Common dolphin

 

Classification:

Population Mondiale

Description Et Histoire Naturelle

Physical Description
There are two recognized species of common dolphin, the shortbeaked offshore species (D. delphis) and the longbeaked inshore species (D. capensis), and many regional forms have also been described. The common dolphin is a sleek, medium sized dolphin, and has a long slender beak and tall dorsal fin. This species is also named the “saddleback” dolphin for of the dark V-shaped saddle patch on either side below the sickle-shaped dorsal fin. The anterior portion of the hourglass pattern is light grey to golden yellow and the posterior portion is grey. The back is grey and the belly is white. The lips are dark and a dark line runs from the tip of the melon around the eye. Common dolphins also have a dark line from the mid lower jaw to the flipper. Adults are generally 1.7-2.5 meters (5.6-8.2 feet) in length, although there is substantial geographic variation. Calves are born 80-85 cm (2.6-2.8 feet) in length.

Natural History 
Common dolphins inhabit both shelf and pelagic waters of tropical, sub-tropical and temperate zones around the world. Common dolphins are fast and energetic swimmers and often bow-ride on the wake of boats and even large whales. They are active in the air, often porpoising, and their squeals can sometimes be heard above the water. They can be seen travelling in groups from a few dozen to 1,000 and even 10,000 individuals. Common dolphins may be found in association with striped dolphins and occasionally with bottlenose dolphins and pilot whales. Breeding has been recorded in spring and autumn, but summer breeding peaks have also been reported. One calf is born annually after a gestation period of 10-11 months. Calves are weaned at about four months of age. Common dolphins feed largely on small schooling fish and squid. Some groups use cooperative hunting techniques, such as herding prey.

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Situation De L'Espèce

Status 
The common dolphin is not listed by the International Union for the Conservation of Nature and Natural Resources (IUCN) but is listed on Appendix II of the Convention on the Trade in Endangered Species of Fauna and Flora.
 
Threats to the Species 
Common dolphins have been taken in substantial numbers in fisheries around the world. Turkish and Russian dolphin fisheries in the Black Sea took huge numbers of this species before the stock declined. Common dolphins are also taken in the tropical Pacific tuna fishery and some are incidentally taken in Atlantic fisheries. Many dolphins have also been taken off Japan and in the Mediterranean. Strandings of groups and individuals also threaten the common dolphin.

International Trade
Listed on CITES Appendix II which prohibits international trade.

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Auteur Et Sources

Sources
CITES.  2001.  Atlantic white-sided dolphin.  http://www.cites.org.
 
Geraci, J.R. and V.J. Lounsbury.  1993.  Marine mammals ashore;  A field guide for strandings.  Texas A&M University Sea Grant College Program.  Galveston, Texas.305pp.
 
Wynne, K. and M. Schwartz.  1999.  Guide to marine mammals & Turtles of the U.S. Atlantic & Gulf of Mexico.  Rhode Island Sea Grant.  114pp.
 
Jefferson, T.A., S. Leatherwood and M.A. Webber.  1993.  Marine mammals of the world.  United Nations Environment Programme.  Food and Agriculture Organization of the United Nations.  320pp.

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