Japanese disguise submarine as fishing boat according to the U.S. Joint Intelligence Committee. Daily summary dated 4 January 1942

An item reported that 3 miles off San Martin, California, USA an American aircraft sighted on the position 30.30 north latitude and 116 west a longitude a fishing boat. When she was approached she disappeared so it was believed that it was a Japanese submarine disguised as fishing boot.

Source

Map Room Papers (Roosevelt Administration), 1942 - 1945. U.S. Joint Intelligence Committee. Daily summary No. 25 dated 4 January 1942