The
coast of Japan is a migratory corridor for the western stock of the gray whales
(Eschrichtius robustus), which was once considered as extinct and remains endangered. According
to the historical records, from 1955 to 2014, only 21 gray whales occurrence
has been recorded in 59 years. However, from 2015 to 2016, intensive occurrence
including the seven sightings and the two strandings were noted. In this paper,
we found that those sightings were re-sightings of the same individual, which
was initially sighted off Sakhalin during August, 2014. On 4 March, 2016, a
young female gray whale (8.9 m in body length) was stranded at Wadaura beach, Chiba prefecture. We also conducted research on this animal
including taking pictures and external measurements. In addition, we flensed this
animal to observe the internal organs and collect a skeletal specimen. The
reason for the death of this animal remains unclear; however, from its external
characteristics, we identified that this animal was not an identical one,
sighted off Sakhalin and the coast of Japan from 2014 to 2016. On 5 April,
2016, another young female gray whale (7 m in body length) was stranded at Arai
beach, Shizuoka prefecture. We concluded that from 2015 to 2016, at least three
distinct gray whales have migrated along the coast of Japan.
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