Barotrauma and Effective Catch
"For every 33ft increase in capture depth fish experience and additional degree of atmospheric pressure. This change in pressure results leads to barotrauma. For example, a fish brought up from over 33ft will suffer a 50% increase in the size/volume of its swim bladder, while a fish brought up from over 66ft suffer a 100% increase. Fish suffering barotrauma are unable to regulate their swim bladders, and will be severely compromised. To facilitate effective catch and release, anglers are encouraged to refrain from fishing in depths over 30 feet, and should use discretion when fishing in depths over 25 feet."
Rebecca Eberts, graduate student & fishery biologist with the University of Regina