Aquaculture

Aquaculture, also called aquafarming, is the controlled farming of aquatic organisms such as fish, crustaceans, mollusks, algae, and other valuable aquatic plants like lotus. Unlike commercial fishing, which catches wild fish, aquaculture grows these organisms in freshwater, brackish water, or saltwater under controlled or semi-natural conditions. This includes practices like mariculture in seawater and pisciculture for producing fish products as food.

Aquaculture can happen in many places: in artificial facilities on land such as fish tanks, ponds, or aquaponics; in sheltered nearshore areas of a body of water; or in enclosed sections of open water using cages or bags. The Food and Agriculture Organization says aquaculture includes activities like regular stocking, feeding, and protection to increase production.

Aquaculture helps provide food and support healthier habitats. It also faces challenges, such as needing large amounts of wild fish to feed certain farmed fish and possible environmental impacts like nutrient pollution.

Overview

People need more food, and it is hard to catch enough fish from the wild. So, many people farm aquatic animals and plants. This is called aquaculture. It helps us get more seafood without only catching fish from the wild.

Scientists have started farming many sea animals. This is safer for humans than farming land animals. New ways to help fish stay healthy are being made. But there are still problems, like finding good food for the fish and making safe things to protect the farming tools.

Species groups

Main species groups

Minor species groups

Aquatic plants

See also: Algaculture and Seaweed farming

Microalgae, also called phytoplankton, microphytes, or planktonic algae, are the most common algae grown. Seaweed is also used, but it is hard to grow on a big scale, so most seaweed comes from the wild.

In 2016, most water plants came from farming. The amount of farmed water plants grew a lot from 1995 to 2016.

Seaweed farming

Fish

Main article: Fish farming

Farming fish is the most common type of aquaculture. It means raising fish in tanks, fish ponds, or ocean spaces, usually to eat. Some places let young fish go back into the wild to help more fish grow. The most common fish to farm are carp, salmon, tilapia, and catfish.

In the Mediterranean, young bluefin tuna are caught and moved to shore. They are kept in special nets to grow bigger. Scientists in Australia made southern bluefin tuna have babies in tanks. These tuna are also caught from the wild and kept in cages to grow fatter.

The same idea is used for farming salmon. Young salmon are helped to grow up. One way is to keep them in nets with good flow and give them food. This helps them grow all year. Another way is to keep them for a short time and then let them go into the sea to grow more.

Crustaceans

See also: Shrimp farming and Freshwater prawn farming

Farming shrimp started in the 1970s and grew very fast. Most farmed shrimp come from Asia, especially China and Thailand. The rest comes from Latin America, with Brazil as a big maker. Thailand is the biggest seller.

Shrimp farming has changed from small farms to big farms around the world. New technology lets farmers put more shrimp in a small space. Almost all farmed shrimp are a special kind called penaeids, and two types make up most of all farmed shrimp. These big farms can get sick, which has hurt shrimp in many places. Because of problems, the industry changed to use better ways to farm.

Freshwater prawn farming has many of the same issues as shrimp farming. The main kind of freshwater prawn has a special life cycle that makes farming it harder.

In 2007, the world made a lot of freshwater prawns. China also made a lot of Chinese river crab.

There is also farming of crayfish in fresh water, mostly in the US, Australia, and Europe.

Molluscs

See also: Oyster farming and Geoduck aquaculture

Farmed shellfish include different kinds of oyster, mussel, and clam species. These animals eat from the water and don’t need special food, so farming them is often seen as good.

Depending on the kind and where they are, these shellfish are grown on beaches, on lines in the water, or hanging from floats. In 2017, a group in Belgium put a trial mussel farm on a wind farm in the North Sea.

Farming abalone started in the late 1950s and early 1960s in Japan and China. Since the mid-1990s, this industry has grown a lot. Most abalone meat now comes from farms. Farms that care for the environment can get certificates from groups like the World Wildlife Fund (WWF). WWF started the "Aquaculture Dialogues" in 2004 to make rules for farming seafood in a responsible way. In 2009, WWF started the Aquaculture Stewardship Council to manage these rules.

