臺灣各河口是三種烏魚隱蔽種(NWP1-3)的共同棲息場，也是烏魚苗的共同哺育場，本計劃藉由分子生物學技術以及耳石生態地球化學分析的不同技術，先以分子生物學技術，釐清台灣周邊烏魚成魚族 群之族群結構，接著以耳石生態地球化學分析不同種烏魚的成魚洄 游模式、稚魚的入添動態，以及不同族群的生物學特性。 成魚種類組成部分，淡水河內烏魚與台灣周邊海域相同，由三個烏 魚共同組成。比例上以NWP2所佔的比例最高，NWP1次之，NWP3的數 量則是相當稀少。而在淡水河流域棲地的選擇上，種類間似乎不存在差異，尤其是體長較大年齡較高的個體，表示烏魚成魚喜好鹽度低的環境，體長小的低齡烏魚仍會為了攝食而停留在高鹽度的河口 區域。種間成長與生殖則具差異，NWP1與NWP2之成長方程式具顯著差異，而NWP2的生殖季節較NWP1來的要早約1至1.5個月，NWP3樣本數始終過少無法加入探討。這對於烏魚養殖在魚苗的選擇上有一定程度上的參考價值。根據耳石核心區域之元素分析的結果，NWP1與 NWP2之產卵場並不相同；NWP2與NWP3之DFA分佈較相近，應具有類似 環境之產卵場。根據耳石邊緣區域之元素分析結果，NWP1與NWP2具顯著差異，顯示在種間具有洄游特性相異性，而NWP2與NWP3則較為相似。 臺灣周圍河口的烏魚苗組成也是以NWP2為優勢種，佔整體比例最高 為81%，NWP1次之，佔整體的17%，NWP3最少，僅佔2%。NWP1和NWP2的初期生活史參數有差異，孵化時間以NWP2最長，高峰期為11月，NWP1次之，高峰期為1月；成長速率則是NWP2快於NWP1。本研究採樣的NWP3樣本過少，僅能推算孵化月份為10月。耳石細微結構 能記錄魚體生長發育以及環境變動的變化，本研究利用耳石的輪距 變化，解析烏魚早期生活史階段成長速率的改變，以及利用AP和 SGZ的出現紀錄魚體進入河口的時間點。耳石細微結構與微化學分析 的配合能夠以更精細的尺度得到魚類生長發育階段的變化以及轉換棲地的時間點，NWP1漂浮期較NWP2長，平均分別為34天以及32天 ，河口適應期分別為16天和8天。Taiwan is the common habitat of the three cryptic mullet species (NWP1-3), and also the nursery ground of their larvae. Present project aims to use both genetic and otolith biogeochemistry techniques, to clarify the mullet population structure near Taiwan coastal waters, and further to understand their migration patter of adult and recruitment dynamic of juveniles of each species. Adult samples show the same species composition between coastal and riverine waters (Tanshui River) with the three species co-exist. The ratio show different pattern that NWP2 is the most abundant species, followed by NWP1. NWP3 is rather rare. In different riverine area, no different in species composition, which indicated mullet prefer low salinity environment in larger adult individual. Younger mullet stayed in estuary for feeding. Growth and reproduction are different between NWP1 and 2, but too few samples of NWP3 were sampled that did not put in comparison here. The reproductive season of NWP2 is 1-1.5 month earlier than NWP1, that peak at November and co-instant to the peak month farmer collected mullet fry for aquaculture. Otolith core chemical composition showed that the spawning ground of NWP1 and 2 are different, while NWP2 showed similar pattern with NWP3. According the otolith edge composition, NWP1 and 2 showed significant differences which indicating different migration pattern, while NWP2 and 3 shared similar pattern in salinity selection. From analysis of mullet juvenile in various estuaries, NWP2 is still the most abundant mullet species (81 %). NWP1 is composed the 2nd to be 17% while NWP3 only composed as rare as 2%. Early life history of NWP1 and 2 are different that NWP2 has loner hatching season with peak at November, but NWP1 only spawn around January. Growth rate is higher in NWP2 than NWP1. NWP3 are hatched mainly in October, but the growth rates are unavailable due to too small the sample size. Otolith microstructure changes at AP and SGZ recorded the time of ontogenetic and habitat change of mullet at entering estuary, and combing the microchemistry analyses can be used as validation. NWP1 with longer average pelagic stage with 34 days than NWP2 with 32 days, and the estuarine transition duration is 16 and 8 days for NWP 1 and 2 respectively.