Peter Herman Petersen: 1890s Norway to New Zealand

Hi, Many thanks for allowing me to join your Forum. I have a enigmatic Norwegian ancestor named Peter Herman Petersen. He was born to Peter Petersen and Jeannie Johnston in about 1850. We do not know much about his family. One family story has it that they were from Oslo and that his parents were both music professors or music teachers, specialising in the violin. Other sources indicate his father was a fisherman. Peter himself is said to have been a whaler and jumped ship in New Zealand in the 1890s. He married my GG grandmother, Annie Edwards, in 1894. He died in 1922. I realise this is very little to go on for events that happened in the distant past. But I thought I would post a message to see if anyone is missing a branch from their Petersen family tree. Plus does anyone have any suggestions for researching music teachers in Kristiana in the 1850s-1860s ? I have looked in the census records, but not had much luck. Thanks, JPJC