13 Environmental Impacts of Aquaculture

Suppose aquaculture is an overall benefit, why the fuss around it?

Well, we will discuss that in this article as we examine the environmental impacts of aquaculture.

Aquaculture is among the methods of food production that is expanding the quickest. Since the world harvest from many wild fisheries has peaked, aquaculture is largely acknowledged as a practical means of supplying a growing population with seafood.

What is Aquaculture?

The phrase “aquaculture” broadly refers to the raising of aquatic organisms for any economic, recreational, or societal purpose in artificial marine settings.

In various kinds of water settings, including ponds, rivers, lakes, the ocean, and man-made “closed” systems on land, plants and animals are bred, raised, and harvested.

Aquatic organism farming is characterized as the practice of raising fish, mollusks, crustaceans, and aquatic plants. The phrase “farming” indicates some type of production-enhancing intervention in the rearing process, such as frequent stocking, feeding, and protection from predators.

Aquaculture aims to achieve the following goals

• Food production for human consumption,
• The rebuilding of populations of threatened and endangered animals.
• Fish culture for zoos and aquariums
• Wild stock enhancement
• Baitfish production
• Habitat rehabilitation

Researchers and the aquaculture sector are “farming” a variety of freshwater and marine fish and shellfish species using aquaculture methods and technologies:

• The term “marine aquaculture” specifically refers to the raising of oceanic animals (as opposed to freshwater). Oysters, clams, mussels, shrimp, salmon, and algae are produced by marine aquaculture.
• Whereas trout, catfish, and tilapia are produced through freshwater aquaculture. Trout and catfish farming in freshwater.

Nearly half of the seafood consumed by humans worldwide is produced through aquaculture, and this number is rising.

Environmental Impacts of Aquaculture

We are going to consider both the negative and the positive sides of this coin.

Negative Environmental Impacts of Aquaculture

The following are the negative impacts of aquaculture

1. Nutrient Accumulation

This is one of the effects of open-water aquaculture that is most frequently discussed. Because there is nothing to stop dead fish, uneaten food, and feces from entering the water column from the cages, nutrients accumulate in the area around the fish.

As the little plants eat up all the extra nutrients, the excess nutrients cause algal blooms.

Studies on the volume of organic matter, nitrogen, and phosphorus released into the environment by shrimp farms have been conducted. The estimated amounts of organic matter were 5.5 million tons, 360,000 tons of nitrogen, and 125,000 tons of phosphorus.

Considering that just 8% of aquaculture production worldwide is produced by shrimp farming, the overall impact is likely to be significantly greater. Numerous sea species are also poisoned by some of the hazardous compounds that accumulate in these places, such as nitrogen.

2. The Spread of Disease

Any illnesses or parasites are likely to spread considerably more quickly when several fish are kept close to one another in a limited space.

One of the parasites generating major issues in aquaculture is sea lice, and because the cages are open systems, there is a chance that these lice could spread to nearby wild fish.

This risk is greater for species that migrate, such as salmon, which may pass several cages in a fjord system as they go from one location to another.

3. Antibiotics

Different medications are used in aquaculture to stop disease outbreaks, promote growth, and prevent parasites.

Due to the creation of vaccines for farmed fish, the use of antibiotics in aquaculture has all but disappeared in various regions. However, antibiotics are still employed globally.

These antibiotics can either directly affect marine life when they enter the ecosystem or they can lead to the development of resistance, which can be harmful in the long run.

4. Energy Use in the Production of Feed

Significant volumes of fishmeal are needed to produce large quantities of farmed fish, such as salmon. Fishmeal is a type of fish feed that is often produced using much smaller fish.

The initial production of this protein necessitates an energy input. On top of that, some of the environmental advantages of aquaculture are defeated by the fact that these smaller fish are frequently caught in the wild by overfished fisheries.

Alongside the growth of aquaculture, feed production has expanded significantly. Production increased thrice in 12 years, from 7.6 million tonnes in 1995 to 27.1 million tonnes in 2007.

