Hooker's sea lion, also known as the New Zealand sea lion, is one of the rarest and most threatened sea lions in the world (2). Adult males are dark blackish-brown in colour and have a distinct light mane that reaches down to their shoulders. Females are grey or buff-coloured, and have a paler belly. Males are much larger than females. Pups are born with a thick covering of dark hair, which is lost at some point after birth (3).