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The Dolphins of the Bahamas

The Atlantic Spotted Dolphin (Stenella frontalis) brings many eco-tourists to the Little Bahama Bank.

Over the last few years Dolphins have undergone a massive change in the public's perception. From mere sideshow attractions in the seventies when, as inmates of various Seaquaria they were taught to do tricks, they have today attained an almost mystical significance. Sick children are now taken to swim with Dolphins, and amazing healing powers have been claimed in the media.

Whatever the truth of this, Dolphins are now regarded with far more respect than in the past, and as a consequence there is far more interest in this animal group. 

Initially a large part in this change of perception must have been brought about the TV series 'Flipper', in which a Dolphin becomes the friend and helper of a young boy in his various fictional adventures. Subsequent films such as 'Free Willy' have also worked to change the public's perception and awaken the interest in Dolphins and their kin.

Naturally, there has been an awakened interest in the Dolphins of the Bahamas, and these animals are now regarded as a tourist attraction with special Dolphin watching boat trips going out on a regular basis.

The Dolphins that have become famous in the Bahamas are Atlantic Spotted Dolphins, just one of thirty-two species of Dolphin world-wide belonging to a family of marine mammals called the Delphinidae that also includes the Pilot Whale and the Killer Whale or Orca. 

The Atlantic Spotted Dolphin (Stenella frontalis) has a long, narrow 'beak' from which it derives its scientific name. It is a relatively small dolphin, reaching an adult length of about 2 metres and a weight of around 200 pounds. This species is found off the Atlantic Coast of the United States, the Gulf of Mexico, and the Bahamas  -particularly on the Little Bahama Bank where they attract a number of dolphin-tourism boats.

Dolphins have demonstrated a wide range of sounds and are believed to have a unique 'language' of their own. They emit clicking sounds or whistles almost constantly. The clicks are short pulses of about 300 sounds per second, emitted from a mechanism located just below the blowhole. They are used for the echolocation of objects and are resonated forwards and amplified by an organ called the melon. This makes up much of the bulge in the Dolphin's forehead just behind its 'beak'. Echoes from these clicks are received at the rear of the lower jaw and transmitted to the middle ear. The Dolphin's echolocation system is similar to that of a bat, enabling the dolphin to navigate in complete darkness and to detect its main prey, fish and squid. The whistles come from deeper in the larynx and are used to communicate alarm and emotion.

While the famous Dolphins of the Little Bahamas Bank are Spotted Dolphins, the Dolphin usually kept in captivity or 'semi-captivity' for people to swim with, are usually Bottle-nosed Dolphins. 

Dolphins use their sophisticated sonar communication systems to co-ordinate the herding of fish shoals.

This species lives in temperate and tropical waters, many of them staying within 100 miles of land. Many live in bays and protected inlets, where the water is relatively shallow. Bottle-nosed dolphins range as far south as Argentina and South Africa and as far north as Norway in the eastern Atlantic.

Dolphins mate in spring and early summer with the gestation lasting from 10 to 12 months. The females almost always give birth to one calf at a time. After the calf is born, it immediately swims to the surface for its first breath of air. The females nurse and protect their young for more than a year with the males taking no part in caring for the young.

Dolphins are 'top predators'. At the end of the food chain they could easily accumulate high concentrations of any environmental pollutants that are not biodegradable. As such they are considered as 'indicator' species - a species that 'flags-up' environmental problems.

In common with many other marine creatures, Dolphins living close to the coast in many parts of the world are threatened with pollution and degradation of their environment. Such concerns include sewage, dumping at sea, and in some places, the exploration for oil, a process that involves a 'seismic survey'. Compressed air guns are towed behind ships and exploded at regular intervals. Echoes from the seabed are picked up on board and the results analysed by geologists. There are concerns that these 'explosions' could affect Dolphins, animals almost entirely dependent on subtle sound signals for group cohesion and feeding.

Fishing nets have recently been targeted as a major killer of Dolphins. As air breathing mammals, they must return to the surface periodically. If they do become tangled in long drift nets, then they will drown - as many are apparently doing today!

 

 

 

 

R. Attrill 2006