Red and Mediterranean Sea.

The Fiordland Bottlenose Dolphins comprise a regional subpopulation inhabiting the coastal fiords and bays of Fiordland, a mountainous, rainforest-covered World Heritage Area in the southwest of New Zealand’s South Island. The subpopulation is located at the southern limit of the species’ worldwide range and is genetically and geographically isolated from other coastal New Zealand subpopulations (Tezanos-Pinto et al. 2008). The nearest subpopulation seen regularly in coastal waters is located more than 500 km north in the Marlborough Sounds. Sightings of Tursiops in other South Island areas are uncommon and sporadic.

The subpopulation is subdivided into three discrete local units: one local unit ranges among the smaller fiords and bays of the northern Fiordland coast while two local units reside within the complexes formed by Doubtful and Thompson Sounds, and Dusky and Breaksea Sounds (Williams et al. 1993, Bräger and Schneider 1998, Lusseau and Slooten 2002, Currey et al. 2007, Currey et al. 2008a). These local units are largely isolated from each other, but there have been records of exchange between units (Lusseau et al. 2006), suggesting the units require management as a collective subpopulation.

The Doubtful-Thompson Sound local unit has exhibited a consistent, high degree of site fidelity since 1990 (Currey et al. 2007, Currey et al. 2008b). The Dusky-Breaksea Sound local unit has also shown a high degree of site fidelity in the three years of study to date (Currey et al. 2008a). Members of the Northern Fiordland local unit have a larger distribution, having been photo-identified in Milford Sound, Sutherland Sound, Bligh Sound, George Sound, Caswell Sound, Charles Sound and Lake McKerrow, which connects to the sea (Bräger and Schneider 1998, Lusseau and Slooten 2002, Lusseau 2003b, Boisseau 2004, Currey 2006, Currey 2009).

The minimum extent of occurrence (EOO) of the subpopulation is approximately 450 km², representing the sum of the established home ranges of the local units. A reasonable upper estimate of EOO for the subpopulation is approximately 2,400 km², encompassing the inshore waters of Fiordland and a coastal range that extends 325 km from Puysegur Point, just south of Dusky Sound to Jackson Bay, north of Lake McKerrow and offshore for 5 km.

Tursiops truncatus typically occupies waters with surface temperatures between 50 and 90 degrees Fahrenheit. Although some bottlenosed dolphins migrate seasonally (for example, populations along the Atlantic coast), they are typically found in tropical, subtropical, and warm temperate waters.

Biogeographic Regions: indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native ); mediterranean sea (Native )

Other Geographic Terms: cosmopolitan

occurs (regularly, as a native taxon) in multiple nations

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Worldwide distribution primarily in coastal and inshore areas of tropical, subtropical, and temperate regions; most common near shore, but occurs also pelagically in the eastern tropical Pacific Ocean and some other areas; generally not poleward of 45 degrees latitude except off northwestern Europe (Jefferson et al. 1993).

Bottlenosed dolphins have a fusiform body that lacks many external characteristics of terrestrial mammals, including hair, external ears and hind limbs. A fusiform body reduces turbulence and allows bottlenosed dolphins to cruise underwater at high speeds. Dolphins have front flippers, a dorsal fin and flukes, which are used in swimming. The dorsal fin is tall, curved and set near the middle of the back. These dolphins are typically black to a light gray on their sides, and their bellies are white, sometimes with a slight pink hue. Bottlenosed dolphins are typically 84 to 140 cm at birth, and typically weigh between 14 and 20 kg. Adult males are usually between 244 and 381 cm long, and weigh about 500 kg. Adult females are typically between 228 and 366 cm, and weigh about 250 kg. This sexual dimorphism may be a result of females using energy to achieve sexual maturity at a earlier age than males, while males continue to grow.

As is true of all modern cetaceans, the skulls of bottlenosed dolphins are telescoped; that is, the rostra are elongated and tapered anteriorly and the nostrils are moved dorsally. This allows dolphins to breathe more easily during swimming. Bottlenosed dolphins are homeotherms and endotherms. They use insulation, in the form of blubber, a relatively small surface area due to their large body sizes, and vascular shunts that allow selective cooling of certain organs and tissues to help thermoregulate. Bottlenosed dolphins have a thermoneutral zone of 13 to 28 degrees Celsius. If the temperature of their environment drops below 13 degrees Celsius or rises above 28 degrees Celsius, their metabolic rate increases.

Range mass: 260 to 500 kg.

Average mass: 400 kg.

