Operation urgent Lightning
fifth fleet
1970s
There is no set number; like all fleet commands around the world, the number of naval assets assigned to 2nd Fleet changes constantly. This is because ships form different Task Forces, Battle Groups, etc., and may leave the 2nd Fleet's operational command area and enter another, or they're formed/assigned as tactical considerations warrant. Ships and other assets that might be assigned to 2nd Fleet's command may be from another Fleet; it depends on the situation and needs of the Navy.
A zone of action is an area of responsibility defined by boundaries and assigned to a military unit in any situation involving action.
the western portion of the Indian ocean, the red and Arabian seas
What country? For the US, a Fleet is an Area Of Responsibility, not a group of ships, which also has many names. Be more specific.
Southwest Area Fleet was created in 1942.
Southeast Area Fleet was created in 1942.
Northeast Area Fleet ended in 1944.
Northeast Area Fleet was created in 1943.
The Atlantic Fleet region, or 2nd Fleet AOR (Area Of Responsibility), covers the entire Atlantic Ocean, Carribean, North to South until the Mediteranean Sea and Indian Ocean. The ships making the fleet are stationed at various ports. Any ship operating in the 2nd Fleet AOR can be considered part of the Atlantic Fleet, including ships that come over from the West Coast to the east coast.
The actual number changes periodically and is classified. Most numbers that you'll see in media outlets are estimates of force numbers. Actual fleet configuration and numbers is considered critical data that can be used by an enemy for attack planning, which is the reason it is not released as a definitive number to the public.