How early escort carriers might have changed the U-boat war

What effect might several small British escort carriers with Swordfish have had early in the Battle of the Atlantic?

They could have raised early U-boat losses, disproportionately removing Germany's scarce prewar-trained crews and improving convoy survival later in the war.

Experienced prewar U-boat crews were difficult to replace. If carrier-borne aircraft had forced more submarines under or destroyed them in 1939-40, the effect could have carried forward through weaker later crews as well as additional merchant ships surviving. The answer is explicitly counterfactual, but its mechanism is grounded in training and attrition.