluting the endangered species gene pools, the purpose of aquaculture is defeated.
In addition to the previous issues, aquaculture’s emission of waste is harmful to the surrounding bodies of water. Food, feces, and antibiotics are washed from farms into local bodies of water. Eighty percent of feed in aquaculture is wasted (Davenport and Black 29). Waste in fish farms comes primarily from fecal matter and in uneaten food. Fecal matter contributes to water enrichment. Waste from fish farms are ammonia, phosphorus, dissolved organic carbon (DOC) and nitrogen (Black 3). Ammonia, phosphorus and DOC contribute to nutrient enrichment. Nutrient enrichment speeds up and increases algal growth (Davenport and Black 35). Algae blooms absorb the dissolved oxygen (DO) in water to grow. DO is the source of air for fish as well. During algal blooms, DO levels drop dramatically and surrounding fish populations cannot breathe (Davenport and Black 36). Aquaculture adds stress on the environment by emitting waste and contributing to low levels of dissolved oxygen, causing suffocation of fish.
Fish farms take up large amounts of space, as seen from the following quotation, “cultivated land, livestock production and aquaculture now cover a quarter of the earth’s land surface” (“Troubling Environmental Trends” para. 2). Coastlines in the Philippines are used to house fish farms, but the farms lead to destruction of local coastline mangrove forests (“Something Fishy” para. 5). Shrimp farms demand shallow coastal pools (Black 183). Mangrove habitats are destroyed and ecosystems are ruined to make way for fish farms. Some regions in Asia have experienced a seventy percent reduction in mangrove habitats (Black 183). Mangrove forests act as nurseries for baby fish and blockage from large waves. Without mangroves, waves are not blocked from crashing further inland, destroying homes and habitats. Aquaculture is adding stress on local mangrove ecosystems, inland habitats, and local fish populations.
Aquaculture is creating more issues within the environment than solving the problem of overfishing. Aquaculture is a breeding house for diseases which could be passed on to local fish populations. Genetically enhanced escaped farmed fish can destroy or dilute local gene pools. Waste from fish farms emits pollution contributing to algal blooms lowering the levels of dissolved oxygen. Lastly, aquaculture destroys mangrove forests and coastlines. Before humans harm the environment further, new solutions ought to be created over aquaculture to solve the issue of overfishing. Aquaculture was originally seen as the solution to overfishing, but since many issues have risen due to aquaculture it appears new ideas are in need of development to relieve the stress formed by overfishing and aquaculture.