Quite a few of you have noted that the sizes I suggested for the Blue Whale and Sperm Whale are absolutely extreme and grossly exceed the often-cited maximum size estimates.
And understandably, think the primary sources cited by McClain et al (2015)'s "Sizing Ocean Giants", that being the IWC, probably aren't the most sensible basis to stake a claim on.
For example, the Sperm Whale's maximum sizes are often cited from 18-22m, and the Blue whales at 25-27-30 meters; especially based on contemporary physical evidence raised in other sources.
Something clearly looks suspicious, and quite a few well-informed readers have erred to taking these outlandish sizes with a grain of salt.
BUT- I am happy to say I did do my homework for these and can confidently say I can vouch these sources are indeed a reliable source, without having to take the researchers' word for it alone.
In addition to this, I've had some (admittedly basic) scientific statistics training while in university, and utilized that in analysing the data McClain et al (2015) thoughtfully provided.
I won't dump heavy formula or anything, as the very most basic statistical or logical assumptions were used (with no reason to assume they wouldn't be enough to cut it).
(note- a lot of this information is based on the FREE online scientific study, I'm far too lazy to link it this time, but entering the name into google will show you a copy- I strongly recommend this as it's worth it!).
So, firstly the source is the International Whaling Commission, who in 1946 passed a standardized set of practices that included measuring catches on-board the decks of ships, using a "between the pegs" method of a straight ruler from the frontermost part of the whale to the base of the notch in the tail fluke.
This means that in *theory*, the most reliable method of measuring whales WAS used, and not stupid ones like dragging the carcass next to the boat and taking a guess, as was often done from other sources; and there was a robust process of measuring the whales without curves being factored in.
So if they measured 33 meters in length, that should match the 33 meter depiction on my chart.
Case closed? Of course not!
So many things could go wrong in practice that would completely corrupt the data that the "theoretical" ideal is thrown out the window.
1- Human error in measurement and false, lazy or fabricated data being entered.
2- whalers measuring around the curves before 1946, and giving exaggerated measurements until this date.
Luckily, our ability to assess this source doesn't stop there, we CAN actually scrutinize all of these issues. And that's besides making generous assumptions that measuring the whale between-the-pegs accurately was easier done than not, we can use statistics from the McClain study.
When measurements from a population in the natural world find their way into statistics, one trend always seems to hold true- "Regression to the mean"- that any measurable attribute can vary, but most members of that species tend to be closer to a 'middle point'.
If we were measuring the height of adult men, you'd expect the vast majority of men to be between 5.5 and 6 feet tall (150-180cm). You'd expect a fair few men to be a little shorter than this, and a little taller (by about another foot), but not quite as many. And you'd get a few rare cases of men under 5 feet and over 7 feet. The same is true for most other animals. And statistically, if you depicted this as a HISTOGRAM, you should end up with a "hill" shape, that gently slopes up from the sides and gets tall and pointy in the center (this is called a "Normal" distribution). Similarly, a "box plot" should show something looking like a box with a line roughly in the middle, and equal lines poking out above and below.
If you see this in your data, there is a good chance it's authentic. A bit of asymmetry or slight bumpiness might be problematic, but there is a good chance it's still legit if the overall shape more-or-less makes this "hill" curve.
Otherwise, there is a good chance something went horribly wrong with data collection.
Fortunately, that is NOT the case with the data on the whales. Looking at either the Blue Whale or Sperm Whale size-by-local-population data.... the box plots and histograms all show reasonable "normal" distributions... at least among the local regions they were shot in.
Well, not quite normal. The sizes seem skewed to bigger whales, with expected smaller whales that would realistically 'balance' the scales, completely missing from the data from all but a few regions. The likely reason? The whalers simply didn't bother going after smaller specimens and discriminated only towards the larger ones. Besides IWC regulations setting minimum permitted sizes for whaling, the statistics themselves actually provide evidence that's exactly what happened; in some areas (mainly Southern Ocean), the whales are generally larger, and the skew vanishes- suggesting "gunners selection" didn't feel the need to discriminate among generally larger whales. Because these records come from completely different parts of the world, and often different whaling teams, it not only suggests none faked their data, but means all coincidentally gave records that suggest authentic measurements; unlikely the IWC would be able to fake data on such a wide scale to conform to "normal" population distributions, especially with no motive. Furthermore, the general size variations appear to be reasonably consistent among wider regions, suggesting the broad variation is based on wide geographical area, and not so much the teams measuring them.
However, this is where I raise an important point; the size of specific populations are SUBSTANTIALLY different. In both Blue Whales and Sperm Whales, the extreme size records are ONLY found in populations among the Southern Oceans, near Antarctica. Everywhere else in the world, both whales tend to conform to far more conservative sizes. The largest Blue Whale in the whole Northern Hemisphere was about 27 meters, and that was an exceptional specimen. Among Antarctic Blue Whales, 30 meters is.... reasonably normal, actually. However, the 33 meter specimen is very much an outlier.
This means, that the conservative sources are, in some regard, still correct.
What about measurement? The crew might be showing some consistency in their method- but what if they were consistently using the WRONG type of measurement the whole time?
This is made more complicated because the largest sizes were recorded BEFORE 1946. What if this was just due to measuring around the curves prior to the new regulations? Actually quite easy to check.
If whalers switched from "around the curves" to "Between the pegs", we would expect every whale they measured to give smaller measurements after 1946. Meaning the sizes of all whales (and also the average) would suddenly drop after 1946.
Once again, McClain kindly provides evidence that isn't the case. They provide a scatterplot of sizes recorded by year- and luckily, the scatter of dots remains basically the same, with one exception- the largest sizes gradually become lower. But, this appears to happen long before 1946, meaning it appears to be a genuine trend among the whales (likely from the very people hunting them). Otherwise, the sizes appear to remain concentrated around the same "average" point.
Because of this, there is only one likely explanation- the whalers cited by the IWC were already measuring "between the pegs" prior to 1948 as well as afterwards.
Overall, the data is surprisingly smooth in every area where strange quirks would reveal a falsehood, even when small sample sizes would expect to corrupt the data a bit already.
As a result, we can be fairly confident that the historical people taking the recordings were consistently and accurately doing their job correctly at all points in history McClain et al 2015 were basing their study on.... and the measurements they reported were the real deal!
(Either that, or this is the most sophisticated hoax ever conceived in the history of recording animal sizes, with no apparent motive for gain as well)