Good News from the Sea …. Whale numbers on the up and up
The view from the lighthouse at Tacking Point, NSW, on the day of the whale count. A perfect day to get an accurate count.
Preliminary figures for the single-day whale count at Tacking Point this year show that some 433 whales passed by on their way to the Great Barrier Reef. This compares with the appalling figure of just 19 whales for the full daylight hours of the day of the first count way back in 1999.
It is also a sizeable lift in the tally from the census just two years earlier when 332 whales were counted in 2018.
This year’s count is encouraging for those who doubt the notion that the marine environment of the world is in a state of collapse.
Due to the fact that the ocean water at Tacking Point is fed from the Great Barrier Reef via the strongly flowing Eastern Australian Current, the marine environment of both the Reef and Tacking Point are linked. The two environments are also linked by the fact that it is the same whales that swim past Tacking Point that meet, socialize and breed in the Great Barrier Reef. With this link the recent count at Tacking Point is also encouraging for those who doubt the Doomed Reef Scenario.
The Doomed Reef Scenario is simply the over-riding belief conveyed in parts of the media that the Great Barrier Reef is incapable of recovering from the twin assaults of cyclone damage and coral bleaching some years ago. The Doomed Reef Scenario – or, more accurately, the Fragile Reef Hypothesis – holds that we are living in the last days of the Reef and that we had better get up there as soon as possible, with our children, to see it before it dies completely.
Is the health of the creatures that visit the Reef – including the whales – showing signs that either the Ocean is unhealthy or that the Reef is so fragile it will die? The count at Tacking Point fails to confirm anything about the Fragile Reef Hypothesis and is, indeed, strong evidence to the contrary.
Tacking Point Lighthouse is on a headland near Port Macquarie on the New South Wales coast. The headland juts out just far enough to create a rounding point where whales come close to the shore on their migration. Simply put, it is the shortest route North on this part of the coast and this causes a funnelling effect making it a great vantage point from which to count whales. This may not guarantee that every last whale in the migration will be counted but a huge percentage of them should come within view.
Sure, there may be some contrarian-cetaceans which persist in taking a route beyond the horizon and simply do not get counted. There may be whales that get missed by the observers because of the sea state or, far less likely because of the controls in place at the counting point, there may be whales that are counted twice. There may also be the frustration that the daily movement of whales may be a little whimsical and a higher-than-usual or a lower-than-usual number might pass by on the day of the count. For example, three days prior to the official count this year, the number of whales that transited Tacking Point was over 600.
So the single-day count must be assumed to be subject to some margin of error. But, even given generous error bars, the fact is that there has been a sustained growth since the single-day census began in 1999.
I can vouch for the rigor with which the count was done because I attended Tacking Point Lighthouse on the day of the count this year (2020). It was an exciting day because, even by 10:00 am, there had been more than 120 whales counted. Prospects were good.
The event was well organised with someone in charge, a specific arc of sea in which to count, nominated counting assistants, various spotters, a tally room and a team of observers equipped with binoculars with a compass in the field of view as well as finely marked graticules, marking angles left and right and up and down. Using this type of equipment it was virtually impossible for two observers at the lighthouse to see the same pod of whales and count them twice.
The person in charge also had radio communications with two motor boats at the northern extremity of the search arc and these could be used to confirm points of detail such as the numbers in a pod.
The Tacking Point census is conducted on the same day every year – the 26th weekend of the year. This year, 2020, the day for the count was Sunday 28th June, just a few days after the Winter solstice.
When this year’s count of 443 is compared with the figure of just 19 whales in 1999, it shows that the whale migration is on a sustained growth trend of around 10% to 11% per annum. For a whale population, a ten or eleven per cent annual growth in numbers is not just a ‘make-do’ or mediocre number, it is an abundant rebound in nature.
The point about this being an abundant growth rate relates back to my book about the Reef (‘Will the Great Barrier Reef Survive: Doubting the Doomed Reef Scenario’) in which I point out that nature has the ability to rebound abundantly when the times are right. Nature is quick to take the main chance and whales on the East Coast of Australia are certainly an example of this.
As a digression I need to outline the history of why the whale population declined in past centuries. It did not decline because the sea got hotter, or because of some other change in the environment, it declined because it faced a phenomenon known as an overwhelming superiority of firepower.
For centuries sea-going cultures had been hunting whales. This was originally on a hunter and gatherer scale but then developed to an industrial scale. In the days of sail, whalers roamed the oceans in their search for whales and killed and harvested them relentlessly. In the decades before whaling was eventually controlled, this firepower extended to harpoons with explosive heads, fast vessels that could out pace whales easily and move rapidly from pod to pod and even to fixed wing and helicopter reconnaissance to locate the target. The decline of the whales had nothing whatsoever to do with a change in the climate. It was all to do with the superior technology of mankind.
