German navy had 6 submersible submarine tenders in service according to the U.S. Joint Intelligence Committee. Daily summary dated 25 February 1942

An item referred to rumors reported by M/A Stockholm, Sweden that six German submersible submarine tenders with a displacement of 5,000-6,000 tons were now in service.

Source

Map Room Papers (Roosevelt Administration), 1942 - 1945. MR0423. U.S. Joint Intelligence Committee. Daily summary No. 77 dated 25 February 1942