Golden keeps eating things off beach and getting sick?

We live on the beach and our 8 yr old golden won't stop eating shells, dead crabs, and drinking sea water. She gets sick every night because of this (throwing up and diarrhea). Obviously, neither of us can keep living like this -- the only solution we see is to send her to live with a friend if we can't get her under control. How can we stop her from eating everything from the beach which keeps making her sick?