Common Bottlenose Dolphin

Marine Creature:  Common Bottlenose Dolphin (Tursiops truncatus)
Kindly compiled by Bruno Diaz Lopez of The Bottlenose Dolphin Research Institute (BDRI)

General Description

The Bottlenose dolphin is a cosmopolitan species with a world wide distribution. It normally lives in small groups, usually containing up to 10 animals. The Bottlenose dolphins live in fission-fusion societies within which individuals associate in small groups that change in composition, often on a daily or hourly basis. Like other species of dolphins, they have a very complex acoustic communication system in which they produce two different types of sounds, whistles and burst pulse sounds. They also produce echolocation clicks in order to gain information about their surroundings. Much of the bottlenose dolphins popularity stems from them being the most common cetaceans in public aquariums, but the extensive geographical range and flexible existence of the species makes it one of the most recognized, and equally one of the most studied, cetaceans in the world.

Distribution

Worldwide distribution. The bottlenose dolphins are environmentally adaptive and range from temperate to tropical climates in a variety of habitats including estuaries, pelagic waters and open coastal zones. Free ranging, wild bottlenose dolphin populations can be found in the Atlantic, Pacific and Indian Oceans, as well as the Black, Red and the Mediterranean Sea. In the Mediterranean Sea, the common bottlenose dolphin is one of the most abundant coastal cetacean species, but despite this, population numbers have suffered a decline in the last 50 years. Mediterranean bottlenoses are believed to be geographically isolated from Atlantic populations, and are most commonly found along the continental shelf in water depths less than 200m.

Interesting Facts

common bottlenose1)     The dolphin communicates by the use of “two languages”; Whistles, which are thought to be used for individual identification and as contact calls. And burst pulsed sounds, which have been shown to be used in settle-rank and agonistic contexts.
2)     The dolphin has a counter-current heat exchange system which cools blood as it approaches extremities and warms it as it approaches the body core; this system also assists in preventing excessive heat loss. By using a combination of these systems, it is possible to continually control body temperature.

  • Food: Shrimp, squid, octopus, eels, crabs and a variety of fish, depending on the area they live.
  • Lifespan: 40-50 years
  • Size: 2.8 m – 4.2 m

bottlenose dolphin 1Reproduction

Sexual maturity occurs earlier for females than males, at 5-8 years for females and approximately 9-12 years for males. The reproductive organs are retained within the male and female body to maintain the streamlined shape of the dolphin. The gestation period lasts approximately 12 months, and calves suckle for 1.5-2 years, although some may retain some level of maternal dependence for up to 6 years. Birth seasonality depends on area, but our studies in the Mediterranean Sea have found the majority of birthing to occur in the spring and summer months. It is possible that this period can be modified by environmental conditions such as rough weather, predators and the availability of food.

bottlenose dolphin 2Feeding & Hunting

An adult Bottlenose will eat up to 15-20 kilos of food per day which is about 5-7% of their body weight. Daily food intake increases in winter as they lose more heat to the outside waters. They use their teeth to grasp the prey but not to chew food and the tongue turns it around so that it is swallowed head first, which stops the spines and scales from cutting the throat of the dolphin. When a shoal of fish is found dolphins work as a team to keep the fish close together and maximize the harvest. They also search for fish alone, often bottom dwelling species. Sometimes dolphins will employ “fish whacking” whereby a fish is stunned (and sometimes thrown out of the water) with the fluke to make catching and eating the fish easier. The high abundance of fish in their diet coincides with them being one of the species most frequently involved in fisheries interactions in the Mediterranean Sea. Numerous reporting within the Mediterranean include observations of dolphins following fishing boats and trawlers, presumably using them as opportunistic feeding platforms. Studies have also shown the increased use of fishing nets and gill nets as alternate sources of prey as well as the exploitation of marine fish farms. Perceived conflict of interactions between common bottlenose dolphins and coastal, small scale commercial fisheries was reported from a number of Mediterranean areas, common bottlenose dolphins are probably often attracted to fishing nets activities because they make it easier for the dolphins to exploit a concentrated food source.

vivamar_eng_logo-www

Vivamar is an ambassador of Dolphins between People. The mission is research & education and conservation of the last resident Bottlenose Dolphins (Tursiops truncatus) in NE Adriatic, precisely in Slovenia, off W coast of Istria, Croatia and the rest of the Trieste Gulf.  Vivamar is the only Society active in all neighbouring countries of the NE Adriatic Sea: Slovenia, Italy (Trieste Gulf) and Croatia (off W coast of Istria). A small, non for profit Society is besides researching Dolphins connecting and educating people and taking care for the sustainable Development for the Sea.

Volunteer with Vivamar

Threats

The exploitation of the sea to provide food, the release of waste products, hunting, accidental kills by boats and destruction of their territory all create an unhealthy and unnatural environment for marine animals. Even if there were to be a continued ban on whaling and dolphin slaughter, all the other harmful factors associated with the human lifestyle will continue to place great pressures on the survival of these animals:

  • common bottlenose dolphin3Pollutants, such as hydrocarbons, adversely affect production of plankton which is the first link of the ocean’s food chain and the main diet of some large cetaceans. Dolphins and seals have been washed up in large numbers on beaches around the world and after autopsies; infectious bacteria and high concentrations of hydrocarbons have been found.
  • A percentage of deaths is through the ingestion and/or strangulation from plastics. With a minimum of 450,000 plastic items, including bottles, bags and 6-pack holders being dumped into our oceans per day, animals will continue to die.
  • Incidental captures in fisheries (gillnets and driftnets).

The Bottlenose dolphin is not endangered at the present time. However, due to the impact of humanity on the marine environment through such things as pollution and netting, steps need to be taken immediately to stop them also joining a long list of endangered animals.

