群集分析探討臺灣第一與第二核能發電廠撞擊魚群的時間變化

Abstract

核能發電廠需要大量海水冷卻機組，入水口進水時，會發生魚群的撞擊 (impingement) 情形。本論文利用階層分群法 (Hierarchical Clustering)、分割環繞物件法 (Partitioning Around Medoids)、和自組型態分析法 (Self-Organizing Maps) 三種集群分析方法和時間圖(Temporal Maps)，分析臺灣第一與第二核能發電廠的撞擊魚群10年間 (2000年9月至2010年8月) 的時間變化。結果顯示絲鰺 (Alectis ciliaris)、松鯛 (Lobotes surinamensis)、隆背小沙丁 (Sardinella gibbosa)、花蓮小沙丁 (Sardinella hualiensis)、真鰺 (Trachurus japonicus)，和叉尾鶴鱵 (Tylosurus acus melanotus) 等魚種在近幾年有減少的情形，這些減少的魚種大多為經濟魚種，此一結果可能反映出近年來魚產資源遭到過度捕撈的現象。 這些減少的魚種在以月份為時間單位的集群分析結果中屬於主要出現在溫暖月份的魚種；時間圖的結果也顯示近幾年的年間群集變化減少，這些消失的群集中的魚種，主要是出現在溫暖月份的魚種。夏季魚種在近幾年減少的原因需要再做探討。

This study was using three cluster analyses, Hierarchical Clustering, Partitioning Around Medoids, Self-Organizing Maps and Temporal Maps to find out the temporal changes of marine fish community based on the impingement data collected at the first and the Second Nuclear Power Plant in Taiwan from September 2000 to August 2010. The species Alectis ciliaris, Lobotes surinamensis, Sardinella gibbosa, Sardinella hualiensis, Trachurus japonicus, and Tylosurus acus melanotus, etc. have been decreasing in individual number in recent years from the results of cluster analysis. Those decreasing species were mainly with higher economic values, so the result might reflect the declination in our fishery resources due to overfishing. Most of the decreasing species belonged to the group of species that mostly appeared in warm months from the results of cluster analysis. Also, from the results of temporal maps, there were groups disappeared in recent years. Those disappeared groups contained mainly the species that mostly appeared in warm months. The reasons why the species that mostly appeared in warm months have been decreasing in recent years need to be found out.