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 the catch data was extensively by Japan, according to the researchers.
Even the IOS was often ineffective.
Clapham said that, in theory, having an inspector of a different nationality on a factory ship ruled out cheating. "But we know from Soviet biologists that it didn't entirely; inspectors couldn't be on the processing deck 24 hours a day, and they were sometimes intentionally distracted with 'celebrations' by officers who took them to drink in their cabin when something illegal was about to come aboard."
He added that whaling nations today maintain that the system of inspection proposed, should commercial whaling resume, is adequate.
"Yet it's clear from genetic analysis of what's being sold in the Japanese market that there's stuff there that you can't account for through the whaling we know about," he said. "Much of this is likely local bycatch by fishermen (it is legal in Japan to kill a whale in a net). But Japan and the other whaling countries have adamantly refused to accept a truly independent, third-party monitoring system that includes every step from the catch to the market."
Another problem concerns assessments of current whale populations, which take into account past catch data. If the data are significantly false, as the scientists have just determined, then the assessments themselves will be inaccurate.
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C. Scott Baker, associate director of Oregon State University's Marine Mammal Institute and a professor in the Department of Fisheries and Wildlife, told Discovery News that the new study presents "compelling evidence that the Japanese commercial whaling fleet was engaged in widespread falsification of records prior to the introduction of international observers in 1972."
"Their careful analysis confirms that the reported lengths of the sperm whales in the Japanese records were intentionally falsified to cover up the killing of females below the legal length set by the IWC," Baker added. "The impact of this illegal hunting of undersized females is unknown and can only be determined once the records are corrected and assessed by the IWC."
Baker said it's ironic Soviet whaling records were used to demonstrate the implausibility of sperm whale lengths documented in the Japanese records, given how much illegal whaling the Russians did over the years.
Several Soviet scientists who were aboard the factory ships at the time, however, have since corrected past data. Japanese scientists have come forward as well, but, Baker said, "to my knowledge, none have come forward with the true records from the fleets operating in national waters."
He concluded, "It is critical that Japan's ongoing scientific whaling, and any future commercial whaling, must have a robust system of observation and inspection, including onboard observers, vessel location beacons and DNA testing of market samples to confirm catches."