Former crest of US 2nd Fleet. US Navy Image.
US Naval Institute News Service is reporting the Navy will be reestablishing the Second Fleet, which will cover the Western Atlantic. In the past it also covered the Caribbean and the Eastern Pacific drug transit zones.
Second Fleet will be the Atlantic counterpart of the Third Fleet in the Pacific.
How it will relate to Forth Fleet that currently handles the drug transit zones is not yet clear.
We are certain to see interaction with the CG Atlantic Area Commander, and probably at least one liaison officer.
Chuck Hill's CG Blog 
The real question is which naval assets will be assigned to 2nd Fleet? Will it get priority over 4th Fleet? In actuality, both Fleets may well be short?
Perhaps most of it will be P-8 aircraft.
“US Navy’s Top Admiral Cites Increased Threat in Ocean Nearest Washington” https://www.voanews.com/a/us-navys-top-admiral-cites-increased-threat-in-ocean-nearest-washington/4515353.html
Looks like the Navy plans for the 4th fleet to operate well North of the Greenland-Iceland-UK (GIUK) Gap. https://news.usni.org/2018/08/24/cno-new-2nd-fleet-boundary-will-extend-north-edge-russian-waters
Their use of “North Atlantic” to denote high latitudes is technically wrong, since any part of the Atlantic North of the Equator is the North Atlantic.
“2nd Fleet Commander Vice Adm. Andrew Lewis still only has about a dozen people on his staff and is still in the process of finalizing the numbered fleet command’s missions, tasks and functions, according to Rear Adm. Doug Perry, director of joint and fleet operations at Fleet Forces Command. 2nd Fleet is gearing up to reach initial operational capability in the spring and full operational capability about a year from now, Perry said while speaking at the Naval Submarine League’s annual symposium last week.”
https://news.usni.org/2018/11/14/2nd-fleet-functions-aor-still-determined-will-support-cross-atlantic-theater-asw