Throughout the year we will present one cetacean per article, to learn more about these animals and how to observe them. These sheets are made by Serge Briez founder of the Peoples of the Sea, a citizen NGO whose goal is wildlife protection through knowledge and the enhancement of our Mediterranean maritime area: the Gulf of Lion and more specifically the Marine Natural Park of Gulf of Lion. For our fourth cetacean sheet: The Common Dolphin !
Today, we present the Common Dolphin, a very common sight in the Mediterranean Sea well-known by boaters.
Sheet 4 : The Common Dolphin
(Delphinus delphis)
Observation areas: in all seas, in the Mediterranean, in the Gulf of Lion.
The common dolphin is a world-spread species. It can be found in all the seas of both hemispheres with water temperatures ranging from 10 to 28 ° C, including the Mediterranean and the Black Sea. Usually he avoids the polar regions. It is absent in the Indian Ocean. It is observed exceptionally in the Gulf of Lion.
3 facts about the Common Dolphin
1 – As the Bottlenose Dolphin, the Common Dolphin is a superior predator. It regulates lower trophic levels and helps to report on the health of an entire ecosystem. Its importance is major and even if this species is not endangered, the IUCN International Union for the Conservation of Nature has classified the DOLPHIN as “Least Concern” but “absent in the western Mediterranean and in sharp decline elsewhere”.
Their population in French territorial waters is estimated between 180,000 and 200,000 individuals. On a European scale, there are 500,000 individuals. There are over 700 strandings annually on the beaches, this is only the visible part. We are trying to assess the real mortality at sea. We can estimate the number of dolphins dead at sea at 4000, which is very worrying.
2 – The gestation period is approximately 10-11 months, the dolphin is weaned after 10 to 12 months. The common dolphin community is very united; this ranges from caring for newborns and injured companions to problems with infirm and elderly limbs. It is even reported that drowning humans were pushed to shore, supported by dolphins. It is common to see dolphins frolicking with floating toys, and even animals like turtles. The mating takes place with delicacy, it seems that a real love is manifested between the male and the female.
Offshore species are found in herds of hundreds or even thousands of individuals (500 on average). The clicking sounds are emitted by its vent and its echolocation system. Its top speed is around 40 km / h. (source Doris)
3 – The COMMON DOLPHIN reaches a maximum size of 2.50 m for males and 2.30 m for females. At birth it measures 70 to 80 cm. Its weight is between 70 and 110 kg. The beck (or rostrum) is fine and is clearly demarcated from the melon (head) by a frontal groove. The dorsal is sickle-shaped and measures a third of the body to the right of it. The caudal is in the form of a brace with a notch in the hemispherical axis. The coloring of the back varies from dark gray to dark brown passing through black; it forms a V under the backbone. The coloring is lighter towards the tail. The belly from the head to the anal region is creamy white and then light gray. On the flanks two lines intersect to form an X.
Observation and interaction tips
1 – Entering the water to swim with COMMON DOLPHINS is not recommended. In France it is even forbidden to approach less than 100 m. If they choose to come swimming from the bow which is frequent, or visit you during a swim in the sea, you can enjoy it while not exceeding 5 knots and maintaining a straight and parallel trajectory without trying to join them. . When meeting while swimming, never try to touch them, their skin is extremely fragile.
2 – Do not try to feed them, they are great hunters and a good part of their time is spent hunting, they can go down to 300 m deep. They feed on fish living in schools such as anchovies, sardines, herring, but also squid and cuttlefish. The hunting technique consists in bringing up the fish by releasing bubbles or by pulling back. It is of course a collective tactic: some feed, others cut back the food and the last protect the group.
3 – The best way to meet COMMON DOLPHINS is not to look for them but to observe them. The encounter can be opportunistic: your paths cross, but these encounters can also be the subject of a different way of NAVIGATING TO OBSERVE and meeting all the species that inhabit our Big Blue.
If you want to know more about the COMMON DOLPHIN visit the excellent DORIS site.
Observing is learning and many associations offer eco-volunteers naturalistic observation embarkations where you will learn a lot about these MASTERS of the oceans, the Cetaceans.
In the meantime, we will meet you very soon for the next sheet produced in collaboration with Les Peuples de la Mer, which will present the common fin whale with its scientific name Balaenoptera physalus. See you soon for new discoveries on the marine fauna of the Mediterranean. Find all Cetaceans sheets here!
Fair winds Captains,
The Octopus.
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