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Present Status
of
Aquatic Organisms
Introduced into Japan
KENJICHIBA
Fisheries Laboratory
Faculty
of
Agriculture
University
of
Tokyo
2971,
Maisaka,
Hamana
Shizuoka
431-02
YASUHIKO
TAKI
KIYOSHI SAKAI
Tokyo
University
of
Fisheries
4-5-7
Konan,
Minato
Tokyo
108
YOSHIOKI
OOZEKI
Dept.
of
Fisheries
F
acuity
of
Agriculture
University
of
Tokyo
1-1-1
Yayoi,Bunkyo,
Tokyo
113
Chib~.
K., Y. Taki, K. Sakai and
Y.
Oozeki. 1989. Present status
of
aquatic organisms introduced into Japan, p. 63-70.
In
S.S. De Silva (ed.) Exotic Aquatic Organisms in Asia. Proceedings
of
the Workshop on Introduction
of
Exotic
Aquatic Organisms in Asia. Asian Fish. Soc. Spec. Publ. 3, 154 p. Asian Fisheries Society, Manila, Philippines.
Introductions
of
aquatic organisms into Japan are controlled only on the basis
of
the Convention on International
Trade in
Endang~ed
Species (CITES)
of
Wild Fauna and Flora and the quarantine acts.
Up
to 1986 more than 120 exotic
species have been introduced,
of
which only
36
were made prior
to
1945.
Introductions are classified into four basic categories. In this paper
of
those in two categories, (i) species which have
spread widely over Japan and are self reproducing, and (ii) those which have been maintained for generations through
artificial propogation
or
in
conf
med natural waters are dealt with.
Since the late 19th century, a great number
of
exotic species
of
aquatic organisms have been
introduced into Japan primarily with a view to enrich the fish resources
of
the country. While the
introduction
of
some
of
these species have caused serious ecological problems in natural waters,
some others have been confined and cultured in aquaculture farms as market fish or well
established in natural waters yielding new commodities
of
food or sports fishing without serious
impact on the ecosystem. The evaluation
of
the transplantation
of
non-indigenous species can
vary among people;
an
exotic fish species in a river or lake may be a acceptable game fish for
anglers while
it
may be an enemy for fishermen who catch other species that are outrivalled
by
the newcomer. Moreover, we have to admit that the 'ecological sense'
of
the people vary in
accordance with the cultural and socio-economic backgrounds
of
the country, even though
conservation is the unanimous consensus
of
all nations. In any event, accumulation
of
accurate
63
64
information on the status
of
fauna and flora is essential to lay down effective schemes for
controlling introduction
of
the species.
The purpose
of
this paper is to give a brief historical review
of
the introduction
of
exotic
species
of
aquatic animals in Japan and a brief description
of
the present status
of
these species.
Species introduced
as
ornamental aquarium fish are excluded from this report.
Review
of
Aquatic Species Introduced into
Japan
It is virtually impossible to trace all
of
the numerous aquatic organisms introduced into
Japan over the last 100 years. However, efforts have been expended to collect distributional and
ecological data on introduced exotic species by various institutions including the Fisheries
Agency, prefectural fisheries stations and universities. The Environment Agency's on-going
nation-wide swvey
of
the distribution
of
freshwater fishes, which is carried out every 5 years,
has also provided disributional information on the exotic species which have been naturalized in
inland waters (Environmental Agency 1976, 1980, 1988).
There has been no regulation to control the introduction
of
aquatic animals from
an
ecological standpoint. Animals brought in from abroad are checked only on the basis
of
the
Convention on International Trade in Endangered Species
of
Wild Fauna and Flora (CITES), the
municipal laws established in relation to the CITES, and the Quarantine Acts. Recently, FAQ's
program
of
the prevention
of
international epidemics was put into operation at the Fish Disease
Center in Tokyo.
According to Maruyama et al. (1987), more than 120 exotic species
of
aquatic animals have
been brought to Japan up to 1986.
Of
these, only 36 species were introduced to Japan before
1945. Entering the postwar period, the number increased drastically, due largely to the increasing
demand for new commodities among commercial fishermen, aquaculturists and sports fishermen
and the development
of
transportation.
