Sustaining Healthy Ecosystems, Livelihoods, and Local Seafood Act or the SHELLS Act This bill directs the Department of Agriculture (USDA) to establish an Office of Aquaculture and an Aquaculture Advisory Committee. The term aquaculture means the propagation and rearing of aquatic species in controlled or selected environments, including ocean ranching (with exclusions). Specifically, the Office of Aquaculture must encourage and promote aquaculture operations that promote U.S. food security and limit adverse environmental effects. USDA must also establish a 14-member Aquaculture Advisory Committee to advise USDA on (1) developing and advancing aquaculture best practices; (2) the history, use, and preservation of indigenous and traditional aquaculture practices and ecological knowledge; and (3) providing technical assistance to aquaculture farmers and businesses.