Short-Beaked Common Dolphin

## Description

Short-beaked common dolphins are medium-sized dolphins. Males are generally longer and heavier. Mature males also have prominent postanal humps. Short-beaked common dolphins have an unusual color pattern on the body. The back is dark and the belly is white, while on each side is an hourglass pattern colored light grey, yellow or gold in front and dirty grey in back. They have a long, thin rostrum with 50–60 small, sharp, interlocking teeth on each side of each jaw. Juvenile dolphins have a more muted appearance and become more distinguishable when they mature.

## Distribution

Short-beaked common dolphins live in areas of the Atlantic, Pacific, and Southeast Indian Ocean. They are also found in the Caribbean and Mediterranean Seas. These dolphins are also abundant in the Black Sea, Gulf of Mexico, and the Red Sea. They follow the gulf stream up to Norwegian waters. Seldom do any Short-beaked dolphin venture near the Arctic. These dolphins are commonly found in warm-temperate and tropical waters. They prefer coastal waters but are also found well out to sea.

## Behavior

Short-beaked common dolphins are very social animals and engage in most necessary activities such as traveling, eating, and breathing together. They usually associate in groups that can consist of 1000s to 100,000s of individuals. Within these groups, adults act as teachers to the young. When some individuals are sick, others in the group assist them by using their fins to help keep them afloat so they survive. They sometimes associate with other dolphin species, such as Pilot whales. They have also been observed bow riding on Baleen whales, and they also bow ride on boats. It is a fast swimmer (over 60 km/h), and breaching behavior and aerial acrobatics are common with this species. These dolphins are a very vocal. They communicate with each other using two voices. One is for social communication, the other is for navigation and location.

## Diet

Short-beaked common dolphins are carnivores (piscivores). Their diet consists of many species of fish and squid that live less than 200 metres (660 ft) deep. These dolphins also eat small fish, such as herring, pilchard, anchovies, hake, sardines, bonito, and sauries, as well as squid and octopus.

## Reproduction

Little information is known about the mating system in Short-beaked common dolphins. They usually only carry one baby at a time but can carry twins, triplets, etc. The gestation period lasts 10-11 months. After a baby is born, it immediately becomes part of the family and takes part in daily life. Until the calf is 6 months old, it obtains its nourishment solely from its mother's milk. For the Black Sea population, weaning occurs at between 5-6 months but occurs later (up to about 19 months) in other areas. Typical interbirth interval ranges from 1 year for the Black Sea population to 3 years for eastern Pacific Ocean populations. Age of sexual maturity also varies by location but can range between 2-7 years for females and 3-12 years for males.

## Population

### Threats

One of the main threats to Short-beaked common dolphins are humans. These dolphins suffer from hunting, exploitation by man, bycatch and other human disturbances. Other notable concerns to the population of the Short-beaked common dolphin are environmental changes and pollution.

### Number

According to IUCN, Short-beaked common dolphins are abundant and widespread throughout their range but no overall population estimate is available. However, there are estimates of its populations in specific areas: in the Pacific: eastern tropical Pacific - 2,963,000 dolphins; US west coast - 352, 000 dolphins. In the Atlantic: Europe - 63,400 dolphins; offshore - 273,000 dolphins; West of the Bay of Biscay - 62,000 dolphins; in the western North Atlantic - 121,000 dolphin. In the western Mediterranean: in the northern Alborán Sea - 19,400 dolphins. Survey results suggest that curent population size in the Black Sea is at least several 10,000s, and possibly 100,000 or more. Overall currently, Short-beaked dolphins are classified as Least Concern (LC) on the IUCN Red List.