It might not. Part of Priest Rapids Fall Chinook management plan is to include wild fish in the broodstock. Last year was the second year for the live capture (which has now become a derby). Immediate mortality was just under 1% from sport handling. The fish stayed at the hatchery for about another month, and the long term mortality exactly matched the fish that swam to the hatchery on their own.

This is one example of one species in one specific location, but it's good data for sports.

http://www.ifish.net/board/showthread.php?t=534465