Page 1
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ic76,4 ' f FISMUJES•4P.,t.i.204 ;01, OF CAMA
!;/.:iftl:.\0, B. C.
ti
FISHbRIES RESEARCh BOARD OF CANADA
Translation Se.ries ',M). 1064
Biological study on hybrids of the salmonid fishes. A note. of F1 hybrids between chum (Oncorhynchus
keta) and pink salmon (Onconlynchus gorbusha)
By Toyohiko Hikita and Yosajiro Yokohira
From: Sake Masu Fukajo Kenkyu Hokoku. Scientific Reports of the Hokkaido Fish Hatchery. No. 18, pp. 57-65, 1964.
Translated by the Translation Bureau (MI) Foreign Languages Division
Department of the SeCretary of Stat:-; of Canada
Fisheries Research Board of Canada Biological Station, Nanaimo, B. C.
1968
29 typescript
Page 2
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Biological Study on Hybrids of the
Salmon,id Fishes. (57)
A Note of F1 Hybrids between Chum
(Oncorhynchus keta) and Pink Salmon
(Oncorhynchus gorbuscha)
Toyohiko Rikata and Ybsajiro YOkohira
Scientific Reports of the Hokkaido Fish
Hatchery No. 18 pp. 57/—, 65 (1964 )
The hybridization between ehum and pink saimon was carried out du ring 1961 to 1963, and the hybrid • fry obtained were released from the Horonal river, Nitami Province, in spring of 1962 mid also 1963.
•The observations On te feature of the hyl;rid fry donc before release are 'summarized ;is follows. The
fertilization and development in reciprocal cros>,-breedings proveeded normally, the cleavage having
been ahnost the same ,s those of ordinal eggs and embryos developed >bowed no abnormality-. ln such f
hybridization. the survival of 0. /zeta (feinale)x 0. goelmscha (m(tle) was higher than that of 0. gothascha
Uvinale)x--0. beta (male) throughout three years, having been 93.3 to 94.5 per cent in the former and in
the latter 8.1.8 to 91.5 per cent, respectively. The hybrids grew with a goo. (1 rate, especially in male
- ping x female chum case. When observed externally the ground coloraticin of the hybrids of 0. hela •
(female)x 0. gorbuscha (male), is obviously divided into two types; namely about a half of the fry is pretty
greenish blue or durk .green while the other hand is light•dark brown, and in all of ;the hybrid of 0.
gorbuscha (fernale)x 0. keta (male) is darltisli brown as seen in the normal fry of parent species. Furth- . . ermore: in the former the 'parr mark along the body side tvhich are a characteristic to the chunisalmon
show much variations, in some being absent as pink fry while in the other present distintly. However, in the latter all have the pztrr marks as chunl fry. Such parr eharactet; seems to vary according to the
' male parent used. The approximate number of hybrid fry released intô the . river wcru 176.600 in the
first year and in the following year 149.186 were released after rearing with various foods for several .
months. We except the fry released to come back successfully as abult sa:mon in several ytutrs.
_ - - - -
Publication No. 178, Hokkaido Sake, Masu HatcherY4
Page 3
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Translator's Note.
It appears that the accurate translation of common !
or of academic names is impossible unless it is done by a!,
specialist with the actual sample in hand.
The major difficulty is that, while the common name,
masu", "sake", and "iwana" may be translated to English
names trout, salmon, and char, respectively, these common) •
names also refer to fish belonging to other species, genu's, 1
and family when they are used together with prefix or suffix
or with adjectives composing compound namea.
The translator also noticed that the common names
clearly vary depending on locality. For example, a kind of
masu" called "boni masu" (beni..pink) in Honshu of Japan
is usually translated to pink trout. However, the translator
does not know the identity of "beni masu" and "Karafuto '
(Saghalien) masu".
