Short-beaked common Dolphin

(Delphinus delphis)

DESCRIPTION

It is a short-nosed  slim dolphin. The dorsal area has a dark grey colour and ventral area is white, creating a dark V-shaped pattern below the dorsal fin. On the side, it has an identifying pattern of the species called “hourglass”, which is yellow/ocher on the top half of the body and light grey on the bottom half all the way to the tail fin.

There is considerable variation of shades and patterns between different individuals of this species.

Size:

Male length: 1.7-2.2m             Male weight: 70-110Kg

Female length:  1.5m            Female weight: 70-90Kg

Newborn length: 0.80-1m    Newborn weight: 10Kg


HABITAT

The Short-beaked common Dolphin is a species with a wide distribution in temperate, tropical, subtropical and warm seas. They live in areas of the Atlantic, Pacific and Southeast Indian Ocean, from the coastal waters to kilometers offshore.

In the UK it is abundant in the western entrances of the English Channel, the west of Ireland and in the south of the Irish Sea .

It is also found in other seas such as the Mediterranean Sea, Black Sea, Okhotsk Sea and Japan.


FEEDING

They feed on small fish (herring, sardines, anchovies, hake and bonito) and cephalopods (squid and octopus), living less than 200 meters deep. They eat approximately between 6 and 9 kg per day.


REPRODUCTION:

Females reach sexual maturity when they are between 3-4 years old, which is also when they have grown 85% of their final size. Males reach sexual maturity at 12-15. The gestation period is 10 to 11 months and lactation lasts for 5-6 months, time during which the offspring remain beside the mother.

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SCIENTIFIC NAME: Delphinus delphis

Common Name: Short-beaked common Dolphin.

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Cetartiodactyla

Family: Delphinidae

Genus: Delphinus


BIOLOGY

They live in large aggregations of hundreds or even thousands of individuals, although it is usual to see them in groups of 10 to 500 individuals. Sometimes they associate with other species of dolphins, such as the pilot whale.

They are very social animals and perform group activities like traveling, breathing and eating, using cooperative hunting methods. They have between 80 and 120 conical teeth in both jaws, ideal for holding prey.

They are very fast swimmers, reaching a speed of 60-65 km/h. Often they jump out of the water and hit the surface with their fins.

They perform short dives, typically between 10 seconds and two minutes and can dive up to a maximum of 8 minutes.

They live about 35 years, although in some populations life expectancy is 22 years.

THREATS

· Fishing: overfishing of prey species has reduced the populations of these dolphins. Namely the place where they have declined most significantly is located on the island of Kalamos (Greece).

Also bycatch (trawling and gillnet), entanglement in fishing and drifting nets, as well as noise and chemical pollution, are severely affecting the populations.

· Stranding: there has been several mass strandings of this species. One of the most important was in 2009 in the Bay of Falmouth (Cornwall, UK).


CONSERVATION

                                                                                                     

· Red List (IUCN): classified as Least Concern (LC).

· Habitats Directive (CE): found in Annex IV.

· Bonn Convention and the Berne Convention: Appendix II and Appendix III respectively, stocks in the North and Baltic Sea, western Mediterranean, Black Sea and eastern tropical Pacific populations.

· Council of the EU: all cetaceans are listed in Annex A of Regulation 338/97, therefore they are treated by the EU as if they were included in Appendix I of CITES, which bans trade.

· United Kingdom: it is a UK Biodiversity Action Plan priority species. Under the Wildlife and Countryside Act of 1981, it is illegal to intentionally kill, injure, capture or harass whales and dolphins in UK waters.

·  ASCOBANS y ACCOBAMS: the species is also covered by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS) and the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS).

The species is further included in the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia and the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU).