In the late 1970s eight Balaenoptera specimens of unknown identity were caught in the lower latitudinal Indo-Pacific waters by Japanese research whaling vessels. The combination of the allozyme patterns and physical maturity of the eight specimens separated them from all acknowledged Balaenoptera species. In September 1998 we collected a medium-sized baleen whale carcass on a coastal island in the Sea of Japan. This specimen and the previously collected eight specimens resembled Balaenoptera physalus (fin whale) in external appearance but were much smaller. Comparison of external morphology, osteology and mitochondrial DNA data grouped the nine specimens as a single species but separated them from all known baleen whale species. Therefore, here we describe a new species of Balaenoptera, which is characterized by its unique cranial morphology, its small number of baleen plates, and by its distant molecular relationships with all of its congeners. Our analyses also separated Balaenoptera brydei (Bryde's whale) and Balaenoptera edeni (Eden's whale) into two distinct species, raising the number of known living Balaenoptera species to eight.

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Two multiplex PCR amplifications were performed to analyse six microsatellite loci of Schlegel's black rockfish, Sebastes schlegeli, an important commercial fish in the northern part of Japan and an important species for the stock enhancement program in this area. We analysed 67 wild samples from Yamada Bay, Iwate Prefecture, Japan. The observed genotype frequencies agreed with the Hardy–Weinberg expectations at all loci, and the observed heterozygosities ranged from 0.072 to 0.897.

Thin-layer isoelectric focusing was applied to the identification of whale (Cetacea) species by using water-soluble sarcoplasmic proteins of skeletal muscles. Twenty-eight samples consisting of 4 species (10 samples) of baleen whales (Mysticeti) and 8 species (18 samples) of toothed whales (Odontoceti) were analyzed. Each sample (approximately 1 g) was electrophoresed with Ampholine PAGplate, pH 3.5-9.5. The electrophoretic profiles were species-specific on the 4 toothed whale species that did not have a marked intra-species difference, and all 4 baleen whale species. However, the profiles were not specific on the 4 other dolphin species, even though they were discriminable from the other 4 toothed whale species. Numerical values of pls and relative peak heights were obtained by densitometric analysis of the isoelectro-focused protein bands. The bands were also species-specific for the 8 toothed whale species mentioned. The values may be applicable to species identification without the need for a standard sample, which may not be readily obtainable. Experiments on test samples of minke and sei whales showed that bloodletting with ice water made the densities of isoelectro-focused bands thinner, although species identification was still possible by using the Inside part of muscles. Heat treatment at below 60°C for 10 min caused little denaturation; at higher temperatures the protein bands were diminished in a temperature-dependent fashion. Therefore, the present isoelectric focusing analysis should be applicable to small samples of whale meat, excluding several species of dolphins.