A population estimate of Heaviside's dolphins, Cephalorhynchus heavisidii, at the southern end of their range
A population estimate of Heaviside's dolphins, Cephalorhynchus heavisidii, at the southern end of their range
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DOI：
10.1111/j.1748-7692.2008.00246.x
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发表时间：
2009-01-01
影响因子：
2.3
通讯作者：
Best, Peter B.
中科院分区：
文献类型：
--
作者：
Elwen, Simon H.;Reeb, Desray;Best, Peter B.
赫维赛德海豚（Cephalorhynchus heavisidii）是非洲西南部的特有种，在那里它们面临着未知程度的人为威胁，包括近海固定网。使用三年多来在南非西海岸收集的照片 ID 数据，我们计算了查普曼修正的彼得森对三个空间尺度上独特个体数量的估计。样本量较小且重新捕获率较低，导致方差较大。总种群丰度是根据种群中标记清晰的动物的比例（14%-17%）推断出来的，并使用科默森海豚的数据对死亡率进行了调整。总种群规模计算为：1999 年研究区域（季节内海岸线 20 公里）有 527 只动物（CV = 0.35，CI 272-1,020）；中心研究区域（海岸线 150 公里，3 年）有 3,429 只动物（CV = 0.36，CI 1,721-6,828）；以及 6,345 只动物（CV = 0.26，CI 3,573-11,267）在整个研究区域（390 公里海岸线，2 年）。配备卫星发射器的海豚在近海摄影研究区域的使用情况各不相同，从 39.5% 到 94.7% 的传输天数（总共 38-51 天）不等。鉴于数据中已知或可疑的偏差，这些丰度估计值可能会出现向下偏差。
Heaviside's dolphins, Cephalorhynchus heavisidii, are endemic to southwestern Africa, where they are exposed to unknown levels of anthropogenic threats, including inshore set netting. Using photo-ID data collected over 3 yr on the west coast of South Africa, we calculated Chapman's-modified Petersen estimates of the number of distinctive individuals at three spatial scales. Sample sizes were small and recapture rates low resulting in high variance. Total population abundance was extrapolated from the proportion of well-marked animals in the population (14%-17%) with between-year estimates adjusted for mortality using data from Commerson's dolphin. The total population size was calculated as 527 animals (CV = 0.35, CI 272-1,020) in the 1999 study area (20 km of coastline, within season), 3,429 animals (CV = 0.36, CI 1,721-6,828) in the central study area (150 km of coastline, 3 yr), and 6,345 animals (CV = 0.26, CI 3,573-11,267) in the full study area (390 km of coastline, 2 yr). Dolphins fitted with satellite transmitters varied in their use of the inshore photographic study area from 39.5% to 94.7% of transmission days (38-51 total). Given the known or suspected biases in the data, these abundance estimates are likely to be biased downward.