2008 Volume 0 Issue 18 Pages 9-12
Following a previous paper (Honma and Kogawara 2007), sighting records of whales by Sado Line (Sado Kisen) jetfoils and car ferry boats operating on the Niigata－ Ryotsu route, Sado Straight, Sea of Japan, were compiled from February to December, 2006. Thirty-six instances, comprising 25 jetfoil and 11 car ferry observations, were enumerated. These numbers were larger than those of the previous year, 2005. Two or three sighting records of different individual in a day were secured on six occasions throughout the investigation period. The greatest number of sightings was in March, 1 or 2 months earlier than would be expected in a normal year, with an exceptional sighting in December. The time zone of higher frequencies was concentrated in 10 a.m. and in 2 p.m. The directions in which the whales were swimming (= migrating route) were noted in 16 instances, consisting of 8 north, 4 south, and 4 others. There was no occurrence of collision with cetaceans in 2006.