Many
of
these species were introduced intentionally for stocking in the natural environment,
commercial culture and/or sport fishing. Some species, such as the silver carp,
Hypophthalmichthys molitrix and the bitterling, Rhodeous ocellatus ocellatus came to Japan
accidentally; these two species arrived in Japan mixed with fry
of
the grass carp,
Ctenopharyngodon idella (Nakamura 1955).
Of
the 120 species brought into Japan, about 9 species accounting for 7 .5%
of
the total
number have acclimatized themselves to the natural environment as self-reproducing
populations; about 32 or 26.7% have been successfully bred; about 26 or 24.6% have
disappeared; the status
of
about
53
or 41.2% remains obscure. In Table 1 they are classified into
four categories; (1) species which have spread widely over Japan and are self-reproducing,
(2)
species which have been maintained for generations in captivity through spontaneous or artificial
reproduction and/or established as self-reproducing populations in limited areas
of
natural
waters, (3) species which are already extinct in Japan, and
(4)
species
of
which the present status
cannot be elucidated. The following description
by
taxonomic group deals with only species
which belong to categories 1 and 2 above and which are considered to have an economic or
ecological importance.
65
Salmonidae
Examples
of
successful introduction
of
species for aquaculture are evident amongst
salmonids, particularly the rainbow trout, Salmo gairdneri. Since its first introduction in 1877,
many strains
of
rainbow trout have been imported from various localities
of
North America. This
species is now the commonest species in cold-water aquaculture ponds in Japan and its annual
production is maintained at 15,000-20,000
t.
Programs
of
stocking
of
rainbow trout fingerlings in
rivers have also been in operation in many areas since 1955. However, reproduction
of
the fish in
natural waters has been confirmed only in Hokkaido (Kawanabe 1980).
Other exotic salmonid species that are known to reproduce in natural waters are
the·
brown
trout, Salmo trutta and the brook trout, Salvelinus fontinalis.
A number
of
species
of
the salmonid genus Coregonus have been introduced from East
European countries for pond culture; still in experimental stages at research institutions and
private farms. Coregonus species C. lavaretus maraena and
C.
peled among others are regarded
as promising candidates for cold-water pond culture in Japan.
Cyprinidae
Four species
of
Chinese carps Ctenopharyngodon idel/a, Hypophthalmichthys molitrix,
Aristichthys nobilis and Mylopharyngodon piceus are reported to reproduce in the Tone, one
of
the largest rivers in Japan (Inaba 1955). Though they are
of
no high commercial value, the
former two species are
of
some importance in the commercial fisheries in the area. Because
of
their low trophic levels, there have been no reports indicating disturbances
of
river fauna because
of
these species.
The bitterling Rhodeous ocellatus ocel/atus is a small cyprinid occurring in continental East
Asia accidentally introduced into Japan mixed with grass carp fry from China, and was first
found in Japanese freshwaters in the mid-1940s (Nakamura 1955). Since then it has been
expanding its distribution, most remarkably in the last decade, expelling the Japanese subspecies
R. ocellatus smithi by ecological pressures and hybridization. R. ocellatus smithi is now on the
brink
of
extinction as a distinct subspecies (Nagata and Nishiyama 1976).
Atherinidae
The atherinid Odonthestes bonariensis, . known as pejerrey in South America, was
introduced into Japan from Argentina in 1966 as a species suitable for pond culture and stocking
in lakes. It has turned out that the species can readily reproduce in captivity and the fish is now
cultured at several fisheries stations and private farms. Seed has been stocked repeatedly in Lake
Ashinoko and Lake Tsukui to create a new commodity
of
sport fishing, but it is not evident that
the fish has adjusted itself in these lakes (Watase 1986).
Centrarchidae
The North American bluegill, Lepomis macrochirus and largemouth bass Micropterus
salmoides have readily established themselves in rivers and lakes and are spreading rapidly over
66
Table
1.
