Rate of increase and current abundance of humpback whales in West Greenland
Rate of increase and current abundance of humpback whales in West Greenland
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格陵兰岛西部座头鲸的增长率和当前丰度
DOI：
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
J. Teilmann
中科院分区：
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作者：
M. Heide‐Jørgensen;M. Simon;J. Hansen;K. Harding;M. Rasmussen;R. Dietz;J. Teilmann
在1984年至2007年期间，对西格陵兰岛海域的座头鲸（Megaptera novaeangliae）密度进行了8次航空线样带调查，以估计夏季觅食地的增长率。只有1993年、2005年和2007年的调查有足够的观测数据来构建独立的密度估计，而1984-85年和1987-89年的调查必须合并并作为两个调查处理。1984年至2007年，年增长率为9.4% yr-1（标准差= 0.01）。这一增长率高于西印度群岛繁殖地的估计增长率，但与北大西洋其他繁殖地观察到的增长率相同。一个矩阵模型的基础上观察到的生活史参数显示，理论增长率的座头鲸人口介于1%和11%之间。这证实西格陵兰观察到的增长在合理值范围内。2007年的调查被用来进行全面校正的丰度估计，包括对调查飞机通过期间被淹没的鲸鱼的校正。2007年的样线估计值为1，020（CV = 0.35）。当估计值用标记-重捕距离采样（MRDS）方法校正感知偏差时，丰度增加到1，505（0.49）。根据时间深度记录仪在地表（0- 4米）所用时间的信息，对可用性偏差进行了校正。然而，直接使用这个校正导致一个正偏的丰度估计，而不是一个校正开发的非瞬时目视瞄准过程中的飞机。最低要求数据集分析得出的2007年估计数为3 272（CV = 0.50）。另一种带状普查估计部署了300米的带状宽度，结果是995（0.33）头鲸鱼。对感知偏差的校正导致了991（0.35）头鲸鱼，并对与MRDS方法相同的可用性偏差进行了校正，导致2007年西格陵兰有2，154（0.36）头座头鲸。
Aerial line transect surveys of the density of humpback whales (Megaptera novaeangliae) conducted off West Greenland eight times between 1984 and 2007 were used to estimate the rate of increase on the summer feeding ground. Only surveys in 1993, 2005 and 2007 had enough sightings to construct independent density estimates, whereas the surveys in 1984–85 and 1987–89 had to be merged and treated as two surveys. The annual rate of increase was 9.4% yr–1 (SE = 0.01) between 1984 and 2007. This rate of increase is higher than the increase estimated at the breeding grounds in the West Indies, but is of the same magnitude as the observed rate of increase at other feeding grounds in the North Atlantic. A matrix model based on observed life history parameters revealed that the theoretical growth rate of a humpback whale population ranged between 1 and 11%. This confirms that the observed growth in West Greenland is within the plausible values. The survey in 2007 was used to make a fully corrected abundance estimate including corrections for whales that were submerged during the passage of the survey plane. The line transect estimate for 2007 was 1,020 (CV = 0.35). When the estimate was corrected for perception bias with mark-recapture distance sampling (MRDS) methods, the abundance increased to 1,505 (0.49). A correction for availability bias was developed based on time-depth-recorder information on the time spent at the surface (0–4m). However, used directly this correction leads to a positively-biased abundance estimate and instead a correction was developed for the non-instantaneous visual sighting process in an aircraft. The resulting estimate for 2007 was 3,272 (CV = 0.50) for the MRDS analysis. An alternative strip census estimate deploying a strip width of 300m resulted in 995 (0.33) whales. Correction for perception bias resulted in 991 (0.35) whales and corrected for the same availability bias as for the MRDS method resulted in a fully corrected estimate of 2,154 (0.36) humpback whales in West Greenland in 2007.