Paul, i suppose it would be good to compare the laboratory results vs in-field results. In field results may be more representative as they include the variability in fish treatment prior to release (eg, weighing, handling wet or dry hands, whether fish is carefully handled, time out of water etc), however the extended time taken to transport the fish to to sea cage from location of capture is of concern. I doubt participating fishos would high-tail it from the spot to the sea cage if there was a hot bite! Fish would sit in a live well possibly for hours. Live wells are fine for 1kg bream, but probably not for a 2 ft long jewie. Also, what happens if a 20L bucket is used as substitute for a live well, how do you account for that?
I think you would need to include a time-of-transfer factor in the study, as fish that are released would be released within a few minutes of capture.