Yes, the commission ruled to classify all salmon 24 inches and greater as adults; which is the reason for the rule. Fisheries data indicates that in over 7000 fish measured only 6 were 24 inches. The odds of catching a salmon exactly 24 inches long are very slim. Recommend measuring the salmon straight with normal tail flair and with the tail slightly bent so the longest portion of the tail fin is in a straight line with the mid-line of the fish. This will clearly remove any doubt the fish is over or under 24 inches. It would be reasonable to validate your permit on a fish very close just to be safe.