Conservation Status & International Protection

The Mediterranean Bottlenose Dolphin is considered “vulnerable” in the IUCN Red list of threatened species. The species is listed in Appendix II of CITES. The bottlenose dolphin has been afforded special protected status under Annex II of the European Union’s Habitats Directive. Commercial hunting of Black Sea cetaceans including bottlenose dolphins was banned in 1966 in the former USSR, Bulgaria and Romania, and in 1983 in Turkey.

How can people help?

People can help by supporting conservation campaigns and research activities. By participating as volunteers or adopt a dolphin programs, direct support is provided to the research of these animals. To support the conservation and research of wild bottlenose dolphins instead of supporting activities with captive dolphins or “swim with dolphins activities” is another way to contribute. If participating in dolphin watching tours, people should make sure that they do so with a serious, responsible and educative organization. People can also provide ID-photos or inform of sightings to the nearest research center, this is also done if a tag is found.

bottlenose dolphin 1Best places in the world to see these creatures:

Sarasota Bay, Florida – US
Monkey Mia – Australia
The BDRI, Sardinia Island (Italy) – Europe
For ethical reviews and rating system for whale watching trips to see Bottlenose Dolphins visit www.planetwhale.com 

Scientist Profile:  Bruno Diaz Lopez

The Bottlenose Dolphin Research Institute BDRI

common bottlenose2

Year(s) Founded

2004

Funding bodies

The Bottlenose Dolphin Research Institute is self-funded. The participation of volunteers and course students makes it economically possible to perform the research..

Website: www.thebdri.com

Contact email: info@thebdri.com

Description/Background of work

Prior to 1999, there was very little known about the bottlenose dolphins of the Sardinia Island. To address this, the Italian non-profit research organisation “Accademia del Leviatano” in collaboration with Mr Bruno Díaz López, a zoologist with 17 years of experience as cetacean researcher, started the “Dolphin-project” in 1999. Over the years the project grew to encompass a wider area and more diverse range of issues and in 2004 the Bottlenose Dolphin Research Institute (BDRI) was established.

Long-term monitoring of a population is perhaps not viewed as exciting science, but is absolutely essential in order to estimate population trends and understand their causative factors. BDRI members seek to contribute to the understanding and conservation of cetaceans (dolphins and whales), expand the public’s knowledge and concern for our marine environment, and add to the knowledge base of bottlenose dolphins and other species of cetaceans through publications of collected and analysed field data.

The BDRI is not a tour operator or dolphin watching organisation, but a well organised team of researchers carrying out one of the most important research projects of a resident dolphin population in Europe. BDRI is partner to ACCOBAMS, the UNEP’s Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area.

Using study techniques that neither harm nor seriously disturb the animals, BDRI’s researchers are engaged in the conduction of a long term study about the ecology and behaviour of a Mediterranean bottlenose dolphin population, as well as collecting detailed information about their environment.

Importance of work

BDRI members seek to contribute to the understanding and conservation of cetaceans (dolphins and whales), expand the public’s knowledge and concern for our marine environment, and add to the knowledge base of bottlenose dolphins and other species of cetaceans through publications of collected and analysed field data.Because of the high degree of behavioural and social flexibility that some species of cetaceans (mostly dolphins) have demonstrated throughout their range, it is essential to understand factors affecting local cetaceans, if their populations are to be managed and conserved. Information on habitat use also seems applicable to coastal management plans.

Volunteer /Paid Work Opportunities

common bottlenose3A great opportunity is open for marine mammal enthusiasts to participate in hands-on research with free-ranging wild bottlenose dolphins and other cetacean species along the Emerald Coast, in North Sardinia Island, Italy. The opportunity is dedicated to those who are interested to participate in dolphin research and conservation. No specific experience is required to participate as a volunteer with the BDRI. Our volunteer program is designed for interested people who are seeking thorough training in approaches to the study of free ranging wild bottlenose dolphins. The program provides experience in specialized research techniques as photo-identification, bioacoustics and behavioural sampling. Volunteers are involved in all aspects of the research, and will help measure different variables of dolphin behaviour by using a variety of instruments, to identify individuals, record behaviours and sounds.A volunteering period can be used for academic or vocational purposes, but students are solely responsible for making all arrangements for receiving relevant credits as a result of completing the period with us.common bottlenose4It requires a minimum of 6 days, and – weather permitting – we will be out on the water at least during 4 days per week.
The nature and demands of the role require prospective volunteers to meet the following criteria:
  • Minimum age of 18;
  • A lot of motivation and interest in dolphin research
  • The ability to work a flexible, full-time schedule;
  • The ability to learn quickly and perform varied tasks in a fast-paced work environment;
  • Enthusiasm, and the open-mindedness to work, live and communicate with other people of mixed nationality and background.

Benefits:

common bottlenose5

  • Travel and explore new places
  • Get involved in dolphin research
  • Gain fieldwork experience
  • Learn to use different research instruments: GPS, Hydrophone, Secchi disk, digital camera, sonar, camcorder, anemometer, etc
  •  Help advance our knowledge of bottlenose dolphins to improve their conservation
  •  Meet interesting people
  •  Enjoy the outdoors of the beautiful Emerald Coast
  •  Enjoy the culinary talents of others and express your own

The volunteering fee is between 70-100 euros/day depending on period of the year. As the BDRI is self-funded, by participating in the BDRI volunteering program you directly support the research and conservation of the Mediterranean bottlenose dolphins.  For more information about the BDRI volunteering program and to download the information package visit: http://www.thebdri.com/education/volunteers.html

 

Return to Toothed Whales or learn more about the Spinner Dolphin