Trevor Branch is a biologist most interested in solving real-life biological problems through synthesis of multiple data types, and through fitting mathematical models to data. These core interests have led him in a variety of directions. His most recent research focuses on global scale analysis of fisheries, including their current status and future directions; whether fishing down marine food webs is detectable in catches and in ecosystems; and which factors influence patterns in fishery development. He also has a long-standing interest in the human side of fisheries, including fishing behavior and fleet dynamics, and the impacts of individual transferable quotas (i.e., catch shares) on target stocks, fishery discards, and the environment. Another major field of interest is the status and trends of large whale populations—interests which have led to papers on abundance estimation, changes in population size over time, and the separation of blue whale subspecies.