Japanese sperm whale hunt figures ‘not credible’ says new report

A new report published by the Royal Society has suggested that historical whaling data supplied by Japan may have been inaccurate, with under-reporting of the size and number of sperm whales hunted during the 1960s.

During the 1990s, it was revealed that the former Soviet Union had falsified its whaling data over the previous 30 years, in particular with respect to the size and number of sperm whales being hunted. Ignoring regulations set by the International Whaling Commission (IWC), the Soviets regularly killed sperm whales that were below the minimum length, and misreported female whales as larger males in order to make their number tally with the amount of oil being produced from the hunts. Only when the Soviet Union collapsed did the truth come out, revealing that around 180,000 whales have been illegally killed.

Now scientists have taken a look at figures submitted by Japanese whalers who were operating in the same areas as the Soviets and discovered that there is a large discrepancy between the two. For instance, in 1968/1969, Japanese whaling fleets in the North Pacific killed 1568 females, of which 1525 (97.3%) were reported as being at or above the IWC’s minimum length of 11.6 m. By contrast, the Soviet fleets operating during this period killed 12,578 females, of which only 824 (6.6%) were above the minimum size. Once adjustments were made for the effort involved, the Japanese figures show they were somehow 9 times more successful at catching whales above the minimum length than their Soviet rivals, and there were considerable differences in the size of whales being taken by the two countries. Further doubt on the validity of the Japanese figures is cast by the fact that once observers began being placed on whaling vessels in 1972, the number of whales Japan killed that met the minimum length dropped significantly.

These findings, along with those on the Soviet illegal catches, clearly emphasize that a proper monitoring and reporting of catch data is close to impossible as there will always be room and loopholes that people can use to cheat and so falsify reports. The study is further proof that there shouldn’t be any discussion about lifting the current ban on commercial whaling  (during which thousands of whales have still died) as this could quite possibly mean the end of some populations of whales. 

As the report notes, this falsified data forms part of the IWC catch database; researchers use it. How many studies are now invalid because of this? If the Japanese whalers falsified their sperm whale catch data, then it is very possible that they submitted inaccurate reports on humpback and fin whale hunts too.

Read the full report:
What’s the catch? Validity of whaling data for Japanese catches of sperm whales in the North Pacific
Yulia V. Ivashchenko, Phillip J. Clapham
Published by The Royal Society

Sperm whale © Tim Stenton