After the translator referred to two authentic
dictionaries, a) Japanese-English Scientific Tenms, Zoology,
compliled by the Ministry of Education of Japan, published by
Dainippon Tosho Publishing Co., Inc., 1956, Revised Ed. 1965,
and h) Kenkyusha's New Japanese-English Dictionary,
S. Katsumata, Editor in General, Kenkyusha Ltd., Tokyo 1954,
the following translation waS applied. They are listed in'
the order of appearance, and the translated words are the
ones which appeared in the translated .article:
Page 4
•
•
-3-
page Japanese Names Appeared Translated Naines
57 Sake-ka salmon family salmonoid fishes
Sake chum (Oncorhynchus keta)
Karafuto masu pink salmon (Saghalien trout) (Oncorhynchus gorbuscha)
Sake-rui chum class
Masu-rui salmon class
Iwana-rui char class
Iwana-zoku char genus
58 Kawamasù river trout
Sake-zoku salmon genus
Yamabe see Sakura masu
Biwamasu biwa trout _
Himemasu hime trout
Sakura masu - sakura trout e:Yamabe (Oncorhynchus masou)
. _ 59 Ginmasu silver trout
(Oncorhynchus kisutch)
Amemasu • rai trout (Salvelinus leu omaemts)
Ito (Hucho perryi)
Chika (Hypomesus japonius)
Kawa yatsume . river yatsume (Lampetra japonica)
Sunayatsume
Sayori
sand yatsume (Lanpetra reissneri)
(Heniramphus sajori)
Page 5
Page Japanese Names Appeared Translated Names
59 Menada (Liza hematocheila)
Ugui (TribolOdon hakonensis)
FUkudojo (Barbatula toni)
Itoyo (Gasterosteus aculeatus)
Hanakajika (Cottus nozawae)
Ukigori (Chaenogobius urotania)
YOshinobori (Rhinogobius brun neus)
Kawagarei river karei (Platichthys stellatus)
62 Hokke lockington
Tara-rui cod
Tara cod
Madara ma cod (true cod)
Suketodara Suketo cod'.
Page 6
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It is very well known that even the higher ver-
tebrates can produce a hybrid between different species of
\P the same genus. The fishes which belong to the genealogi ally
lower class in the animal kingdom produce a hybrid not only
between different species but also between different genei-a.
The fish hybrids can be produced with most of teleosts but
rarely with selachians. The fish hybrids are produced by
experimental crossine but they have also been found in nature
by a number of research workers. It has been known that he
chum and salmon class, both of which are classified to the
lower class fish by genealogists because of their certain
primitive physical structures and of their capabilities of •
surviving in both fresh and salt water by quickly adapting!
their ecological fitness to the changing environment, have
some other characteristically close, inter-species, intert
genera relationship. Therefore, the hybrids between the
two species belonging to these classes can be obtained muCh
easier than between other different species. Of the salmon
family fishes, Winge and Ditlevsen (1948) and Alm (1955) have
euccessfully produced experimental hybrids of Atlantic chum,
salmon and char classes, and Inaba (1953) of river trout of
char genus, and Yamabe and biwa trout of salmon genus. •
Of the Pacific salmon, Fujita (1926) and Foerster (1935)
discussed morphogenesis of hybrids between various species.
Hikita (1962) concluded that the hybrids between chum and ;
hime trout and between chum and pink salmon, which are closely
Page 7
related morphologically and ecologically, should have ex- 1
collent probability of survival. Recently Terao and
Hayashinaka (1961) prepared a hybrid of hime trout of
Shikotsu Lake and salmon'of Chitose River and reported that
the hybrid showed excellent growth. They are feeding the
hybrid fry in a freshwater pond and have released some to
lakes and ponds and continuously studying their growth and ; eging, with the purpOse of improvement of the breeds by '
crossing.
The crossing of pink salmon and chum has been known
to be experimentally feasible, but there SOOM to be sonie
difficulty in practice as well as acedemic problems to be
solved. Recently Karinine Hatchery (previously Taranhaku
Hatchery Of Japan) at the west coast saghalien of U.S.S.R.
is experimenting the crossing of these two species.
Although we do not have detailed data of the results,
the prime purpose of the study has been described by the chief
of Karinin Hatchery as "This hatchery started its operation
in 1954, and somehow in that year, we found only female fish
of chum coming up the stream to the spawning area. We were
convinced that the natural source of chum in Karinin area
would be extinct if the situation was left without correction.
There was only one thing that could be done to save the
extinction of the fish. It was to fecundate the eggs of chum
It In Hokkaido Translator's Note. tat Transliterated (T.N.)
Page 8
: • s •
-7-
with the spermatozoa of salmon. The work was risky but we
* decided to take a chance."
