What Kind of Fish Is Salmon? A Full Analysis of Origins, Varieties and Characteristics

What is salmon? To answer this question, we must first clarify the origin of the name "salmon."

According to research, the Chinese term "sanwenyu" was first proposed in Hong Kong, China and Taiwan, China, as a transliteration of the English name salmon, because the English pronunciation of salmon sounds similar to "sanwen," while the standard Chinese translation of salmon should be "damahayu" or "guiyu."

Salmon is not a taxonomic name for fish, but a commercial name for certain salmonid or salmon-trout species. To qualify as salmon, its muscle must be firm and elastic, with clear white marbling, and its color must be deep red or orange-red. So to be precise, salmon should be orange-red salmonids, salmon meat, or salmon-trout. Internationally, the naming of salmon-trout species is rather chaotic; by convention, salmonid fish are collectively called salmon-trout. In the consumer markets of different countries, salmon covers different species: Norwegian salmon is mainly Atlantic salmon, Finnish salmon is mainly farmed large-size red-fleshed @#@241@#@, and American salmon is mainly Alaskan salmon.

Salmon occupies an important position in the modern fish classification system, comprising a large group. Most species have the characteristic of anadromous migration, that is, they are born in freshwater, grow in the ocean, migrate back to their natal streams to spawn, and then die; individuals are relatively large, prefer cold water, have delicious flesh and high commercial value, and are rich in omega-3 fatty acids (20-carbon 5-ene acid EPA, 22-carbon 6-ene acid DHA and 22-carbon 5-ene acid DPA), which are the main components of brain gold and deep-sea fish oil. Therefore, they are a high-end aquatic consumer product worldwide today. Within the Salmonidae, the species called salmon are concentrated in two genera, namely Oncorhynchus and Salmo, each composed of eight species. Among the most famous are six species in the Pacific Oncorhynchus genus: king salmon (chinook), red salmon (sockeye), silver salmon (coho), humpback salmon (pink), masu salmon, and autumn salmon (chum), and one species in the Salmo genus: Atlantic salmon.

In addition, rainbow trout, which was formerly placed in the Salmo genus and is now placed in the Oncorhynchus genus, is a globally farmed fish. The above commercially collective term "salmon" has now become the largest traded group among aquatic products in the world. Wild-caught salmon resources are limited and far from meeting world market demand, thus creating a global salmon farming boom. The earliest large-scale artificial farming was of rainbow trout, Atlantic salmon and coho salmon. Foreign rainbow trout salmon farming mostly uses all-female stock to grow large fish, which is convenient for making fillets, steaks and segments for supermarket supply, with a small size of 150--250 grams. The most popular size in the Chinese mainland consumer market is about 750 grams, suitable for ordinary families and banquets for one-time consumption. China's early imported salmon mostly came from Northern Europe, mainly Norway. The annual import volume of chilled fresh Atlantic salmon (not live Atlantic salmon) totals around 20,000 tons, so some people habitually call it Norwegian salmon. In recent years, the Chinese mainland has been carrying out large-scale production of coho salmon, king salmon, Atlantic salmon and rainbow trout in seawater aquaculture. It is expected that salmon produced in China with high freshness and good value for money will soon occupy the main consumer market of the Chinese mainland.

Artificially farmed salmon-trout grow relatively fast and have strict water quality requirements, so their finished products are free of any contamination and are natural green food, deeply welcomed by consumers. However, because the feed of artificially farmed products lacks some components found in natural prey, their muscle is mostly white. To improve product quality and meet consumer demand for salmon, producers add a carotenoid called astaxanthin to the feed at 40--60 milligrams per kilogram of feed. After a period of time, the product's muscle becomes colored, forming muscle marbling consistent with naturally caught products and appearing orange-red, thus improving product quality. This coloring process is called indirect coloring or physiological coloring, and is completely different from the dyeing of some foods. The astaxanthin used for coloring is all imported carotenoid, namely a precursor of vitamin A, which is a nutrient and can also enhance the nutritional content of the fish meat. In addition to astaxanthin, to ensure muscle quality, the feed used for salmon production must meet strict requirements, such as a protein content of >=45%, of which fishmeal protein is >=1/6, fat composed of fish oil and soybean oil is >=20%, and 15 kinds of vitamins and necessary mineral salts must also be added.