Ocean-going dolphins are not the only ones suffering. The Chinese river dolphin, or baiji, was declared functionally extinct in 2006 after an study couldn't find a single individual.
The baiji was probably done in by a combination of problems caused by humans, including accidental deaths by getting trapped in fishing gear, vessel strikes, underwater explosions, excessive noise and depletion of prey species, according to Tim Ragen, executive director of the U.S. Marine Mammal Commission.
"Broadly similar threats face marine dolphins," said Ragen.
Other possible accomplices in the dolphins' demise were abnormal weather, toxic algae blooms, parasites, pollution exposure, loss of prey leading to starvation, disorientation due to loud noises from ships and oil exploration and physical injury.
"In many cases, the cause of stranding is unknown and difficult to discern," said Barclay.
What isn't in doubt is that human impacts on the ocean are hurting dolphins around the world.
"People should recognize that the dolphins need the waters to survive -- that we are visitors to their homes," said Wells. "As visitors, we should be good stewards, and respect the needs of these animals as they try to make a living in the aquatic environment."