We’re back in the Banda Sea in November spotting magnificent Blue Whales. We still have one cabin left by the way. Let me know soon if you’d like to join me as we’re just finalising flights and accommodation for everyone.
Blue Whales don’t behave like the whales we see on TV or go whale-watching for. They are fast, deep-diving, nonchalant eating machines. They occur at the junction of the world’s most powerful oceanographyThe study of the physical, chemical and biological properties of the ocean. More and even influence our weather. Between June and August is when violent trade winds drag nutrientsEnergy and nutrients are the same thing. Plants capture energy from the Sun and store it in chemicals, via the process of photosynthesis. The excess greenery and waste that plants create, contain chemicals that animals can eat, in order to build their own bodies and reproduce. When a chemical is used this way, we call it a nutrient. As we More from the deep. And this creates enough planktonA soup of micro-organisms. Usually refers to all the zooplankton and algae in the ocean but can also be used to describe tiny insects in the atmosphere (see aerial plankton). More concentration to sate these megalitihic creatures’ appetites.
When we watch Blue Whales we’re reminded that animals aren’t just there for our enjoyment. They play a serious role in our everyday lives. When you’re seeing the largest animal that ever lived (yes, bigger than dinosaurs) it’s simpler to understand. Few people who travel searching for whales get to know the awe behind them. This is my quick guide to spotting magnificent Blue Whales in the Banda Sea. I can’t wait to go again and share more about this fascinating region and its wildlife.
Blue Whale ecology in the Banda Sea
By the time we visit Banda the winds have calmed. October and November are the only months you can practically guarantee good seas. And while it’s the tail-end of the Blue Whale season, enough remain and we usually know where to find them. However, the majority are feeding in depths of over 3,000m which means they generally occur quite far offshore. Although they can also be abundant around Banda Neira and it’s not unusual to see a dozen whales at once.
An interesting thing happens when you compare the number of blows at the surface with the whales’ dive depth.
I went through numerous scientific papers and was able to extract the data (below). It shows a strong relationship between how often Blue Whales need to inhale and how deep they are diving. While Blue Whales are capable of diving to 1,000m (perhaps more), they generally don’t. They limit their foraging to near the surface.
The second graph (below) shows the number of blows versus the time Banda Sea Blue Whales spend underwater. Again, this is a clustered relationship. It indicates a strong relationship between how long they spend underwater and how often they need to breathe. Therefore, we can reasonably assume that they feed in a narrow band of depths. Their surface time is even narrower. They rarely surface for more than 2.5 minutes.
A three-dimensional world
Ninety percent of the time, Blue Whales we observe in the Banda Sea are expected to breathe 9.5 – 12 times at the surface. This means they are diving to depths of between 180 – 460m. Yet the majority are seen in depths between 2,000 and 4,000m. So depth cannot determine their abundance. In fact, the distribution of Blue Whales changes each year. It depends on currents, wind and other conditions.
There is a phenomenon called the Indonesian Throughflow Current and it affects everything. A blanket of warm water flows from the Pacific into the Indian Ocean. Food is scarce here but the mid-year upwellings drive plankton (especially copepods) to its bottom edge. Think of it like the top layer of a trifle or cocktail.
It’s at this boundary where the mass of food is most dense. This is why Blue Whales will migrate 5,000 km from southern Australia each year to find it.
Upwellings and countercurrents
In the diagram below, I’ve tried to summarise what happens. No-one has ever put this evidence together before. The top layer shows satellite tracking data collected by Australian researchers a few years ago. The second layer shows the path of the Indonesian Throughflow Current heading west. The bottom layer, however, flows at half the speed, in the opposite direction. The Blue Whales are looking for food sandwiched between those two layers.
I suspect areas of highest abundance are where the currents settle down. Bottom features provide oceanographic crannies where plankton can settle rather than be swept away.
Blue whale feeding machinery
In the cold, deep depths, Blue Whales lunge an average of three and a half times up through the cloud of plankton. Lunge feeding uses a lot of energy though, so it helps to look upwards to spot prey against the slight glow from the sun above. To find prey they use a combination of special bristles on their face and listen for tell-tale sounds. What’s certain is they employ a range of acute senses and can quickly deplete the plankton before moving on.
When they open that enormous mouth they take in about 280 tonnes of water containing maybe 170 kg of plankton. This is the equivalent to about 8,700 kJ of energy consumed each day. It’s the amount that 450 humans eat! And they do this night and day for months on end.
Join me in November for more discovery
I first visited this region so I could see whales and dolphins. Banda Sea is a pretty good area at this time of year. It’s not only Blue Whales we see but a wide range of other species too. Here are some of the many other species we’ve spotted during our time there.
