What Is Salmon Aquaculture?

Salmon, also known as salmon ^[1] , is a deep-sea fish and a very well-known migratory fish. It lays eggs in streams and rivers in the upper reaches of the Tamsui River, and then returns to the ocean for fattening. It is often used for food and has high nutritional value and therapeutic effect.

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How to properly distinguish salmon from trout or other salmon? We can distinguish them from the simple methods listed below:

1. Salmon is toothless on the top and bottom of the mouth, with only a few small teeth in the middle of the mouth. Trouts have serrated fangs on the upper and lower mouths;

2. Salmon is slender like a submarine, while trout is wide and has a large belly;

3. The scales of salmon are small and hard to see with the naked eye, while the scales of trout and salmon are larger;

4. The spots on salmon are white, gray, yellow, orange, and bright red, while the spots on trout are black or dark brown;

5. Salmon belly has a white striped edge on the bottom fins, wings and tail, which is very obvious and beautiful, while trout and salmon do not.

6. In the natural environment, salmon lay their eggs in autumn, while trout lay their eggs in winter and spring.

Salmon meat has the functions of tonic depletion, spleen and stomach, warming stomach, and can cure weight loss, edema, and indigestion. King salmon has the highest fat content. Red salmon, Atlantic salmon, and silver salmon have medium fat content. Raw pink salmon and salmon are lean meat. Salmon has the effect of nourishing and nourishing the stomach. ^[3]

Salmon spawning

In the autumn, horse fat grass grows. This is the most magnificent scene depicted on the ancient yellow sand desert. But in a river east of Seattle in the United States, "autumn salmon fat" is the true portrayal of this moment. Salmon is actually a rather wonderful fish. Born in freshwater rivers, it swims out of the sea during its growth period, grows up in saltwater environments, forages, and travels thousands of miles when it spawns, and returns again The birth of the next generation in the hometown of the freshwater environment is endless and endless. At the Salmon Breeding and Breeding Center in Seattle East, salmon from thousands of miles worked hard to swim up and down against the turbulent currents. Occasionally a leap, a big salmon up to sixty centimeters in length, swept up The meter-high fish ladder is full of dynamic beauty.

Salmon

What is the "fish ladder" mentioned here? It turned out that salmon have the instinct to swim up during the spawning period. In the environment of nature, they will go up the river along the turbulent river to reach the upper reaches, and then start to spawn. After opening, many rivers suitable for them to swim up have disappeared, so the conservation unit made artificial rivers: "fish ladders", creating a drop of one meter high every few meters, so that salmon can Go back. Interesting to say, some people have done experiments that allowed salmon to swim to the spawning ground in a stable river, eliminating the process of trekking and leap. In this way, salmon could not spawn eggs, because the Kinetic energy and hard work are actually the best recipe for their birth. Because of this, such an ingenious "fish ladder" will be built in the maternity education center.

In nature, the salmon parent-child relationship is very moving. In the autumn birth center, we saw a lot of strange salmon looking at each other. It turned out that during the long journey, salmon will meet In order to scare away enemies, male salmon will grow stabbed jaws during this period to protect the female salmon dutifully. When they complete their spawning responsibilities, they will die with scars, and the body that sinks in the water is the food for the small salmon born in the future. The small salmon grows and then flows into the sea. When the spawning period returns, This has continued for generations.

Salmon, a well-known migratory fish, spawns as follows: It lays its eggs in the upper reaches of the Tamsui River, and then returns to the ocean for fattening. Juveniles live in fresh water for 2-3 years, then enter the sea, live in the sea for one or more years, and return to their original native land eggs when sexually mature. The spawning period of Atlantic salmon, for example, is from September to February of the following year, but within a year, schools of fish approach the coast almost every month, and with the help of the tide, they trace back to the river from the estuary. To reach the upper reaches after entering the estuary, they must rely on their swimming ability. They have very strong strength to complete reproductive tasks. In order to fly over obstacles in the river such as waterfalls and weirs, they must use strong swimming. ability

Salmon

To reach the surface and jump over obstacles. Their behavior of "flying over" the waterfall has been praised as a spectacle for many years. They stopped feeding as soon as they arrived in fresh water, so they lost weight gradually after leaving the ocean and entering the river. When it first entered the river, the salmon had a healthy and graceful shape and a bright silvery white color because the broodstock stored sufficient nutrients in the ocean.

However, after a long journey, as soon as the spawning ground was approached, there were significant changes, especially the external appearance. The bright silvery color disappeared and became dark russet. The front teeth of the male changed, and the snout and lower jaw were prominent. The front end of the lower jaw is bent upward to form a hook shape. At the upper reaches of the river, the skin on the back became quite thick and spongy, the scales were buried in the middle, red and orange spots and markings appeared on the body, and black spots surrounded by white circles appeared. Salmon is also called red fish, and black strong mature female salmon is called black fish. Salmon muscles have undergone important changes during the river course. The salmon that has just left the ocean has firm and red muscles and rich fat in the tissues when it starts to go back to the river. However, when it reaches the upper reaches and spawns, the fat has been consumed due to the development of the reproductive organs. Gray and dull. The process of the rapid transfer of fat from muscle to the reproductive organs causes a sexual bimorphism in the fish. This is also a by-product formed during fat transfer. Because it cannot be completely excreted, a protrusion of the front end of the upper and lower jaws is formed, or it appears on the skin. Pigmentation.

