Clarke (2004) proposed a "pygmy" subspecies ("B. p. patachonica", Burmeister, 1865) that is purportedly darker in colour and has black baleen. He based this on a single physically mature female caught in the Antarctic in 1947–48, the smaller average size (a few feet) of sexually and physically mature fin whales caught by the Japanese around 50°S, and smaller, darker sexually immature fin whales caught in the Antarctic which he believed were a "migratory phase" of his proposed subspecies. His proposal is not widely accepted and no genetic evidence for their existence is available.