I learned this method from the teacher in a pasta-making class I once took. Once I started using this method to defrost seafood, I've never had a problem.

In the wintertime, it takes about 1 hour to defrost. In other seasons, try shaking it around to see how well the seafood is defrosting. By the way, the salt water has the salinity of seawater (3.5%). Try defrosting frozen scallops this way, too; they'll come out plump and juicy. Recipe by Nishinomajo