We do not have a record of releasing this particular
hybrid fry to rivers. Therefore, we have experimented on
crossing of chum and pink salmon that come up the Horonai
River which runs into Okhotsk Sea, fed the fry for a certain
period, and released.to Horonai River.
We.also made detailed observations of the fry in order
to accumulate the fundamental knowledge on the possible
fixation of the hybrid thus produced. This report is a
summary of the works carried out by us in the last three years.
The authors thank Mr. Takeo Mihara, Chief of Hokkaido
Salmon Trout Hatchery, Mr. Fumihiko Hayami, Assistant Chief
of same, Mr. Seizo Sano, Chief of Investigation Section of
sanie, and Mr. Shigehide Takeda, Chief of the Kitami Branch
Station of same, for their various, useful suggestions. The
authors are indebted to Mr. Toshio Sakaguchi of Atsuki Branch
of Hokkaio Hatchery (previously of Horonai Branch of same),
Mr. Norio Urushizaki of Fisheries Section of the Government
of Soya (previously of Kitami Branch of Hokkaido Hatchery) and
the members of the Capturing Group of Horonai Hatchery for
their assistance in obtaining the references, catching the
fish, feeding the fry, and sampling, and to the members of
Otake Fisheries Association for the storage of the feed and
other technical assistances.
I
•
e Naigai Fisheries News 1959 (Published November 24)
Page 9
Outline of Horonai River
Horonai River is situated in the north-west of ,
Otake, Monbetsu Province, Hokkaido, and has relatively clean
water running into Okhotsk Sea. The total river length is
35 km and the river has Osa river, Pankeoropirikai river,
Penkeoropirikai river, Ikitaraironie river, Shyakin river;
Orowen Horonai river, Nisekoomanai swamp, Ottotsu swamp and
others as its branch. streams running into the main stream.
Near the bank of the lower stream of the river, there are
farms and pastures, and the upper stream turns gradually to
a ravine, which is covered by thick, virgin shrubbery. The
-right bank of the mouth of the river is a tableland, where
the villages of Horonai district are located. This plateau
also oVerlooks the estuary. Since the estuary is covered
by sand, the sandy beach is constantly subjected under the
severe 'effàct of wind and waves, and also the direction of
the river water running4nto the sea changes almost always.
As there is only.% small difference of the height
above the sea level even at a distance of about one km. along
the river from the sea, the sea water back-flows at the full
tide. There is a dam for a generating station at about
:6.5 km. from the estuary and, thereforb, chum and salmon
cannot reach up-stream beyond this dam.
Also ; there is Horonai branch station of Hokkaido Fish
It Table .of the Rivers in Hokkaido. Documents of Hokkaido Salmon-Trout Hatchery 101, 1955.
Page 10
• t•
-9-
Figure 1 Map'of Horonai River.
Hatchery at about -,3 km. from the river mouth, and at 2.35km.
up-stream at the branch stationA
, a fish capturing station
that belongs to the Horonai branch station is located. The
Horonai branch station is engaged in artifical hatching of
three kinds of fishes of salmon genus each year.
11 or from the esturary (T.N.)
Page 11
•
-10-
Thus, only the lower stream of this river is pre-
sently being used for the fisheries industry.
The quality of the river water is shown by the results
of quantitative analysis in Table 1. Turbidity of the 'river
due to à small-scale, starch powder manufacturing factory and
relatively large-scale digging of pebbles is the only and the
slight unfavorable effect for the fisheries in this river.
Since Horonai river has relatively large numbers of
chum and pink salmon coming up-stream every year, a part of
the river;, down-stream at the dam, was designated as a protected
area, where salmon fishes are protected for their natural
breeding in 1963. Since 1962, a group of research workers
have been studying the various problems related to natural
breeding and spawning in this saine protected water of the
- river.
Table 1
MI 6.6 •
COD 6.5 ppm
151(1 15.0 *
P.Ot 0.068* U 113 * So,
8.2 *
Ca 14.0 * . N1 11 - N 0.02 * htte; D. *
'Matter
Analysis by Mr. Hiroshi Eguchi
The fish that inhabit in or come up-stream to (59)
this river from the sea are chum (Oncorhynchus keta),
Page 12
sakura trout yamabe (Oncorhynchus masou), pink salmon
(Oncorhynchus gorbuscha), silver trout (Oncorhynchus kisutch),
rain trout (Salvelinus leucomaenis), ito (Hucho perryi), chika
(Hypomesus japonicus), river yatsume (Lampetra japonica)
sand yatsume (Lampetra reissneri), sayori (Hemiramphus sajori),
manacle_ (Liza hematocheila), ugui (Tribolodon hakonensis)
fukudojo (Barbatula tohi), itoyo (Gasterosteus aculeatus),
hanakajika (Cottus nozawae), ukigori (Chaenogobius urctania),
yoshinobori (Rhinogobius brun nous), river karei (Platichthys
stellatus) and others.
