In general, lethal control for wildlife should be avoided when there are other solutions available. With rats, for example, minimizing attractants and rodent-proofing your buildings is usually both more humane and more effective in the long run. Gophers are the exception. It is extremely difficult to discourage them from living in your yard once they have found it unless you dig up your whole garden and put down hardware cloth. The best and most humane solution to a gopher problem is often, in fact, trapping the first ones you see.
"I can live with one gopher, so why kill it if it isn't causing too much damage?"
That's what some homeowners think when a gopher mound first appears on their property. They may indeed be able to tolerate one gopher, but that gopher will quickly reproduce and there will be many more. The more gophers that live in your yard, the more damage will occur. At some point, when their tunnels start undermining your hardscape, they will all have to be trapped. Why wait and trap ten gophers (and have to repair the damage they have caused) when you could have only trapped one at the beginning and prevented the problem?
If there are gophers in your yard, even just one, the time to control them is now. Follow these gopher control tips to ensure that you are practicing the most humane and effective strategies, and don't wait until you have twice the number of gophers to get rid of. And there's no need to dig up your whole yard to gopher-proof it, but if you redo any part of your yard, consider putting gopher baskets around the new plants or putting them in a raised bed. More information on keeping gophers away from your plants can be found here.