We had a really bad rat infestation last year. I ended up getting as many sticky traps as i could buy and placing them inside the cockpit lockers. One by one i sent those little rodents on their own private cruise. The ones that didn't go cruising, met a worse fate with the snap traps. Nothing better than to be sleeping and hear the snap and squeak that comes afterwards.
Turned out the neighbors boat was the nest for them and the food was running out.
I'm not some mean person that doesn't like animals, but these little jerks were in my food and crapping all over my boat. I did find out that great stuff(the foam spray in a can) works great for sealing little holes and other areas that they would travel though, and for some reason they wont try to chew into it.