臺灣西岸中華白海豚的生殖參數與族群動態

Reproductive Parameters and Population Dynamics of Indo-Pacific Humpback Dolphins (Sousa chinensis) off Western Coast of Taiwan

李玠志(Chieh-Chih Lee)

指導教授 ： 周蓮香

國立臺灣大學/生命科學院/生態學與演化生物學研究所/碩士(2019年)

https://doi.org/10.6342/NTU201903316

摘要

在台灣西岸沿海的印太洋駝海豚(Sousa chinensis)，又俗稱中華白海豚。其族群量很小，過去估計約60-80隻，在IUCN紅皮書中被列為“極危物種”。本研究蒐集自2008年至2018年執行海上調查1,174趟所拍攝約41萬張白海豚照片，透過照片辨識技術來探究台灣西岸中華白海豚族群的生殖參數與族群動態。首先將幼豚個體達3歲以上者視為非嬰幼個體，納入個體資料庫。調查期間一共辨識80隻非嬰幼個體，其中有25隻確認為母豚(曾伴隨嬰幼個體)且伴隨34隻幼豚。回推幼豚出生月份，母豚全年都可生育但以5-6月是生殖高峰，但多數母豚在研究期間只觀察到生一胎。年平均出生率0.03 ± s.e.0.008，年補充量在一歲為0.04 ± 0.012 (s.e.)及在三歲時為0.02 ± 0.008(s.e.)，生殖間隔平均為5.01 ±0.57(s.e.)年。將11年的研究期間分成3期進行幼豚（1-3歲）的存活率比較，發現幼豚存活率與個別年齡存活率都在第一期後明顯的下降。34隻幼豚中僅11隻幼豚存活過3歲納入個體資料庫，換言之，平均每年僅有1隻個體補充入族群，突顯此族群成長速率緩慢。另外，由R模擬程式推估族群量動態發現從早期約65-70隻到近年降低為60-65隻，依據已死亡或極可能死亡者共17隻 個體失蹤(超過3年於海上無目擊)，年移除率平均為1.55隻。綜合以上結果可知整體族群量在11年間呈現下滑趨勢。本研究結果顯示台灣中華白海豚族群的永續性有緊急危機，急需採取積極性的保育行動。

關鍵字

中華白海豚 ； 照片辨識技術 ； 生殖參數 ； 存活率 ； 年補充率 ； 年移除率

並列摘要

The population of Indo-pacific humpback dolphin (Sousa chinensis) off western coast of Taiwan, also called Chinese white dolphin. It has been very small and estimated as 60-80 individuals. It also was classified as “Critically Endangered” in the IUCN Red list. The purpose of this study is to estimate its reproductive parameters and explore its population dynamic though photo-identification techniques based on over 410,000 photographs taken during the year 2008 to 2018, when 1174 boat-field surveys were conducted. When the calve survived to age 3, it was given an ID and recruited into the population. In total, 80 adult individuals have been identified, and 34 distinct mother-calf pairs from 25 breeding females were identified. Overall, female dolphins gave birth all year around with higher peak in May and June. The crude birth rate was 0.03 (s.e.= 0.008); The annual recruitment rate at age 1 was 0.04 (s.e.=0.012) and at age 3 was 0.02 (s.e. = 0.008). The average calving interval was 5.01 (s.e.=0.57) years, and most of female only carried one calf during study period. Comparing the calf survivorship from age 1 to age 3 in three periods divided within 11-year. Both calf survival rates and age-specific survival rates decreased significantly after period I. Only 11 out of 34 (32%) calves had survived to age 3. Thus, only one dolphins per year had been recruited, indicating the population were in slow growth rate. Based on R modeling analysis, the estimated population size was from around 65-70 individuals in the beginning and declined to 60-65 individuals later. The removing rate was estimated as 1.55 dolphins per year, according to 17 (4 dead +13 missing) disappearing individuals. So, this population is in decreasing trend. Overall, the results indicate an emergency sign for sustainability of this vulnerable population. Active conservation acts are urgently required.

並列關鍵字

Indo-Pacific humpback dolphin ； photo-identification ； reproductive parameter ； calf survival rate ； annual recruitment rate ； annual removal rate

參考文獻

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