Yup. you can use the one rod for crab, and another for fish. You just have a crab pot attached to a mini winch. Kind of like the rule where in some areas you can fish one rod for salmon, and another for forage fish (herring).

I have used one called the "Cast A Crab", shaped like the outline of a house with a peaked roof. Caught many a crab with that off of the jetty in Westport.

You may want to "up" the pound test on the reel for that rod to 15-25 pound test minimum. I use a 6500 C3 when casting mine with 60# spider wire on a medium heavy rod. If you catch a crab, there is a lot of drag created, and if you hang up on the bottom, it is nice to have the ability to pull it free.

Have fun!