After testing in 2012, a commercial "sea ranch" was made in Flinders Bay, Western Australia, to grow abalone. The ranch uses an artificial reef made of concrete parts called abitats. Each abitat can hold 400 abalone. The reef is seeded with young abalone from a place on land. The abalone eat seaweed that grows naturally on the habitats, and the bay also helps other fish grow.

Other groups

Other groups include water reptiles, animals that live in water but are not fish, and many other sea animals, such as echinoderms and jellyfish. They are shown separately because they do not make up enough to show clearly on the main chart.^{[citation needed]}

Commonly farmed echinoderms are sea cucumbers and sea urchins. In China, sea cucumbers are farmed in very big artificial ponds.

Global fish production

Global fish production reached about 182 million tonnes in 2021. This came from both wild-caught fish and fish farmed in controlled environments, called aquaculture. Aquaculture has grown quickly and now provides about half of all fish used for food worldwide.

Aquaculture is very important in China, where it has been a big part of the economy for many years. Other countries, like Chile, also farm fish such as salmon. The industry creates many jobs, with millions of people working in fishing and aquaculture, especially in Asia and Africa.

Over-reporting by China

China reports very high amounts of aquaculture production, more than the rest of the world combined. Some scientists have questioned if these numbers are completely accurate. They suggested that in the past, China may have reported higher numbers to meet government goals. However, China defended its reports, saying they were correct. The United Nations' food agency noted that there were concerns about the reliability of some of China's data during that time.

Aquacultural methods

Main article: Mariculture

Main article: Integrated multi-trophic aquaculture

Mariculture is the farming of sea creatures in seawater. It can happen near the coast, far out in the ocean, or on land. Farmers grow things like seaweed, shrimp, lobster, oysters, and fish such as salmon. Some animals, like salmon, are kept in special nets and fed by people. Others, like oysters, eat naturally from the water.

Integrated multi-trophic aquaculture is a way to farm where the waste from one animal helps feed another. For example, waste from fish can be used to grow plants or feed shellfish. This helps keep the water clean and supports many types of animals. It also makes farming more stable and friendly to nature. Different kinds of animals work together, helping each other grow better.

Netting materials

Different materials are used to make nets for farming fish and other sea creatures. These include nylon, polyester, polypropylene, polyethylene, plastic-coated wire, rubber, special rope products, galvanized steel, and copper. These materials are chosen because they are strong, last a long time, and don’t cost too much.

Recently, copper alloys have become popular for making these nets. They help keep the water clean by stopping tiny living things like bacteria, viruses, fungi, algae, and other microbes from growing on the nets. This makes it easier and cheaper to keep the fish healthy and happy.

Main article: Copper alloys in aquaculture

Technology

People use special uncrewed boats, like ROVs and AUVs, to help farm fish and other sea creatures. These boats can check on nets and watch the environment. This makes things safer and faster. Before, people had to dive underwater, but now these boats do it more quickly.

New computer programs can spot and sort different kinds of fish underwater. Also, a method called biofloc technology helps keep the water clean and gives food to the animals being raised.

Issues

See also: Issues with salmon aquaculture

When fish farming is not planned well, it can sometimes harm nature more than catching wild fish. But it usually creates less waste. Problems can include managing waste, the effects of medicines used to keep fish healthy, and competition between farm fish and wild fish. There is also a risk of introducing new plants or animals that can cause problems.

Fish waste is natural and contains nutrients that help water ecosystems. However, farming fish in the ocean can create too much waste. This waste can settle on the sea floor and harm animals that live there. It can also lower oxygen levels in the water, making it hard for wild fish to survive. One way to help is by building artificial reefs that give more space for sea life.

Impacts on wild fish

Some farm fish are fed wild fish to help them grow. Even though this is only a small part of fish farming, it uses up many wild fish. For example, to grow one kilogram of farmed salmon, several kilograms of wild fish are needed as food. This can put pressure on wild fish populations.

Another concern is that farm fish might escape and mix with wild fish, which can change the genes of wild populations.

