Studies on diving behavior of odontocetes using the suction-cup attached TDR tag.

采用吸盘式TDR标签对抹香鲸和印太宽吻海豚的潜水行为进行了研究。在熊野海岸和小笠原群岛分别对2头抹香鲸和4头抹香鲸以及九州天草群岛的4头宽吻海豚进行了标记。所有被标记的抹香鲸重复下潜40-45分钟，下潜深度400-1300米。它们大多数的潜水都是u型的，被认为是为了觅食。在潜水的底部，鲸鱼在深度和速度方面都非常活跃，偶尔会爆发速度。这表明抹香鲸在觅食时采取了积极的搜索和追击策略。夜间潜水深度较浅。这可能反映了猎物的垂直迁移，或者它们根据深度捕食不同类型的猎物。后者也被以下事实所证实：水底的游泳速度和爆发次数都随着深度的增加而增加。我们认为鲸鱼以深海中更大更稀有的猎物为食。先前的研究表明，由于宽吻海豚对标签的强烈反应，吸盘附着的标签不可行。然而，我们证明了这对宽吻海豚来说并不总是不可行的。印度太平洋宽吻海豚通常在白天的大部分时间里旅行或休息，晚上则定期进行深度潜水。在夜间的深潜中，它们往往会回到相同的深度，这表明它们在海底觅食。这种鱼大部分时间生活在20米以下的浅水中。呼吸的表面次数与它们停留在表面的时间明显相关。我们可以利用这个关系来估计学校的规模。

We investigated diving behavior of sperm whales and Indo-pacific bottlenose dolphins using the suction-cup attached TDR tag. The tag was deployed to 2 and 4 sperm whale off Kumano coast and off Ogasawara Islands, respectively, and 4 bottlenose dolphins off Amakusa Islands, Kyushu.All tagged sperm whales repeatedly dived for 40-45 min duration down to 400-1300m. Most of their dives were U-shaped-and thought to be for foraging. At the bottom of the dive, whales were very active in terms both depth and speed with occasional bursts of speed. These suggest that sperm whales take an active searching and pursuing strategy while foraging. Dive depth was shallower in the night. This may reflect the vertical migration of the prey or they feed different types of prey according to depth. The latter was also suggested by the fact that swimming speed at the bottom and number of bursts both increased with depth. We think that whales feed on larger and scarcer prey in the deeper water.Previous studies suggested that the suction-cup attached tag was not feasible for bottlenose dolphins because of their intense reactions for the tag. However, we showed it is not always unfeasible for bottlenose dolphins. Indo-Pacific bottlenose dolphins usually traveled or rested in the most of daytime and made a deep regular dive at night. They tended to come back to the same depth in the deep dive at night, suggesting they foraged at the bottom of the sea. This species spent most of their time in the water shallower than 20 m. Number of surfacings for respiration was clearly correlated with the time they stayed near surface. We can estimate the school size using this relationship.