Coho salmon — this is one of the best fish in terms of gastronomy, it is characterized by low-calorie soft meat with a delicate taste and a small amount of bones. Few amateur anglers have been lucky enough to hunt this rare fish, and for most it remains a desirable but unattainable trophy.
Origin of the species and description
Coho salmon is a typical representative of a large salmon family. Salmon-like fish are one of the very first ancestors of all modern bony fish, they have been known since the Cretaceous period of the Mesozoic era. Due to the special similarity of the forms of representatives of this family and herrings, they were sometimes combined into one order.
The researchers argue that during the formation of species, they were even less distinguishable from each other than they are now. In the encyclopedias of the Soviet times, there was no order of salmonids at all, but later the classification was corrected — a separate detachment of salmon-like fish was singled out, which includes the only salmon family.
This ray-finned fish, whose oldest ancestors date back to the end of the Silurian period – 400-410 million years ago, is a commercial anadrob fish. Like many salmonids, coho salmon go into rivers for spawning, and in sea waters they only fatten up, hibernate.
Interesting fact: coho is a very valuable object of fishing, but its population is not so numerous , like other members of the large salmon family. From 2005 to 2010, Russian catches of coho salmon increased fivefold from 1 to 5 thousand tons, while the world's catches remained at the same level – 19-20 thousand tons annually.
Appearance and Features
Because of the peculiarities of color in some countries, coho salmon is called silver salmon. The back of adults in the oceanic phase is dark blue or green, while the flanks and belly are silvery. The upper part of her tail, the back is decorated with black spots.
Young individuals have more of these spots than mature ones, besides, they are distinguished by the presence of vertical stripes on the body, white gums and black tongues. Before migrating to the sea waters, the young lose their protective river camouflage and become similar to adult relatives.
The body of the coho salmon has an oblong shape flattened laterally. The tail is square, wide at the base, strewn with many dark spots. The head is conical, rather large.
When entering the river for spawning, the body of the male coho salmon undergoes significant changes:
- the silver color of the sides changes to bright red or maroon;
- males have significantly enlarged teeth, a strongly curved key-shaped jaw develops;
- a hump appears behind the conical head, and the body flattens even more;
- the appearance of the female practically does not change depending on the life cycle.
Mature individuals from the Asian part of the habitat can gain weight from 2 to 7 kilograms. North American individuals are larger in size: weight can reach 13-15 kilograms with a body length of about one meter.
Interesting fact: Small spawning males with a length of 20 to 35 centimeters are often called ” jacks.”
Where does the coho live?
This fish is found in the waters near Northern, Central California, found in the North Pacific Ocean, coastal rivers near Alaska. Its population is numerous in Kamchatka, off the coast of Canada, and is found in small numbers near the Commander Islands.
On the territory of our country, this fish is found:
- in the waters of the Sea of Okhotsk;
- in the Magadan region, on Sakhalin, Kamchatka;
- in Lake Saranoye and Kotelnoe.
Coho salmon is the most thermophilic of all types of Pacific salmon, with a range of comfortable temperatures from 5 to 16 degrees. In sea waters coho salmon spends about a year and a half, and then rushes to coastal rivers. On the American coast, there are special residential forms that are found only in lakes.
For coho salmon, it is important that the current in these reservoirs is not too intense, and the bottom is strewn with pebbles. In recent years, the habitat of the population of this salmon representative has narrowed significantly. Its spawning routes have been reduced or even eliminated in some tributaries, but it is still common in large river systems.
Interesting fact: There is a special type of coho salmon that is successfully grown on Chilean artificial farms. Fish are smaller than wild fish and have low fat content in meat, but higher growth rates.
What do coho salmon eat?
When in fresh water, the young feed first on mosquito larvae, caddisflies and various algae. When the body size of juveniles approaches 10 centimeters, fry of other fish, water striders, river bugs, adults of some insects becomes available to it.
The usual diet of older individuals is:
- young growth other fish, including salmon;
- crab larvae, crustaceans, krill;
- squid, herring, cod, saffron cod, and so on.
Due to the rather large mouth and the presence of strong teeth, coho salmon can eat quite large fish. The type of fish in the diet depends on the habitat of coho salmon and the time of year.
An interesting fact: coho salmon ranks third in the list in terms of fat content of meat, ahead of sockeye salmon and chinook salmon. This fish is frozen, canned, salted. Use all waste after its processing in the production of feed flour.
During spawning, the fish does not eat at all, the instincts associated with the extraction of food completely disappear, and the intestines cease to function. All forces are aimed at procreation, and exhausted adults die immediately after spawning is completed. But their death is not meaningless, since they themselves become a nutrient medium for the entire ecosystem of the stream of the reservoir, including their offspring.
