金門海域中華白海豚生態調查研究
中華白海豚(Sousa chinensis)棲地偏好於水深二十公尺以下水域，鄰近人類開發區域，導致白海豚容易受到直接或間接的衝擊，相關的保育研究與措施刻不容緩。台灣西海岸的中華白海豚族群生態已有初步的資料，但金門離島海域雖然有中華白海豚在此棲息，至目前僅有1992-1995 年的漁民訪查及四次擱淺記錄，而其他生態資訊完全闕如。為了瞭解金門白海豚的生態狀況，本計畫以面敘訪問金門漁民或海邊活動相關人士，以及海上租船調查等方式來調查中華白海豚在金門海域的數量與分佈資訊。
今年度共完成問卷調查46 份及海上調查10 趟。金門地區的漁民及海邊受訪者認為較常見海豚月份集中農曆三-六月份，除了新湖、復國墩和料羅海域的受訪者目擊比例50%以下外，其他海域曾有50%以上的目擊受訪者；目擊中華白海豚群體大小以1-5 隻為主，感覺近五年來數量有減少趨勢，且似與漁獲量下降有關，但白海豚對船隻的反應多為不理會，漁具漁獲被海豚破壞的事件也極為稀少，誤捕也不常發生；除了中華白海豚，金門漁民也曾目擊江豚、瓶鼻海豚、虎鯨。海上租船調查金烈水域附近約120 平方公里水域AB 航線各五趟，共發現中華白海豚三群、江豚兩群。
兩種物種的目擊點分布不同：江豚主要在小金門島南部；而中華白海豚主要分布在大金門島的西北邊海域，即古寧頭附近水域。本區白海豚的X棲地因子如水深、鹽溫度等與台灣本島調查無明顯差異。藉由照片辨識出八隻中華白海豚，尚未發現老年與少年個體。這些個體中並沒有與台灣族群相同的個體。此外，育幼群的發現顯示此區可能為育幼棲地之一。海上調查與漁民訪談結果顯示中華白海豚數量非常少，比台灣西海岸明顯較少，其保育行動亟需盡速研擬。
Abstract
Chinese white dolphins, Sousa chinensis, usually stay in waters shallower than 20 meters, often close to the coastal regions of high human impacts. Although some studies on the population ecology of this species have been conducted in the western coastal waters of Taiwan, little information about their presence in the waters around Kinmen Islands is available. The only records were gathered from four stranding events and fisherman interviews conducted between 1992 and 1995. To expand this knowledge base for future conservation management of the Chinese while dolphins around Kinmen Islands, we carried out additional fishermen interviews, boat survey trips, and photo-identification in the nearby areas to investigate their population distribution and abundance. Forty six questionnaires and 10 boat survey trips have been conducted to date this year. The fisherman interviews indicated that the time period with the highest probability of sighting of the Chinese white dolphins was between March and June of the lunar calendar. Except for the waters near Xinhu, Fukoutung, and Liaoluo where sighting was made by less than 50% of the responders, more than 50% of the responders reported sighting in all other water areas around Kinmen. Group size of the Chinese white
VII
dolphin ranged between 1 and 5. However, it should be noted that sighting frequency has been decreasing over the past 5 years and the decline seems to have to do with the reduction in fish catch in the region.In general, the Chinese white dolphins did not seem disturbed by the presence of the fishing boats. Rarely were they reported to have caused damage to fishing gears or have interfered with fishing operations. By-catch incidents on the other hand were also rare. Aside from the Chinese white dolphins, other cetaceans such as finless porpoises, bottlenose dolphins, and killer whales had also been seen in Kinman waters. According to the boat surveys, 5 each along the AB transect lines in the water area of 120 square kilometers, 3 groups of the Chinese white dolphins and 2 groups of finless porpoises were sighted. The sighting areas were different between two species: while finless porpoises were
found in the southern Little Kinman Island waters, Chinese white dolphins gathered up in the southwestern Big Kinmen Island waters, near Kuningtou. Environmental variables, such as water depth, salility, and water temperature, of the Chinese white dolphin sightings in Kinmen were similar to those in waters around the Taiwan island. Finally, photo-identification confirmed that 8 individuals have been sighted,
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including 1 individual of repeated sightings and 2 calves. No unspotted adult or mottled-stage individual were seen. These individuals were not the same animals as in the population off western coastal Taiwan. The presence of the calves suggested that Kinman waters could have been used as a nursery area. Based on these data, we conclude that the population size of Sousa chinensis in the waters around Kinmen Islands is significantly less than that off the western coastal Taiwan. Its conservation requires immediate attention.
