Sierra Blogging Post Archives

California sea lions have recently begun dying of cancer at alarming rates. And scientists want to know why.

Over the past 14 years, cancer has become a leading cause of death for sea lions off the California coast.

“It’s such an aggressive cancer, and it’s so unusual to see such a high prevalence of cancer in a wild population,” said Dr. Frances Gulland, director of veterinary science at the Marine Mammal Center. “That suggests that there’s some carcinogen in the ocean that could be affecting these animals,” Gulland said.


With all the pollution and chemicals we dump into our oceans, it's really not surprising that marine mammals are coming down with the same disease that plagues humans. It could be a multitude of things that's causing the cancerous tumors in 18% of sea lions. Scientists think the answer lies in a combination of 3 things - PCB's, viruses and genetics.

Sea lions aren't the only ones getting cancer. Whales are too. In fact, 18% of beluga whales in the St. Lawrence River in Canada had cancerous tumors definitively linked to industrial pollutants.

“We don’t have all the answers by any means,” said Dr. Linda Lowenstine, a veterinary pathologist at UC Davis who works with Gulland. But the plight of sea lions will affect humans, since they “eat a lot of the same things we do,” said Gulland, echoing a familiar refrain. “We really should start paying attention to what we’re putting into the oceans.”

Cancer is the scourge of the Earth - for us and the animals we share the planet with. It's sad to think we're causing it all.

What do you think? Are we spreading disease with our pollutants?