台灣東部秀姑巒溪沼蝦屬(Macrobrachium)幼體全日上溯特性初探

Characteristics of all-day upstream migration of juvenile Macrobrachium spp. in the Hsiukuluan River, eastern Taiwan

台灣的淡水沼蝦絕大部分是兩側洄游型，其中除大和沼蝦(Macrobrachium japonicum, de Haan, 1849)有初步的上溯洄游之研究發表外，餘物種仍尚待探討。本研究於2007年4月至2009年7月在秀姑巒溪，利用改良式的採樣設備，採集沼蝦幼體，探討其全日之上溯特性。共採獲10種沼蝦653隻個體（其中沼蝦幼體為586隻），分別為大和沼蝦(M. japonicum)、南海沼蝦(M. austral)、台灣沼蝦(M. formosense)、寬掌沼蝦(M. lepidactyloides)、熱帶沼蝦(M. placidulum)、貪食沼蝦(M. lar)、闊指沼蝦(M. latidactylus)、日本沼蝦(M. nipponense)、毛指沼蝦(M. jaroense)及短腕沼蝦(M. latimanus)。結果顯示，沼蝦幼體上溯最高峰時段為上半夜(19:40-23:40)，其次為下半夜(23:40-03:40)，白天2個時段07:40-11:40及11:40-15:40僅有個位數上溯個體。依不同物種上溯月份及水溫高低，大致可分成3種類型：第1種為全年型，即大和沼蝦幾乎全年皆有；第2種為高溫型，包括南海沼蝦、台灣沼蝦、熱帶沼蝦、貪食沼蝦、闊指沼蝦、毛指沼蝦及短腕沼蝦；第3種為低溫型，包括寬掌沼蝦及日本沼蝦。本研究之初步成果將有助於未來各種沼蝦之上溯研究，尤其台灣大部分的沼蝦物種仍待釐清其洄游特性。

Freshwater prawns in Taiwan are mostly amphidromous. A preliminary upstream migration study on Macrobrachium japonicum (de Haan, 1849) was published, but the remaining species are still to be discussed. In this study, improved sampling equipment was used to collect Macrobrachium juveniles in the Hsiukuluan River from April 2007 to July 2009 to investigate their all-day upstream migration characteristics. A total of 653 individuals, including 576 juveniles, of 10 Macrobrachium species were collected, specifically M. japonicum, M. austral, M. formosense, M. lepidactyloides, M. placidu-lum, M. lar, M. latidactylus, M. nipponense, M. jaroense, and M. latimanus. The results showed that the peak period of juveniles migrating upstream occurred in the early night (19:40-23:40), followed by the second half of the night (23:40-03:40). There were fewer than 10 upward tracking individuals in the two periods of 07:40-11:40 and 11:40-15:40 in the day. Three types can be roughly categorized according to the different months of upstream migration and water temperature. First is the annual type, that is, M. japoni-cum occurred almost all year round; the second is the high temperature type, including M. austral, M. formosense, M. placidulum, M. lar, M. latidactylus, M. jaroense, and M. latimanus; the third is the low-temperature type, including M. lepidactyloides and M. nipponense. The results of this research will be helpful for future studies of various Macrobrachium species, especially the migration characteristics of most of the Macro-brachium species that have yet to be clarified in Taiwan.