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Dolphins

Earth Platform > Animals > Marine Life > Dolphins
Every seven years, half of all dolphins in captivity die from marine pollution, habitat degradation, harvesting, low frequency sonar, entrapment in fishing gear and other stress-related illnesses. Luckily, a number of countries have now stopped or reduced the capture of wild dolphins, and knowledge and conditions are vastly improving. However, there are still many countries where conditions for captive dolphins are well below standards.
 

Dolphins

A lot of dolphins die in fisheries. In the North Sea alone, an estimated 10,000 harbour porpoises are killed in fishing gear each year.  In recent years there have been gear modifications  that make it possible for the dolphins, to escape once a fishingnet is closed. Not every country has made these modifications mandatory yet, so dolphins are still killed in this fishery. The dolphins killed in fishery are mainly common dolphins, spotted dolphins and spinner dolphins. Occasionally other species, including bottlenose dolphins, are caught as well, but their numbers are lower.

dolphinsEspecially in coastal areas, marine mammals are often disturbed by human activities. Collisions with boats and jet skis have already resulted in severe traumas and even deaths of marine mammals, including dolphins. Also, boat traffic in areas where dolphins usually rest or forage can disrupt their normal behaviour. The seemingly harmless human behaviour, such as swimming in areas where dolphins naturally rest, can result in disturbance and changes in behaviour. In a bay in Hawaii for example, where spinner dolphins came to rest, the increase in swimmers, has resulted in the dolphins leaving the bay. They had to find another resting area.

Dolphins are very acoustically oriented animals. With their natural sonar, they rely heavily on sound for their orientation, navigation and communication with other dolphins. Since the last century, the increase in boat traffic around the globe has resulted in a considerable increase in noise in the world's oceans. This has a negative effect on dolphin and whale navigation and communication. 

 

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Dolphins in the news

Dolphins and Whales News -- ScienceDaily

Crocodiles and dolphins evolved similar skulls to catch the same prey - Despite their very different ancestors, dolphins and crocodiles evolved similarly shaped skulls to feed on similar prey, new research indicates.
First underwater video footage of the True's beaked whale - The True's beaked whale is a deep-diving mammal so rarely seen that it often defies recognition at sea by researchers. As a result, we have little data about its distribution, abundance and calving rate -- information essential for its conservation. Scientists have now found a new coloration pattern in the species and obtained the first images of a calf along with the first underwater video of these whales -- helping to reveal the secrets of this species.
Newborn harbour porpoises have the fastest hearing development among mammals - All mammals can hear -- but it is not an ability that is fully developed at birth. Some mammals like humans take years to fully develop their hearing abilities, but for a newborn harbor porpoise it takes less than 30 hours. This is the fastest in any studied mammal.
Diving deep into the dolphin genome could benefit human health - A new database of bottlenose dolphin DNA and associated proteins just completed could possibly aid in dolphin care and research of human medical problems such as stroke and kidney failure.
Cutting-edge cameras reveal the secret life of dolphins - Dolphins have been recorded in rarely-seen activities of mother-calf interaction, playing with kelp, and intimate social behaviors like flipper-rubbing through the use of largely non-invasive new cameras.