Cancer in California Sea Lions

Buried in this tiny story about a sea lion rescue attempt near Monterey is this quote:

"Whatever the causes of that might be, whether it's pollution, a food chain problem, we're seeing cancer in 20 percent of the adult California sea lions on this coast," said Marine Mammal Center spokeswoman Sue Andrews. "So, that's a pretty scary number."

Even if that's only 20 percent of the animals admitted to The Marine Mammal Center, presumably a less healthy sample than the population at large, it's a remarkable number. Why, one wonders, hadn't we heard of this before? This quote from an SFSU course syllabus indicates that it's been known since at least 2001:

In the Spring 2001 issue of The Newsletter of The Marine Mammal Center, Sue Spong reported that The Marine Mammal Center has found a high rate of cancer among California sea lions. 18% of those examined post-mortem were found to have cancer, most commonly in the urinary and genital tracts. This incredibly high rate of cancer could be due to high concentrations of PCBs and organochlorinated pesticides that run off of land and work its way up the food chain to the sea lion. While the California sea lion population is not endangered, this species could serve as a indicator species on the overall general health of the coastal food chains.

Another possible cause of urogenital cancer in pinnipeds is a new herpes virus, judging by the titles of papers in The Marine Mammal Center research bibliography.