The following paper was just published: Clapham, P.J. & Ivashchenko, Y.V. 2016. Stretching the truth: Length data highlight extensive falsification of Japanese sperm whale catch statistics in the Southern Hemisphere. *Royal Society Open Science, *DOI: 10.1098/rsos.160506 ABSTRACT Falsification of reports on Japanese catches of sperm whales (*Physeter macrocephalus*) is known to have occurred at both land whaling stations and in North Pacific factory fleets. Here, we conduct an analysis of pelagic sperm whale catches in the Southern Hemisphere: we compare true Soviet length data from the *Yuri Dolgorukiy *factory fleet during 1960-75 to data for the same period reported to the International Whaling Commission (IWC) by Japan. Prior to implementation of the International Observer Scheme (IOS) in 1972, the Soviet fleet killed 5,536 females, of which only 153 (2.8%) were at or above the minimum legal length of 11.6 m. During the same period, Japan killed 5,799 females and reported that 5,686 (98.5%) were of legal size, with 88.5% of the entire length distribution reported as being between 11.6 and 12.0 m. This unrealistic distribution, together with the fact that Japanese fleets were supposedly able to catch 37 times the number of legal-sized females as the Soviet fleet, indicates extensive falsification of catch data by Japan. Further evidence of mis-reporting is that females >11.5 m dropped to 9.1% of the Japanese catch after 1971, when the IOS made cheating much more difficult. That 99.6% of 10,433 males in the pre-IOS catch were also reported to be of legal size indicates that illegal catches were not confined to females. We caution that the Japanese sperm whale data in the IWC Catch Database are unreliable and should not be used in population assessments. The ease with which illegal catches were apparently made underscores the past failures of the IWC to effectively regulate whaling. The paper is Open Access and is available for download at: http://rsos.royalsocietypublishing.org/content/3/9/160506 -- 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 tel 206 526 4037 fax 206 526 6615 email phillip.clapham@noaa.gov