The numbers of the captured chum and pink salmon in
the Horonai river within the last twenty-six years are taken
from the Hatchery Report and shown in Figure 2.
Figure 2 shows that the number of captured chum is
relatively large in the seven year period between 1942
(Showa 17) and 1948 (Showa 23), and became gradually smaller
and it is presently somewhat stabilized.
The number of captured pink salmon repeats approxi-
mately in two year cycles of large and small capture, although
we miss the number for 1946, and it was particularly large
for the eight year period between 1951,(Showa 26) and 1958
(Showa 33), and later it.became considerably small.
-
Page 13
-12-
. . 40117
1
. (.i / • h ill
Q o (1.r•r1)..1.. Ido 11.14 i g • . 0— — ,Do i'? 7 eiè .:11.,,F.tt.te
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11.113
S.CIA II
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1.0»
1 s
u
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r.en
2
II
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SIUUMUU
Figure 2
The number of Chum and Pink Salmon caught in the Horonai River in the last 26 Years.
1 117 43 a 43 41 IS 07 47 YEARS
37
05
0 Ef il , I j 4 11 I '‘
1.
11 ? 1 1 i 1 • I g
I g 1 1 A 1 , 1 ,
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Ig II I I I 1 1 1 1 \ i ..
-81 88 I il I I I I
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a 1 I li 1 4 0 i 4. e) s:
111 I. 1/
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t t
it
Page 14
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Material and Method.
The eggs and spermatozoa used for this study were
obtained from the two species of parent fishes, which were
caught in the Horonai river. Particular attention was paid
in selecting the parent fish and only the eggs in full
maturity were chosen from the good parent fish. Extraction
of thé eggs and the fertilization were conducted by the dry
introduction method which had been used in this hatchery.
The fertilized, hybridized eggs were treated in the same
way as the normal eggs , without uSing specially controlled
hatching tanks, since the comparison of hybridized eggsee
and normal eggs could be done more conventiently when they
were compared in the same hatching room. The conditions of
controlling fry varied slightly from a year to another, during
the three year period of experiment. In order to compare the
observation results of growth of the hybridized eggs, pink
salmon ( ) x chum ( ) and chum ( e ) x pink salmon' ( ),
were completely isolated and handled separately.
Each year, 100,000 eggs of one combination, and thus
total 200,000 hybridized eggs were prepared. In the first
year, the breeding of hybridized fry was conducted as a
preliminary test, and the hatching and the feeding of the fry
11 Normal Egg - Fertilized egg from the 'parents of the same species.
«elt Hybridized Egg - Fertilized egg from the parents of the different species.
Page 15
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were carried out under the saine conditions as those for the
normal eggs, but in the second year, the fry were released
after feeding under the experimental conditions.
In 1961 at Kitami branch station, we conducted a
set of the same experiments as were done at Horonai branch
station, using four parent fish, to determine the limit
of possible pure water breeding of fry and to observe
the morphogenetic change during their growing period.
(60)
• 'Results of Observation.
The size of parent fishes used for the hybridization
and their eggs.
Male and female parent fish used for the hybridization
were checked carefully and their size was determined. As
an example, the parent fishes (male and female) used in
1962 had the size shown in table 2. The size was almost the
same in 1961 and 1963. .
The age distribution of the fish listed in table 2
was as follows: the four year old individuals had the
largest distribution, 60.7%, the five year old 29.4%, and the
three year old 19.9% in case of chum. Almost all of the
pink salmon were two years old and only three of them were
suspected to be three years old. The weight distribution was
not investigated, but chum weighed between 2.5e,-J3.6 kg. and
pink salmon 1.3, ■ 2.6 kg.
