Abundance decline in the narrow-ridged finless porpoise population off the Pacific coast of eastern Japan
Abundance decline in the narrow-ridged finless porpoise population off the Pacific coast of eastern Japan
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日本东部太平洋沿岸窄脊江豚数量下降
DOI：
10.1002/1438-390x.12003
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发表时间：
2018
影响因子：
1.7
通讯作者：
Miki Shirakihara,Kazuhiko Hiramatsu,Takahiro Irie
中科院分区：
文献类型：
--
作者：
Kunio Shirakihara;Fumio Nakahara;Masanori Shinohara;Miki Shirakihara,Kazuhiko Hiramatsu,Takahiro Irie
窄脊无鳍海豚Neopocaena asiaeorientalisis是一种沿海栖息地的小齿鲸，对人类活动非常敏感。2012年进行了航拍调查，以评估日本东部太平洋海岸外仙台湾-东京湾种群的丰度和分布。在北纬34°57‘~38°21’之间，沿35个东西向断面飞行，间隔11.6公里，共探测到25个群。平均群体大小为1.44只。江豚的丰度估计为1,491只(变异系数 = 为32.4%)，低于2000年估计的丰度(ztest，p<； 0.05)。使用四种可用的丰度估计(自助线性回归，p= 0.040)，也发现了2000年至2012年期间种群数量下降的趋势。这一下降的一个可能原因是2011年日本东部大地震造成的沿海栖息地干扰和海啸造成的死亡。密度低至0.221只/平方公里，是日本水域中最低的水平之一。此外，本研究和过去的遗传研究再次确认的分布差距表明，种群应至少分为两个种群：北部(“仙台湾-福岛”)和南部。在2000至2012年间，北部人口的密度有所下降。与地震不同，人类活动可能会继续影响江豚。未来应该对这些小种群进行生存能力分析。
The narrow‐ridged finless porpoiseNeophocaena asiaeorientalisis a small‐toothed whale with a coastal habitat and is sensitive to human activity. Aerial sighting surveys were conducted in 2012 to evaluate the abundance and distribution of the Sendai Bay‐Tokyo Bay population off the Pacific coast of eastern Japan. We flew along 35 east–west transects at intervals of 11.6 km over the study area between 34°57′ and 38°21’ N. In total, 25 groups were detected by two observers. The mean group size was 1.44 individuals. Porpoise abundance was estimated to be 1,491 individuals (coefficient of variation = 32.4%), which was lower than the abundance estimated in 2000 (ztest,p< 0.05). A population decline trend during 2000–2012 was also detected using four available abundance estimates (Bootstrapping linear regression,p= 0.040). A possible cause of this decline was coastal habitat disturbance and deaths by tsunami waves caused by the 2011 Great East Japan Earthquake. Density was as low as 0.221 individuals/km2, which is among the lowest levels in Japanese waters. Furthermore, distributional gaps reconfirmed by the present study and past genetic studies show that the population should be divided into at least two populations: northern (“Sendai Bay‐Fukushima”) and southern. Density decline was detected in the northern population between 2000 and 2012. Unlike the earthquake, human activities may continue to affect the porpoises. Viability analyses of these small populations should be conducted in the future.