2007年夏季與2008年冬季東海陸棚仔稚魚的時空分布

Abstract

本研究利用研究船海研一號於2007夏季CR836航次與2008冬季CR855航次以圓口仔稚魚網(Round Mouth Ichthyoplankton net, RMI)和溫深鹽度計(CTD)進行仔稚魚的採集和水文資料的觀測，以群集分析、迴歸分析與BIO-EVN分析來探討東海陸棚海域水文環境對仔稚魚群聚時空分布的影響。結果顯示在水文方面，東海陸棚海域之水文環境變化十分複雜，隨著季節改變，水文流場亦有相當大的變動，不過大致上水文流場的分布與前人的研究相符。仔稚魚方面，夏季共採集到1702尾仔稚魚，可分類為60科148類，測站平均豐度為2038 ± 3546 ind./100m²;冬季航次中共採集598尾，可分類為42科89類，測站平均豐度為534 ± 937 ind./100m²。在夏季前八種的優勢種分別為:舌鰨屬(Cynoglossus spp.)佔21.46%、日本鯷(Engraulis japonicus)佔13.28%、鰕虎科(Gobiidae)佔9.33%、圓花鰹(Auxis rochei) 佔5.42%、鑽光魚科(Synodontidae) 佔4.31%、石首魚科(Sciaenidae) 佔2.49%、青沙梭(Sillago japonica)佔2.23%、鮨科(Serranidae)佔2.16%，合計佔夏季航次總豐度的62.64%。在冬季前七種優勢種為石狗公(Sebastiscus marmoratus)佔25.3%、鮻屬(Liza sp.)佔8.16%、天竺鯛科(Apogonidae)佔11.23%、燈籠魚科眶燈魚屬(Diaphus spp.)佔5.23%、鰕虎科(Gobiidae)佔4.08%、鼠□科(Callionymidae) 佔3.66%、燈籠魚科(Myctophidae)佔2.13%，合計佔冬季航次總豐度的69.79%。兩季節的物種組成與豐度有明顯差異。在仔稚魚群集特性方面，冬夏兩季分群明顯，顯示兩季物種組成相當的不同。兩季節皆觀察到不同水團的交匯造成仔稚魚的組成呈現高度多樣性。夏季測站間的群集特性推測主要與成魚分布有關，並且在長江河口處提供高豐度的舌鰨屬與日本鯷的仔稚魚，而冬季的群集特性主要受溫度影響呈東南向西北遞減的分布，並於台灣北部黑潮湧昇海域提供高豐度的石 狗公與鯔科仔稚魚。

To clarify the species composition and distribution of larval fish assemblages in the East China Sea, the larvae were sampled by vertical towing using ORI net from July 2007 and January 2008. Hydrological data were collected by CTD at the same time. CLUSTER, correlation analysis and BIO-ENV analysis were used to analyze the communities of larval fish. Totally, 2300 larvae were identified to 193 taxa in 76 families, and the mean abundance was 1497.99 ± 2930.31 ind./100m². In summer, 8 dominant taxa including Cynoglossus spp. (21.46%), Engraulis japonicus (13.28%), Gobiidae (9.33%), Auxis rochei (5.42%), Synodontidae (4.31%), Sciaenidae (2.49%), Sillago japonica (2.23%), and Serranidae (2.16%) constituted 62.64% of the fish larvae. In winter, 7 dominant taxa including Sebastiscus marmoratus (25.3%), Liza sp. (18.16%), Apogonidae (11.23%), Diaphus spp. (5.23%), Gobiidae (4.08%), Callionymidae (3.66%), and Myctophidae (2.13%) constituted 69.79% of the fish larvae. The abundance and species composition of the larvae were significantly different between summer and winter. The larval fish assemblages were clustered into summer and winter groups. That showed a high diversity in interface of two water masses in summer and winter. In summer, cluster characteristics of larval fish were mainly affected by the distribution of broodstock. In winter, fish larvae abundance decreasing from southeast to northwest, which may be affected by temperature. In summary, the fish larvae were abundant in Yangtze River Basin and northern Taiwan in summer, mostly contributed by Cynoglossus spp. and E. japonicus. In winter, the high abundance dominant with S. marmoratus and Liza sp. occurred in the Kuroshio upwelling area.