One never searches for a submarine utilizing the battle group. That's akin to searching for the predator with the prey, a generally unproductive endeavor that tends to reaffirm Darwinian selection. Back to the general discussion. Far-Forward ASW is generally offensive and conducted with intelligence, cueing, submarine and where feasible air forces. A premium is placed on cueing, endurance and stealth.
Submarines are the obvious choice.
As a practical matter today, submarines may contribute in only a limited manner in the battle group due to the reduced detection ranges noted above, communications issues and water space management concerns. In a hostile environment some commanders would rather not have a blue force submarine underfoot to confuse the tactical situation and to simplify his Rules of Engagement. That appears to be more of a political than tactical issue and will sort itself out under duress. With all this as background, let's see where the Revolution in Business Affairs and the associated Revolution in Military Affairs plays. Some would say that the current network centric warfare strategy emanates from Wal-Mart.