Range length: 228 to 381 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

Length: 3700 cm

Weight: 650 grams

• Marine

• Marine

Bottlenosed dolphins are found everywhere except polar waters. Deep water bottlenosed dolphins come up to take breaths every 1 to 2 minutes, whereas inshore bottlenosed dolphins take breaths two times per minute. Bottlenosed dolphins have been known, however, to dive deep enough to go 4.5 minutes without taking a breath. Bottlenosed dolphins are found in bays, estuaries, sounds, open shorelines and large, estuarine rivers.

Average depth: 1 m.

Habitat Regions: temperate ; tropical ; saltwater or marine

Aquatic Biomes: pelagic ; coastal ; brackish water

Other Habitat Features: estuarine

Habitat Type: Marine

Comments: Offshore form frequents pelagic waters, especially in tropics. Coastal form usually shoreward of 20 m contour, often in lagoons, bays, river mouths; ascends river in some areas; common near passes connecting large bays with ocean. Young are born in the water.

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Makes regular movements between inshore and offshore areas, and for distances up to 100 km linearly along coast. Much larger movements may occur (Wells et al. 1999), but whether these constitute migrations is uncertain.

The diet of bottlenosed dolphins is broad and varies from one place to another. Inshore bottlenosed dolphins typically feed on fish and invertebrates found near the shoreline, while deep water bottlenosed dolphins typically feed on squid and pelagic fish. Bottlenosed dolphins found along the U.S. Atlantic coast typically feed on Atlantic croakers (Micropogonias undulatus), ‘spot’ fish (Leistomomus xanthurus), and silver perch (Bairdiella chrysoura), while dolphins in South Africa typically feed on African massbankers (Trachurus delagoae), olive grunters (Pomadasys olivaceus), and pandora (Pagellus bellotti). Bottlenosed dolphins typically choose prey between 5 and 30 cm in length. They eat between 4.5 and 16 kg per day, depending on the size of the individual and if it is lactating. Most of the time, bottlenosed dolphins feed individually. At times, however, dolphins participate in cooperative feeding with other dolphins, especially when feeding on a school of prey. They have also been known to trap their prey on the shore, stranding themselves in order to feed on stranded prey ("strand feeding"). And in some cases dolphins use echolocation calls to stun their prey. Some bottlenosed dolphins use passive listening rather than echolocation to locate prey. When prey is detected, these dolphins either rush in or alert others of the prey’s presence.

The sharp teeth of these dolphins allow them to grasp prey while the tongue maneuvers prey down the throat. Dolphins teeth are not used to chew and prey is typically swallowed whole. They may break up their prey by shaking it in the air and striking it with their tails, called fish-whacking. Bottlenosed dolphins in Australia may mount a sponge on their rostrum to protect their snouts as they forage on the bottom. They have also been known to follow the boats of fisherman and catch discarded prey or bait.

Animal Foods: fish; mollusks; aquatic crustaceans

Primary Diet: carnivore (Piscivore , Eats non-insect arthropods, Molluscivore )

Comments: Very opportunistic feeder; prefers fishes (e.g., mullet), squid, crustaceans, and cephalopods. Sometimes drives fish ashore and comes out of the water in pursuit. Foraging by plunging the head into sandy bottoms has been observed in the Bahamas (Rossbach and Herzing 1997).

Bottlenosed dolphins feed on small fish and squid. They are hosts for a few species of parasites including the fluke Braunina cordiformis, tapeworms such as Monorygma delphini, roundworms (Anisakis marina), and thorny-headed worms (Corynosoma cetaceum). It has been said that healthy bottlenosed dolphin populations indicate a healthy marine ecosystem.

Ecosystem Impact: keystone species

Commensal/Parasitic Species:

• flukes (Braunina cordiformis)
• tapeworms (Monorygma delphini)
• roundworms (Anisakis marina)
• thorny-headed worms (Corynosoma cetaceum)

The most common predators of bottlenosed dolphins are larger sharks, such as bull (Carcharhinus leucas), tiger (Galeocerdo cuvier), and dusky sharks (Carcharhinus altimus). These sharks prey on smaller dolphins, calves and female dolphins more than larger dolphins. It is not uncommon to observe dolphins with shark bites, demonstrating their survival of an attack. Blubber may provide some protection against predators. Many shark populations have decreased up to 80 percent since 1970, so some populations of dolphins may be experiencing lower predation by sharks. More recently, stingrays have been recognized as causing deaths in bottlenosed dolphin populations.

