By January, Marriott's approximately 780 full-service hotels are expected to source at least 50 percent percent of their seafood from certified sustainable, responsible fisheries and aquaculture farms, Brad Nelson, Marriott's culinary vice president and corporate chef, said.

The program, quietly launched in June, will influence how individual chefs purchase their seafood, what types of seafood they buy and how hotels market their seafood to customers. Guests may also notice new types of seafood on hotel menus - or a certain type of fish that's missing because it's not deemed sustainable.

Nelson