Todd -
One study on the Fraser pegged the release mortality for sturgeon on rod and reel (direct and delayed) at about 2.5%. Of course the real rub is the longevity of the sturgeon. Over the decades individual sturgeon are likely to be caught multiple times and it would take much to make the cumulative mortality to become significant and perhaps more importantly shorten the average life span of the fish and the number of times a given fish might spawn.

Curt