The 27-year-old Dutchman beat Michael van Staeyen and Stefan van Dijk to the line at the end of the 183.6km race that comprised 11 circuits of a 16.7km course.
A leading group of eight riders entered the final lap with a lead of 18 seconds but Argos-Shimano reeled in the leaders for their speedster Marcel Kittel.
But it was Stroetinga, who is better known as a track specialist and took bronze in the scratch race in this year's World Championships in Melbourne, who took the victory.
WorldTour teams Lotto and Vacansoleil fielded teams in the 79th edition of the race that is classified as a 1.1 event on the UCI Europe Tour.
- Michael van Staeyen