It is likely that most catching and releasing of large or Smallmouth Bass could result in 1-3% of hook mortality. This is much more likely when using livebait and in deep hooked situations with any type of lure or bait. Learning effective ways to remove deep hooks will lessen mortality. If you don't know how to safely remove a hook, cut the line leaving at least 12 inches of line andm leave the hook in. This will help to keep the shank of the hook pulled to one side of the gullet and allow the fish to continue to feed until the hook erodes. A good article on Deep Hooks In or Out can be viewed at http://www.mnbfn.org/conservation/hooksinout.html
Delayed mortality happens days, hours or weeks after release and comes from handling and/or exposure to diseases. Here in Minnesota tournament organizers are working with the MN DNR to develop 'Best Practices Guidelines" for live release fishing contests to decrease delayed mortality. Factors effecting all fish are improper handling, temperature, oxygen levels and release sites/depths. During periods of very warm water and air temperatures such as in July and August; helping fish to survive requires very sophisticated practices. Some studies indicate that under poor circumstances and without special precautions 10% -25% delayed mortality is realistic (this includes the 1-3% hook mortality). It is hoped that this gold standard of "Best Practices" will educate not only tournament anglers to better techniques but also influence all anglers to use state of the art C/R methods.
As both anglers and tournament fishermen, we need to ask ourselves what fishing might be like 25 -50 years from now, and how those anglers will look back at the year 2010 when we hear folks bragging about hooking 50- 100 bass a day. Will we find that we did no harm, or will we have evolved to different practices and for what reasons?