Page 16
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The size of eggs usually vary in their diameter
depending on the river where they were spaWned, and also
depending on the size of the parent fish that reach up-stream
of the same river to spawn. These findings had already
been confirmed by chum (Watanabe, 1955). The average egg
diameter of chum is about 7.8 mm and that of pink salmon
is around 6.0,./6.5 mm.
Table 2
Aver Total Fork age Sample .
SIDecies Length Length Fork Number chum pink 53. 5-78. 0" 52. 0-76. 5" 68. 5" 51 .-klead salmon 52. 5-67. 5 50 0-64 7 56 7 134 _ i_ • . - '-----
Fertilization and hatching of the hybridized egg. (61)
Since we suspected that the hybridized eggs might
be weaker and more delicate than the normal, artificially
fertilized eggs from the male and female of the same species,
- we have paid particular caution in extraction of eggs and
fertilization. The eggs after fertilization were treatecqin
the same manner at storage, sterilization and other steps as
were done for the normal eggs.
We did not find any difference in the proceedings of
the hatching between the hybridized eggs and normal eggs, às
far as they were observed with naked eyes. However,
Page 17
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Kobayashi (1963) has published, in a separate article, his
microscopical observation of the process of fertilization
and hatching of hybridized eggs. The ratings of hatching
of reciprocal, hybridized eggs are shown in table 3.
Table 3
Combi
nat
ion
;-• ce G) ›-■
g.:12.17Kx()
›
Q C) O IUD O 40
C4 CO
G)
I I • 0 Pi al
0 0 H >>
O 0 0 b.0 b.0 cI-1 CD
rd 4-.) ai g O 0 0
F.A en O G)
Ç- G) ai ai CD
b0
bf) .1-1 4-4 b0 Pi 0 O 0
O • rcl G) •,--1 • > 1:10 O G) 0 to A '0 Ha
tched fr
y.
Hatch ra
te.
Rele
ased fr
y.
4;1-lead i33. 3
• 8.49 ' 91,510 91.51 :• •
18.01 81,592 81.",9 nOt completed
1961 sa]xmon 1962
( ) 1963 C1'11.1111" '
.4)- (•) 1961 chum pinrk 1962
6) 1963 • :-..._.1_111_171tar_
100, 000 e1: 9, 660e. 7,00O ' 16. 66%; lee,
.100,000 6,810 1,680
100,000 9,187 8,821
100,000 4, 990 1, 750 . 6. 74 93, 260
100,000 3, 180 2, 290 5. 47 94, 53.)
100, 000 3,844 1, 881 5.72 1 . 91, 275
93.2'3
L'53 • not
94. 28 • completed
The comparison of the records of the both hybridizations
in table 3 shows that pink salmon ( e ) x chum ( t) has inférior
. rating throughout the three year period than chum (g) x
pink salmon ( de). The hatching record of the normal eggs, on
the other hand, shows the slightly higher rating for pink ;
salmon than chum, as seen in table 4.
Page 18
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« Table 4
0
0 ›
0 0 ttO
tIO — ›-1 -
• 0 0 4-,
o cd C4 PG
rct cd o
rcj
0 .12b
churn 1961 I 4, 950, 000 :!•' 379, 000 1962 2, 420, 000 129, 500 I 2.290, 500 J 94.6 2, 270, CC:', 1963 2, 473, 000 124.200
. . .
••••
I 1961 I 1, 4 00, 000 111,300 i 1,368, 7. 00 1 92.5 I 1,360, ■.4.,0 . 99. ..t .-- 5 1962 i 1, 110,000 50, 300 1 1, 059, 700 95.5 : 1, 050. CV.) . ... •
7 ....„ H
1963 I 1, 142, 500 82,900 I 1, 059, 600 .. 92.7 in
However, by the normal eggs, there is not much
difference of hatching rate between the two species. Therefore,
the poor rating of the eggs of pink salmon ) x chum (e)
may be explained best and only by the observation, as already
reported and discussed by Kobayashi (1963) in the separate
article, that the eggs of pink salmon (e. ) x chum ( ) need
much longer time than the reverse hybridized eggs, after
fertilization until the first fission. We did not find any
recognizable difference in the total hatching days between
the hybridized eggs and normal eggs.