今年度共完成問卷調查46 份及海上調查10 趟。金門地區的漁民及海邊受訪者認為較常見海豚月份集中農曆三-六月份，除了新湖、復國墩和料羅海域的受訪者目擊比例50%以下外，其他海域曾有50%以上的目擊受訪者；目擊中華白海豚群體大小以1-5 隻為主，感覺近五年來數量有減少趨勢，且似與漁獲量下降有關，但白海豚對船隻的反應多為不理會，漁具漁獲被海豚破壞的事件也極為稀少，誤捕也不常發生；除了中華白海豚，金門漁民也曾目擊江豚、瓶鼻海豚、虎鯨。海上租船調查金烈水域附近約120 平方公里水域AB 航線各五趟，共發現中華白海豚三群、江豚兩群。
兩種物種的目擊點分布不同：江豚主要在小金門島南部；而中華白海豚主要分布在大金門島的西北邊海域，即古寧頭附近水域。本區白海豚的X棲地因子如水深、鹽溫度等與台灣本島調查無明顯差異。藉由照片辨識出八隻中華白海豚，尚未發現老年與少年個體。這些個體中並沒有與台灣族群相同的個體。此外，育幼群的發現顯示此區可能為育幼棲地之一。海上調查與漁民訪談結果顯示中華白海豚數量非常少，比台灣西海岸明顯較少，其保育行動亟需盡速研擬。
Abstract
Chinese white dolphins, Sousa chinensis, usually stay in waters shallower than 20 meters, often close to the coastal regions of high human impacts. Although some studies on the population ecology of this species have been conducted in the western coastal waters of Taiwan, little information about their presence in the waters around Kinmen Islands is available. The only records were gathered from four stranding events and fisherman interviews conducted between 1992 and 1995. To expand this knowledge base for future conservation management of the Chinese while dolphins around Kinmen Islands, we carried out additional fishermen interviews, boat survey trips, and photo-identification in the nearby areas to investigate their population distribution and abundance. Forty six questionnaires and 10 boat survey trips have been conducted to date this year. The fisherman interviews indicated that the time period with the highest probability of sighting of the Chinese white dolphins was between March and June of the lunar calendar. Except for the waters near Xinhu, Fukoutung, and Liaoluo where sighting was made by less than 50% of the responders, more than 50% of the responders reported sighting in all other water areas around Kinmen. Group size of the Chinese white
VII
dolphin ranged between 1 and 5. However, it should be noted that sighting frequency has been decreasing over the past 5 years and the decline seems to have to do with the reduction in fish catch in the region.In general, the Chinese white dolphins did not seem disturbed by the presence of the fishing boats. Rarely were they reported to have caused damage to fishing gears or have interfered with fishing operations. By-catch incidents on the other hand were also rare. Aside from the Chinese white dolphins, other cetaceans such as finless porpoises, bottlenose dolphins, and killer whales had also been seen in Kinman waters. According to the boat surveys, 5 each along the AB transect lines in the water area of 120 square kilometers, 3 groups of the Chinese white dolphins and 2 groups of finless porpoises were sighted. The sighting areas were different between two species: while finless porpoises were
found in the southern Little Kinman Island waters, Chinese white dolphins gathered up in the southwestern Big Kinmen Island waters, near Kuningtou. Environmental variables, such as water depth, salility, and water temperature, of the Chinese white dolphin sightings in Kinmen were similar to those in waters around the Taiwan island. Finally, photo-identification confirmed that 8 individuals have been sighted,
VIII
including 1 individual of repeated sightings and 2 calves. No unspotted adult or mottled-stage individual were seen. These individuals were not the same animals as in the population off western coastal Taiwan. The presence of the calves suggested that Kinman waters could have been used as a nursery area. Based on these data, we conclude that the population size of Sousa chinensis in the waters around Kinmen Islands is significantly less than that off the western coastal Taiwan. Its conservation requires immediate attention.