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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

Are drones disturbing marine mammals? - Marine researchers have made sure that their research drones aren't disturbing their research subjects, shows a new report. And they're hoping that others will follow their example to help protect wildlife in the future.
Feeding wild dolphins can hurt them, new study says - Wild dolphins are more likely to be injured if humans feed them — even through unintentional means like discarding bait — reports a new study.
Data on blue whales off California helps protect their distant relatives - A research team has found a way to translate their knowledge of blue whales off California and in the eastern tropical Pacific Ocean to the other side of the world, revealing those areas of the Northern Indian Ocean where whales are likely to be encountered.
Why do killer whales go through menopause? Mother-daughter conflict is key - Killer whales are one of only three species that are known to go through menopause, surviving long after they've stopped reproducing. Those older females play an essential role in helping their younger family members to find food and survive even in lean times. But, researchers report in a new study, the reason older females stop reproducing has more to do with conflict between mothers and their daughters than it does with cooperation.
Ancient dolphin species Urkudelphis chawpipacha discovered in Ecuador - An extinct dolphin species likely from the Oligocene has been discovered. The fossil is one of the few fossil dolphins from the equator, and is a reminder that Oligocene cetaceans may have ranged widely in tropical waters.