Why are there so many whales and dolphins in the Canaries?
An inspiring guest contribution by marine biologist Volker Boehlke
The waters between La Gomera and Tenerife have been declared a Whale Heritage Site . Many representatives of local tourism put on this “certification” as if they had contributed to the fact that there is so much to see here. There are very special conditions that interact here and enable us to bring many very satisfied guests back to shore after a whale watch.
The nimble spotted dolphins, acrobatic bottlenose dolphins , the shy beaked whales , seemingly calm pilot whales , mackerel-eating Bryde's whales or mighty rustic sperm whales , all are represented here all year round and the official list includes 26 different representatives of whales and dolphins that appear here.
If you only want the "short" answer, you could, very roughly, name 4 aspects:
2.) The position between the nutrient-rich African cold water area and the deep, open ocean. The average water temperature in the west of the Canary Islands is 4 degrees above that of the eastern coasts. Cold water species, such as minke whales, are accordingly more likely to be found near the African coast and those who prefer cozy warm water, such as rough-toothed dolphins, further to the west, near La Gomera. Since the shallow water area quickly drops to great depths a short distance from the coast, we find deep-diving species such as round-headed dolphins, sperm whales, beaked whales and pilot whales in addition to those that occur anyway. Here they live permanently under the best conditions, are resident, on the flat African coast or in the shallow North Sea one looks for them in vain.
3.) Small population, no trawling. Relatively few people live here between huge masses of water. Through whaling, water pollution , fishing (food competition and direct problems) as well as collisions with ships and ferries, man has brought and continues to bring many species to their limits. In the history of the Canary Islands there has only been sporadic hunting for sperm whales and bottlenose dolphins, extensive and rich shallow water areas are rare and trawls cannot be used on irregular or / and deep volcanic seabeds. In addition, the self-cleaning power in the vast, deep and turbulent sea around the Canary Islands is very great, so the water is relatively clean .
4.) Under special oceanographic conditions, shoals of fish that appear temporarily in a limited manner pull a whole rat's tail of large predators behind them. This is where Bryde's whales, sei whales, fin whales, spotted dolphins, common dolphins, striped dolphins and others appear. For example in clockwise vortices in which plankton are concentrated in great density. In addition, we occasionally experience whole years with great diversity and unique encounters. In 2005 we had a special guest on board, a spokesman for the environmental protection organization Ben Magec, who was amazed: he was allowed to observe 7 different species.
An average of 2 - 3 different whale and dolphin species per trip
Some species are almost impossible to observe ; Pygmy sperm whales are very shy, northern right whales are extremely rare and Cuvier's beaked whales simply lead a very inconspicuous life. On average we encounter 2 - 3 different whales or dolphins on a trip and the ones just mentioned are rarely there.
Each species has different spatial and temporal preferences, and they all have completely different demands on their environment. The real background is always a combination of different factors. I would like to illustrate this to you with the most frequently sighted species of pilot whales.
La Gomera: perfect conditions for pilot whales
The tropical variant of the pilot whale , also known as the short-finned pilot whale (Globicephala macrorhynchus), finds perfect living conditions here. For him, two aspects are particularly important: slipstream and water depths. In order to understand this, however, you have to know their habitat and their way of life.
Pilot whales are sprint hunters who hunt nimble prey with dives to an average depth of 700 meters at high speeds (up to 30 km / h), mostly medium-sized squids. Of course, this is only possible in water depths in which these occur. Before Valle Gran Rey we drive an average of 3.5 miles out, there the water is about 1000 m deep . In the northwest, this depth is much further out than in the south of the island. If we had to go as far as the Norwegian whale watchers to get to their sperm whales, such a large whale watching industry could never have developed.
In doing so, they spend masterful sporting performances. Anyone who has tried to step on the gas while freediving knows that. In addition, at this depth the pressure is 80 times that of the water surface and the water temperature is 10 ° C.
Pilot whales need long periods of rest, ideally in protected areas where recovery is more effective
This hunting strategy is so energy-intensive that they spend long phases dozing on the surface of the water in order to digest their digestion and replenish their oxygen supplies. What better way to do that than in the slipstream of a volcanic island, where the wind regularly blows from the same direction?
If one generally assumes that whales often move between different feeding areas or between them and their reproductive areas, which are often thousands of kilometers away , the pilot whales have won the lottery, because here they can do both. Even under water, volcanic islands in the ocean show slopes that descend so quickly to great depths that the slipstream zones (in addition to the resting phases, also important for a successful first phase of rearing the offspring) are sufficiently covered by deep water with food resources.
So you can always (more or less) stay in one place and thus save a lot of energy.
Since the quiet zones of the pilot whales are the best possible conditions for a relaxing time on the boat, our visitors get the impression that our sea is a bathtub full of fish full of contentedly dozing whales.
The operators of the Whale Heritage Site draw up a list of boats that behave respectfully with the animals and comply with local rules. This will be issued in every port in the future. Maybe you choose a respectful observation boat.
Author: Volker Boehlke, Gomera Vive
The author
Volker Boehlke
Volker Boehlke is one of the leading marine biologists in the Canary Islands and he loves his "critters" - as he affectionately calls them. On Volker's website you will find exciting background information about the marine mammals in the Canary Islands, their habitat, exciting articles about the island and the unique nature of La Gomera. You can also book guided hikes and whale watching trips with Volker. In between, he also offers so-called eco tours - a whale watching tour with underwater microphone, camera & marine biological support - don't miss it!