The Wild Dolphins of Gibraltar

The Bay and Straits of Gibraltar with their large population of whales and dolphins, are unique in being situated in a major tourist area accessible to most Western Europeans

The Straits of Gibraltar are one of the great natural land bridges of the world and are famous for the biannual migration of bird life. What is generally not so realised, is that there is a continual passage of cetaceans passing between the Mediterranean and the Atlantic. It is certain that the Straits are monitored by NATO listening devices. It would be of invaluable assistance to marine biologists to know what record, if any, is kept of cetacean movements which are much noisier than those sounds created by submarines. Because the Straits are only 13 miles wide at their narrowest point, the concentration of cetaceans is very high, especially so towards the middle. It is about 3 miles offshore that you find the larger examples, such as the Sperm Whales. For some reason most sightings show that they are heading in a westerly direction. The prevailing surface current is easterly and these animals may be just stemming the current flow, and not in fact travelling out of the Straits at that particular time.

Cetacea is the group name given to those mammals that are born and live the whole of their lives in the sea. By definition, this would exclude such animals as the Seal and the Walrus, who have to come onto land to give birth.

The large population of dolphins that visit the Bay of Gibraltar is a fact not very well known. There are three main species; Common Dolphin, Striped Dolphin, and Bottle Nosed Dolphin. We know they are capable of diving to a depth of 280 metres and can stay below without breathing for 8 minutes. They can swim at speeds of thirty to forty miles per hour, depending on the species, and in the wild they live approximately 25 years. However, taken at birth and put in captivity their life span can be more like five or six years. These mammals reproduce in waters rich with food. So we are lucky enough to be able to observe them in their natural environment without disturbing them. (Or should I say they are taking a look at us.) It seems that dolphins are friendly to man and nearly always come to greet our boat as if it were an old friend.

From prominent headland, with an expert in this matter, it is possible to see the cetaceans closer inshore. In the Bay of Gibraltar, Common and Striped Dolphins are always present and Can be viewed from the Dolphin SafariTM, a specialist boat trip that is available for this purpose. Cetaceans are mainly social animals, they are not solitary but spend all of their lives together in groups of varying numbers ranging from a family of three to many hundreds. They work together using systems of organisation and cooperation. They are able to collaborate in order to obtain food, assist at giving birth, or if one is infirmed, and assist eachother to sleep.

The Bay of Gibraltar seems to be a favourite place for nursery schools of Common Dolphins, and it is a very common sight to see baby dolphins accompanied by their mothers who always stay very close to them, rising to the surface a few inches away from eachother when coming up to breathe.

Most of these cetaceans seem to hunt in an organised manner. We have seen a large shoal of garfish corralled into a compact group by about a dozen dolphins, who were taking it in turns to swim through them at high speed and catching several before coming out on the other side. Flying fish are another favourite food of the dolphin and provide a good example of the contest between creatures that ultimately influences their development. Cetaceans find their food by using sonar in the same way as bats do. They emit a series of high pitched clicks or squeaks and then wait for the echo to return. The direction and time taken for this return supplies them with the information as to the bearing and distance from them. Not only this, but because they can vary the frequency and power of the sound beam, they can receive further information as to size, shape and density of the object being scanned. They normally emit two types of sound, some linking the echo location and position of their food and others for communication between individuals. Their intellectual capacity is very high, superior to any other order, family or species, except to the human. One of the manifestations of their intelligence, apart from their social structure, is that dolphins can adapt to constantly changing situations. Dolphin intelligence seems to be directed along paths of enjoyment, which in themselves do not bring a physical reward but are rewarding mentally and in some cases appear to involve a sense of humour. We have seen in the Bay of Gibraltar a group of 50 dolphins taking it in turns to race around a circular path of about half a mile in diameter, this went on for an hour with much boisterous leaping and splashing and was nothing to do with feeding or mating, but appeared to be some sort of contest. Dolphin Olympics? All this shows that these creatures require a large degree of mental stimulation and perhaps the big brain is being developed for the purpose of enjoyment. They seem to have an awareness of social obligation towards eachother and we have seen an injured animal being supported on the surface by others to enable it to breathe. This awareness also extends to other creatures and there are many authentic cases of them aiding human beings in distress when they are in the water. There are also stories of dolphins helping man to catch fish. These lovable creatures can be seen on most days in the Bay of Gibraltar and are the subject of much folklore since time immemorial, as they are extremely friendly.

Signed by Tim Montgomery and Conchy Lopez.