Known Predators:

• bull sharks (Carcharhinus leucas)
• tiger sharks (Galeocerdo cuvier)
• dusky sharks (Carcharhinus altimus)

10,000 to >1,000,000 individuals

Comments: Population in the southeastern Pacific Ocean was estimated to be 588,000 in 1978. NMFS estimated in 1989 that the population off the Atlantic and Gulf coasts of the U.S. was 14,000-23,000 (see Nowak 1991).

Group size usually less than 10 (coastal form) or 25 (offshore form), though herds of several hundred sometimes are reported offshore. Individuals may segregate by age and sex.

Coastal form apparently has limited home range along segment of coast; for example, resident dolphins in a South Carolina estuary had home ranges over four years that averaged 51.3 square kilometers (95% adaptive kernel method; Gubbins 2002). However, in the Southern California Bight, dolphins are highly mobile within a relatively narrow coastal zone, extending from at least Santa Barbara to Ensenada, Mexico (Defran et al. 1999). Offshore form apparently is less restricted in movements and may move long distances over deep water (e.g., see Wells et al. 1999).

In Florida, mean mortality rate was 19% in first year, up to 3.8% annually thereafter (see IUCN 1991).

Bottlenosed dolphins use sound to communicate with other members of their groups. They use both audible sounds and high frequency echolocation. Each dolphin is believed to possess its own signature whistle and, once it is developed, it is retained for the duration of the dolphin’s life. Kin recognize one another by their whistles and these sounds help maintain group cohesion. Signature whistles develop in calves as young as one month, allowing them to maintain contact with their mother. Surprisingly, the signature whistle of a male calf tends to resemble its mother's more than that of a female calf. The signature whistle also gives the location and emotional state of each dolphin. Bottlenosed dolphins also navigate with echolocation, used to detect bottom topography, prey, and the presence of predators. It is even sometimes used to stun prey. Echolocation calls pass through the melon and intramandibular fat body, which contain acoustic lipids; these structures serve as acoustic lenses to focus sound. The intramandibular fat bodies focus sound to each ear, while the melon is used as a lens to focus outgoing sound.

Bottlenosed dolphins also use vision to perceive their surroundings. Like those of humans, their eyes contain rods and cones, but they are not used in the same way as humans. Cones, for example, are used to provide good acuity when light levels are high. These and other adaptations allow dolphins to use their vision at different times of the day and at different depths.

Communication Channels: visual ; tactile ; acoustic

Other Communication Modes: vibrations

Perception Channels: visual ; acoustic ; echolocation ; vibrations

Comments: Active day and night.

Bottlenosed dolphins are threatened by a variety of factors, both natural and of human origin. Natural mortality is due to injury, disease, and predation. Male bottlenosed dolphins typically live about 40 to 45 years and female dolphins can live over 50 years (the oldest female documented lived to be 53 years old). Because in many cases dolphins are found in shallow waters, they encounter many humans and human activities. Recreational fishing gear causes many deaths when dolphins become entangled in nets or swallow fishing hooks. Dolphins are sometimes preyed upon by sharks, although this is may be less of a problem now than in the past due to declining shark populations. One of the largest and most serious threats to bottlenosed dolphins is environmental contamination, caused mainly by the increase of human development along shorelines. Chemicals of human origin find their way into coastal ecosystems through runoff from agriculture, residential, and industrial sources.

Range lifespan

Status: captivity: 53 (high) years.

Average lifespan

Status: captivity: 45 years.

Average lifespan

Status: wild: 25.0 years.

Average lifespan

Status: captivity: 30.0 years.

Average lifespan

Status: wild: 25.0 years.

Average lifespan

Status: wild: 35.0 years.

Average lifespan

Status: wild: 25.0 years.

Bottlenosed dolphins are polygamous. They engage in mating behavior in either of two ways, in alliances or individually. Males that form alliances look for females that are in estrous. When males find a female in estrous they separate her from her home range for a chance to mate with her. Sometimes they flank the female to prevent access by other males to insure that only they have the opportunity to mate with her. Waiting for a female to become receptive can take several weeks. Some males do not engage in alliances, instead remaining in their home ranges. When an estrous female enters the home range of such a male, he attempts to attract her to mate. During courtship, a male postures by arching his back. He strokes and nuzzles the female, and he may clap his jaws or yelp. Bottlenosed dolphin copulation typically occurs belly-to-belly with both animals facing the same direction, although an animal facing the opposite direction is not uncommon. Intromission lasts only around 10 seconds and involves vigorous pelvis thrusts.

