Over 100 Dead Dolphins Have Washed Ashore In Brazil And No One Knows Why

The dolphins are washing up on Sepetiba beach, around 70 kilometers from Rio de Janeiro. Aimoré/Flickr CC BY-NC 2.0

Conservationists in Brazil are scrambling for answers after four or five dead dolphins have washed up on beaches every single day since mid-December. Experts are now examining the carcasses that have been found, and trying to deduce what is behind this sudden and horrific mass die-off.

At the time of writing, it is thought that at least 102 dead dolphins have been discovered over the past month. The cause of their deaths still remains unclear, and while some have seemingly been at sea for a while, others look relatively fresh, with no obvious signs of trauma.


“We've never experienced this before. It’s a tragedy,” Leonardo Flach, chief coordinator of local NGO Boto Cinza Institute, told ABC News. “Every day we are finding four or five dolphin carcasses. One day we will find dolphin corpses that are male and adults, and the next day, female and puppies. But most of them are skinny and with deep skin lesions. I've never seen anything like that.”


Local conservation NGOs are worried that this might point to a bacterial or viral infection spreading through the group, but at this stage, nothing is really known. If it is something infectious, then Flach is seriously worried about the future of the population. As dolphins are naturally social creatures, the potential for it to spread is high.

There are only thought to be around 800 dolphins in the Bay of Sepetiba, which is located some 70 kilometers (45 miles) west of Rio de Janeiro. The population of cetaceans off this bit of coast is thought to be one of the highest concentrations in the world, making the death of over 10 percent a massive blow to the dolphins.


The waters off this patch of coast, being so close to such a major city and frequented by ships, are known to be highly polluted already. But even so, conservationists in the region usually only come across around five dead animals a month, let alone five a day. In most cases, they have died due to being caught in nets, pollution, or illegal hunting.


Those at the Boto Cinza Institute are now trying to pressure the local authorities to officially recognize the dolphins in the bay as an endangered species, as well as set up a marine refuge in the area. This, they hope, will help safeguard the future of the dolphins, and save them from disappearing altogether.


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