Conference presentation: 21st Biennial Conference on the Biology of Marine Mammals

13-18 Dec 2015

A noisy dinner? Passive acoustic monitoring on the predator-prey interactions between Indo-Pacific humpback dolphins and croakers

Tzu-Hao Lin, Wen-Ching Lien, Chih-Kai Yang, and Lien-Siang Chou
Institute of Ecology and Evolutionary Biology, National Taiwan University

Shane Guan
Office of Protected Resources, National Marine Fisheries Service, Silver Spring, MD, USA

The spatio-temporal dynamics of prey resources have been considered as important factors for shaping the distribution and behavior of odontocetes. Indo-Pacific humpback dolphin (Sousa chinensis) is a costal species, which primary feeds on benthic croakers. It has been hypothesized that the distribution pattern and periodic occurrence of humpback dolphins are results of their prey movement. However, the interactions between humpback dolphins and croakers remain unclear. During May 2013 and November 2014, underwater sound recordings were collected in western Taiwan waters. Croaker choruses and humpback dolphin echolocation clicks were automatically detected using custom developed algorithms. Both croaker choruses and dolphin clicks were frequently detected in shallow estuarine waters during spring and summer. In addition, shorter inter-click intervals were detected with higher frequencies in these areas, indicating more likely foraging behavior. Current results suggest that the core habitats of humpback dolphins show an agreement with the areas of prominent croaker chorus. Diurnal cycle analysis showed that croaker choruses were most evident after sunset to until approximately 4 A.M. In estuarine waters, humpback dolphin clicks were most frequently detected during the nighttime, with reduced detection rates after 8 A.M. This suggests that the diurnal behavior of humpback dolphins could be associated with the calling behavior of croakers. Although whether the position of a calling croaker could be passively localized by a dolphin remains unknown, our results indicate that the foraging probability of humpback dolphins may be elevated during the nighttime chorus of croakers. Information regarding the spatio-temporal dynamics of croaker chorus can be important for the conservation management of humpback dolphins. Further details on the predator-prey interactions between humpback dolphins and croakers can be investigated by using hydrophone arrays.

Poster (pdf)

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離岸風場開發噪音對沿岸鯨豚類動物之衝擊

離岸風場開發噪音對沿岸鯨豚類動物之衝擊

林子皓1、林思瑩1、余欣怡1、周蓮香1*

1國立台灣大學生態學與演化生物學研究所

摘要

台灣西岸的風能豐沛,離岸風力發電將為重要的再生能源產業。然而台灣目前預定的風場位置大多與中華白海豚活動範圍重疊或比鄰。中華白海豚在台灣西部沿海的族群極度瀕危,少於100隻個體,因此亟須審慎評估離岸風場開發對中華白海豚之生態影響,尤其是所產生的水下噪音的潛在衝擊。離岸風場開發過程中,以打樁工程、船隻交通所產生之人為噪音衝擊層面最廣,運轉的噪音影響較小,可能造成的生態影響尚不明。高強度的噪音可能會對鯨豚造成的影響包括:聽力損傷,行為反應、棲地位移、遮蓋效應,或增加鯨豚長期的生理壓力。目前尚未見離岸風場開發影響中華白海豚生態之研究發表,本文彙整國際上離岸風場對沿岸鯨豚類之短期與長期生態影響資訊,並根據目前了解之噪音衝擊面向,研擬三大方向的減輕措施:預防性措施、減輕衝擊措施以及施工管制措施。利用以上資訊依循預警原則的觀念進行開發計畫,減低對於中華白海豚的影響。

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offshore windfarm impact_CH