以衛星標籤研究台灣產日本鰻、鱸鰻、太平洋雙色鰻之晝夜垂直洄游行為

A Study of Diel-Vertical Migration Behaviors of the Freshwater Eels, Anguilla japonica, A. marmorata, and A. bicolor pacifica by Pop-up Satellite Archival Tags (PSATs)

陳石崇(Shih-Chong Chen)

指導教授 ： 韓玉山

國立臺灣大學/生命科學院/漁業科學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202000948

摘要

鰻鱺屬的魚類在水產方面擁有很高的商業價值，且以有降海產卵的行為而聞名。然而，過度捕撈、棲地破壞等因素，造成鰻魚資源量的急遽下滑，引起相關各國極高的關注。雖然在過去因產業因素，已研究鰻魚不下三十餘年，但對其生態、行為等卻仍未了解透徹，這些知識上的缺塊可能造成鰻魚的保育無法切中真正的要害，因此完全解析其生命週期中的關鍵點是必須的。前人的研究發現，鰻魚在大洋中會表現晝夜垂直洄游的行為，且在多篇論文中皆有發現此行為與光線強度有某種關係。本研究分析2015-2017年進行的鰻魚放流實驗的資料，魚種包括了日本鰻、鱸鰻以及雙色鰻，探討其在遠洋中進行晝夜垂直洄游時的環境利用模式。同時，從前人論文中蒐集其它鰻種的資料，除了上述三種鰻種外，再加上歐洲鰻、美洲鰻以及大口鰻的晝夜垂直洄游環境利用資料，用來綜合分析晝夜垂直行為與環境因子的關係。結果顯示，鰻魚可能因種類差異而有不同的溫度利用限制，在本實驗的資料中，日本鰻的溫度利用最低到攝氏5度，雙色鰻到6度而鱸鰻最高，6.5度。月亮盈缺以及太陽光的強度 (入射角) 對鰻魚的洄游深度造成顯著影響，滿月時，鰻魚在夜間的深度利用會比平常的時候深，且深度隨著月相盈虧呈現線性關係; 太陽入射角反應地面接受的太陽光強度，在高入射時光度較強，鰻魚在白天下潛深度比低入射角時深，且隨著角度也成正向線性關係。綜合6種鰻魚的DVM資料發現，日間洄游深度越深，其夜間洄游深度亦越深。由此可推測鰻魚對光的敏感度會表現在DVM行為上，且不同鰻種表現的模式具有一致性，顯示鰻鱺屬鰻魚的DVM行為受到光照度強烈的影響。未來需要更多的樣本以及研究，以期更完整了解鰻鱺屬之降海洄游行為。

關鍵字

鰻魚 ； 生殖洄游 ； 衛星標籤 ； 晝夜垂直洄游 ； 光照

並列摘要

Fish in the genus Anguilla is a migratory species specialized for its oceanic behavior, and also of high commercial value. However, attribute to overfishing and habitat loss, their biomass is facing a severe situation of declining. As knowledge remains insufficient, there are still many difficulties in the conservation of the anguillid population. The diel-vertical migration (DVM) behavior that eels have was considered a necessary motion for unknown reasons. Previous studies found that DVM during their oceanic migration may have certain correlation with illumination. In this study, we released three kinds of native Taiwan eel species: A. japonica, A. marmorata, and A. biocolor pacifica, offshore during 2015-2017 and the DVM data were recorded by pop-up satellite archival tags (PSATs). We also collected the data from papers for other three kinds of species: A. rostrata, A. anguilla, and A. megastoma, for analyzing the relationship of DVM behavior and environmental factors. Results showed that eels could tolerate different limitation of temperature, depending on species. Temperature floor of A. japonica is the lowest, about 5oC, and A. bicolor pacifica could tolerate the highest temperature, about 6.5 oC. Moreover, the DVM depth the eels use has a positive correlation with the solar zenith angle; likewise, during nighttime the DVM depth differs in different lunar phase, and reaches to the deepest at full moon. Although different species of eels showed different sensitivities to lights, there was a high positive correlation between anguillid DVM depth and illumination. Among six species of eels, if represented in deep daytime depths, it would have a deep nighttime depths, suggesting that DVM behavior of eels would be influenced by light intensity. This result provides a reference for anguillid species migration studies.

並列關鍵字

Eels ； Spawning migration ； Satellite tags ； Diel-vertical ； Illumination

參考文獻

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