ISLAND CONSERVATION-Commotion on Beau Vallon beach


11-May-2009

 The news spread quickly around Mahé and over the next few days large crowds gathered to see the beached whales. Teachers and pupils alike skipped classes to go to Beau Vallon. Photographer François Vel (1875-1946) of Rue Quincy was among those who rushed to the scene. It is to him that we owe the photograph accompanying this article.

One account (published in Cluny Missions, the magazine of the Sœurs de Saint Joseph de Cluny!) speaks of “une plage en émoi”: “Quelle foule sur les lieux! Tout Mahé est là, même le Gouverneur [British Governor De Symons Honey] dont nous avons suivi la voiture sur la route.

A crowd gathering around the beached whales (photographed by François Vel)

Effectivement, les onze cétacés gisent là, de distance en distance. Ce sont, nous dit-on, de jeune cachalots. Le plus gros mesure 36 pieds (presque 11 mètres). Des enfants grimpent sur le dos de ces monstres et prennent plaisir à sauter de l’un sur l’autre.”

In Francois Vel’s photograph we see even a full-grown man standing atop one of the whales. Of course, this was long before people realised that the whaling industry was driving many species of these giant sea mammals close to extinction. The fate of the kasalo and other balenn was not yet a matter of public concern.

We know that adult male sperm whales can grow up to 18 metres in length, and that they lead a mostly solitary life. Mature females tend to reach around 11 metres and to live in social groups with calves and immature whales of both sexes. This suggests that the group that got stranded at Beau Vallon was either such a “nursery school”, or a juvenile or bachelor school containing immature males (and possibly females) that had broken away from a nursery school.

Disorientation

But the sperm whale is adapted to deep water and seldom found in coastal regions in waters less than 300m deep. How come, then, this group ended up on the shore? After studying whale strandings all over the world scientists believe navigation error is one possible explanation for such disasters. Whales and dolphins sometimes become disoriented as they use the Earth’s magnetic fields to navigate the seas. For some reason, they become confused, misread these magnetic fields and become lost.

Another type of navigation error is due to the fact that sperm whales use echo-location or sonar to map out their surroundings. They emit a series of high frequency clicks and listen to the reflections or echoes of this sound from neighbouring underwater objects. The brain of a sperm whale decodes this information to establish the distance, size, shape and even texture of nearby objects. It is believed that if a whale approaches a steep underwater rock face, its sonar system warns it of the obstacle and it can avoid it. However, a gently sloping beach and sea bottom may be more difficult for the whale to detect.

Then there is noise pollution – noise produced by human activity (drilling, dredging, blasting, shipping, etc.) that can cause disorientation and distress. We can probably exclude this as a cause for the Beau Vallon stranding, just like we can discount naval sonar – sound waves from military submarines used for detecting other submarines and ships, also believed to disorientate whales and dolphins.

Blessé

Going through the accounts of what happened back then in January 1933 we discover that in the afternoon of Saturday January 28 “enormous fish” were seen jumping out of the water on the other side of the reef (a sperm whale often propels itself out of the water and splashes down on its back or side – something called “breaching”). A fisherman armed with a gun set off in a pirogue to investigate. “Arrivé à proximité de ces énormes masses noires, semblables à des rochers,” we are told, “il tira hardiment [boldly!] 50 balles. Comme les cachalots voyagent par bandes, sous la conduite d’un capitaine, il est fort probable qu’il fut blessé et que, dans sa fuite vers le rivage, il entraina tous les autres. Ainsi s’explique cette incroyable aventure qui a fait date dans les fastes de l’histoire des plages seychelloises.”

Few of us will share the writer’s jubilant mood! But this account seems to sum up what happened. These very social animals follow the dominant leader. If the leader (a female, by the way) is injured and swims into shallow water, the rest of the group may follow and become stranded together. Usually, they suffer massive internal injuries due to their unsupported weight. They often topple over and then drown when their blowholes fill with water and sand. They may roll onto a flipper, which loses its blood supply and can no longer be used for steering.

Sharks

Interestingly, after people started cutting up the whales for their meat and blubber , large numbers of sharks  are reported to have congregated in the vicinity: “Aussitôt, des hommes vigoureux se mettent à la besogne: hache ou coutelas en main, ils taillent hardiment [again!] dans la chair.

Cette viande sera salée ou fondue pour en extraire de l’huile, une huile claire, blanche et qui brûle si bien. Quelle aubaine! Ces centaines et centaines de litres se vendirent 0,15F le litre. Le soir tombant, le flux recouvrit à moitié les squelettes et les requins attirés par l’odeur du sang frais s’approchèrent du rivage. Alors commença une autre capture, un horrible spectacle… la pêche aux requins! De mémoire de Seychellois, personne n’avait rien vu de tel…”

It is interesting to reflect that less than half a century later, in 1979, Seychelles was to press the International Whaling Commission (IWC) to declare the Indian Ocean a whale sanctuary. And that today there is growing concern for the plight of endangered sharks.

by Pat Matyot

The Island Conservation Society promotes the conservation and restoration of island ecosystems.

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