Here is the stuff about Muskies.....interesting because they intentionally were rough with radio tagged fish and found almost no mortality.
Chippewa Flowage Muskie Study - Y1
To save you wading through it,
"Although no previous study, to our knowledge, has ever examined the validity of these widely-held beliefs, we too, shared concern for the survival of released Muskies, especially after reviewing tables 3 and 4 of the CFMTP. For this reason, we made the decision to subject the study Muskies to a variety of popular and unpopular holds, netting practices, and release practices, etc. Considering that the catch and release participants of the study have caught and released in excess of 1,500 Muskies; and, for the most part, practice the "proper" release methods, it was determined that it was necessary to expose the Muskies of the study to the same type of conditions, practices and treatment that they would receive while in the control of inexperienced musky fishermen. Only then could we make confident determinations as to the affects of such treatment, practices and conditions on musky survivability. The first year results are in. in terms of the types of holds: horizontal vs. vertical vs. diagonal-- there was no affect on mortality. The same was true of netting and release practices. We had four study Muskies that bled from slightly to profusely from the gills and all survived more on that later. in addition, two others were hooked during battles in one eye. They also survived. At the time of their releases we "experts" would have bet that at least four of these Muskies would have died. But none of these Muskies died! The good news is that Muskies are much hardier than previously thought. in fact, 95.6% of the Muskies caught, radio-tagged and released for the study survived the open-water fishing season! Only two out of the forty-five Muskies of the study expired. Now, does this mean that we should abandon the cautious release methods that most have come to accept over the past few years? Absolutely not. But, these findings illustrate that we must be careful to label something as proper" or accept something as "fact" without appropriate supporting research data."