List of exotic aquatic species {Status 1 - Established
as
self reproducing populations; Status 2 - being reproduced in certain experimental or natural
ponds; Status 3 - extinct
at
present; Status 4 - accurate
inf
onnation not available;
UI.
unintentional).
Taxonomic Status
Status
Pisces
Acipenseridae
Acipenser guldenstodli 3
A.
baeri 3
Husohusox ?
Acipenser ruthenus
Clupeidae
Alosa sapidissima 3
Anguillidae
Anguilla japonica ?
?
?
A.anguilla ?
?
?
A. rostrata ?
A. dieffenbachi and or 3
A. australis
A. bicolor pacijica 3
Salmonidae
Sa/mo gairdneri 2
S.
trutta 2
S.salar ?
Oncorynchus tshawytscha ?
0.
nerka ?
?
0.
/cisutch
2
Salvelinus namaycush 2
S.fontinalis 2
Coregonus lavaretus maraena 2
C.
I.
ludoga ?
C. autumnalis migratorius ?
C.muksun ?
C.peled 2
C.
clupeaformis 3
C.
olbus 3
C.
lavaretus baeri 3
C. lavaretus maraena 3
Cyprinidae
Aristichthys nobilis 2
Ctenopharyngodon idellus 2
Hypophthalmichthys molitrix 2
Mylopharyngodon piceus 2
Rhodeus ocellatus ocellatus
Introduced
From
USSR
USSR
USSR
USA
Korea
China
Taiwan
France
Italy
England
Canada
New
Zealand
Philippines
USA
USA
USSR
USA
Canada
USA
USA
Canada
USA
Ci.echo
USSR
USSR
USSR
Czecho
USSR
USA
USA
USSR
USSR
China
China
China
China
China
Year
1963-
1964
1974-
1928129
1964-
1964-
1964
1969
1971fl2
1970n3
1972
1877
? -
1926
1980/83
1881-
1957
1968
1965
1966/69
1901126
1977n8
1981
1969-
1981/83
1972-
1978-
1926129
1926129
1929130
1929130
1878-
1940
1878-
1955
1878-
1940
1878-
1940
1942-
Remarks
Elver for commercial culture
Elver for commercial culture
Tone River
S.
UI
(mixed
in
grass carp
fry)
Tone River. S
Tone River. S.
Tone River. S.
UI
(mixed
in
grass carp
fry)
UI; Its Japanese counter-
part R.
o.
smithi is
endangered by ecological
pressure
of
and hybridization
with this subspecies.
Continued
•
·"'
.
67
Table
1.
Continued
Taxonomic Status Introduced Remarks
Status From Year
Cyprinus
carpio
ruscus
2 China
1971
Cyprinus
carpio
2 Gennany 1905- Cross bred
2 Austria
1970
2 Indonesia
1980
Cirrhina
molilorella 7 China 1965/66
Megalobrama
amblycephala
2 China
1978
Tinca
tinca
2 Netherlands
1961
Carassius
auratus
gibellio 3
USSR
1930/64
Calla
catla
3 India
1960
Pakistan
1970
Barbus
tor 3 India
1960
Labeo
rohita
3 India
1960
Cirrhina
mrigala
3 India
1960
Ictaluridae
/ctalurus punctalus 2
USA
1971
Poeciliidae
Gambussia
affmis Taiwan
1916
Atherinidae
Odontesthes
bonariensis
2 Argentine
1966
Percidae
Perea
jlavescens 3
USA
1960
Centrachidae
Lepomis
macrochirus
USA
1960
Micropterus
salmoida
USA
1925
Predation
on
native species
Morone
interrupta
3
USA
1960
Pomoxis
nigromaculatus
3
USA
1927/36
Roccus
saxatilis 3
USA
1927/28
1972{13
Chichlidae
Oreochromis
aureus
2 Taiwan
1980
USA
1983
Syria
1984
0.
macrochir 3
USA
1964
0.
mossambicus
2 Thailand
1954-
Colonized polluted brackish
waters around Okinawa Island.
