Exotic Aquatic Organisms - International Development Research ...

Caiman latirostris and Alligator mississippiensis
Caiman latirostris or caiman is commercially cultured in Taiwan under intensive conditions.
Alligator mississippiensis or alligator is also commercially cultured, but under semi-intensive
conditions.
Both of these reptiles are already part of a budding industry in Taiwan and probably hold
good prospects for the future.
Usefulness of introductions
Discussion
When properly planned, recorded, documented and managed, introductions of exotic aquatic
species can be very beneficial. One successful introduction in Taiwan (aside from the tilapias)
involves Plecoglossus altivelis - that is, assuming it falls under the definition of "exotic" or
"introduced" species. It was originally a native species in Taiwan, but as a result of manmade
damage to its environment, the populations decreased greatly, and eventually, this species
disappeared completely. Eyed eggs were then introduced from Japan and under the guidance of
research institutes and the protection of game fishing clubs, Taiwan's reservoirs and rivers were
once again restocked with P. altivelis.
Several other species, such as M. rosenbergii and R. catesbeiana, are also very popular and
commercially important. Before the recent heavy industrialization of Taiwan, these species
helped in improving the social and economic conditions of a big number of aquaculturists. The
culture of these species had a very visible social impact on the country. Their popularity and
commercial viability are also demonstrated in other parts of the world.
Exercising caution
Many other exotic species, out of the 38 mentioned above, turned out to be successful
introductions. These species have the proven qualities for culture in most conditions and are
generally quite popular. One important factor which enhanced the success of these introductions
was the careful and systematic process in which they were carried out. Without such careful
testing, the consequences could be quite detrimental, as in the case of the two snails, Achatina
fulica and Ampullarius insularum.
However, caution must still be exercised, even with successfully introduced species. The
case of the tilapias is an example of the benefits and dangers of introduced species. Although the
tilapias offer many advantages as a culture species, and most tilapia introductions into Taiwan
(see Table 2) have been successful, it is important to note that tilapia introductions into other
countries have been blamed for the transfer of certain parasites. For instance, six species of
Cichlidogyrus (gill flukes) were transferred from Africa to Israel as a result of tilapia
introductions (Hoffman and Schubert 1984). This is a potential threat and should be considered
whenever tilapia is being introduced. Furthermore, 0. mossambicus, T. rendalli and T. zulu are
generally regarded as pests when introduced as exotic species (Welcomme 1984).
Another species which should be regarded with caution when being considered for
introduction is the S. gairdneri. The introduction of S. gairdneri can be somewhat controversial,
since this species has been associated with the spread of furunculosis. This disease is thought of
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