Anyone who says gilling a fish won't hurt it is just plain wrong. Obviously the gills themselves can be damaged. The next time you clean a fish take a look at the " throat latch". This is the connecting point of the head on the underside. It's very small and when gilling a fish this area is supporting the total weight of the fish. Not good. This method also bends the fish's head in a unnatural position in relation to the rest of it's body.

The least damaging way to hold them (if you must) is to hold them by the caudal peduncle (the tail wrist) with one hand and the other hand under the belly. Two things to keep in mind about this method; first, the hand under the belly is exerting pressure on the internal organs. There are no ribs and very little muscle tissue to protect them in the belly area. Second, the the caudal peduncle must be kept straight. One of my pet peaves is when people bend this area downward at a sharp angle. This bruises the muscle tissue and stretches the spine.

Keep in mind these creatures are used to having their weight supported by water which exerts an even ammount of pressure everywhere on their bodies. Lifting them out of the water changes this. Best to be quick and get them back in the water. If you want pictures or measurements for a repro think about how you're going to do this AHEAD of time so it can be done quickly. Catch and release is only good if the fish survives. Despite the best of intentions, it becomes nothing more than killing fish and throwing them back in the river if you handle the fish improperly.

Off my soapbox (for now!!)
Doug