Mating System: polygynandrous (promiscuous) ; cooperative breeder

Female dolphins typically reach sexual maturity between 5 and 10 years of age, while males reach sexual maturity between 8 and 13 years old. Sexual maturity is usually achieved years before reproduction; males that reach sexual maturity at age 10 don’t typically breed until they are at approximately 20 years old. Reproductive seasons vary from region to region. Typically, females ovulate at a particular time of year while males are active throughout the year (but with a peak of testosterone production when females ovulate). Gestation lasts about 12 months and each pregnancy produces one calf. Females nurse their young from nipples on each side of their genital slit until the calf is between 18 and 20 months. Bottlenosed dolphins reproduce every 3 to 6 years, with females usually becoming pregnant soon after their calf is weaned. Calves can be born at any time of the year but with a peak in birthing during warmer months. Females can reproduce well into their late forties.

Breeding interval: Female bottlenosed dolphins breed once every 3 to 6 years.

Breeding season: Breeding may occur throughout the year but is often concentrated in the warmer months.

Average number of offspring: 1.

Average gestation period: 12 months.

Range birth mass: 14 to 20 kg.

Range weaning age: 18 to 20 months.

Average time to independence: 5 years.

Range age at sexual or reproductive maturity (female): 5 to 10 years.

Range age at sexual or reproductive maturity (male): 8 to 13 years.

Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Average gestation period: 365 days.

Average number of offspring: 1.

Females provide the bulk of parental investment, investing especially heavily during lactation. Lactation in bottlenosed dolphins typically lasts 18 to 20 months. Lactating females require 88 to 153 cal/kg as opposed to non-lactating females that typically require 34 to 67 cal/kg. Bottlenosed dolphins participate in allomaternal care, that is, all of the females within a group help care for each others' offspring. When a bottlenosed dolphin calf is born, it learns to ride the pressure waves alongside its mother during its first few days. The mother assists the calf to keep it alongside her body.  Females also protect calves from predators.

Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female); post-independence association with parents

Gestation lasts about 12 months. Produces one young every 2-6 years. Young are closely tended by adults for 1st several months, weaned in 12-18 months or more. Males are sexually mature in 8-12 years, females in 5-12 years; average age of sexual maturity is around 11-12 years; a few live up to at least 40 (males) to 50 (females) years (Leatherwood and Reeves 1983, IUCN 1991).

The body of the dolphin has low friction in water by having an optimal length to diameter ratio.

The blubber of the bottlenose dolphin absorbs heat by acting as a phase change material

"There is substantial evidence to support the classification of the integument, and specifically the blubber layer [of the Atlantic bottlenose dolphin], as a phase change material. First, many of the fatty acids found in blubber are classified as phase change materials and have melting points in the range of mammalian body temperatures (Sari, 2003; Sari and Kaygusuz, 2001; Sari et al., 2003; Suppes et al., 2003). Suppes et al. (2003) classified palmitic (C16:0), steric (18:0), oleic (C18:1), linoleic (C18:2), linolenic (C18:3) and arachidic (C20:0) fatty acids as excellent phase change materials. All of these fatty acids have been identified in cetacean blubber (Koopman et al., 1996). Mixtures of these fatty acids yield phase change materials with melting points between 29° and 38°C (Suppes et al., 2003), which include the range of mammalian body temperatures. Second, these fatty acids also satisfy the requirement that the material has a relatively large latent heat plateau, with latent heat values generally greater than 180·J·g–1 (Suppes et al., 2003). Third, their stratification in blubber may be prevented by their containment in adipocytes as well as the highly structured nature of adipocytes in the blubber tissue. Finally, cetaceans are known to have fine vascular control to their appendages and to the periphery of their body (Elsner et al., 1974; Kvadsheim and Folkow, 1997; Ling, 1974; Meagher et al., 2002; Pabst et al., 1999b; Scholander and Schevill, 1955). Intermittent heat loads could be applied to the blubber through shunting of warm blood to the blubber layer, followed by periods of vasoconstriction. Future studies are needed to fully characterize blubber’s potential phase change properties as well as investigate the possible functions that may be associated with such a property." (Dunkin et al., 2005: 1479)

The members of bottlenose dolphin pods stun prey by emitting low-frequency sound waves.

