Cancer the Leading Cause of Death for Many Sea Lions
A disturbing number of deaths among sea lions were caused by mestatic cancer. Surprising numbers of sea lions every year was seen to have huge advanced tumors that lead to their death.
“Mestatic Cancer” is a cancer that has spread from the site where it was developed to the other parts of the body. Normally cancer begins from a single tumor, when new tumors appear to the other parts of the body we then call it “metastasis”. This involves the spread of cancer cells to the blood stream, or the lymph system to the lymph nodes (a bean-shaped collection of immune system cells that are important in fighting infections), or to the other organs, and continue to grow into new tumors.
A study conducted by the team of Dr. Frances Gulland, the director of veterinary science at the Marine Mammal Center in Sausalito showed that 18% of deaths among stranded sea lions were caused by tumors in the reproductive and urinary track area.
It was a mystery how the sea lions got such an aggressive cancer, but Dr. Gulland believed that there’s some carcinogen in the ocean that could’ve affected these sea lions. Years of study gave them enough evidence that these carcinogens actually came from industrial contaminants in the ocean. Cancer in sea lions often starts on their genitals (both male and female) which paralyze the whole genital area. A field observation showed that two to five sea lions a year are reported to have huge advanced tumors.
There have been less reported cases of cancer in wild animals, but it is still continuously monitored. Recently it was found that cancer became a great concern for endangered species like green sea turtles, Attwater’s prairie chickens and Tasmanian devils. In St. Lawrence River estuary in Canada, stranded beluga whales were found to have intestinal tumors or other cancers. The obvious suspect for the occurrence of cancer among land and marine animals was environmental contaminants. Sea lions collect high concentrations of PCBs and DDTs in their blubber from eating contaminated fish; mothers also pass the compounds to babies. Animals with higher blubber PCB concentrations were more likely to have died of cancer.
According to Dr. Gulland, “Sea lions do eat a lot of the same things we do, so we really should start paying attention to what we’re putting into the oceans.”
So what we do on land greatly affects marine animals, and may affect us too since we also get our food from the sea and what makes these marine animals sick can also make us sick.