Salmon, mainly distributed in the waters at the junction of the Atlantic Ocean, the Pacific Ocean, and the Arctic Ocean, is a highly cold-water highly migratory fish. Studies have shown that both tuna and salmon are delicious and nutritious, and are rich in bioactive substances such as EPA and DHA. Japan uses salmon for sashimi and sushi. There are more than 30 species of salmon with commercial value. At present, the two most common are two types of trout (salmon trout, golden trout) and four types of salmon (Pacific salmon, Atlantic salmon, Arctic salmon, and silverfish).
Salmon is cold-water fish. Inhabiting freshwater and seawater, it is a migratory fish that traces back to the river. Salmon is a cold-water spawning migratory fish. Originally inhabiting the northern Pacific, they lived in the ocean for 3 to 5 years (usually reaching sexual maturity at the age of 4) and only swarmed for reproductive migration in summer or autumn. According to the river receding time, it can be divided into two biomes, summer type and autumn type, and those entering Heilongjiang in China only fall type. Most spawn downstream and only a few reach upstream. They go up the river, take part in the day and night, and work hard. They can go 30-35 kilometers every day and night. They will not retreat, whether they encounter a shoal canyon or a rapid waterfall. Adults do not feed after entering the freshwater reproduction period.
Although the Japanese people have no concerns about raw salmon, the incidence of anisakiasis in Japan is not low compared to other countries. There are many parasites in wild salmon. Anisakis is the most common and can easily cause abdominal pain and diarrhea, but seawater parasites cannot survive in the human body for a long time. By comparison, farmed salmon may have fewer parasites. It is worth noting that freshwater farmed rainbow trout is sometimes used for sashimi, but its risk is much greater than salmon. This is because the parasites in freshwater fish can survive in the human body, the most common of which is liver fluke. Therefore, freshwater farmed rainbow trout cannot be eaten raw.
In 1985, the Minister of Fisheries of Norway led a national team to fly to Japan to promote Norwegian salmon, hoping to use salmon for sushi. In 1994, Japan used Norwegian salmon for sashimi and sushi. Salmon has been endangered many times. Salmons on the Thames disappeared in the 1940s and 1950s as a result of human dam construction and river pollution. Uncontrolled human fishing over the past 100 years has also contributed to the disappearance of some precious salmon species. With the development of science and technology, artificial salmon farming has begun in the world, which not only ensures the quantity of wild salmon, maintains ecological balance, but also greatly meets human demand for it.