You will be amazed: during your beach walk on the Dutch coast, a bubbling fountain just pops up out of the water. A colossal whale jumps into the air and with a lot of clatter its unwieldy body plunges back into the seawater. Images that you only knew from nature films on TV, with the indefinable sound decor for which that genre has a patent.
Since October last year, it has sometimes been a daily hit, according to reports on social media and the site observation.nl: a humpback whale swims in Dutch waters. The humpback whale, according to the website of Ecomare seen as ‘the happiest of all whales’: ‘That’s because they make spectacular tumbles when they jump high above the water. You can recognize them by their large, somewhat plump body, their long flippers and their pockmarked, flat head.’
The whale (length: up to 18 meters, weight: up to 30,000 kilograms) was almost never seen in the North Sea. Artists of centuries ago captured sperm whales washed up and other details on their canvases only once (in 1751) a humpback whale.
At the beginning of this century, something changed: in September 2003, the first humpback whale in the Netherlands was found near the mouth of the Nieuwe Waterweg. He was dead. Four months later a (living!) mother with young appeared off the coast of Scheveningen; unfortunately the young washed ashore dead and seriously mutilated after a short time.
Three years later, another dead man was found off the coast of Belgium. Suspected victim of a collision with a boat. After that it got tough. In May 2007, whale watchers flocked to the dyke of Den Helder to catch a glimpse of a live humpback whale swimming there.
After that it happened more often. In 2012, a failed rescue for a humpback whale near the Razende Bol (between Texel and Den Helder) made headlines. If you look at the site observation.nl now, you will see dozens of reports of a humpback whale in recent months. If it is always the same – which researchers suspect – then the mammal bathes happily between Hoek van Holland and Kijkduin up to the Hondsbossche Zeewering in North Holland.
Fixed migration route
Nice. But scientists are once again baffled. After all, what happened to make the humpback whale, on its regular migration route from Norway to the Azores near Portugal, after countless centuries near Shetland, take the left turn to the shallow North Sea, instead of passing Great Britain clockwise through the Atlantic Ocean?
Mardik Leopold, marine biologist at Wageningen Marine Research, sees only two possibilities, he says: ‘Something must have changed. Maybe in the animals themselves and something else in the North Sea.’
Little has changed in the latter in recent decades, he thinks aloud. ‘Unless newly constructed wind farms would attract humpback whales, but I don’t believe that. Even if that were the case for whatever reason, the humpback whales should know how to migrate to it during their stay in the far north. That seems out of the question to me.’
Moreover, it would not explain how it is possible that the movement also takes place in reverse: humpback whales are also increasingly seen in Boulogne-sur-Mer in northern France, but then from the south. The whale thus enters the North Sea from two directions.
Is it the food supply? According to Leopold, not much has changed in the fish stocks in the North Sea. Yes, the North Sea is full of sprat, which is what the humpback whale likes. The strip of sea between Den Helder and Hoek van Holland is precisely the location of the sprat, but as far as Leopold is concerned, the following also applies: ‘That has always been the case and does not explain why new humpback whales keep appearing.’ Remarkable: ‘The humpback whales seen here are migratory animals. We have always thought that a whale eats completely before the migration and needs very little food during the migration. It seems more and more that the humpback also gets its food outside the fixed areas.’
What probably plays a part in the resurrection of the humpback whale, is the stop on the whaling industry. Commercial whaling decimated the stock last century, but after the International Whaling Commission in 1982 a moratorium (a temporary ban) on whaling, the stock of humpback whales increased sharply worldwide.
Evolutionary change
This may have been accompanied by an evolutionary change, says Leopold: ‘When a population has been under pressure for a long time, the survivors are specimens with characteristics to survive under those conditions. The animals that were not shot for whatever reason. Because they were very shy, or happened to swim the other way. Those qualities can crystallize in offspring, so that we now have more whales with explorative, wandering qualities.’
According to Leopold, this assumption is supported by the fact that humpback whales are also more often seen in the Mediterranean, where they were not traditionally found either.
Another explanation could lie in forms of communication between the humpback whales. They certainly are. For example, Irish biologist Rebecca Dunlop published in 2010 an investigation to the vocabulary of the humpback whale. She deciphered a total of 34 sounds that allow the humpback whale to communicate underwater with other species up to about 18 kilometers away. Leopold also confirms that there is some information transfer between the humpback whales, just like with other cetaceans. ‘But it is unlikely that they will tell each other in Norway that you should be at Katwijk’.
Leopold does not mention one obvious explanation: climate change. Could it not be that warming seawater has consequences for the food supply or otherwise affects the humpback whale?
That seems unlikely to the biologist. ‘Over the centuries, we have had periods of warming and cooling more often. As far as we know, this has never led to large numbers of humpback whales in the Netherlands.’ Moreover, he says: ‘The North Sea may have warmed up by one degree, but that does not make much difference to the food supply.’
In short: climate change can be ticked off.
transmit
So that’s not the end of the science. Of course, more research could shed light on the humpback conundrum. Researcher Leopold would like to target humpback whales to map their migratory behavior and to know whether it is always the same specimens that appear here. Unfortunately, it’s not that simple. ‘The chance of hitting a humpback whale is not that great and such an investigation is difficult to plan in the Netherlands. That does not make the chance of funding very great, partly because a financier will wonder what the research is actually needed for. At most to satisfy our curiosity, but there is no great social purpose.’
Once the opportunity was close: when a humpback whale stopped at the harbor of Den Helder. But yes: ‘Then you have to apply for permits, which must first be assessed. Before such a procedure has been completed, the humpback whale has long since swum away’.
Norway is experimenting with transmitters. The outcome is not yet very exciting: ‘The tagged animals all swim neatly as they have been doing for centuries.’
Gathering of seagulls
Whatever the reason, the unsuspecting beach walker has a reason to take a good look around. Watch for gatherings of excited gulls over the sea: a whale may be sitting there. Or even more, because the humpback whale is a social animal (groups of up to 200 individuals sometimes occur) and according to biologist Leopold, the North Sea offers enough space for many more humpback whales.
Are there any dangers or objections to the resurrection of the humpback whale in the North Sea? ‘If a dead specimen floats at sea, it can damage a sailing boat that collides with it,’ says Leopold. After all, it is an animal the size of a sea container. That is why dead ones are immediately cleaned up.
The jumpy nature of the humpback whale can sometimes go wrong: ‘If you sail next to a jumping whale, it can end up on your deck’, says Leopold. A surfer was once launched in the United States who had this happen. ‘But usually humpback whales know what they are doing’, says Leopold. “Only when you’re too pushy, as some photographers can be in their hunt for an evidence photo, you’re at risk.”
The best viewers are ashore. It is great to enjoy the whale wonder there.