Book excerpt: The Large Marine Ecosystems (LMEs) of the world annually produce 95% of usable global marine biomass. LMEs are presently being subjected to stresses from unsustainable fishing, climate change, coastal eutrophication, toxic algal blooms and degradation of critical habitats, resulting in significant losses of socioeconomic benefits to coastal countries. The volume provides assessments of the changing states of selected polar, temperate and tropical LMEs using the case study method. From the studies of changes in biomass yields and environmental health, new insights are provided on the causes of the changes and actions presently underway to improve the health and sustainability of LMEs. Twelfth in the series on LMEs (see http://www.lme.noaa.gov), this book is essential reading for scientists and students in marine relevant fields, conservationists, marine resource managers, policy makers and others interested in the fate of ocean ecosystems.