At a watercraft inspection station along the highway a few miles from the Idaho border, one very good boy is doing a very good job. Fin is the Washington Department of Fish and Wildlife’s mussel-smelling dog. He’s about 4 years old and is a Catahoula leopard dog, blue lacy and Australian kelpie mix. Like a drug or bomb-smelling dog, his nose is particularly good at sniffing out tiny, invasive mussels.