Small but notable numbers of California sea lions are dying of cancer that appears to originate in the animal’s urinary systems and reproductive organs, then spreads, says Richard Evans, medical director of the Pacific Marine Mammal Center in Laguna Beach.
“Over at least the last decade, we and other marine mammal centers in California have noted a significant (10-20 percent of our patients) number of adult, male and female, California sea lions admitted with a highly disseminated form of cancer (that) spreads completely via the lymphatic system.
“A Gamma-Herpesvirus as been universally found associated with the cells in these tumors, but it is as yet not known whether this is the cause in part or whole. (We’re) in the midst of a 2 year study to determine the degree to which this virus is present in animals with these tumors in southern California waters.”
Evans will present an overview of the research Friday when he meets with viral researchers at UC Irvine. (The image shows one of the animals from the study. Photo courtesy of PMMC.)
The research says that the sea lions probably pass the Gamma-Herpesvirus among themselves through sexual contact. But he stressed that the animals, which sometimes approach humans in local waters, aren’t passing it on to people.
“Herpesviruses tend to be specific for a species,” Evans says.
There’s also no indication that the cancer will cause a widespread die-off of sea lions, which were once hunted to near extinction. NOAA estimates that there are currently about 244,000 sea lions, which marks their “optimum sustainable population.”
But Evans says it’s important to identify the precise cause of the cancer, and how widely it occurs.
“We’ve seen the cancer in sea lions that are dying and have beached themselves,” Evans said. “But we don’t know whether the cancer is common among animals out in the ocean.”
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optimum sustainable population? They are over populated and need to have their numbers reduced by some type of hunting. I hope there is a huge die off of these sea dogs that disrupt the fisherman and owners of waterfront homes.
This is in response to #1 local says:
It is a shame that once again a human being becomes arrogant enough to see his waterfront home or sports hunters for fish become more important than beautiful animals which we are guardians of. This planet needs more humans to be in cooperation with life forms and stop killing the balance and beauty that can co-exist.