Exotic Aquatic Organisms - International Development Research ...

Other introductions did not make much impact and these were not regarded by Filipinos as
significant in terms of benefits and adverse effects. The introduction of Ictalurus catus, Ictalurus
punctatus, Lepomis macrochirus, Misgurnus auguillicaudatus (bach), Puntius javanicus,
Osphronemus gorami and others for a time created some interest but did not affect the
environment as much as other introductions. The Ictalurus species did not survive in natural
conditions in the Philippines and no natural population is known. Lepomis (bluegill) is believed
to have survived in some reservoirs at high elevations and serves as forage fish for the M.
salmoides. The Japanese bach (Mis gurnus anguillicaudatus) established itself in some waters in
Trinidad Valley and rice terraces in Bontoc Province but has not had any negative effect. Puntius
(tawes) and Osphronemus (giant gouramy) for a while became known as good aquaculture
species but eventually lost out to other more favorable and acceptable species for freshwater
famiing.
The introductions of other cyprinid species in the Philippines and tilapia species have made
more impact economically for the Philippines than the other exotics. All available commercial
species of cyprinids in the country except in Lake Lanao are considered exotic species. Even the
presence of the varieties of goldfishes and carps for aquaria are exotic species but records of
their introduction do not exist. The aquarium fish industry benefits from these species.
Cyprinus carpio (common carp), and Chinese and Indian carps (such as grass carp, silver
carp, bighead carp, rohu, catla, mud carp, and mrigal) have been introduced into the Philippines.
Several Chinese carps and rohu have become a part of natural populations of lakes and reservoirs
and contribute to natural fish production. Many have become important cultured species such as
the common carp, bighead, silver carp and grass carp particularly for pen culture in Laguna de
Bay and freshwater ponds. Since they can be artificially bred, their domestication has helped the
freshwater aquaculture industry. Oreochromis niloticus is now an important freshwater fish
cultured in pens, cages and ponds.
Among the exotic anabantids in the Philippines, Trichogater pectoralis and T. trichopterus
have thrived well in lakes. They have been accepted by consumers inland where marine species
hardly influence their preference for fish.
Other Exotic Aquatic Species in the Philippines
Nonpiscine aquatic introductions are not weil recorded but mention will be made of them. In
the recent past Ampularia gigas (golden miracle snail) generated interest as a cultured species
that can thrive in tanks and even small containers when fed with vegetable materials. They breed
in the culture containers and grow at a fast rate. Its success was temporary and many now
consider it as a pest in rice paddies because they feed on young rice plants.
Cristaria plicata, a big freshwater clam, all of a sudden appeared as a natural population in
the 1970s in Laguna de Bay. It is claimed that the clam may have been accidentally introduced
into the lake as glochidia in the gills of imported Chinese carps stocked in the lake.
Crassostrea gigas is believed to have been introduced in Pangasinan by Mr. Ablan from
Japan. Its culture was studied but without much success.
Penaeid shrimps were also introduced into the Philippines (Iloilo) for aquaculture. It is
claimed that two species, Penaeus stylirostris and P. vanamei from Latin America when
introduced to the Philippines, may also have introduced diseases to local penaeid species.
Table 1 summarizes the exotic aquatic species in the Philippines. The data may not be
complete as some of the old records are hard to trace.
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