the rats we have are that size I have water all the way around me the locals call them wharf rats they are found mostly around piers wharfs etc they are from 1/2 to 3/4 the size of a muskrat so I use muskrat size traps 120 conibears and keep my feed in steel trash cans SS sells them here I just set the traps in the travel ways they are using ( no bait ) they die here every day 2-6 most days