The fatty acid composition of Bryde’s whale oil obtained through commercial whaling in 2019 was investigated and compared to the results of a reference study conducted in 1979. The measured proportion of long-chain fatty acids was higher than that obtained in the previous study. The proportion of the polyunsaturated fatty acids detected was approximately 1.5 times higher than that detected in the previous study. Bryde’s whale oil, as a new material, is expected to have applications in the development of healthy foods.
Pygmy sperm whale Kogia breviceps is found in temperate to tropical areas throughout the world. In Japan, it is often reported to have stranded ashore on the Pacific side of Honshu Island, but only six individuals have been reported in Hokkaido. Its feeding habits in the waters surrounding Japan have not been reported. In this study, the stomach contents of three pygmy sperm whale individuals stranded on the Pacific coast of Hokkaido from 2011 to 2014 were investigated. As a result, ten species of cephalopods from 8 families and one species of fish were found. All individuals fed on cephalopod of the family Gonatidae and Watasenia scintillans, Gonatus pyros, and Chiroteuthis calyx appeared from two out of three individuals. The largest percentage (73.0%) of the total number of prey species belonged to the family Gonatidae spp., followed by Watasenia scintillans (6.2%) and Chiroteuthis calyx (3.4%). Only one individual fed on fish, which were identified as Gadus chalcogrammus. The size composition of the prey showed that the smallest prey was Chiroteuthis calyx with a dorsal mantle length of 29.4 mm and the largest prey was the Galiteuthis phyllura with a dorsal mantle length of 420.2 mm. These results indicate that the pygmy sperm whale use mainly mesopelagic cephalopods off the coast of Hokkaido.
On 20 July 2020, the partial skeletal of a gray whale was found on the coast near the mouth of Notoro Lagoon in Abashiri, Hokkaido, Japan, facing the southern Okhotsk Sea (44.105° N, 144.175° E). This is the first confirmed stranding of a gray whale on the Hokkaido coast of the Okhotsk Sea. The recovered bones were a posterior part of skull, the right mandible, four caudal and one caudal or lumbar vertebrae, two epiphyseal plates and a single phalanx. The length of the right mandible was 150 cm in a straight line. The body length was estimated 790 cm by the length of mandible, which means the whale was less than one year old at the time of death.