 She took a trip to Cape York, leaving Melbourne by boat a year later on 12 March 1959.Whilst on Fisherman Island on 1 December 1959, Gillham discovered a species of seal yet to be seen on the island; during a four-day trip around the Jurien Bay islands (Favorite island, a satellite of Long island, Fisherman island and Cervantes island).Once back in Melbourne, the discovery sparked debate between scientists at the Royal Society of Victoria symposium, with some insisting them to be fur seals and others believing them to be hair seals.