Bottlenosed dolphins in the United States are protected under the Marine Mammal Protection Act of 1972. The goal of this Act is to allow marine species to obtain optimum sustainable population levels keeping in mind the carrying capacity of the habitat. Anyone who removes a marine animal (e.g., a dolphin) without proper procedure faces fines up to $20,000 or periods of incarceration up to one year. Bottlenosed dolphins are also protected under the Environment Protection and Biodiversity Conservation Bill of 1998 in Australia. This bill is applied to waters up to 200 miles from the shores of Australia. It involves environmental impact assessments, conservation of biodiversity and endangered species as well as management of protected areas. Bottlenosed dolphins are found in most waters and so are protected by many different laws in a large number of countries.  Although there are laws that protect bottlenosed dolphins, humans need to become more aware of the way our daily lives affect the livelihood of dolphins. Much of the environmental contamination found in the habitats of bottlenose dolphins are caused by humans. Common pollutants found in the tissues of dolphin are polychlorinated biphenyls (PCB), used as dielectric fluids in coolants, lubricators and transformers, and pesticide DDTs (1,1-bis-(4-chlorophenyl)-2,2,2-trichloroethane). Eighty percent of the total amount of these toxins in a female dolphin may be transferred through breast milk to its calf, causing suppression of the immune system or in some cases death. It is one thing to make sure that we are not removing dolphins from their habitats but it is also important to make sure their habitats are not being destroyed by our negligence.

US Federal List: no special status

CITES: appendix i; no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Unknown; probably breeding.

United States

Rounded National Status Rank: N4 - Apparently Secure

Rounded Global Status Rank: G5 - Secure

Reasons: Widespread and common in many areas worldwide.

There are currently eleven stocks of Tursiops truncatus in U.S. waters, five of which occur in the Gulf of Mexico. The Western North Atlantic Coastal stock is listed under the Marine Mammal Protection Act as "depleted" i.e., below its optimum sustainable population.

Global Short Term Trend: Relatively stable (=10% change)

Comments: Local declines have occurred but overall relatively stable.

Degree of Threat: C : Not very threatened throughout its range, communities often provide natural resources that when exploited alter the composition and structure over the short-term, or communities are self-protecting because they are unsuitable for other uses

Comments: Incurs low to moderate levels of direct exploitation and incidental take in fisheries (Leatherwood and Reeves 1983, Jefferson et al. 1993). See Duignan et al. (1996) for information on recurrent epizootics of morbillivirus infections in the western Atlantic and Gulf of Mexico.

There are no known adverse effects of Tursiops truncatus on humans.

Humans receive a considerable amount of economic gain from bottlenosed dolphins. They are often used in captivity to swim with humans and perform. Dolphins are used in tours in which participants are educated about the lives of dolphins and encouraged to preserve their livelihood and habitat. Bottlenosed dolphins have also been known to fish cooperatively with humans, letting Brazilian fishermen, for example, know when and where to drop their nets. Bottlenosed dolphins are even used for research by the U.S. Navy on echolocation and thermoregulation. These research dolphins have also helped navy divers to find submerged objects in the ocean. Research on bottlenosed dolphins has contributed substantially to our understanding of social communication and behavior and the nature of intelligence.

Positive Impacts: ecotourism ; research and education

Comments: Most commonly displayed cetacean in marine aquaria. Historically has been harvested for meat, leather, oil, and meal. Today the main directed fishery is in Japanese waters, producing meat for human consumption; limited direct take occurs in many other parts of the range (IUCN 1991). Blamed for damage to fisheries and fishing gear in many areas (see IUCN 1991 for examples), but claims of damage are not always adequately substantiated.

Comments: Certain populations (e.g., subspecies gillii) have been regarded as distinct species by some authors, but most authors regard Tursiops as comprising a single, geographically variable species (Jones et al. 1992; Mead and Brownell, in Wilson and Reeder 1993) or two species (worldwide T. truncatus and Indian Ocean T. aduncus) (Rice 1998; Mead and Brownell, in Wilson and Reeder 2005).

LeDuc et al. (1999) used cytochrome b gene sequences to examine phylogenetic relationships among delphinids and found that Tursiops aduncus of the Indo-Pacific is distinct from Tursiops truncatus and moreover may be the sister species of Stenella frontalis; the genera Tursiops and Stenella as presently construed apear to be polyphyletic. Further taxonomic work is needed to resolve the relationships within the Delphininae before taxonomic revisions are made, other than recognizing T. aduncus as a distinct species.

Two forms are recognized, coastal and offshore. An offshore form exists between the 200- and 2000-m isobaths in distinct Gulf of Mexico and western North Atlantic stocks, whereas one or more coastal forms inhabit the waters inshore (Wells et al. 1999).

An opinion of the ICZN conserved the specific name truncatus and suppressed nesernack (see Mead and Brownell, in Wilson and Reeder 1993). See IUCN (1991) for further discussion of taxonomy.