Japan’s commercial aquaculture production has developed rapidly since the Second World War, and now it occupies an important position in the fisheries sector. Aquaculture production in 2003 is estimated to be 1,301,437 tons, worth $ 4,199 million, accounting for 22% of the total output of the National Fisheries in Japan, and 31% of the country’s total output value. Sea water aquaculture accounted for 96% of the total aquaculture production, accounting for 90% of the national total output value.
Japan is a country eating more fish, consuming 36.9 grams of animal protein per person/day, about 47% of which comes from fish and shellfish. The increased demand really helped develop the aquaculture industry. With the rapid development of Japan’s national economy in the 1960s, in addition to the requirements of increasing animal products, the demand for high, middle-grade fish, shellfish, shrimp, and crab has increased. Japan’s fisheries production remained at levels of an annual output of 10 million tons, mainly relying on fishing sardines and Trachurus japonicus in the coastal and offshore waters of Japan. The reason is that since the early 1970s the United Nations Sea Laws stipulated a fishery zone of 200 miles, Japan’s ocean fishing has been greatly affected, and the amount of fishing overseas has been greatly reduced. In order to meet the needs of its people, the government took another step, active development of fishery resources in the surrounding waters of the country, implementing a new development policy, focusing on the development of the coastal area of fish and shellfish.
In addition to Marine Fisheries (fishing and marine cultivation), Japan has also taken aquaculture inland, marine and freshwater aquaculture is conducted in all 47 Japanese prefectures.
Inland fisheries production is low, in addition to objective reasons, also related to the Japanese living habits, most Japanese are not interested in other freshwater fish except Anguilla japonica, many Japanese never tried such expensive Cyprinus carpio, crucian carp, Oncorhynchus mykiss, and so on. In terms of resource conditions and the existing technical level, the Japanese inland aquaculture production should be far more than 90-100 thousand tons, but the market demand has restricted the development—overproduction, prices fall, all the producer is affected by the loss. The main types of inland fisheries production are Anguilla japonica, Cyprinus carpio, crucian, Oncorhynchus mykiss, Plecoglossus altivelis, etc.
A. Main aquaculture species:
Yellowtail, Seriola quinqueradiata
The culture of the yellowtail, Seriola quinqueradiata, is the most successful marine fish farming venture in Japan, and production from farming now exceeds landings from fishing of wild stocks. Yellowtail culture is conducted by individuals, companies, or fishermen’s associations in floating net cages and in fish ponds which are made by partitioning sheltered places from the sea with nets or earthen dams. The great expansion during recent years is because of the increase in the number of floating net cages since the number of locations suitable for ponds is limited.
Amberjack and greater amberjack
Japanese amberjack and greater amberjack are the most economically important species in Japan; they account for 25 percent of the total production value of aquaculture. The Noami family in Kagawa Prefecture started enclosure aquaculture in 1930. Since the 1950s, cage culture has been widely adopted in the western region of Japan. Production rapidly increased from 1 431 tonnes in 1960, reaching 43 354 tonnes in 1970 and 149 311 tonnes in 1980. Today, production is around 150 000 tonnes, aquaculture production doubled that of marine capture production. Although artificial seed production was technically accomplished in the 1960s, wild seeds are still mainly used for production.
Puffers, also known as globefish or blowfish of the genus Fugu, are in high demand as a luxury food in Japan even though certain species are extremely toxic. About 10 species of edible puffers occur in Japan, but one species, Fugu rubripes rubripes, is used principally for farming ventures. The toxicity of puffers changes seasonally, becoming the greatest in the spawning season from May through June. The toxic substance “Tetradotoxin” occurs mostly in the ovary, liver, intestines, and skin, and rarely in the muscle. When prepared carefully by licensed cooks in Japan, puffers are completely safe to eat.
Red sea bream
Since ancient times, red sea bream has been prized as the ‘king of fish’ in Japan, because of its elegant appearance and color as well as its superior taste. It has become essential for celebrity meals for New Year parties or wedding ceremonies as an “auspicious fish.” The production value accounts for 10 percent of the total value of aquaculture. The seed production technique was developed in the 1960s and the main production method is cage culture. It is commonly cultivated around Kyushu Island and in the Seto Inland Sea.
The Japanese black porgy, or sea bream, Mylio macrocephalus (also listed as Acanthopagrus schlegelii), is a nonmigratory species found in shallow water along the coasts of Japan, Korea, Taiwan, and China. The annual catch of this species in Japan is 3,600-3,900 tons, about 65% of which is landed in the Seto Inland Sea (Fujiya, 1969). Black porgy can be raised in floating net cages or seawater ponds; and, since this species is more resistant to lower temperatures than some other species which are used in aquaculture, the geographical range suitable for farming is greater. Black porgi are reported to stop feeding at water temperatures below 10°C but can survive temperatures several degrees colder.
Eels (Anguilla spp.)
