Key to species of Genus Balenoptera in Korea

1 Ventral pleats end before navel........................................................................... 2

- Ventral pleats extend to or beyond navel................................................................... 3

2 Ventral pleats 22–70; 200–300 baleen plates each side............................................ B. acutorostrata

- Ventral pleats 32–65; 219–402 black baleen plates each side............................................ B. borealis

3 Three conspicuous ridges on rostrum; 40–70 ventral pleats............................................... B. edeni

- One ridge on rostrum; 55–100 ventral pleats................................................................ 4

4 Head u-shaped from above; dorsal fin 1% body length; maximum body length 33 m. ....................... B. musculus

- Head v-shaped from above; dorsal fin 2.5% body length; maximum body length 27 m. ...................... B. physalus