In 1924 Tratz founded the Haus der Natur, a natural history museum in Salzburg. As its director, after the “Anschluss” he was successful in getting the museum integrated into the SS “research” organisation Ahnenerbe (Ancestral Heritage). Tratz was himself a high-ranking SS officer. He took part in the theft of cultural artefacts from occupied Poland and accepted objects stolen from church organisations and families persecuted as Jews. As part of the SS Ahnenerbe, his museum received objects from expeditions to Tibet.
In 1945 Tratz was removed as director. In 1949 local politicians arranged for him to be classified as an “exonerated” individual. This made it possible for Tratz to remain museum director until 1976 and he was the recipient of numerous honours.