Page 19
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The treatmebt of the hybridized eggs after hatching
was carried out in the following manner. Namely, in the first
year, as we have forcused our efforts in the production of
hybrid fry, the fry were left in a breeding-pond immediately
after hatching, and after absorption of their navel-sacks
were completed, they were released to a river, in the saine way
as the artificially fertilized eggs have been 'treated at the
hatcheries in the past years. The release rates based on
the numbers of hatched fry are 99.4% for . pink salmon and 99.5%
for chum in 1961 at Horonai branch station, 'as shown in
table 4. Therefore, we assume that the same release rates held
for the hybridized eggs. Calculation based on the afore-
described release rates show that the numbers of the released
. fry in the first year are; the number of hatched fry 83,340
multiplied by 0.994 is equal to 82,840 for pink salmon (.?..)
x chum (s), and 93,260 x 0.995 is equal to 92,790 for
chum (..c.?. ) x pink salmon (1). In the second year (1962), the
two kinds of hybrid fry after hatching were moved separately
in two outdoor troughs (Figure 3) with the size of
360 cm x 160 cm x 120 cm. -The troughs were placed in a
• spring pond up-stream of the breeding pond which is currently -
still being used.' During the feeding in the troughs, the
comparison of the rate of growth, and external» morphological
change of the two hybrid fry was conducted.
Page 20
-
.e •,_ , . .
• .• .
/'
-19-
f.
• .• •
Fig. 3 Outdoor trough for rearing hybrid fry in the spring pond.
(Photo by Yoneka%;/a)
As the feed of fry, the liver of chum, meat of cod
and lockington,codroe (eggs of ma cod and suketo cod), and
vegetables were used. At the beginning, only the liver wâs
used and later as the fry grew, the afore-described feed
stuff was mixed and knead at a proper ratio, and used as a
feed.. The feed was placed in a wire-basket suspended in the
middle of each trough, and feeding was done twice a day,
in the morning and in the (pirening.
The seek-after-feed behavior of the fry was typically
timid at first, but later as they became acquainted with their
feed, they were positively after the feed. It was found that
the hybrid fry of chum (g) x pink salmon (0 ) were more .
active in seeking after the feed throughout the three year '
experiment than the reverse hybrid fry, and they also absorbed
the navel-sack faster. The absorption of the navel-sack by
Page 21
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both hybrid fry in 1964 is compared in table 5.
Table 5
Jan. Feb. Mar. ' 10 4 3
chum (.1- ) x pink salmon (e) ,„,,, 100,, Pink salmon ( q ) x chum ( e ) m 80
* Once the wire net of a trough which held the fry
of pink salmon (1-) x chum (e) was broken, and 33,250 fry, died, and some more escaped to the spring pond. They were
caught on April 10th, and on the same day 58,250 fry of '
pink salmon (..?) x chum (g) and 90,934 fry of chum (..e ) x
pink salmon (i ) were released at the joint of Horonai river
and a branch river Osa, which is the down stream of the
breeding pond. In the third year, 1963, 81,992 fry of pink
salmon (e- ) x chum ( ) and 94,275 fry of chum ) x pink
salmon (e ) were hatched and they are being reared in the
same feeding trough. These mayipe:releaà- ed at theend of Ma.rch,
1964, after marking each hybrid species separately so that •
the ratio of completion'at maturity could be obtained. •1n
table 6, the growth of the fry which were released in 1962 •
is shown.
A which year is not described, but it must be 1962 from the number of the released fry. (T.N.)
Page 22
Chum (.?- ) x pink salmon ( t) Pink Salmon (e) x chum rg),
bn c4-ig 0.-1 H
aS <D r4
â A c/a
1962 11.26
1963 1.10
1.17
2. 4
2.20
3. 3
3.22
0 0
aS 4 W
H4 cd -p p. 0 <4
EA
(-n 2.04-2.35(2.18)
2.97-3.47(3.28)
3.23 --3.60(3.39)
3.33-3.98(3.59)
3.50--4.12(3.71)
3.46-4.20(3.76)
8.55-4.14(3.80)
2.72 --3.10(2.89)
2.85-3.20(3.04)
2.98--3.44(3.17)
3.02--3.58(3.19)
3.06 --3.44(3.24)
3.34-4.23(3.70)
bO g 0G) 4 b0
4-1 F-1 cd
4-5 0
cm 2. 00 25(2. 13)
2.64--3. 00(2. 77)
2.63-3. 15(2. 93)
2.98—;. 13(3. 02)
2. 93-3. 22(3. 09) 1
2.84 32(5. 07)
2. 97--3. 33(3. 12)
3.02-3. 74(3. 39)
;S1 . 4) 40"
b0 4 M
) G)
o d
2.37-2.68(2.4e
2.53-2.64(2.58)
2.42--2.76(2.58)
2.38-2.75(2.56)
2.35--3.05(2.62)
.2.50-3.10(2.85) _ 4.10 3.92--4.95(4.35
2 1 - ... -;
1.76 --2.12 .(1.89)1§ '21
2.16--2.58(2.36)
,
15
0
g-t 0.) H
,C)
5 g z re,:1
1.80-2.15(1.95) 14r 21
2.54 -2.96(2.815F' 14
4-)
0 0 CIO
14 0
›I■
le■
15
9
12
12
10
13
ef-1 0
g-4 gl) H
6
9
10
11
-21-
6 Table
IX Appears to be due to the limited numb sampling from the trough.