Now you know where coho is found. Let's see what this fish eats.
Character and lifestyle features
This species of salmon begins its life journey in freshwater, where it spends about a year, and then migrates to the seas and oceans for growth and further development. Some species do not go far into sea waters, preferring to stay near rivers, while others are able to migrate over vast distances exceeding a thousand kilometers.
They spend about a year and a half in salt waters and again return to rivers or lakes, where they were born for the last stage of their lives. The duration of the entire life cycle of coho salmon is 3-4 years. Some of the males die in the second year of life.
Coho salmon keeps in flocks. In the sea, it inhabits water layers no lower than 250 meters from the surface, mostly fish are at a depth of 7-9 meters. The time of entry into the rivers depends on the habitat. There are summer, autumn and winter coho salmon. Individuals become sexually mature only in the third year of life.
It has been noticed that males mature faster in freshwater reservoirs. Coho salmon spawn much later than all other representatives of the salmon family. Anadromous species winter in the sea or ocean.
Interesting fact: This type of salmon is valued not only for tender red meat, but also for slightly bitter, but very nutritious caviar. It is not as high in calories as other members of this family and is considered more useful.
Social Structure and Reproduction
Sexually mature individuals are sent to spawn in the period from early September to January. In some regions, the spawning schedule may differ. The fish moves up the river only at night, very slowly and often stops to rest in deep pits.
Females use their tail to dig at the bottom of the nest, where eggs are then deposited. Laying is carried out in several approaches and each portion of eggs is fertilized by different males. For the entire spawning period, one female is capable of producing up to 3000-4500 eggs.
The female digs recesses for laying one by one upstream the river, so each previous one turns out to be covered with gravel from a freshly dug one. After the completion of the last, but the most important stage of their life, adults die.
The incubation period depends on the water temperature and can range from 38 to 48 days. The survival rate is very high, but, nevertheless, this is the most vulnerable stage of life, during which young coho salmon can become prey to predators, be frozen, buried under a layer of silt, and so on. The larvae remain in the gravel from two to ten weeks until they completely absorb the yolk sacs.
45 days after birth, the fry grow up to 3 cm. The young growth keeps near tree trunks, large stones, in creases. The migration of juveniles down the river begins about a year later, when their body length exceeds 13-20 cm.
Natural enemies of coho salmon
In their natural habitat, adults have few enemies. Only rather large and fast species of predatory fish are able to cope with coho salmon, besides, it has good protective camouflage and is difficult to notice in the water column. Seabirds cannot reach them, as sexually mature individuals stay at a considerable depth.
Young growth can become the prey of many predatory fish, including adult relatives. Greater damage to the population of this species is caused by changes in climatic conditions, loss of spawning sites due to the construction of dams, and urban sprawl. Logging and agriculture have a negative impact on water quality in traditional coho salmon breeding areas.
If in other species of fish the survival rate of eggs often does not exceed 50 percent, then the loss of coho salmon is no more than 6-7 percent. The main reason is the special arrangement of nests for laying eggs, which contributes to good aeration of eggs and embryos, and washing of waste.
Interesting fact: This type of fish in Russia can be caught by amateurs, but for this a special license is required. A large number of coho lives near Kamchatka — it has long been considered practically Kamchatka fish. In other regions of the country, it is much less common.
Population and species status
The last analysis of the coho salmon population near the coasts of Alaska and Kamchatka was carried out in 2012. The number of this most valuable commercial fish is now more or less stable, and nothing threatens it in the places of its greatest accumulation. Over the past decade, in the waters near California, Alaska, there has even been some increase in the number of this salmon representative. The only concern is the fate of one species of coho salmon, which lives only in a few lakes.
To maintain the coho salmon population, it is necessary to maintain favorable conditions in their usual spawning places, introduce a complete ban on fishing in some water bodies, and tighten control over the use of chemicals to treat fields with crops.
Due to the small number of enemies in their natural habitat , very high fecundity and impressive survival rate of young, coho salmon is able to independently restore its population in a fairly short period of time. A person needs only a little help, but the most important — do not rudely interfere with natural processes and do not create obstacles.
Interesting fact: Coho salmon can only be caught by spinning and fly fishing. This strong fish never gives up without a fight, so fishing is always very exciting.
Coho salmon, like all members of the salmon family, is a unique and very valuable fish for healthy human nutrition, but that's not all. The ability to swim against the current, climb up the rivers to achieve the main life goal, despite all the obstacles, makes this fish a real fighter, an example of purposefulness and strong character.