"George Shepherd, who was the museum curator, decided to retrieve the whale and preserve the skeleton for the museum.
"He brought it back to Whanganui on a horse and cart and the carcass was placed on the roof where it was dried and picked clean."
Dr Dickison said beaked whales are rare and had not been seen in New Zealand before and the species, now known as Shepherd's beaked whale was named after the curator.
The collection contains many stuffed and mounted birds including the extinct piopio and huia as well as some exotic animals including a couple that died at the old Aramoho zoo.
Visitor Anne Paynter from Opotiki was impressed at how extensive the collection is.
"I'm involved with the museum in Opotiki and we are just getting organised to move into a bigger building but it won't have this amount of storage."
Geoff Potts lives in Whanganui and said he is something of an "amateur paleontologist" with a strong interest in fossils and local history.
"The shellrock around here provides me with a lot of interesting finds - I like to have a bit of a dabble."
Mr Potts said he had also enjoyed the first Summer Programme activity visiting pa and kainga sites around the city with Huia Kirk on Monday.
Kevin and Miriam Williamson have recently moved to Whanganui from Katikati in the Bay of Plenty and Mr Williamson said he "takes his hat off" to Whanganui for having such a good museum.
"Tauranga is a place with three times the population and I believe they are still discussing whether they should have a museum," he said.
Dr Dickison encouraged the visitors to drop by again on January 21 when there would be a tour of the museum's textiles collection.