Northern fin whale

Northern fin whales are smaller than their southern hemisphere counterparts, with adult males averaging 18.5 m (61 ft) and adult females 20 m (66 ft).[4] Maximum reported figures are 22.9 m (75 ft) for males and 24.7 m (81 ft) for females in the North Pacific, while the longest reliably measured were 20.8 m (68 ft) and 22.9 m (75 ft) — all were caught off California, the former in the 1920s and the latter in the 1960s.[5] At sexual maturity, males average 16.8–17.6 m (55–58 ft) in the North Atlantic and 17.4–17.7 m (57–58 ft) in the North Pacific, while females average 17.7–19.1 m (58–63 ft) in the North Atlantic and 18.3–18.6 m (60–61 ft) in the North Pacific. At birth, calves are 6.4 m (21 ft) in the North Pacific.[4]

Because of the opposing seasons in each hemisphere, B. p. physalus breeds at a different time of the year than B. p. quoyi. Peak conception for B. p. physalus is December–January, while peak birthing is in November–December — in both the North Atlantic and North Pacific.[4]