Habitat & Distribution

Distribution

Bottlenose dolphins live in temperate and tropical waters worldwide. Distribution is generally limited to surface water temperatures of 10° to 32°C (50°-90° F).

In the Pacific Ocean, bottlenose dolphins are found from northern Japan to Australia and from Southern California to Chile. They are also found offshore in the eastern tropical Pacific as far west as the Hawaiian Islands. Off the California coast bottlenose dolphins have been observed as far north as Monterey, particularly during years of unusual warmth.

Known range of bottlenose dolphins are indicated in dark blue.

In the Atlantic Ocean, bottlenose dolphins are found from Nova Scotia to Patagonia and from Norway to the tip of South Africa. They are the most abundant dolphin species along the United States' coast from Cape Cod through the Gulf of Mexico.

Bottlenose dolphins are also found in the Mediterranean and Black Seas.

Indo-Pacific bottlenose dolphins are found in the Indian Ocean from Indonesia to Australia to South Africa, the Red Sea, and in the tropical and subtropical waters of the western Pacific.

Habitat

Bottlenose dolphins live in a variety of habitats, from coastal waters to the open ocean.

Scientists recognize two bottlenose dolphin ecotypes (forms): coastal and offshore. In the northwest Atlantic, bottlenose dolphin coastal and offshore ecotypes can be differentiated by skull and body measurements as well as by characteristics of their blood.

In general, the coastal ecotype seems to be adapted for warm, shallow waters. Its smaller body and larger flippers suggest increased maneuverability and heat dissipation. These dolphins frequent harbors, bays, lagoons, and estuaries. In general, the offshore ecotype seems to be adapted for cooler, deeper waters. Certain characteristics of its blood indicate that this form may be better suited for deep diving. Its larger body helps to conserve heat and defend itself against predators. In northwest Atlantic bottlenose dolphin studies, researchers determined that dolphins within 7.5 km (4.65 mi.) of shore were coastal ecotypes. Dolphins beyond 34 km (21 mi.) from shore were offshore ecotypes.
Migration

Variations in water temperature, movements of food fish, and feeding habits may account for the seasonal movements of some dolphins to and from certain areas.

Some coastal dolphins in higher latitudes show a clear tendency toward seasonal migrations, traveling farther south in the winter. For example, coastal bottlenose dolphins on the Atlantic side of the U.S. migrate seasonally between New Jersey and North Carolina.

Coastal dolphins in warmer waters show less extensive, localized seasonal movements.

Some coastal animals stay within a limited home range: an area in which individuals or groups regularly move about during day-to-day activities. Individual dolphins that live within a home range are called "local residents". Resident dolphins have been identified along the coasts of Georgia, Florida, Texas, southern California, Gulf of California, and South Africa. Groups of dolphins that reside within a home range make up "resident communities". The Sarasota, Florida resident dolphin community home range is an area of about 125 km2 (48.3 mi2). Home ranges may overlap.

Population

Bottlenose dolphins are not endangered or threatened.

The worldwide population of common bottlenose dolphins is about 600,000.

Indo-Pacific bottlenose dolphins are abundant, but the overall population is unknown.

Chromosome banding techniques have proven useful in bottlenose dolphin population studies. In some areas, scientists can identify individuals and determine relationships among dolphins in a group.

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