We only had seven carriers, when Pearl was attacked. CV's 2 through 8. (CV-1 Langley had been converted to a Seaplane tender).
Three of these were in the Pacific, and none of them were damaged at Pearl.
But over the course of 1942, we moved three of the Atlantic Carriers into the Pacific, because the Japanese kept sinking or disabling the carriers we had. Only Ranger was left in the Atlantic, despite the desparation of the submarine warfare there.
Out of the six carriers we moved to the Pacific, four had been sunk by October. And the other two were out of service due to battle damage for extended periods.
Saratoga was in the dock at Bremerton from January to May, and at Pearl from August to November.
Enterprise was in the dock at Pearl for much of September and October, was severely damaged on October 26th, but continued to operate until November 16th, because she was the only carrier in the Pacific still floating.
It wasn't that only six carrier hulls were sunk, but that damned-near all of our carriers were sunk, in the year following Pearl.