Read our COVID-19 research and news.

No 'Smoking Gun' for Killer Oil

The National Aquarium has ended dolphin shows like these and is considering moving the animals to a marine sanctuary.

Bye-bye? The National Aquarium has ended dolphin shows like these and is considering moving the animals to a marine sanctuary.

Chris Williamson/Wikimedia Commons

In the last few weeks, 228 dead sea turtles and 29 dead marine mammals have been found in the Gulf of Mexico. But determining why they died is far from straightforward, and it may take months before officials can say whether they are casualties of oil.