This I thought was some good info and worth posting over here too. Its worth a review I think. If you are going to release might as well do it right. One of the most important things I think with releasing in the winter is minimizing exposure to the cold. Also the handliing of the fish and body support i.e. not holding it up by the gill plate.

Even with proper technique its estimated 16% of released fish go on to die as a result of being caught.