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Marine Science Graduate Program

Robert J. Olson, PhD

Senior Scientist, Inter-American Tropical Tuna Commission

Dr. Olson’s research is designed to contribute toward the eventual goal of ecosystem-based approaches to fisheries management. His main focus is the ecological role of tunas and other large pelagic fishes in the eastern Pacific Ocean (EPO), and the indirect effects of fisheries removals that act through the food web. This requires an improved understanding of food web connections, energy flow, and dynamics in the open ocean, and Olson’s studies involve pelagic species caught by the tuna fisheries as well as other key ecosystem components not directly impacted by the fisheries, such as vertically-migrating mesopelagic fishes and squids, and planktonic crustacea.


Ph.D., University of Wisconsin, Oceanography and Limnology

M.A., San Diego State University, Zoology

B.S., California Polytechnic State University, San Luis Obispo, Biology

Scholarly and Creative Work

Dr. Olson and colleagues have studied various aspects of food-web dynamics in the EPO using diet analyses, stable isotope analyses, and ecosystem modeling. His recent work includes ecological implications of a decadal-scale diet shift in yellowfin tuna, amino-acid compound specific isotope analysis of EPO food-web components spanning several trophic levels, dietary and isotopic indicators of the tuna-dolphin association in the EPO, intra-guild predation by large pelagic predators on tunas, ecological metrics of purse-seine fishing for tunas in the EPO, and ecological risk assessment for data-poor bycatch species.

Olson has used bioenergetics modeling to examine large-scale implications of predation by the yellowfin tuna population on the pelagic ecosystem. He and colleagues have developed an ecosystem model for the pelagic EPO and applied it for addressing the relative top-down effects of fishing and bottom-up effects of environmental forcing on the ecosystem.

Olson is active in IMBER’s regional program CLIOTOP , and is co-chair of CLIOTOP Working Group 3 (Trophic Pathways in Open-Ocean Ecosystems). He is currently co-guest editor of a Deep Sea Research II special volume on the Role of Squids in Open Ocean Ecosystems