His research focuses on the energetics and feeding of deep-sea fishes and other animals. His work has characterized abyssal fish feeding habits and evaluated their metabolic rates through in situ experiements. His work also uses a variety of biochemical approaches to study food webs in a variety of habitats including the abyssal plain. Jeff has participated in 49 research cruises (11 as chief scientist) including dives with the Alvin and Pisces submersibles and Jason, Tiburon and Ventana ROVs.