Elephant Island is forever famous as the location where the stranded men of Sir Ernest Shackleton’s Endurance expedition sheltered while ‘the Boss’ made his heroic voyage in the tiny James Caird to get help. Less well known is that the seas here were particularly rich hunting grounds for the whaling ships that followed in the decades after Shackleton. The ocean fell silent as a result.
At the end of my visit we were gifted by the presence of five fin whales feeding close to our ship. Amazingly this was no rare sighting: recent surveys point to a slow but real recovery in the numbers of fin whales in these waters. I spoke to Dr Helena Herr, the lead scientist on the first major research project to monitor fin whales numbers to discover more.
How did you start your research on fin whales?
I’m a marine mammal ecologist based at the University of Hamburg in Germany. I spent many years flying in small aeroplanes over the North Sea and the Baltic Sea observing porpoises to estimate their population density and distribution, and German waters. I eventually became interested in exporting that method to other areas of the world that had seen such a large over-exploitation in the 20th century by whaling. My interest was in the whale populations of Antarctica and how they are recovering from whaling or what their population status is?
The first time I went south was in the austral summer of 2008-09 and I’ve been engaged in Antarctic whale research ever since.
Could you introduce the fin whale to us?
Fin whales are the second largest animal that’s ever lived on the planet, second only to blue whales. The largest specimen that was ever caught measured 27m long, but today we see all the average fin whales are around 20–23m long. The largest individuals were all caught first and the population still hasn’t had enough time to recover to the full length distribution.
What’s their lifespan? We don’t know the maximum but fin whales can live up to 60-80 years. That’s the estimate. And since their whaling was only banned in the mid 1970s, it’s only since then that fin whales have the chance to live out their full lives again.
How many were killed during the period industrial whaling in the 20th century?
Fin whales started being hunted from Antarctica-based whaling stations in 1904 and the whaling ban on them came into place in 1976. Over that period it’s estimated that more than 720,000 fin whales were killed in the southern hemisphere and that the population had been reduced to about 1% of its original population size. There are no reliable figures because no one really counted the whales, but just based on the catch quota, it is estimated that the original population size was around 325,000 whales, and there were just a couple of thousand whales left at the end.
If you bring a population down to one or 2%, that is the brink of extinction, and you cannot be sure that a species will recover. The fact that the fin whales seem to be recovering is a very positive sign that would not have necessarily have to be the case.
What have you found in your new research?
It was in 2013 when we were doing research on Antarctic minke whales, that we unexpectedly came across a large feeding aggregation of fin whales. When I looked into the current research on fin whales, I found there had hardly been any dedicated work since the end of whaling, and that no one really knew what they had been doing in the meantime.
There were have been just anecdotal reports from cruise ships and from fishing vessels or from research vessels doing any whale research. So here and there, we found reports of these fin whale feeding aggregations, and so we thought it would be worthwhile going down there with a dedicated survey to to see if these fin whale aggregations were a reoccurring event or if we could even find them again. We went down in 2018 and we conducted dedicated fin whale surveys to a standardised method to estimate marine mammal populations in a specific area.
On a practical level, how do you do these surveys? What are the techniques you use?
You can do it by ship or by air. Firstly, you have to design the survey to have a representative set of transit lines throughout that area. And then you travel along these transit lines either by ship or by plane to record all sightings of your target species. And along with the position of the sighting, you record the distance of the animal to the transit line so you have a statistical baseline from which you can extrapolate from your transit lines to the full survey area.
If you use a ship, you have observers upfront and they calculate the sightings along these lines as you move in a grid. And we use helicopters onboard the ship because you can cover the area much faster. You have to make use of small time windows with good weather conditions, because observing whales when it’s stormy weather is so unpredictable.
Could you describe what these big feeding aggregations are like? What does it feels like to see these enormous numbers of whales?
You can’t just neutrally look at them as a scientist! It’s a very emotional sight. You see hundreds of large animals feeding together, the whole water surface boiling with blows and bodies and splashes. These animals are in such an active state – they’re diving down, they’re opening their mouths, they’re turning and lunging. It looks like an orgy!
If you observe that from a ship or from a helicopter, usually the first thing that you will see are the blows, just like a cloud on the horizon. The very first time that we approached one of these feeding aggregations from a helicopter, I wasn’t even sure what I was seeing. And then coming closer, you start seeing the singular blows over a wide area, lots of animals breaking the surface blowing, feeding, diving. It’s almost a chaotic scene. But then if you look at it from a scientific perspective, you see that it’s not that chaos at all – that they’re going in certain synchronised circles, and they seem to have their own way of exploiting the krill that they’re encountering.
Are they sharing a memory of old feeding grounds? Would these aggregations contain individuals who had survived the whaling industry?
That’s absolutely possible. They must have been young at that time. It’s probably a mixture of cultural memory and a very good prey resource. Where we see these fin whales is an area known for its rich krill biomass, so it is not much of a surprise that a large predator would feed there. But of course, they would have had to either rediscover that area, or they would have had to have old individuals that continuously came to that area, but in very small numbers, and somehow handed down the memory of that particular feeding spot to other fin whales. And probably it’s a mixture of both.
So can we now say that the fin whale is in recovery?
I feel positive enough to be able to say that. If you want to really confirm that species is recovering, you’d have to survey the full range of the population. And for fin whales, we just don’t know the population structure. We know there’s a southern hemisphere subspecies that doesn’t mix with the northern hemisphere, but on a smaller scale, we don’t know if there are different subpopulations within the southern hemisphere, or if it’s all one population. Our information is just from this small sector of the Southern Ocean.
We do see that there is an increase in fin whales in that area which is a very positive sign and we have the restoration of historical behaviours, we have these large groups. All this points to a population recovery. And we have opportunistic reports from East Antarctica that people are witnessing larger numbers of fin whales there. So all together we can say that they are recovering. But for true estimates we’d have to have a circumpolar survey, or have numbers from all feeding grounds. They haven’t recovered to numbers that they used to have – it’s just the start of a recovery. We can’t lie back and say OK they have recovered. But they are on the route of recovery.
What effect does the fin whale recovery fit into the wider context of the Antarctic ecosystem?
The first thing to note is that during the times of industrial whaling, more than a million whales were removed from the ecosystem so we would have had to expect an increase in krill because a large number of their predators were just removed from the food web. But this was not the case. At the same time that whales were removed from the ecosystem, krill numbers went down. And there is reasonable evidence that this is related to whales fertilising their own feeding grounds and providing nutrients for phytoplankton to bloom – phytoplankton being the food for krill.
The principle behind this is that the whales feed at a depth on iron-rich krill and then they release their faeces at the upper surface layers [of the sea] where light and nutrients promote phytoplankton bloom. With the removal of whales, this so-called ‘whale pump’ was removed. Basic ecosystem functions were just eliminated by removing the whales. So if whale species are recovering, we can somehow restore these ecosystem functions that were in place for hundreds of years.
What’s next for your research?
We’re going south at the end of February 2023 for five weeks for a dedicated fin whale cruise. We’ll be conducting a visual survey along the South Shetland Islands up to the South Orkneys and we’ll be tagging fin whales as well, deploying satellite transmitters on fin whales to see where they go after the feeding season. We still don’t know where they spend the remainder of the year or where their breeding grounds are located – and we want to find out!