From 1999 on, Port of Nagoya Public Aquarium (PNPA) had been collecting information on cetaceans in Aichi prefecture and its vicinities. The primary concern had been stranding of finless porpoise (Neophocaena phocaenoides). In February 2010, there was a finless porpoise wrongly entered into a river that ran through the city of Nagoya. PNPA immediately took it in and kept it in captivity for 346 days. In recent years, cases that finless porpoise was seen within the port of Nagoya and in rivers within the city had been frequently reported in. PNPA started research by visual observations for finless porpoise using a small research ship in the port of Nagoya. During August 2011 and July 2013, the research was conducted twice a month, in total 48 times. Finless porpoises were recognized 24 times; the number of recognized groups was 73; the number of recognized individuals was 165 (the use of towing type acoustic data logger included). Most of the contacts took place in winter (December - February.) and that took up 80 percent of all. 83.6 percent of the contacts were solo or duo. Through the 2-year-resarch, it was concluded that many individuals of finless porpoise enter in the port of Nagoya in winter.
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