Eel is the main species in freshwater aquaculture and accounts for 40 percent of total production both in amount and value. Almost 100 percent of domestic eels are produced by aquaculture. Production of Anguilla japonica was first commercialized in 1879 and then developed mainly in the central regions of the Pacific Coast. It is now also actively conducted in the western region of Japan. In recent years, it is thought that Anguilla anguilla and A. rostrata fry from Europe and the United States, respectively, have escaped into the wild in Japan. As for fish seed, wild eel fry is commonly captured for use, but since 2003, the National Research Institute of Aquaculture (NRIA) succeeded with seed production.
Kokanee salmon (O. nerka kennerlii) are native to only two lakes in Japan, both on the island of Hokkaido. They have, however, been widely transplanted and now occur in about 20 lakes. Lake Shikotsu, a large natural lake on Hokkaido, contains a population of kokanee salmon and is the site of a hatchery devoted to the propagation of the species. Because of the low mineral content and consequent low productivity, it is difficult to maintain a satisfactory commercial harvest of kokanee salmon in Lake Shikotsu without depleting the spawning population. Officials of the Hokkaido Salmon Hatchery are searching for sources of kokanee salmon eggs with which to supplement their own supply. They have requested eggs from the State of Montana, but to date have not been able to get any.
Ayu (Plecoglossus altivelis )
Commercialization has progressed since the 1960s. Currently, Ayu is released into rivers for use by commercial and recreational fisheries. Ayu production accounts for approximately 20 percent of the total amount earned in freshwater aquaculture.
Other freshwater fish
For rainbow trout (Oncorhynchus mykiss ), 10,000 eggs were brought in from California in 1977. Currently, the culture of rainbow trout is commercialized across the country and they have been released into many rivers. The culture of common carp (Cyprinus carpio ) commenced in the Edo era. In addition, ornamental carp (or koi carp), which are species with various color mutations, are produced for display. Carp production in Japan has been severely damaged by the Koi Herpes Virus (KHV) since 2003.
Yesso scallop (Patinopecten yessoensis ) , Oyster (Crassostrea gigas, C. nippona ), and other shellfish cultured in Japan there are Abalone (Haliotis discus ), Japanese carpet shell (Ruditapes philippinarum ), Japanese scallop (Pecten albicans ) and tunicate (Tunicata ).
IV. Other species (Seaweed, prawn, pearls)
Nori or laver (Porphyra spp. – Porphyra pseudolinearis and P. yezoensis ) ， Sea mustard or wakame (Undaria pinnatifida ) ，Japanese kelp, or kombu (Laminaria japonica , L. angustata, L. longissima, L. ochotensis ) and Cladosiphon okamuranus , are also cultured.
For kuruma prawn, hatching and raising in ponds started in 1889. Artificial seeds were introduced in 1963, which led to increased production.
Kôkichi Mikimoto was the first to succeed in pearl culture in 1893, followed by the technical developments needed for producing full-orbed pearls. After 1910, the production of full-orbed pearls was enabled by technical progress which has since been adopted by pearl farmers worldwide. These days, pearls are raised by hanging aquaculture.
B. Practices/systems of culture
Mainly for fish, and extensive aquaculture for shellfish and seaweed. Until around 1960, natural seawater ponds and inlets surrounded by embankments or nets were widely utilized for extensive aquaculture. However, in recent years, this practice has only been applied to kuruma prawns and a few other fish and shellfish species.
Japanese eel farming technology and fish feed formulation are more advanced and nutritional, more intensive farming, a plastic greenhouse can automatically add water and control temperature, the production level is higher, and the general yield is 15-20 tons per acre. Eel is distributed around the country in Japan, but many places are kept neither raising carp nor eating carp, Carp aquaculture is conducted in five Japanese prefectures–Ibaraki , Gunma, Fukushima, Fukuoka, Nagano. Its production accounts for over 75% of the total output of common carp, The main ways to cultivate are net cage culture and recirculating aquaculture, but seed rising is used in the still water pond, and feeding density and feeding management technology is generally consistent with the technology we are now using, adult fish pond is general 50-100 square meters, average yield is about 50 kilograms per square meters.
Trout farms in Shizuoka Prefecture, are typical of Japanese trout farms in general and are as modern and efficient as any I have seen. The fish are reared in raceway-type ponds with a high rate of water exchange. The food is pelleted dry food, commercially manufactured. The chemical analysis is very close to that used in the United States and a 1.4 conversion ratio of food into fish flesh also approximates that achieved at successful hatcheries in the United States.
Japan has great advantages in the development of commercial aquaculture:
1. Island, there is a rich fish culture, mainly eating fish feed produced by fish feed machine
2. Shoreline twists and turns with a lot of excellent harbors
3. Have a strong team of ocean catch floods
4. A current advantage can be formed by the rich bait near, and the large fishing ground of Hokkaido fishing ground
5. Nature: The Kuril cold current and the Japanese warm current come together in the sea area near Hokkaido, This natural environment causes seawater disturbance, the seawater that has been thrown takes the nutrient salts to the sea surface, making the plankton flourish, so as provide abundant bait for fish, rich the fishery resources. so the world’s first major fishing ground came into being—Hokkaido fishing ground.
6. Society: Japan is not only developing the offshore fishery, but also expanding coastal aquaculture, the developed shipbuilding industry makes the Japanese a powerful fleet for deep-sea fishing, Japan fishing is ranked first in the world, and fish play an important role in Japanese food.