ers of
The data shows that, although there is considerably (63)
a large difference . in the size of individual samples measured,
the fry of chum ) x pink salmon (1 ) grew as large as 1.9
times of the size on the starting day of the measuring after
a 136 day period, but the reverse hybrid grew only 1.5 times in
the same period. The mortaility of the hybrid fry of pink
salmon (g) x chum ) was also a little higher, throughout the three year - period, than that of the reverse hybrid fry.
Page 23
• "*.
-22-
Difference of the External, Inherited Characters of
the Hybrid Fry. •
The sizes of both fry are different, and that of
pink salmon (4?) x chum is smaller than the other,
corresponding to the smaller size of the egg of pink salmon.
After the fertilization, while the deutoplasm is absorbed
gradually and pigments appear, the differences of the extecnal
characters of the hybrid fry become evident.
First, the comparison of normal fry of chum and pink
saimon reveals certain distinct differences of the species.
Namely, the chUm fry have the characteristic pearl-mark of
the family on the body side, but pink salmon fry do not have
it, but both fry show the same ground color of brown or dark
brown on the posterior body. The most remarkable differences
of the hybrid fry and normal fry can be found by comparison
of the body color and the pearl mark. Particularly the body
color.of the fry, chum (e).x pink salmon ( 1à), show two
distinctively different sets of color. One is indigo blue,—
dark green.,..-green from the head to the tail, and the other,
4 which is the color of the half of the total hybrid fry, is
light brown ,,,dark brown and resembles the color of the nànnal
fry. On the other hand, all of the fry,.pink salmon
x chum _( 6 ), have light brown—Jdark brown color. The develop-
ment of the pearl-mark varies considerably by the fry,
0 chum (+) x pink salmon (C), and some fry do not developl
the mark at all while other. fry show the characteristic park
of chum fry, and still others develop only smaller numberà of
Page 24
-23-
the mark or obscUre marks. In general, however, the green
colored fry showed the tendency of showing no mark at all.
On the other hand, all of the fry, pink salmon (e) x
chum ( e), showed the pearl-mark and the mark was relatively
much clearer than that of the reverse hybrid fry. Their small,
black dots on the back werè also similar to those of the '
normal chum fry (Figure 4).
/
.\
0 • C.,.
4 Remarkable ft.attireA of both hybrid fry :
. Ahoy, _P i nk (Fon;(1.4 x Chtun 1..`. 1 Iklow - Chum (Female) x Pink tNt ,1
Page 25
In
not
-24-
The green colored fry seemed to have a better chance
of survival as the green color functions effectively as a
protective color when they hide by the hydrophites in the
spring pond, or later when they are released to the river.
Finally, we want to reflect the reason the reason for
choosing the hybrids of chum and pink salmon, the later
release of the fry and the related complicated circumstances.
First we chose the particular species as we intended to breed
and release the fry that could live in the'ocean at a later
period . . In order to . satisfy the purposes, 1) the artificially
hybridized fry had to be produced from two species that have
the same area of circular trip in the ocean and that come to
breed to the same river, and 2) these two species must have
totally or partially overlapped period of swimming up-stream
in the river, or have their periods of coming up-stream close
enough so that the first arrival could be saved . under co trol
to meet the second for the possible hybridization.
