2014 Volume 24 Pages 15-22
In March and April 2014, a gray whale Eschrichtius robustus appeared in the coastal area off Teradomari, Niigata Prefecture, Sea of Japan, adjacent to the estuary of Ohkouzu Diversion Channel of the Shinano river. The whale had been observed during the period between 21 March and 24 April. The whale often appeared very early to about eleven o'clock in the morning. The area where this whale was sighted ranged 3,700m along the coast, 50m to 1.5 km off the coast around the mouth of the Ohkouzu Channel. On April 9, we approached the animal by a boat as close as 10m, and confirmed the narrow and convex snout, the serially bumped dorsal ridge of the peduncle and scattered white spots on the body surface, all of which are characteristic for the species. No barnacle was found on the body surface. The body length was estimated to be about 10m. It seems that this whale was a healthy adult, but somewhat thin compared to the whales observed in the Sakhalin feeding ground. The whale stayed in the area where the bottom was sandy mud, depth at 3 to 7m. The whale was frequently observed staying with the right side down and exhausting smoky mud may be feeding. Behavior of this individual suggests up-going migration while carrying out eating. It suggested there is the recent migration route of the gray whale along the Asian west coast of Japan.
