So, first flight guys have to be at the ramp at 3:00. Weighin started at 5:00. Are the boats sitting in the water for thise 2 hours keeping fresh water in the livewell? If not, how do they keep the fish alive for the 2 hours without replanishing the oxygen? Are they in tubs and put them back in the boat at weighin time?

It is unlikely that a competitor would not keep his fish with him at all times until the weigh in. The live wells should be able to aireate enough with use of live well oxygenator chemicals.

The fish stay in their livewells the entire time. Those livewells are fully capable of ensure the fish are happy and comfortable.