striped gopher eradication
Striped gophers have a varied diet, eating insects, small animals and birds as well as seeds and green shoots. They are also rather difficult to manage. Since they burrow into the soil and are quite small most fencing materials will not be effective unless you use very small mesh, like 1/4" hardware cloth and bury it in the soil at least 6" deep all the way around the perimeter of the garden. and extend up at least 2' high. But, gophers can climb so this may not be very effective unless further topped by a foot of sheet metal.
If they are already in your garden area, now is a good time to go after them, before your garden is planted. First of all you need to find all of the holes to their tunnels, which can be rather tricky. Usually there will be at least two or three, sometimes 5-10' away from a primary entrance. Fill in each opening with soil and mark it so you can find it later. After a day or two you should be able to tell which entrances are active because they will have been re-opened by the gophers. Once you know where the active burrows are you can use live traps made for gophers at those burrows. Push the end of the trap into the opening, propping it up as needed so that it closes off the opening. Once you capture them you can relocate them.
Drowning can be an effective means of killing gophers if you have all but one of the burrows closed off. Cover the remaining borrow opening with hardware cloth and fill with water until it no longer drains away. Rat traps or sticky board traps may also be used. Peanut butter is a good bait to use.
Poison baits labeled for gophers may also be used but one must be careful so that non-target animals are not harmed and that the dead gophers do not get eaten by other animals. Follow the label directions completely.