Table:
text: German submarine U-404
Raiding history
Raiding history
Date_ Ship Nationality Tonnage Fate
26 September 1942 HMS Veteran Great Britain 1120 Sunk
29 March 1943 Nagara Great Britain 8791 Sunk
30 March 1943 Empire Bowman Great Britain 7031 Sunk
12 April 1943 Lancastrian Prince Great Britain 1914 Sunk

Question: What was the tonnage of the German submarine U-404 on March 30, 1943?