0.
urolepis
hornorum
(reported
as
2 Israel
1981
Tilapia
macrocephala)
0.
niloticus 2
Egypt
1962
Sarotherodon
melanotheron
3
USA
1960
S.
galilaeus
3
USA
1964
Tilapia
sparrmanii 2
USA
1959
T.
zillii 2 Egypt
1962
Belontiidae
Macropodus
chiMnsis Korea
1914
Osphronemidae
Osphronemus
goramy
'l Thailand
1956
Scienidae
Aplodinotus
grunniens
3
USA
1960
Continue
~
68
Table 1. Continued
Taxonomic Status Introduced Remarks
Status
From
Year
Channidae
Channa argus 2 Korea 1923/24 Predation on native species
parasites
C. maculata Taiwan 1906/19 Parasites
Crustacea
Astacidae
Pacifastacus /eniusculus 2 USA 1909/29 Pond Tankai in Shiga Pref.
P. trowbridgii 2 USA 1928(30 Lake Mashu in Hokkaido
Procambarus clarlcii 1 USA 1930
Parastacidae
Cherax tenuimanus 3 Australia 1981-
Nephropsidae
Homarus Americanus ? USA 1914
1915n8
Penaeidae
Penaeus chinensis ? Yellow 1965-
Sea
Palaemonidae
Macrobrachium
rosenbergii 2 Malaysia 1967-
Thailand
USA (Hawaii)
Mollusca
Unionidae
Lamprotula (Quadrula) bazini 3 China 1917
Lampsilis luteo/a 3 USA 1926
Anodonta woodiana 3 Taiwan 1962
Mytilidae
Mytilus edulis galloprovincialis ? ca.1926
UI
Ostreidae
Ostrea lurida 2 USA 1948
0.
edulis 2
France
1952
Crassostrea angulata ?
France
1952
C. virginica ? USA 1968
Haliotidae
Haliotis rufescens 2 USA 1966
Ampullaridae
Pila leoporavillensis Taiwan 1981 Hybrid; it is unknown
x Ampullarium insclarum whether pure strains have
have been introduced
or
not
. .
69
the Japanese main islands. After its first introduction into Lake Ashinoko in 1925 for lure fishing
(Akaboshi 1959) and an initial unsuccessful attempt
of
its transplantation into several other
lakes, transplantation
of
M.
salmoides from Lake Ashinoko to other waters was prohibited to
prevent possible destruction
of
local fish fauna by this predaceous species. However, the
attraction
of
this fish as a game for lure fishing has led some indiscreet anglers to secretly
transplant it into many lakes. This resulted in its subsequent rapid dispersal over Japan and its
predation on many native fish species. The impact
of
the largemouth bass on indigenous fish
fauna appears to vary particularly in relation to the depth
of
water (Nomura and Furuta 1977).
The predation on indigenous fish by largemouth bass has caused serious problems in shallow
waters and efforts to eradicate this predator have not been successful (Kikukawa 1980). In deep
waters such as Lake Ashinoko, largemouth bass coexist with native fish by habitat segregation.
Cichlidae
Nine species
of
tilapia have been introduced into Japan for the purpose
of
pond culture
utilizing heat from hot springs or cooling-water discharge from power plants or factories. Of
these species, Oreochromis niloticus is enjoying a comparatively high reputation as a food fish,
with its annual production reaching more than 5,000
tin
1985 (Maruyama 1986).
0.
niloticus,
0.
mossambicus, Tilapia sparmanii and
T.
zillii have colonized estuarine waters in the Okinawa
Islands (Imai 1980). ·
Changes in the Japanese Freshwater Fish Fauna
The freshwater fish fauna
of
Japan has been changing rather conspicuously in recent years.
The freshwater fauna is originally rich in southwestern Japan and comparatively poor in
northeastern Japan. The recent changes in freshwater fish fauna are characterized primarily
by
the dispersal
of
many species endemic or indigenous to southwestern and northeastern Japan.
This northeastward dispersal is considered to be attributable largely to the transplantation
of
a
species called "ayu" from Lake Biwa in central Honshu. Though this has little to do with the
introduction
of
exotic species, we believe it worthwhile to briefly mention
of
what is going on in
the Japanese freshwater fish fauna.