The particular advantages of choosing pink salmon and
chum for hybrid formation are based on their clearly dis-
tinguishable«morphological characteristics. Naffiely 1) their
eggs are different in size; 2) their fry are different
size immediately after hatching, and 5) pink salmon does
have the pearl-mark which is characteristic to the family of I
chum, but chum has that mark. Further, since the adult ish
î of both species are distinctively different, it was expected
that the adult hybrid fish from the two species might still
show some different characteristic appearances in future when
Page 26
-25-
they return to the river. We have already known that the adult
fish of the two pure species have the following different
characteristics when they return to the river to breed. They
are: a) the posterior projection which is a secondary sexual
characteristic,
h) appearance of puberty color,
e) ground color and spot formation,
d) pigment distribution at the palate,
e) the number of gills and their shapè.
Besides, pink salmon attains full growth usually in two years
but chum in years, and mostly in four years. The degree
of the growth of their scales are also different.
After considering .all .the factors listed above,
thé two species were chosen. The authors, at the beginning of
this àtudy, expected the return of the. adult hybrids in three
years to the saine river. In the autuMn of 1963, we could
catch (à) two year old hybrid(s) which was strongly suspected
to be the hybrid fry released in the previous year, and,
therefore, the expected.probability of the return of the three
year old hybrid has become better. The authors plan to pilblish
the results of morphological observation of the hybrid later.
(64)
Page 27
Summary
We report the progress of a three year study between
1961 and 1963 on the artificial reciprocal hybridization of
male and female of pink salmon and chum.
1. Hatching rate of the hybrid eggs of pink
salmon ( .e. ) x c1i ) was 81.--191% which
is inferior to that of normal eggs, but
that of the hybrid eggs of chum (4a) x
pink salmon (e ) was higher than 93%, which is almost the same of . that of normal eggs.
2. Growth of the body and the disappearance of
the navel sack of the fry were . faster by the
hybrid of chum (i. ) x pink salmon ( e) than by the reverse hybrid.
3. The most distinctive chromatic .characteristic
of the hybrids was that about half of the
hybrid fry of chum (41) x pink salmon ( e)
had green or dark green colr which is entirely
different from the color of normal fry. The
pearl-mark of the hybrid fry varied considerably
and it ranged from non-existant to as clear as
the normal fry.. On the other hand, the hybrid
4 fry of pink salmon (-r) x chum (o ) had the
same color as that of normal fry, i;_nd they also
had pearl marks similar to those of chum.
4. The fry were releas6d in 1961 without feeding,
but in the second and third year, they were fed
Page 28
4. (Continued)
in a special trough. .The fry of 1962 were
kept in the trough for several months and then
released at a confluence of the main- and a
branch river. The 1963 fry are still under
feeding, and they will receive a . different
identification mark for each hybrid species
and then will be released.
Page 29
• •
s.
-28-
REFERENCES
Alm, G. 1955 Artificial hybridization between different species
of the Salmon family. Ann. Rep. Drottuningholm, 36:
pp. 13-56.
Disler, N.N. 1957. Development of the "Osenniaia" salmon of
the Amur River. Oncorhyncus keta (Walb.). Proc. Inst.
A Morf. Acad. Sel. U.S.S.R., 20: 1-70.
Foerster, R.S. 1953. Interspecific cross-breeding of pacifie
salmon. Trans. Roy. Soc. Canada, See y. pp. 21-33.
Fujita, K. (or T) 1926. On the characteristics observed in
hybrids (F1 ) of salmon and trout. Dobutsu-gaku-zasshi
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Hubbs, O. and K. Strewn 1957. Relative variability of hybrids
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caprodes. Evolution, 11 (1): pp. 1-10.
1959 Artificial production of an intergeneric Atherinid
fish hybrid. Copeia, 1: pp. 80-81.
and G.E. Drawry . 1962 Artificial hybridization of
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Texas Jour. Soi. 14 (1): pp. 107-110.
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1963. Some cytological observations on hybridization
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A This translated by Dr. N. Rumin, McGill University, Montreal, Que.
Page 30
-29-
1963 Morphological and genetical observations in
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Terao, T. and Hayashinaka, N. 1961 Hybridization experiments
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Watanabe, M. 1955. Some observations on salmon eggs spawn
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Winge, 0. and E. Ditlevsen 1948. A study on artificial hybrids
between salmon (Salmo'salar) and brown trout (Salmo
trutta). Comp.-rend. Lab. Ber. Physiol., 24(23):
pp. 317-339.