臺灣博碩士論文加值系統

臺灣東北海域在本文中係指24.5-27 oN及120-123 oE所涵蓋之水域
，此區域主要為東海南區之海水，但亦有黑潮在東南方流經，因此海域含
有三 個水團--東海南區陸棚水，黑潮水與混合水。本論文先由總體浮游
魚類的角度來判別不同水團間之魚類相 (fish fauna) 差異，再藉由初春
出現的日本鯷仔魚的生物特性，說明東北海域的水文變動會如何影響此魚
種之添入 (recruitment)。換言之，本論文主要目的是以日本鯷為材料，
導引式地明瞭不同水團的效應對浮游魚類的分布、成長及營養狀況的影響
程度，期望對沿岸漁業資源的年級群變動有更清楚的瞭解。
首先，我們用取自臺灣東北海域的14個航次採集的327個樣品 (1989年6月
至1992年9月)，來說明此海域浮游魚類的密度及組成在不同季節及不同水
文生態區 (hydrographic ecotope) 所具有之差異。在季節方面，浮游魚
類的密度在此區的變化大要是：冬季密度最低，春季漸增，夏季達到最高
，及秋季漸減。浮游魚類在三個水文生態區之平均密度顯示：東海陸棚水
最高，黑潮水其次，及混合水最低。本研究的四年中，共檢視了59789尾
魚，它們至少屬於124科的547物種。若以每個採樣數量百分比多於1﹪的
物種定為主要種，則主要種佔所有採集總數量的60﹪，且此主要種相對於
季節及水文生態區均有差異。春季主要種為圓類 (Decapterus spp.,
14.0﹪) 及花鰹魚 (Auxis spp., 6.2﹪)；在夏季為花鰹魚 (Auxis
spp., 6.9﹪) 及七星魚 (Benthosema pterotum, 5.8﹪)；在秋季為七星
魚 (B. pterotum, 55.2﹪)，蝦琥 (godiids, 4.1﹪) 及尖齒鯛(
Synagrops sp., 3.2﹪)；在冬季為七星魚 (B. pterotum, 15.4﹪) 及纖
鉆光魚 (Gonostoma gracile, 7.48﹪)。在三個水文生態區之主要種分別
為：在東海陸棚水為七星魚 (B. pterotum, 23.0﹪) 及花鰹魚 (Auxis
spp., 5.1﹪)，在混合水為圓類 (Decapterus spp., 28.6﹪)及花鰹魚
(Auxis spp.,7.1﹪)，及在黑潮水為七星魚 (B. pterotum, 5.6﹪) 及串
燈魚(Vinciguerria nimbaria, 4.4﹪)。用聚類分析所得之樹狀圖顯示七
個關聯物種群， 此物種群可分別用季節及水文區之聯合特性加以說明。
以日本鯷為實驗生物材料，探討東北海域水團對其仔魚生存的作用與影響
，共有三個發現。(一) 以RNA/DNA比值來判別日本鯷仔魚的營養狀況，其
結果顯示：仔魚的RNA/DNA比值，在三個生態區之間有顯著差異存在，並
以黑潮區中的仔魚 RNA/DNA比值最低；這結果表示黑潮流域日本鯷仔魚的
營養狀況為較差，其中仔魚 的饑餓率為27.9﹪，比東海南區海域
(2.8﹪) 與混合區 (5.0﹪) 高出許多。 (二) 以耳石成長的變動
不對稱性來偵測仔魚發育歷程所遭遇的環境變異程度， 其結果顯示
：左右耳石的不對稱性，以最長半徑值與周長為測量值，在不同生態區間
並沒有顯著差異存在；而耳石表面積，在不同生態區間有明顯差異存在,
即來自黑潮區的仔魚變異性較大。(三) 由成長方程式的觀察得知：黑潮
區日本鯷仔魚的日成長率比混合區快；黑潮區日本鯷仔魚的耳石日成長率
比混合區高；各生態區間耳石半徑與標準體長的相對關係則無不同；年間
及生態區間之體長頻度分布有顯著差異存在。

The area 24.5-27 oN and 120-123 oE off northeastern
Taiwan was selected for ichthyoplankton study. It
included the three watermasses--southern East China Sea (SECS),
mixing zone (MIX) and Kuroshio (KUR) and thus three hydrographic
ecotopes were identified. The seasonal variation of the fish
fauna based on ichthyoplankton was analyzed. This study also
applied the biological parameters of Japanese anchovy larvae,
which hatch in early spring, to interpret the effects of the
hydrographic dynamic on the recruitment of the population off
northeastern Taiwan. The major purpose of this study were to
explore the effects of water masses on the distribution, growth
and nutritional condition of ichthyoplankton, and to clarify the
variation of year stock in coastal fishery. A total of
327 ichthyoplankton samples were taken during 14 cruises from
June 1989 to September 1992 in the waters off northeastern
Taiwan. The density of ichthyoplankton was lowest in winter,
increased in spring, reached the maximum in summer, and declined
in autumn. Average densities of the ichthyoplankton in the 3
hydrographic ecotopes were highest in the SECS, moderate in the
KUR, and lowest in the MIX. In total, 59 789 individuals of
ichthyoplankton belonging to at least 124 families and 547
species were collected.The major ichthyoplankton species,
comprising about 60% of the total catch, were distinctive in
different seasons and waters. Decapterus spp. (14.0%) and
Auxis spp. (6.2%) were abundant in spring; Auxis spp. (6.9%) and
Benthosema pterotum (5.8%) in summer; B. pterotum (55.2%),
gobiids (4.1%), and Synagrops sp. (3.2%) in autumn; and B.
pterotum (15.4%) and Gonostoma gracile (7.5%) in winter. B.
pterotum (23.0%) and Auxis spp. (5.1%) were abundanct in SECS;
Decapterus spp. (28.6%) and Auxis spp. (7.1%) in MIX; and B.
pterotum (5.6%) and Vinciguerria nimbaria (4.4%) in KUR. The
dendrogram of these major ichthyoplankton species exhibits 7
species-associated groups. The survival of Japanese anchovy
larvae is affected by water masses off northeastern Taiwan.
Three conclusions were drawn from this study: 1. The RNA/DNA
ratio of the larvae were different significantly among the
hydrographic ecotopes. Based on the RNA/DNA ratios, the
nutritional condition of Japanese anchovy larvae from the KUR
was poorer than that from the SECS and MIX. The starvation
probability was higher (27.9﹪) in the KUR than in the SECS
(2.8﹪) and MIX (5.0﹪). 2. Indices of the fluctuating
asymmetry (FA) were calculated for 3 otolith traits, i.e., mean
absolute asymmetry (differences between right and left) maximum
radius (MOR), perimeter (OP) and surface area (OA)). Mean
absolute asymmetry in MOR and OP were not significantly
different among the hydrographic ecotopes. Mean absolute
asymmetry in OA was significantly different among the
hydrographic ecotopes, greater in KUR than in the SECS and MIX.
3. According to the growth equation, the daily somatic and
otolith growth of larval anchovy was faster in the KUR than in
the MIX. The relative growth between the MOR and standard
length was not significantly different among the hydrographic
ecotopes. The length frequency distribution of the larval
Japanese anchovy exhibited significant differences between year
classes and among the hydrographic ecotopes.