The subpopulation problem in Pacific sardine, revisited

Pacific sardine (Sardinops sagax) is federally-managed in the U.S. under the assumption of three subpopulations. This hypothesis was formalized by John Marr in the late 1950s. In the decades since, studies of subpopulation structure in Pacific sardine were designed with the assumption that subpopulations exist. We conducted a critical review of studies in the literature in reference to subpopulation structure in the species across its North American range, including those used by Marr to formulate his hypothesis. Our review of these older works (1925-1970) revealed that, while based on the best available information and scientific practices at the time, many do not support the hypothesis of subpopulation structure in Pacific sardine.