Salmon spawning sites are selected in shallow waters where the currents are quite turbulent and gravelly. Once the broodstock arrives at the spawning ground, the males and females scatter in pairs, and then the females start to work, shaking the body and tail to dig out shallow depressions, and lay a few eggs in the depressions. The eggs were immediately fertilized by a male fish, and the fertilized eggs sank to the bottom of the depression. Because the surface of the eggs was sticky, the eggs could attach to the bottom of the river. The females then cover the eggs with fine gravel. Because the water can quickly pass through the gap between the fine gravel, the eggs can get sufficient oxygen. This spawning behavior is repeated every few minutes. After each spawning, the broodstock gradually swims upward. This spawning operation lasts for 1-2 weeks, until all eggs have been laid and fertilization is completed. Salmon spawning beds or depressions are called "reproductive beds", and a pair of salmon's reproductive beds can be several meters long. During the spawning period, males are generally very rude. If there is an invader, the males immediately chase and drive away, even if they encounter the same type of males, they will cause fierce struggle. The most difficult enemy in the spawning ground is male trout, which trouts sperm on salmon eggs when the male is not present.

Spawning is very costly for salmon, especially males. Broodstock after laying eggs appear very tired, with large heads and thin bodies. In the state of extreme fatigue, it is very difficult to return to the ocean after a long journey. Most individuals are either too tired, or sick or trauma and hungry, or killed by water birds, river otters and other enemies . There are only a few males who can return to the ocean to live a second time to spawn. However, most of the females can still return to the ocean, get rich food in the ocean, restore the previous normal state, reappear the bright silvery white, and the protruding part of the jaw also shrinks due to absorption.

Salmon black salmon

Black salmon was talked about in Miike's movie "Skin of Love".

It is said that black salmon were male when they were born. When they grow to fifteen centimeters long, they will become hermaphrodites, and then they are divided into females and males.

Natural enemy of salmon

Salmon is born in fresh water, but lives in the ocean, and goes back thousands of miles each year from the ocean to return to the place of birth to mate. The difficulties and obstacles on the way are equivalent to a long march. There are many and many natural enemies of salmon. There are sharks in the ocean, grizzly bears on the land, and white-headed sea eagles in the sky. There are all kinds of ferocious beasts. A lot of courage, but they have no need to look back for future generations. This long march of salmon is very tragic that the strong man will never return because most salmon will die because of the long march, and some will be captured by natural enemies, even if they are fortunate and not caught. Soon, life ended as most of the successfully mated salmon were exhausted. Most salmon die in vain, because they leave their roots, and by the next spring, new life will be born.

Salmon protection

Salmon

A course taken by a friend at the University of Washington who took a master's degree in architecture, said: Almost every class and every design project is inseparable from salmon. From small-scale street designs to large-scale community development projects, teachers always ask students to think about salmon, and strive to design the environment without negative impacts on salmon.

Salmon is a superstar conservation animal in Seattle. Why is salmon important? In the past, salmon was the main food source for Indians and an important cultural and spiritual symbol. Once, in the season of returning, thousands of salmon raced up against each other and returned to the place of birth to conceive the next generation. In the eyes of Europeans in Seattle, salmon is an inexhaustible bargain.

However, large-scale commercial fishing and environmental damage caused by urban development, today, many urban rivers can no longer see salmon. Seattle people know things aren't going well, so they need to act quickly. Conservation is to make Seattle a salmon-friendly city (SalmonFriendlySeattle).

The Seattle Public Works Bureau, which is in charge of public facilities, strives to reduce the damage to river habitats caused by urban drainage. At the same time, it also takes water from the river to meet the needs of citizens' drinking water, and does not forget to ensure the amount and hydrology of salmon. KingCounty, where Seattle is located, has tailored salmon rehabilitation programs for each river basin.

Throughout the Northwest, countless government units and environmental groups have also provided related manuals that teach people how to protect salmon in their lives, and even a little secret for "How to Become a Salmon Friendly Gardener". There are also local artists sending salmon prints that will slowly disappear over time, reminding people that salmon is on the verge of extinction.

Although salmon is still the favorite of the Seattle spotlight, today's concept of conservation has actually changed. Experts and scholars no longer focus on the protection of star species, but have begun to emphasize biodiversity so that diverse species can inhabit and reproduce in Seattle. Seattle's salmon conservation has expanded into an overall awareness of environmental protection, and not only the government and academies, but even private agencies are paying more and more attention to environmental protection.