Exotic Aquatic Organisms - International Development Research ...

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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 109
110 to be native only to S. gairdneri of western North America. After introductions of S. gairdneri, furunculosis became a serious problem in European brown trout. Now, this disease can be found in most places where salmonids are cultured (Welcomme 1984). S. gairdneri is also known to be a carrier of Myxosoma cerebalis (Hoffman and Schubert 1984), a virulent parasite, which can survive in extremely low temperatures. It remains as a threat even if the carrier is already frozen. A danger such as this would warrant even more care to prevent the spread of an unwanted parasite that may do much damage to local species. Inadequate documentation The documentaticn of introductions, even of the successful ones, has general:ly not been satisfactory. However, solving this problem may not be as simple as it seems. Some naive aquaculturists may introduce a potentially harmful species, unaware of the ecological effects of such an action, while unscrupulous traders or businessmen may do the same, quite deliberately, even with full knowledge of the detrimental consequences. In either case, the proper authorities are usually left uninformed of the introduction and thus, an already difficult problem is compounded. Ecological pact Inadequate documentation, itself an already complex problem, leads to an even more serious problem - the inability to monitor the impact of unrecorded exotic species on the native ecosystems. The danger of this lack of information and knowledge is that some of the species introduced could actually assume dominant niches in the natural ecosystems which may, over time, prove detrimental. Although most, if not all, are maintained in very controlled environments, the number that may escape these environments would not be easy to trace. There are still other exotic species not discussed in this report, for lack of data, but which are strongly suspected to have caused damage to the populations of some indigenous fishes. Among these "controversial" exotics are Poecilia velafera, which has endangered the native species Rhyacichihys aspro and Mesopristes cancellatus, and Tricogasrer trichopterus, which has endangered Capoera semfascio1ata (see Table A.IIl). Sometimes, because of unmonitored or unrecorded introductions, the scientific names of some species which have been brought in could not even be determined. With all these unidentified exotic species coming in to Taiwan, the task of studying the ecological impact of these species becomes even more complicated for fisheries scientists and authorities. In Taiwan, the tilapias were introduced by research institutes. Fisheries and aquaculture scientists studied them carefully before disseminating them among the interested farmers. Screening and meticulously experimenting on these exotic species before releasing them for commercial culture have helped prevent environmental and other problems. It enabled the researchers to gather valuable information regarding the ecology of these species, and therefore also enabled them to provide the necessary instruction to the people interested in the culture of tilapia.
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Exotic Aquatic Organisms in Asia /
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Exotic Aquatic Organisms in Asia Pr
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The Introduction of Exotic Aquatic
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Introduction This special publicati
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help to promote national awareness
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Conditions in Europe and North Amer
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2 taken as the basis for the introd
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4 with respect to other introductio
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6 Costa-Pierce, B. 1988. Study miss
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8 extinction of the endemic rainbow
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10 bottom substrates by European ca
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12 Arthington 1988; Lloyd 1987); G.
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14 Apparent Extinction of the Lake
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16 successful and more often than n
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18 Reznick, D. 1981. 'Grandfather E
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20 -24° 4' 4 - I- .300 Cl) '1 S 36
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22 The terminology associated with
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24 Table 2. Translocations of indig
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26 MELANOTAENIIDAE Melanotaenia spl
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28 ELEOTRIDAE - GUDGEONS Hypseleotr
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30 POECILIIDAE - LIVEBEARERS Gambus
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32 References Allen, G.R. 1982. A F
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34 Robinson, S.E. 1982. The ecology
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36 1973. It has been cultured in so
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38 northern Japan, settled off Dali
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40 Table 1. The exotic aquatic food
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42 Table 2. The preliminary list of
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Impact of Exotic Aquatic Species in
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Table 1. Salinonids introduced into
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Grass carp The grass carp, Ctenopha
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Table 4. Total catch and tilapia yi
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Salvinia molesta, a floating fern o
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Joy, PJ., K.R. Sathesan and D. Jose
Page 69 and 70: 58 Table 1. Introduced aquatic spec
Page 71 and 72: 60 The 1940s The Inland Fisheries D
Page 73 and 74: 62 Indonesia includes three differe
Page 75 and 76: 64 information on the status of fau
Page 77 and 78: 66 Table 1. List of exotic aquatic
Page 79 and 80: 68 Table 1. Continued Taxonomic Sta
Page 81 and 82: 70 From this historical review, it
Page 83 and 84: 72 what they perceived as economica
Page 85 and 86: 74 Table 1. Fate of the introduced
Page 87 and 88: 76 While it is likely that at the o
Page 89 and 90: 78 Pearl Spot The pearl spot, Etrop
Page 91 and 92: 80 Trengganu Enactment No. 8 of 196
Page 93 and 94: 82 References Annual Fisheries Stat
Page 95 and 96: 84 long time ago as shown by the fa
Page 97 and 98: 86 Discussion and Recommendations E
Page 99 and 100: Table 1. Exotic aquatic species int
Page 101 and 102: Table 1. Continued Diseases/Parasit
Page 103 and 104: 92 Fisheries (Piranhas) Rules 1971,
Page 105 and 106: 94 (Caranx ignobilis) golden treval
Page 107 and 108: 96 Table 1. Main species of aquariu
Page 110 and 111: Status of Introduced Species in Sri
Page 112 and 113: Exotic Aquatic Species in Taiwan I-
Page 114 and 115: appreciated in the context of the w
Page 116 and 117: However, A. anguilla cannot tolerat
Page 118 and 119: Today, most of these carps are poly
Page 122 and 123: Conclusions The case of the tilapia
Page 124 and 125: Table 1. Continued Culture Status P
Page 126 and 127: Table 2. Record of tilapia introduc
Page 128 and 129: Annex I. Continued Dascyllus melamu
Page 130 and 131: Exotic Aquatic Species in Thailand
Page 132 and 133: Present Status of the Exotic Specie
Page 134 and 135: Table 1 a. Exotic fishes introduced
Page 136 and 137: Australian Government Position: Int
Page 138 and 139: There are presently eight State or
Page 140 and 141: egulate any activity likely to have
Page 142 and 143: Appendix II. Continued Name State o
Page 144 and 145: Recommendations of the Workshop 1.0
Page 146 and 147: (two more to be co-opted) was appoi
Page 148 and 149: Mr. J. Maclean, do ICLARM, MC P0 Bo
Page 150 and 151: Appendix I Definitions of Exotics T
Page 152 and 153: Appendix II Assessment of the Impac
Page 154 and 155: Table All.3. Assessment of the stat
Page 156 and 157: Table All.6. Assessment table of th
Page 158 and 159: Table All.8. Assessment table of th
Page 160 and 161: Table All.10. Continued Family/Spec
Page 162 and 163: Table Affi. Indigenous species whic
Page 164 and 165: Appendix V Existing Legislation or
Page 166: TITLES IN THE ASIAN FISHERIES SOCIE
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