The lesson from this is that, if we just stopped actually hunting these creatures, they would rebound and rebound abundantly. And contrary to the non-role of climate in their decline, the role of a favourable climate and a favourable marine environment has been critical in their recovery. If the marine environment had been adverse, then the whale numbers would have stalled. Again, I repeat an assertion in my book that neither the sea generally nor the waters of the Great Barrier Reef are a toxic soup inimical to life.
Does the 10% to 11% increase per annum represent a rebound that is ‘abundant’? This is important because I have gone on at such length about this in my previous Quadrant essay and in my book. Abundant rebound is a feature of many processes in nature, including the annual coral spawning on the Great Barrier Reef.
Well, considered against any life form that has a short gestation period, the capacity to produce multiple live births, short (or nil) nurturing time, and an ability to quickly become pregnant again, 11% per year across a whole population of whales may not seem all that exciting.
How then is an increase of 11% per year abundant in the case of whales?
The back-of-the-envelope calculation goes like this: Firstly, the gender balance between males and females is around fifty/fifty. Secondly, the gestation time for a Humpback female is around ten months. Thirdly, the females only rarely produce twins and, when they do, the twins’ survival rate is poor. Fourthly, whales are mammals and, like us, suckle their young for a long time following birth – for Humpbacks this period is about a year. Fifthly, the females do not make themselves available for breeding again until the previous calf is ‘off their hands’. As a result, the full cycle between calves for each female is between two and four years – let’s assume three on average.
Let us take a herd of 100 Humpback whales and do some figures. Of the whole herd, around 50 will be males. That leaves a remainder of 50 females. Let’s assume that five of the females are too young and five are too old. This leaves a potential group of 40 females which may be available to reproduce but, as the full cycle for each female between successive calves is around three years, it is not possible for all of them to give birth in each and every year. They can only do it once every three years. This means that, roughly speaking, the maximum yearly reproduction rate is 40 divided by three – which comes to 13.
So, if a Humpback population of 100 produced 13 calves each year – a 13% growth rate – this would reasonably be seen as abundant for that species. This is because it is tracking at the maximum potential rate. The two percent difference between the theoretical maximum and the actual count at Tracking Point may be accounted for by the level of predation Humpbacks and their young face in the Southern Ocean and on their migration route.
The 11% annual growth rate is therefore at, or close to, the maximum potential. For Humpback whales, the growth rates being achieved along the east and west coasts are great examples of abundant rebound.
One challenge to this essay might be that Tacking Point is a long way from the Great Barrier Reef and why therefore should it be regarded as a good proxy to judge the health of the Reef.
My response is that the whales are only at Tacking Point for a moment in time on their migration. When they get to the Great Barrier Reef they spread out into the lagoon of the Reef, north along the tip of Cape York and into the Coral Sea and spend months there. If the environment at their final destination was degraded, the health of the whales would also become degraded in this time.
In addition to this it would be hard indeed to count them all in these dispersed locations. The point is, however, that once they get to the Reef, they all have a jolly good time and return south with new and healthy calves and, in many cases, pregnant.
The fact that the population of migrating whales is increasing at any point in the migration circuit vouches for the proposition that the health of the entire ocean along the full route must be healthy. If it were not the case, it would be impossible for the numbers to be growing abundantly.
The growth of whale numbers at Tacking Point also serves as a proxy for the resilience and survivability of another tiny life form – the plankton and krill in the Southern Ocean where whales ‘graze’ in the summer months of the Southern Hemisphere. These tiny life forms in the cold waters of the Southern Ocean are as small as the coral polyps and zooxanthellae of the warm waters of the Great Barrier Reef and they must be available abundantly each year to support the growing whale population. If the whale population is expanding – and it is – then the annual plankton and krill population explosion must also be taking place strongly. So, on this basis, the whale count at Tacking Point is also a valid proxy for the abundance of the whales’ food source in the ocean to the south of Tasmania.
Finally, the evidence that the marine environment is not a degraded place on the very brink of collapse comes from many more sources than just the whale count at Tacking Point. These are covered in my book.
In conclusion, the sustained increase in whales heading for tropical waters is good news from the sea and is a proxy by which some of the predictions of Reef doom can be tested. Together with a number of other indicators of marine health, the rebound in whale numbers argues strongly for the proposition that, far from being some sort of toxic soup, the waters of the Pacific Ocean and the marine environment of the Great Barrier Reef are healthy and a great place to have your kids – for whales, that is.