Synopsis of Biological Data on the Chum Salmon, Oncorhynchus keta

The length and weight <strong>of</strong> churn salmon at maturity
(table 12) indicate that most Asian churn
salmon are 45 to 96 cm. long and weigh 1.0 to
11.9 kg. and that most NorthAmericanfishare
53 to 92 cm. long and weigh 0.8 to 13.4 kg.
Mature churn salmon under 50 cm. appear to
be more commoninAsia thaninNorthAmerica.
The maximum length and weight for mature
churn salmon is about 100 cm. and 20 kg. (Lovetskaya,
1948).
3.13 Mating
Promiscuous, male fish frequently attend
more than one female (Kuznetsov, 1928; Hunter,
1959; Strekalova, 1963).
3.14 Fertilization
External; ova and sperm are ejected simultaneously
into a depression excavated by the
female in streambed gravel.
Yamamoto (1952) described the fertilization
process in churn salmon. The area at which
the spermatozoan enters the egg is mark'3d by
a funnel-shaped depression. Penetration by the
spermatozoan takes place when the female
nucleus is in the metaphase stage <strong>of</strong> the second
maturation division; the fact that one polocyte
has already been extruded from the female
nucleus indicates that maturation <strong>of</strong> the egg is
activated by water before insemination. About
1 hour after insemination, a sperm aster de ­
velops at the base <strong>of</strong> the head <strong>of</strong> the spermatozoan
and the second polar division<strong>of</strong>the female
nucleus proceeds to the telophase stage. After
extrusion <strong>of</strong> t he second polocyte, the chromosome
mass begins its conversion into the
vesicular female pronucleus. The head <strong>of</strong> the
spermatozoan completes its metamorphosis
into the male pronucleus at the same time and
migrates from the margin toward the center <strong>of</strong>
the egg accompanied by the sperm aster. The
movement <strong>of</strong> the male nucleus starts about
2 1/ 2 hours after ins emination and is completed
in about 30 minutes. After completing its
metamorphosis a t about 3 hours after insemination,
the female pronucleus begins its migration
toward the male pronucleus. T his
movement also takes about 30 minutes. Conjugation
<strong>of</strong> the pronuclei generally takes place
within 3 1/2 to 4 hours after insemination. The
first cleavage spindle appears about 8 hours or
more after insemination.
3.15 Gonads
Neave (1948) discussed the relation between
the number <strong>of</strong> eggs produced by species <strong>of</strong>
Oncorhynchus and the differences in their life
histories which regulate the stability in relative
abundance between the species. Only
species with many eggs and relativelyfavorable
Table 12.--Range in length and weight <strong>of</strong> chum salmon at maturity in Asia and North America
Area Year(s)
Sample Fork
size length
Number em. !5&..
Weight Authority
Asia:
Okhotsk coast 1948, 1952-53 3,353+ 45- 78 Birman (1956).
Amur River 1925- 27, 1933 10, 848 48-96 1.2-11.9 Kuznetsov (1928).
1948-49, 1952- 53 19,013+ 45-90 Birman (1956).
Sakhalin 1946-49 2,397 45-82 1.1- 6.8 Dvinin (1952).
Primore (Tumnin River ) 1948-49 515 55- 85 Birman (1956).
Hokkaido 1956, 1958- 59 852 1.0-10.4 11 J
Honshu (Miomote River ) 1936 50-90 1.0- 8.0 Kubo (1938 .
.North Arneri c a :
Northwest Alaska 1920 448 53-80 1.8- 5.9 Gilbert (1922
1955- 59 1,324 1.4- 5.8 (1)
Central Alaska 1955 - 59 1,603 0 .8- 8 . 2 1)
Southeastern Alaska 1955-59 1,913 1.8-10.8 '1
Bri tish Columbia 1916-17 1,024 53-84 1.8- 4.9 Fraser 1921,
1955-59 1,784 1.2-13.4 (l
Washington and Oregon 1910, 1914, 1947-61 3,721 56-92 Gilber 1'913
Marr 1943 j
Oakley 1966 .
1955- 59 410 1.8- 8.6 1 )
1 <strong>Data</strong> on file, Bureau <strong>of</strong> Cornrnerc i al Fisheries, <strong>Biological</strong> Laboratory, Seattle, Nash. 2.
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