For fish like trout I can believe it. I suppose that research you are basing your statement on was probably done on trout or was done by PETA.Truth be told: All sport fishermen should know by now that the majority of fish that are ever caught and released - often DIE for multiple reasons, shortly after they are returned back into the water (e.g., proven research studies) ! Doesn't sound all that much like a sport to me after all.
The majority of catfish simply do not die after being caught and released.
Mortality of most fish after being caught has a lot to do with how the fish was handled and how they were caught (gut hooked vs corner of mouth).
What I can tell you is that "ALL" the fish that are caught and kept do "DIE".