Sorry to hear this - - Any idea how deep he was jigging? When I am not bass fishing I go for walleye and have to keep an eye on depth - bringing them up from over 20-30 feet too fast leads to “baratrauma” - bladder expands too fast due to the lower water pressure and then they cannot get right in the water when you return them - - -Some recommend “fizzing” the fish when this happens but there is controversy even about that as a solution . . .