"14 inch Brown that took a size 26 spinner with antron wings," Spring Creek near State College, Pennsylvania. Image credit:John Gremmer, via Central Wisconsin Trout Unlimited
Remember that debate over whether 'little things' with lifestyle changes, versus sweeping government policy actions, are more requisite? Rhetoric offers no answer. Political debate over the intrusiveness of government: same problem. See that little fly hooked into the lower corner of the fish's mouth? Rising to the smallest bait makes a difference, metaphorically speaking. Don't see the point? Example: Coal-fired electricity is responsible for the majority of the mercury contamination of both fresh and marine fisheries. Whatever you do to minimize this problem - support renewable power, conserve energy, demand accountability from your elected officials - helps.
Including joining a conservation oriented group like TU, if for no other reason then it gets you out into nature.