Mattson/Johnson

I would like some help finding the roots of my mother's family. Nels A. Mattson b. May 13, 1849 in Tromso. His father was Mathias Mattson b. abt. 1822 in ?Tromso? Mathias was married in Norway to Anna Johnson b. Feb. 1823 in ?Tromso? Nels came to the US prior to 1882 but I don't know when. Nels married Baret Maria Anderson in Minnesota in 1882. Baret was born in Norway on May 10, 1857. My grandmother, Agnes Berntine Johnson, was born Nov 29, 1903 in Balsfjord, Troms County, her father was Carl Olai Johnson b. June 12, 1875. Carl's parents were John Anderson and Bertha Vanberg. Carl's wife was Nelle B. Larson. Carl, Nelle, and Agnes left Norway on June 9th 1904. The port was Trondheim I think. The ship was Merian? I know that Carl's brother Sorn Albert Johnson, b. Jan 26, 1877, came to Minnesota too. At least four other siblings stayed in Norway. Siblings names were John, George, Nick, Andreas, Hensina, Ole, and Nels. WOW! I would be most gracious for some leads. Thanks.