Animal welfare

See also: Pain in fish and Pain in invertebrates

When farming animals, it is important to treat them well. This means making sure they are healthy, comfortable, and not scared or stressed. Some people wonder if fish and other sea animals can feel pain. Research shows that fish can sense harmful things, so it is important to care for them properly.

Coastal ecosystems

Farming fish near coasts can harm important areas like mangroves, which are forests that protect coastlines. Some of these areas have been lost to make space for fish farms, which can cause long-term damage.

Freshwater ecosystems

Experiments show that farming fish in lakes can change the water and harm the plants and animals that live there.

Genetic modification

Some fish, like a special type of salmon, have been changed through science to grow faster. However, these fish have not been approved for widespread use because of concerns.

Fish diseases, parasites and vaccines

One big challenge in fish farming is keeping fish healthy. Diseases can spread quickly in crowded farms. Vaccines are an important way to protect fish from diseases without using medicines that can harm the environment.

Salinization/acidification of soils

When fish farms are left unused, the land can become too salty or acidic, making it hard to use for farming again.

Plastic pollution

Fish farming can also create plastic waste, such as pieces from nets and floats, which can end up in the ocean and harm sea life.

Ecological benefits

See also: Nitrate vulnerable zone

Some types of aquaculture can help the environment. For example, farming shellfish like oysters can improve water quality because they clean the water. This helps keep the water clear and supports more plants and animals.

Aquaculture can also create homes for small sea creatures, helping them stay safe and grow. This can support more fish and other sea life. Farming seaweed can also help reduce carbon in the air and improve ocean health.

Prospects

Global wild fisheries are decreasing, and some habitats are in poor condition. Farming some fish, like salmon, can cause problems because these fish need to eat other fish to grow. This can harm wild fish.

However, not all aquaculture is harmful. Growing seaweed or farming oysters, clams, mussels, and scallops can help the environment. These animals clean the water by eating pollutants, which improves water quality. Seaweed also takes nutrients like nitrogen and phosphorus from the water.

New farming methods aim to reduce harm to the environment. These include ways to lower stress on fish, letting farms rest between growing periods, and using natural ways to control pests. Vaccines are also used more to prevent diseases.

Some farms recycle their water by filtering out waste and using the clean water again. This saves water and the waste can be used to make compost or treated for use on land. Scientists have found ways to farm saltwater fish in special tanks with less salty water.

A few countries, such as China, Israel, and the United States, use natural heat from the earth to keep water warm for fish farms year-round. For example, in California, fish farms use this warm water to grow tilapia, bass, and catfish more quickly.

National laws, regulations, and management

Laws about growing fish and other water animals are different in every country and can be hard to understand.

In the United States, rules for growing fish on land or near the shore are made at the national and state levels. There are no national rules for growing fish far out in the ocean. In 2011, groups like the Department of Commerce worked together to make new rules. These rules help provide healthy food, create jobs, and protect nature. Large fish farms that release water need special permission, and very large farms must follow special rules about what they can release into the water.

By country

Aquaculture is done in many countries around the world. Each country has its own way of farming aquatic animals and plants, using both fresh water and salt water. This helps give food and jobs to many people.

History

The Gunditjmara, a group of Aboriginal Australians, may have raised eels as early as 4,580 BCE. They made channels and dams near Lake Condah to catch and store eels for food.

Stories from China talk about farming carp around 2000–2100 BCE. Early farmers used natural materials to help fish grow. Ancient Egyptians may have farmed fish from Lake Bardawil.

In Korea, people farmed a type of seaweed called "gim" for a long time, using bamboo sticks. Japanese people grew seaweed using bamboo poles and oyster shells. Romans kept fish in ponds and farmed oysters before 100 CE.

In medieval Europe, monasteries kept fish because it was an important food, especially when meat was not allowed. In the 1800s, better transportation made fresh fish easier to get, so aquaculture became less common in some places. Fishponds in the Czech Republic are still important today.

People in Samoa and Hawaii also farmed sea creatures. In the 1700s, a German scientist began experiments with breeding trout and salmon. By the late 1800s, fish hatcheries were set up in Canada, the United States, and Newfoundland. These facilities helped people raise fish more efficiently.