評估印度-太平洋大型大洋性經濟魚類分布變化與溶氧之關係

由於大型大洋性魚類具有高耗氧需求，氣候變遷所導致的溶氧程度降低將使其分布改變。本篇研究中，我們針對印度洋-太平洋（40°N〜40°S，100°W〜45°E）的11種鮪魚、旗魚根據Tuna Atlas (1955-2010) 的資料，評估其分布的重心變化與低溶氧環境（dissolved oxygen <150μmol/kg）的相關性。我們將魚種根據體長大小與泳動能力相關的六種生物學特徵做主成分分析分出四群，並假設具有較大體長與魚尾鰭長度的魚種組群，受到溶氧變化所導致的分布重心變化更為敏感。研究結果顯示，在印度洋、西太平洋與東太平洋中，鮪魚平均重心分布於低溶氧的海域僅發生在印度洋，並且魚種緯度分布重心隨溶氧的變化趨勢與其生物學特徵也僅在印度洋呈正相關。混合線性模型的結果顯示，印度洋的魚群在緯度分布與溶氧量具有顯著負相關，即魚群往南緯方向移動到高溶氧環境。西太平洋魚群的緯度分布與溶氧量為顯著正相關，即魚群往北緯移動到高溶氧的環境。而東太平洋魚群則在經度分布與溶氧量具有顯著負相關，顯示東經方向為具有相較高含氧量的海域。我們的結果顯示，具有高移動性的大型大洋性魚類對低溶氧環境較為敏感。在針對大型大洋性經濟魚類的永續資源管理時，需考慮氣候變遷之下的低溶氧區域變化。

關鍵字

印度-太平洋；生物學特徵；鮪魚；旗魚；溶氧；分布變化

並列摘要

Given their relatively high dissolved oxygen demands, large pelagic fishes such as tunas and marlines are expected to change their spatial distribution under warming, leading to shifts in fishing grounds. We assessed distribution changes in relation to low dissolved oxygen (DO) conditions (DO <150 μmol/kg) for 11 commercially-important tunas and billfishes based on catch data of the Tuna Atlas, 1955-2010, in Indo-Pacific Ocean (40°N~ 40°S, 100°W~ 45°E). We classified fishes into 4 groups based on 6 biological traits primarily related to body length and mobility using the principal component analysis (PCA). We hypothesized that the group with larger body length and aspect ratio, which denote higher mobility and metabolic demands, would display greater sensitivity to dissolved oxygen; i.e., with larger changes in distribution centroids. Our results revealed that centers of distribution of billfishes and tunas in the low DO condition only occurred in the Indian Ocean but not in the Western Pacific and Eastern Pacific Ocean. Related to this, positive correlation between the PCA scores and changes of distribution, denoting species sensitivity to DO, was detected only in the Indian Ocean. Results from the linear mixed-effect models suggest significantly negative correlation between latitude distribution and DO in the Indian Ocean; this suggests that fishes move toward area with high DO in the southern latitudes. Positive correlation between latitude distribution and DO is observed in the Western Pacific Ocean; this suggests that fishes move toward area with high DO in the northern latitudes. Negative correlation between longitude distribution and DO is observed in the Eastern Pacific Ocean; this suggests that fishes move toward area with high DO in the eastern longitudes. Together, these results suggest that the highly mobile large pelagic fishes are indeed sensitive to the low DO condition. Thus, sustainable management of large pelagic fishery resources requires to assess changes of hypoxic regions in the face of climate change.

並列關鍵字

Indo-Pacific Ocean ； biological traits ； tunas ； billfishes ； dissolved oxygen ； changes of distribution

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評估印度-太平洋大型大洋性經濟魚類分布變化與溶氧之關係

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