MDC employees Biologists that monitor stream populations of fish and other species. When they set a season, they are pretty sure it will not affect the population of the stream in a negative way. A few years back, MDC tried a age old method of fishing called Grabbing or Hogging. At the end of the first season, they determined that too many large, mature catfish were being taken with the method and the season was discontinued to preserve the population.
I have never gigged a fish and have never wanted to gig a fish. If there are poachers taking illegal fish, then it needs to be stopped, but gigging is a valid sporting method that provides entertainment and nourishment to a group of sportsmen. I don't bow hunt any longer and I know alot of deer are crippled by bow hunters each year. This may affect my gun season, should I get on a high horse and campaign against for my interests only? I don't snag paddlefish and am sure game fish are caught and harmed by that method also, should I campaign against that? NO.
Just because you don't understand something does not make it wrong or odd or incorrect, it just means you lack the ability to reason and learn about them before you cast judgement. I don't have any links or papers that show actual data on the matter, I just trust the MDC to do the research for me. If you want, google "gigging effects on missouri streams" and see what pops up or do a similar one on the MDC site. Or, if you are really bored, call a fisheries biologist and ask him to provide some statistical data on the subject.