Along with the bulk of the rest of our naval warships. Submarines were simply not effective at hunting other submarines at that time.

Interestingly, the US submarine doctrine also trailed Germany badly at the time, and the Navy viewed them primarily as scouting and support vessels to the surface fleet. So while Japan had long, exposed supply lines and very poor anti-submarine weapons and tactics, our submarines were squandered for much of the Pacific campaign in largely ineffectual attempts to attack Japanese warships. Once we redeployed our submarines as commerce raiders and replaced our criminally defective torpedoes, they quickly put a tight stranglehold on Japanese shipping.