That's exactly what we see in seas around Antarctica. (realclimate.org)
But they were distributed in seas around all continents, and in all palaeoenvironments from the equator to the (sometimes freezing) ancient north and south poles. (palaeontologyonline.com)
«Fish stocks are like bank accounts,» says co-author Dirk Zeller, senior scientist and executive director of Sea Around Us. (sciencemag.org)