Whale sightings during POLARASTERN cruise PS139/2

Data on whale distribution and abundance in the polar oceans is rather sparse, as implementing the standard surveying method, line-transect surveys, is challenging and costly....极地海域鲸类分布与种群丰度的相关数据相当匮乏，这是因为标准调查方法——线样调查法（line-transect surveys）的实施既充满挑战，又成本高昂。