Finless porpoise abundance in Omura Bay, japan : Estimation from aerial sighting surveys

We used aerial surveys and line-transect methods to estimate the abundance of the finless porpoise (Neophocaena phocaenoides) in Omura Bay, Japan. We conducted 4 surveys once each season from August 1993 to May 1994. We surveyed 621.5 km and sighted 54 porpoise groups (87 animals). In the spring survey, we detected porpoises offshore as well as inshore, whereas porpoises were mostly inshore in all other seasons. The abundance of porpoises was estimated to be 187 animals (0.6 individuals/km 2 , CV = 20%).