The most significant losses for the Japanese Navy were in aircrew. The U.S. lost 81 of the 175 aircraft that were available at the start of the battle; of these, 33 were fighters, 28 were dive-bombers, and 20 were torpedo bombers. Only 26 pilots and aircrew members were lost, though. The Japanese fared much worse, especially in airmen; in addition to losing 99 aircraft of the 203 involved in the battle, they lost 148 pilots and aircrew members, including two dive bomber group leaders, three torpedo squadron leaders, and eighteen other section or flight leaders. The most notable casualties were the commanders of the first two strikes – Murata and Seki. Forty-nine percent of the Japanese torpedo bomber aircrews involved in the battle were killed, along with 39% of the dive bomber crews and 20% of the fighter pilots. The Japanese lost more aircrew at Santa Cruz than they had lost in each of the three previous carrier battles at Coral Sea (90), Midway (110), and Eastern Solomons (61). By the end of the Santa Cruz battle, at least 409 of the 765 elite Japanese carrier aviators who had participated in the attack on Pearl Harbor were dead. Having lost so many of its veteran carrier aircrew, and with no quick way to replace them—because of an institutionalized limited capacity in its naval aircrew training programs and an absence of trained reserves—the undamaged "Zuikaku" and "Jun'yō" were also forced to return to Japan because of the scarcity of trained aircrew to man their air groups. Although the Japanese carriers returned to Truk by the summer of 1943, they played no further offensive role in the Solomon Islands campaign.