The following was just published online and is available for free download: Clapham, P. 2016. Managing Leviathan: Conservation challenges for the great whales in a post-whaling world. National Academy of Sciences Revelle Lecture Series. Oceanography http://dx.doi.org/10.5670/ oceanog.2016.70. http://tos.org/oceanography/article/managing-leviathan-conservation-challeng... ABSTRACT Perhaps no group of animals has come to better symbolize human misuse of the global environment than the great whales. Almost three million whales were killed by whaling in the 20th century alone, with some populations estimated to have been reduced by 99% of their pristine abundance. Attempts to promote regulated, sustainable whaling by international agreement, notably through the International Convention for the Regulation of Whaling (1946), were almost immediately derailed by over-capitalization and profit-based self-interest. The major whaling nations used uncertainties in abundance estimates to ignore increasing evidence of population declines, and consistently exploited procedural flaws in the Convention to obstruct either the passage of rules designed to enact conservation measures, or proposals for independent inspection of the industry. This major failure of regulatory efforts was exacerbated by secret, large-scale illegal whaling by the former USSR and Japan that remained undisclosed for decades. Today, the status of the great whales varies widely: some species or populations are recovering strongly from exploitation, while a few others remain critically endangered. Although some whaling continues, the scale is greatly reduced from that of the 20th century, and in this largely post-whaling world other threats to whales are more significant. These include well-documented problems such as ship strikes and entanglement in fishing gear, as well as issues for which population-level impacts are unclear (ocean noise) or largely unknown. The removal by whaling of so many whales likely had significant impacts on the ecosystems in which they played a major role as consumers and, through their transport and recycling of nutrients, in the enhancement of primary productivity. As populations recover, the effect of their reintegration into the marine environment represents a fascinating issue in ecosystem dynamics. Overall (and with some notable exceptions) whale populations will likely continue to recover; however, this generally optimistic outlook is clouded by the potential for large-scale oceanic ecosystem changes precipitated by global warming. -- Phillip J. Clapham, Ph.D. Leader, Cetacean Assessment and Ecology Program National Marine Mammal Laboratory Alaska Fisheries Science Center 7600 Sand Point Way NE Seattle, WA 98115, USA Associate Editor, *Royal Society Open Science* http://rsos.royalsocietypublishing.org/ tel 206 526 4037 fax 206 526 6615 email phillip.clapham@noaa.gov