i dont know if you were able to get any info on your family, and i see that you asked so long ago, but if your still interested. i have just got some info. in efforts to obtain a family history interview with my grandmother i have found a book that has the geneology of the island of fohr, the book is called CHRONIC DER GERMEINDE WRIXUM VON 1898 BIS 2007.
hope this can help if you havent allready found what you were looking for. oh by the way my grandmothers maiden name was also Clausen.