Sir James Hector, founded the marine mammal collection in 1865. Hector has two species of cetacean named after him, Hector's dolphin and Hector's beaked whale.
Each of the subsequent curators and technicians associated with the marine mammal collection have added to it by acquiring material from strandings and more recently from fisheries by-catch. Key contributors to the collection are Walter R.B. Oliver, Charles McCann, Alan N. Baker, Michael Huaki, and Anton van Helden, with significant fossil whales collected by Frank Climo.
External researchers have gifted voucher specimens of the species they were working on, including Martin W. Cawthorn (New Zealand Sealions and fur seals), Liz Slooten and Steve Dawson (of CETOS, Hector's dolphins), and the Massey University by-catch programme. The marine mammal collection of enthusiastic private collector Frank Robson was also purchased by the museum.
Many specimens come into the collection through the enthusiastic support of the staff of the Department of Conservation, and from members of the public.