Biological Features Of Chum Salmon (Oncorhynchus Keta)

2023 Author: Molly Page | [email protected]. Last modified: 2023-11-27 22:49

As a representative of the genus of Pacific salmon, chum salmon naturally has a lot in common with all other salmon species, but it also has its own specific features, by which it can be easily distinguished from other species. The chum salmon is characterized by a large number of pyloric appendages (up to 185), 19-25 gill stamens, 12-15 gill rays, and 125-150 scales in the lateral line.

The range of chum salmon is limited to the North Pacific Ocean and partly the Arctic Ocean. For spawning, it enters the rivers of Siberia (Lena, Kolyma, Indigirka and Yana) and the Far East from Provideniya Bay to Peter the Great Bay and the river. Tumen-Ula. Across the American continent - from the Bering Strait to San Francisco.

Chum salmon (Oncorhynchus keta)

In the marine period, chum salmon, like other representatives of salmon, has a silvery color and a roll shape without stripes and spots. In the river, the color changes, the silvery color disappears, crimson-purple vertical stripes appear on the sides (mainly in males). Such a chum salmon is called a catfish, "glossy". By the time of spawning, the body of the chum salmon, as well as the palate, tongue, and bases of the branchial arches, become completely black. The teeth become larger (especially in the male), the meat becomes light pink or yellowish pink, skinny, flabby. Nevertheless, in comparison with pink salmon, its commercial qualities are much higher.

It enters rivers for spawning at 2-6 years of age. IB Birman (1950) indicates that the Amur chum salmon is characterized by spawning at the age of 3 years - 10-11%, 4 years - 77-83% and 5 years - 6-13%. Summer chum salmon r. Poronai, on average, over 12 years had the following age groups: 2-year-olds - 8.5%, 3-year-olds - 80.0%, 4-year-olds 17.0% and 5-year olds - 0.1% (Gritsenko et al., 1987).

Chum salmon have two races:summer and autumn, differing in a number of behavioral, morphological and physiological characteristics. There is reproductive isolation between the races, that is, in nature they do not mix during spawning, which leads to the strengthening of their genetic differences. The development of embryos of summer chum salmon occurs, as a rule, in the under-channel stream, and in autumn, in places where groundwater flows out. This ecological diversity is due to the different temperatures of the sources. For earlier spawning summer chum salmon, a lower temperature is needed, allowing embryogenesis to be completed in spring at the most suitable time. For the autumn chum salmon that spawns later than the summer chum, a higher temperature is needed to go out to sea almost simultaneously with the summer one. Hence, the summer chum salmon prefers the under-channel flow with a rather high temperature in autumn (up to 16 ° C) and low winter (less than 1 °)and autumn - groundwater with a stable temperature of 4-8 ° C throughout the entire period. Thus, belonging to different seasonal races means adaptation to different environmental conditions, contributing to divergence within the species.

Significant differences between summer and autumn chum salmon in the length of spawning migration routes, body size and fertility. So, summer chum salmon r. Amur spawns in tributaries at a distance of no more than 400 km from the sea, and the autumn one rises to the river. Ussuri, Hungari and others, which are 2,000 or more kilometers away. According to IB Birman (1950), the summer chum salmon has an average length of 56 cm and a mass of 2.545 kg, and the autumn chum salmon, respectively, 66 cm and 4.263 kg. These races differ in fertility and other characteristics.

Differing groups are also distinguished within the Amur section. According to IB Birman (1950), in the autumn chum salmon, there are 3 groups that have not only their own timing of the spawning run, but also some differences in meristic characteristics.

On Sakhalin, chum salmon are also represented by summer and autumn races. Autumn chum salmon are common along the entire Okhotsk coast of the island. On the northwestern coast, it is found in all rivers from the northern tip of the island to the Nevelskoy Strait. The largest herds reproduce in the Bolshiye Langry, Chingai and Bolshaya rivers. Along the eastern coast, the autumn chum salmon enters practically all rivers from Cape Elizabeth to Cape Terpeniya. In the southern regions of Sakhalin, chum salmon populations exist in the Naiba and Lyutoga rivers. In the area of the coast of the Sea of Japan, autumn chum salmon are reproduced in the basins of the Kalininka, Zavetinka and Yasnomorka rivers (Gritsenko et al., 1987). V. N. Ivankov (1972) distinguishes 4 groups in the populations of the autumn chum salmon of Sakhalin, differing in the timing of the course, fertility, size and age composition of spawning stocks,as well as the severity of the nuptial dress when entering the rivers.

Summer chum salmon is available in the river. Poronay (Dvinin, 1952). Most of it goes for spawning in the second half of July. In the second half of the spawning run, the autumn chum salmon go with it to spawn. There is a gap of about two months between the rune moves of both races.

Chum salmon (Oncorhynchus keta)

Kamchatka's chum salmon is also heterogeneous. It is believed (Smirnov, 1975) that the summer chum salmon of Kamchatka can be identified with the autumn Amur chum salmon by a number of ecological characteristics. However, in Kamchatka, summer and autumn races are also distinguished. VV Abramov (1948) notes that the autumn chum salmon is distinguished by its large size (average length 66.10 ~ 0.23 cm) and low fertility (21224-36). Summer chum salmon are smaller, with greater fertility, and fewer vertebrae. A special form of the Kamchatka summer chum salmon is considered to be the chum salmon r. Anadyr (Pravdin, 1940).

Chum salmon breeding in the rivers of the Primorsky Territory coast can be attributed to the autumn race. Spawning begins in October and lasts until December. The main age groups are from +2 to + 4 ° C. There are also + 5 ° C. Size of producers in r. Aspen - 66.1 cm, weight - 3.0 kg.

Article on the topic Developmental biology of chum salmon

Chum salmon spawning, as shown above, begins at different times depending on the population and climatic region. Summer chum salmon in the Amur spawns in August, at temperatures of 6-7 ° C. Autumn breeds at the end of September and continues to spawn in October - December even under ice.

On Sakhalin, the autumn chum salmon begins to spawn at the end of August, the main course begins in the second half of September - early October and can continue until December. In p. Naiba distinguish 3 moves of autumn chum salmon, differing not only in the timing of entry to spawning grounds, but also in water temperatures (15 °, 12 ° and 0.5-0.2 ° C).

Chum salmon enter rivers for spawning with gonads at different stages of maturity and often take a long time to ripen. In order to assess the degree of maturity of the gonads, it is necessary to know the classification of gonadogenesis. At present, the classification developed by N. A. Butskaya and O. F. Sakun (1968) has been adopted.

Source: V. P. Bushuev. Chum salmon cultivation guide