外來種淡水魚類及蝦類在台灣河川之分布概況

Distribution of Exotic Freshwater Fishes and Shrimps in Taiwan

依據文獻記載及本研究從2000-2002年所作之野外調查，在台灣51條河川中已有49條河川發現到外來種淡水魚類或蝦類，共記錄15種外來淡水魚類及2種外來淡水蝦類，分別為吳郭魚cichlids、大肚魚 Gambusia affinis（Baird et Girard）、琵琶鼠 Pterygoplichthys multiradiatus（Hancock）、三星鬥魚 Trichogaster trichopterus（Pallas）、香魚 Plecoglossus altivelis（Temminck et Schlegel）、泰國鱧 Channa striata（Bloch）、日本鯽 Carassius cuvieri Temminck et Schlegel、虹鱒 Oncorhynchus mykiss（Walbaum）、帆鰭胎生魚 Poecilia velifera Regan、劍尾魚 Xiphophorus hellerii Heckel、孔雀魚 Poecilia reticulata Peters、高體四鬚 Barbodes pierrei Sauvage、珍珠石斑 Cichlasoma managuense Guther、泰國鯽 Barbodes schwanen feldii（Bleeker）、大口鱸 Micropterus salmoides Lacepede、美國螯蝦 Procambarus clarkii（Girad）及羅氏沼蝦 Macrobrachium rosenbergii（de Man）。其中珍珠石斑及泰國鱧為本研究新紀錄外來種。吳郭魚分布最廣且數量最多，從河口至海拔高度700m均有其分布；其次為大肚魚，從河口分布至海拔高度1,340m；琵琶鼠則以中部及南部河川較多，從河口分布至海拔高度300m；香魚則限於北部及中部河川，分布之海拔高度為30-1,472m；虹鱒集中於中部河川，分布之海拔高度介於600-2,050m。外來種種數最多的河川為高屏溪有8種，其次為八掌溪、曾文溪、東港溪及宜蘭河各有7種。楓港溪及和平溪乃現在未有外來種淡水魚類、蝦類之河川。隨著海拔高度遞增，外來種淡水魚類、蝦類種數遞減。本研究自行調查之河川有26條，與文獻相較在中部河川之外來種種數減少且海拔高度降低，南部河川之外來魚種數量則增加且海拔分布提高。 According to the literature and our field investigation in 2000 to 2002, there were 15 species ofexotic freshwater fishes and two species of exotic freshwater shrimps in 49 of 51 rivers and creeks ofTaiwan. They were cichlids, Gambusia affinis, Pterygoplichthys multiradiatus, Trichogaster trichopterus,Plecoglossus altivelis, Channa striata, Carassius cuvieri, Oncorhynchus mykiss, Poecilia velifera,Xiphophorus hellerii, Poecilia reticulata, Barbodes pierrei, Cichlasoma managuense, Barbodesschwanenfeldii, Micropterus salmoides, Procambarus clarkii, and Macrobrachium rosenbergii. Of themC. striata and C. managuense were the exotic species newly recorded to Taiwan. Cichlids were the mostabundant and widely distributed fishes. They occurred from river mouth to an elevation of 700m. G.affinis was the second most abundant and widely distributed species from river mouth to 1,340m inelevation. P. multiradiatus occurred in the central and southern Taiwan from river mouth to 300m. P.altivelis was found in the northern and central Taiwan in elevations between 30-1,472m, while O. mykisswas in the central Taiwan between 600-2,059m in elevation. Kaoping River had eight exotic species,while Pachang, Tsengwen, Tunkang and Yilan rivers each had seven species. Fengkang River andHoping River were the only two rivers where no exotic species were present. The number of exoticspecies decreased with the increase in elevation. When the exotic species in 26 rivers investigated in thisstudy were compared to those reported previously in literature, the number of the exotic species and theiraltitudinal distributions decreased in the central Taiwan but increased in the southern Taiwan.