Recent large-amplitude interdecadal-scale population variations in some of the world's largest fishery stocks have exhibited a remarkable degree of global synchrony. This has been difficult to ascribe to fishing and other direct human interventions. The connotations of large-scale synchronized stock fluctuations for the theory and practice of fishery management, if real, are substantial. Thus the question of the reality of the apparent synchrony looms very large. In an effort to begin to illuminate the mechanisms that could account for such large-scale synchrony, a preliminary exploratory data analysis of evident decadal-scale "regimes" in small pelagic fisheries and of potential causative factors in the earth's global climate system was commissioned by FAO. This document reports results of this analysis.