I study the anatomy, systematics, evolution, and biogeography of fishes, primarily epipelagic marine fishes. I specialize in the economically important scombroid fishes, the group that includes mackerels, bonitos, and tunas. I also study other epipelagic fishes such as halfbeaks and needlefishes as well as some bottom fishes such as toadfishes. My research relies heavily on morphology but many of my recent students have contributed molecular methodology to some of our joint research. Some of my research is done alone, some with students, some with colleagues in the U.S. or abroad. I have spent a lot of time in the field, on board ships, scuba diving, and in the underwater habitat Tektite.

Material and observations from my field work have contributed directly to my research and the specimens added to the national collections have benefited many other researchers. I have visited all the major fish collections in the world to obtain specimen-based data for my research.

The first step in managing living marine resources is to know what organism is involved. My research has clarified and stabilized the names and relationships of the 60 species of scombroid fishes over the past four decades. For example, determining that the yellowfin tuna of the Pacific Ocean (Neothunnus macropterus) was actually the same species as the yellowfin tuna of the Atlantic Ocean (Thunnus albacares) allowed research on behavior, food habits, and early life history from one ocean to be used in management in other oceans. More important biological information was available on Spanish mackerel from Brazil than from the U.S. Gulf coast so this information was going to be used in management of the U.S. population until we showed that the South American species was a distinct and undescribed species that grew larger and matured later. This discovery avoided using inappropriate data for managing the U.S. species.

Several of the major revisionary publications by my co-authors and me have won awards from the National Marine Fisheries Service for best papers in the Fishery Bulletin. My published research on the systematics of fishes led to my being awarded the first Robert H. Gibbs, Jr. Memorial Award by the American Society of Ichthyologists and Herpetologists in 1989.

In addition to research, I have been very active in scientific societies and have served as an officer in several of them. For 30 years, I have used my summer vacation to teach an intense course on the biology of fishes, first at the Institute of Marine Science of Northeastern University at Nahant, MA, then at the Bermuda Biological Station, and now at the Shoals Marine Lab in the Gulf of Maine. In addition, I have adjunct appointments at Northeastern University and the Virginia Institute of Marine Sciences and have served on M.S. and Ph.D. committees of students at these and other universities. I integrated parts of my research with my teaching in co-authoring a highly successful ichthyology text, The Diversity of Fishes, with Gene Helfman and Doug Facey.