According to one study, the feed accounted for 80% of all emissions produced over the life cycle of farmed trout, from hatchery to consumption.

5. Use of Freshwater Resources

Some hatcheries and aquaculture facilities are located on land. This does allay some of the worries about keeping so many fish in cages in a natural setting.

However, it takes a lot of fresh water to operate these facilities, which must be pumped in. Pumping, cleaning, and filtering the water all consume a significant amount of energy.

6. Mangrove Forests are being Destroyed

Millions of hectares of mangrove forests have been lost due to aquaculture in nations like Ecuador, Madagascar, Thailand, and Indonesia. In Thailand, where the area covered by mangrove forests has more than halved since 1975, this is mostly due to conversion to shrimp farms.

This has serious environmental repercussions. Many fish species that reproduce and raise young can find food and refuge in mangrove forests, which also provide a habitat for a variety of other animals like birds, reptiles, and amphibians. By serving as a physical barrier to coastal erosion and storm damage, they also protect human coastal settlements.

Because these trees are so effective at absorbing carbon dioxide (CO2), their removal has an impact on climate change as well. According to one study, only one pound of shrimp produced in these regions releases one ton of CO2 into the sky, which is more than ten times the amount of CO2 created by cattle raised on a land cut from the rainforest.

Due to sludge buildup, these farms soon become unprofitable, often within 10 years of operation. Most of them have been abandoned, leaving behind highly acidic, poisoned soils that cannot be used for anything else.

7. Soil Acidification 

The soils may become degraded and too salty to be used for other types of farming in the future if a land-based farm is forced to be abandoned for any reason.

8. Contaminated Drinking Water

Water bodies utilized for human drinking water are contaminated as a result of inland aquaculture. According to one of these studies, a farm producing 3 tons of freshwater fish would produce the waste of 240 people.

9. Bringing in Invasive Species

25 million fish escapes have been reported globally, most frequently as a result of netting that has been broken during hurricanes or intense storms. Because they compete with wild fish for food and other resources, escaped fish have the potential to have an impact on wild fish populations.

In addition to having an immediate impact on wild fish populations, this forces nearby fishermen to fish in places that may already be overfished. Additionally, there is concern that these escaping fish would mate with wild fish and harm the species as a whole. This is because of how it affects the gene pool.

The gene pool is the variance in all the genes among different fish, which may be responsible for a variety of traits like their size or muscle density. A population’s chances of survival are increased by a big gene pool of fish with a wide range of characteristics.

The genes are likely to become dominant in the population when the farmed fish enter the system since they have typically been bred to be bigger and more muscular. This causes the gene pool to narrow, which affects the survival rate.

This effect has been seen in certain wild populations, therefore it is not just a theory. Atlantic salmon have been observed to stray in Norway and breed with local populations.

The same phenomena have been seen in the Rocky Mountains and the Gulf of Maine, where farmed species have even bred with fish of related but distinct species.

It is challenging to control this effect and to incite industry-wide improvement efforts. Instead of aquaculture, the commercial fishing sector and conservation are the main targets of escaping fish.

Fish farmers won’t be affected by the effects on wild fish, even though they lose some money from the escaping fish. In reality, if it has an impact on wild fish populations, it will raise the price of that commodity and boost demand for fish raised in aquaculture.

Depending on the region, different fish have a different chance of escaping farms and infiltrating wild environments. Divers frequently inspect some farms for any potential cage openings while underwater cameras closely monitor them.

Additionally, some fish have undergone genetic modification to make the females sterile. If these fish were to escape, there would be little chance of them mating with wild fish and changing the gene pool.

10. Interfere with other Wildlife

Acoustic deterrents have occasionally been used to try to ward off seals, which can harm underwater netting. Due to the whale and dolphin populations’ sensitivity to acoustic disturbance over a broader range, these devices are believed to have unanticipated detrimental effects.

Positive Environmental Impacts of Aquaculture

When practiced sustainably and under strict regulation, aquaculture can have some favorable effects on the environment.