Ayu, Plecoglossus altivelis, a small, annual fish closely related to salmonids is one
of
the
favourite game fish and an inland water delicacy among the Japanese. Young and sub-adult ayu
inhabit the middle to upper reaches
of
clear water rivers and reach maturity as they descend to
the lower reaches where they spawn. Larvae migrate to the sea and juvenile ayu ascend rivers
after spending the whole winter in the sea. Due to obstructions on the migration route by dams
and other structures, fry
of
ayu are being released into upstream areas all over Japan in large
numbers every year. The majority
of
the fry released are collected from Lake Biwa where a land-
locked population
of
ayu abounds.
This stocking activity is certainly a boon to more than
10
million amateur anglers who enjoy
ayu fishing. However,
it
has created a side-effect; colonization
of
the inland waters
of
northeastern Japan
by
species that had been found only in southeastern Japan. It is widely
accepted that the dispersal
of
southwestern elements has caused by incidental transportation of
fry
of
many species mixed in ayu seed collected from Lake Biwa. These immigrants include a
few carnivorous cyprinids and the predaceous largemouth bass.
70
From this historical review, it can be seen that the introduction
of
aquatic species into Japan
is closely related to the development
of
transportation. Before the World War II, shipping was
the only mode
of
transportation live species from foreign countries to Japan. It was difficult for
private enterprises to introduce live aquatic species from foreign countries because
of
shipping
costs. Therefore, only the national and/or local governments were able to introduce the aquatic
species from other countries for productive increase
of
animal protein. As the target species were
selected by the government authority itself, rules governing introduction
of
aquatic species were
not thought to be necessary.
Entering the postwar period, the development
of
transportation drastically increased the
number
of
species introduced from other countries; they are not only used in pond culture, but
also as ornamental pet fish in aquariums. Critical changes in fauna and flora caused by exotic
species have never been observed as a result
of
unrestricted introduction
of
aquatic species.
However, some changes, as mentioned above, have already been reported. Those are Rhodeus
ocellatus smithi being replaced by
R.
o.
ocellatus, colonization
of
northeastern Japan by native-
bom species found in southwestern Japan, and the predation
of
largemouth bass Micropterus
salmoides on many native fish species in certain places. These situations should be considered
as
a warning alarm for unrestricted introduction
of
aquatic species and the need for deliberation and
care for further introduction
of
aquatic species in Japan.
References
Akaboshi,
T.
1959. Blackbass. Miyazaki-ken Tansui-gyogyos hidojyo, p. 1-71.
Envirorunental Agency. 1976. Dai 1 kai shi7.en kankyo ho:ren kisochosa houkokusho (Repon
of
the first national surveys
on
the natural
environment). Shakai-chosa- kenkyusho. Tokyo, Japan.
Envirorunental Agency. 1980. Dai 2 kai shi:ren kankyo hozen kisochosa houkokusho (Repon
of
the second national surveys on the natural
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of
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no
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et
al
.•
Tokaidaigaku-shuppankai.
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124-132.
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of
the Chinese
Carp
in the Tone River). Z.Cnkoku-kosho--kasen yoshoku
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H.
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al.,
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Y.
1980. Blackbass in "Nihon
no
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T. Kawai
et
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.•
T.
Fuji, Kijima and
H.
Maeda. 1987. Gaikokusan shingyoshu
no
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of
exotic species from
foreign countries). Fisheries Agency, Tokyo.
Nagata,
Y.
and K.
Nishiyama
1976. Remarks on the characteristics
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the fins
of
bitterling. Rhodeus ocellatus ocellatus (Kner) and R. ocellatus
smithi (Regan). Memoirs
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Nakamura, M. 1955. Kanto-heiyani shutsugenshita ishyokugo (Some exotic fishes appeared at the Kanto Plains). Nihon-seibutsu-chiri-gakkaiho
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Nomura,
M.
and
Y.
Furuta
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S.
1986. Pejerrey in "Shingao
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·!!..
• .
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