Improved aquaculture technology will save the world!
- Turning Southeast Asia into a world food storehouse -

Seafood is an important source of protein as well as a food source rich in functional compounds such as DHA and taurine. Japan has always been a major consumer of fish, and demand for fisheries products has increased in recent years due to increased health-consciousness in Europe and America, and the economic growth of China. With the global population expected to exceed nine billion in 2050, demand is likely to increase even more. However, fisheries resources are limited. Even now, many fish are already on the brink of extinction due to overfishing. For this reason, the production of fisheries products through aquafarming has become important to the challenge of securing food resources.
There are some obstacles that must be overcome in order to obtain a stable supply of fisheries products using aquafarming. For example, there are the problems of infectious disease and the need to obtain feed. This project aims to develop new aquaculture technology in collaboration with the Kingdom of Thailand. In addition to being an important trading partner to Japan for fishery product imports, Thailand is a leader in Southeast Asia in the science of fisheries. This project aims to establish a range of technologies with the potential to turn Southeast Asia into a new storehouse of food for the world.

Project summary

Creating superior strains

We are creating superior strains that grow rapidly and are also robust and resistant to disease and changes in environment. In particular, we aim to make improvements in aquafarming to facilitate the farming of fish with high commercial value, and achieve stable profits. In order to develop superior strains in a short time, this project breeds fish by leveraging genetic / genome findings.

Utilizing surrogate technology

Utilizing surrogate technologyIn surrogate technology, one strain of fish is used to bear another strain's offspring. Surrogate technology can be used to have small fish bear the offspring of large fish. If the parent fish are small, they are more efficient, because they can be maintained using less space and feed. Also, the time before the fish reach maturity can be shortened using small fish--because large fish take longer to mature and bear young--so there are also advantages in terms of breeding.

Preventing infectious diseases

Like people, fish are treated with medicine when they come down with an infectious disease, and they are sometimes also inoculated with vaccines. Technology for analyzing the immunity of fish is required in order to take appropriate measures against disease. Therefore, this project is developing methods for analyzing fish immunity and their bodies' defense responses at the genetic level. We are also conducting research on pathogenic microorganisms in order to develop effective vaccines.

Developing new feed

Fishmeal is used as feed for aquacultured fish. Currently, 4-5 kg of fishmeal is required to produce 1 kg of aquacultured fish, which constitutes a deficit in terms of animal protein. Project researchers have been feeding soy beans, corn, and poultry by-product^* to aquacultured fish and observing their growth with the aim of developing an alternative feed to fishmeal.* Poultry by-product: The leftovers from poultry meat processing.

Detecting polution from chemical substances and shellfish poison

In order for aquacultured fish to be a safe source of food, it is necessary to confirm that there is no pollution by dangerous substances. Project researchers are studying inexpensive methods of checking for the existence of pollutants, targeting malachite green^* and shellfish poison.* Malachite green: A chemical used as a dye and disinfectant that is carcinogenic.

Around what time did aquafarming of fish begin?

Dr. OKAMOTO

The oldest recorded mention of aquafarming is considered to be Chinese records about the aquafarming of carp from the 11th century B.C. Carp aquafarming is thought to date back to the 17th century in Japan and to 1947 in Thailand. The first saltwater fish to have been farmed is reputed to be young yellowtail, which was farmed in 1927 in Kagawa Prefecture, Japan. In Thailand, work began on farming sea bass in 1973.

At what density are fish reared in a fish preserve?

Dr. OKAMOTO

Rearing density differs depending on the type and size of the fish being farmed and also on the water temperature and other aspects of the aquafarming environment. For example, when aquafarming yellowtail, which accounts for nearly half of aquafarming production in Japan, 1 cubic meter per 7 kg is said to be the proper rearing density. In order to make the aquafarming industry sustainable, it is important to adhere to proper rearing densities and prevent water pollution due to aquafarming.

Fish pens are made in the ocean, right? Are the fish OK when storms come?

Dr. OKAMOTO

In Japan, it is common to aquafarm saltwater fish inside fish pens suspended in the water off the coast. However, in Thailand, fishermen build fish pens in rivers and other waterways that connect to the ocean. When storms come, however, the pens sometimes get washed away, or fish die due to environmental changes caused by the storm. In order to curb this kind of damage, submersible cages^* are being developed and there is research into land-based aquaculture technology.
* Submersible cage: A fish pen that can both float and be submersed in the ocean. Submersing the cage reduces exposure to storms, protecting the fish.

Do wild fish and aquacultured fish taste differently?

Dr. OKAMOTO

Because aquacultured fish don't need to roam around to find their feed like wild fish do, they inevitably become physically inactive and develop a higher fat content and softer meat than wild fish. The flavor of aquacultured fish in the past used be considered poor, but today, thanks to rearing methods that are much more advanced than before, some report that it is even tastier than wild fish.

When fish are vaccinated, are they injected? That sounds a tough job.

Dr. OKAMOTO

In addition to injections, there are also methods that mix the vaccine with feed or submerge fish in a vaccine solution. Currently, injection is the prevalent method because it uses only a small amount of vaccine and makes it possible to deliver a fixed amount with certainty. Injection is a labor-intensive task, because it requires the vaccine to be injected into each individual aquacultured fish. This burden can be reduced by developing and using a device to perform a number of injections in succession.

What fish are the main ingredients for the fishmeal used in aquaculture? Is the need for a lot of feed the reason aquafarming has yet to resolve food shortages?

Dr. OKAMOTO

The main ingredients in fishmeal are anchovy, horse mackerel, and mackerel. Actually, aquafarming requires far less feed compared to raising farm animals like cattle and pigs. The aquafarming industry has grown rapidly since the 1980s, so there are hopes that it will provide an answer to food problems in the future. We feel certain that the outcomes of our project will contribute to solutions for food problems.

What kind of fish cuisine is popular in Thailand? What fish do you like?

Dr. OKAMOTO

In general, sea bass and tilapia are often eaten in Thailand. I like catfish and grouper. Because these fish are cooked in a variety of ways, including fried in oil, boiled in soups, and steamed, they are served in a broad range of cuisine, from normal household cooking to banquets at special occasions.

Pla nin (tilapia)--A bond between Thailand and Japan

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  Tilapia (pla nin in Thai) is a delicious freshwater fish popular in Thailand that originally inhabited the Nile River. It is thanks to Japan's Crown Prince Akihito, an ichthyologist and now the Emperor of Japan, that this fish made it to Thailand. At a time when the Thai people suffered from a lack of animal protein, His Imperial Highness gave tilapia to His Majesty the King of Thailand. The King reared and studied tilapia in his palace, and was successful in breeding them. Later on, the Fisheries Department reared them through aquafarming. Due to its outward appearance being characterized by black horizontal stripes, brown fins, and white spots, it was named pla nin, incorporating the meaning "black" in Pali/Sanskrit.

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Please see the project's webpage for details.

Bioresources

Kingdom of Thailand

Development of Aquaculture Technology for Food Security and Food Safety in the Next Generation