1. Lessens the Demand Placed on Wild Fisheries

Increasing global demand for fish is the primary cause of overfishing, a serious environmental issue. Over 70% of the wild fish species in the world, according to the Food and Agriculture Organization (FAO), are either completely exploited or depleted. Removing predatory or prey species from the water disturbs ecosystems.

Other issues caused by commercial sea fishing include:

• Bycatch, or the capture of undesired species in big nets that are then abandoned
• Harming or killing wildlife caught in abandoned fishing nets and lines (sometimes referred to as “ghost fishing”)
• Damaging and upsetting sediments by dragging nets down the sea floor.

Aquaculture lessens the demand for wild fish and the overexploitation of this extremely fragile resource because, according to the World Health Organization, 1 billion people on earth use fish as their primary source of protein.

It is simpler to keep an eye on the effects of aquaculture than it is to keep an eye on fishing in the vast open oceans, even though poor practices sometimes happen.

2. Greater Production Efficiency compared to other Animal Proteins

Generating protein through aquaculture is significantly more efficient than producing protein in many other ways from the perspective of energy efficiency and, consequently, carbon emissions.

The “feed conversion ratio” (FCR) quantifies the amount of feed intake necessary for the weight the animal gains. It takes between six and ten times as much feed to produce a comparable amount of beef, according to the ratio for beef.

Pigs and hens have lower ratios (2.7:1 to 5:1) (1.7:1 – 2:1). However, because farmed fish tend to be more productive than many warm-blooded alternatives due to their cold-blooded nature, this ratio is frequently 1:1.

Some researchers have questioned these numbers, and the ratio can creep up to a similar range of hens depending on the species. Some contend that we should instead focus on “calorie retention” rather than FCR.

Studies are still being conducted to determine exactly how much more efficiently fish is produced than cattle. Additionally, a study that examined the whole life cycle carbon emissions of farmed fish found that trout emitted 5.07 kg of CO2 per gram, compared to 18 kg of CO2 per kilogram for beef.

3. Certain farming techniques offer even more favorable effects.

Seaweed and related goods like kelp are also produced through aquaculture, which goes beyond the production of fish and prawns.

Growing these has several positive effects on the environment:

They may be harvested up to six times per year, require considerably less area, require no fertilizer or pesticide inputs, operate as a carbon sink by absorbing CO2, and can be utilized as animal feed, which eliminates the need to cultivate feed on land.

Growing shellfish like oysters, mussels, and clams also has similar advantages. For instance, oysters can filter 100 gallons of seawater every day, enhancing water quality and eliminating nitrogen and particles. Oyster beds also produce an environment that other marine animals can use as a source of food or as a form of defense.

Conclusion

The environmental concerns surrounding aquaculture must be treated seriously, yet it is one of those difficult challenges because it also offers so many advantages. This method of producing seafood supplies 15–20% of the world’s 2.9 billion protein eaters.

In addition to being a considerably more affordable source of protein than alternatives, fish produced through aquaculture also contains vital vitamins and minerals. Locally grown and consumed food increases food security in a region and provides a source of employment and money for the local populace.

The idea is to maintain these farms close to home, where they can support residents with jobs and food, as opposed to massive industrial farms, which are more harmful to the environment and don’t help underprivileged areas.

Here are several approaches that could be used:

There will be numerous ways to find solutions. This method of producing fish should be more efficient thanks to technology, which should also result in less waste entering ecosystems and fewer fish escaping.

There are numerous rational responses to many of the identified problems. These could include:

• Selecting the appropriate site and ensuring that it is accurately assessed;
• Reducing waste by not overstocking farms;
• Using native species to reduce the effects of escaped fish;
• Improving feed quality (i.e., feed that doesn’t disintegrate as quickly);
• Better waste management, using strategies like settling lagoons or treatment tanks;
• Certification and legislation around sustainability.

There are a lot of advantages to some farming practices. As was already established, producing seaweed and shellfish has many advantages over land-based alternatives.

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