Population ecology of the finless porpoise

本项目旨在通过分析飞机拍摄的照片，检查标本，以及飞机和船只的观察调查，估计长崎附近沿海水域无鳍江豚种群的生态参数。总共为46个人拍摄了照片。体长估计在0.7到2.2米之间。根据这些照片，有明湾和塔班湾的数量估计超过800只。从空中观察调查中，另一个估计是3093只。发表了一篇关于分布和季节性密度的论文。在长崎附近沿海水域，主要分布于有明湾、立花湾和大村湾。有明湾中部的密度估计为1.31 ~ 1.60只/km^2。学校平均规模为1.7人，发表了一篇关于年龄、生长和繁殖的论文。该物种出生时身长80厘米，5岁时可长到140厘米。雌性在6-9岁达到性成熟。长崎附近的分娩是从秋天到春天。发表了两篇关于骨骼形态学的论文。一种描述了随着年龄和两性异形的发展。另一项研究试图根据颅骨形态的地理差异来识别种群。这个物种在4岁时达到颅骨成熟。在大多数颅骨特征中未发现性别二态性。我们建议在中崎附近沿海水域存在两种种群，即有明湾-立花湾种群和大村湾种群。

This project aimed to estimate the ecological parameters of the finless porpoise (Neophocaena phocaenoides) populations in the coastal waters near Nagasaki by analysing photos taken from an airplane, examining specimens, and sighting surveys from the plane and boats.A total of photos for 46 individuals were taken. Estimates of body length ranged from 0.7 to 2.2m. Using these photos, the population size in Ariake Sound and Tachiban Bay was estimated to be more than 800 individuals. From airo sighting surveys, another estimate for this population was 3093 individuals.A paper was published on distribution and seasonal density evaluated from the boat sighting surveys. In the coastal waters near Nagasaki, the species is distributed mainly in Ariake Sound, Tachibana Bay and Omura Bay. Density was estimated 1.31-1.60 individuals/km^2 in the middle part of Ariake Sound. The mean school size was 1.7 individualsA paper was publised on age, growth and reproduction. The species is born at length of 80 cm and grows up to 140 cm at age of 5 years old. Females attain sexual maturity at ages of 6-9 years. Parturition near Nagasaki is from autumn spring.Two papers were published on morphology of skeltons. One describes development with age and sexual dimorphism. The other attempted to identify stocks based on geographical difference in the skull morphology. This species attains cranial maturity by 4 years. Sexual dimorphism was not detectable in most of cranial characters. We suggested two stocks exist in the coastal waters near Nakasaki, that is, Ariake Sound-Tachibana Bay stock and Omura Bay stock.