AGI - Intelligence Gathering Ship
AGI (Auxiliary General Intelligence).
A spy ship or reconnaissance vessel is a dedicated ship intended to gather intelligence, usually by means of sophisticated electronic eavesdropping. In a wider sense, any ship intended to gather information could be considered a spy ship.
Spy ships are usually controlled by a nation's government, due to the high costs and advanced equipment required. They tend to be parts of the nation's navy, though they may also be operated by secret services.
Naval trawlers masquerade as civilian ships such as fishing trawlers, which could be reasonably expected to remain in a certain area for a long time. http://en.wikipedia.org/wiki/Spy_ship