Gustav Olaf Tonning - Poragrund

I am new to this forum so please excuse and ignorance about Norway. My ancestor Gustav Tonning was naturalised in Adelaide, South Australia 27 June 1898, he had been in Australia 18 months at this time. He was 23 in 1897 when he married, so would have been born about 1874. His occupation was given as Mariner. His father's name was Ludwig. And Gustav was from Poragrund. I am trying to find any information about him or his family. Thanking you in anticipation.