During a recent visit to San Cristóbal, we stayed in a hotel located on the Malecón, the bay shore promenade, of Baquerizo Moreno. Every night we went to sleep serenaded by the barking sounds of the sea lions that have taken over the area. (click here to hear the sounds.) The sea lions sleep on the benches, they use the slides destined for children, they swim in the bay and board any available boat, they have even trespassed into homes when the owners left the street door open.
On the positive side sea lions are cute and offer a great opportunity to get closer to nature in the middle of a town. On the negative side their bodily functions create a rather unpleasant aroma but worse than that being so close to humans and other introduced species such as cats, dogs, rats, mice, etc. may expose the sea lions to health threats.
A recent study conducted by the Zoological Society of London, in collaboration with the Galapagos National Park, the University of Leeds, the Sea Mammal Research Unit at the University of St. Andrew’s and the Autonomous University of Queretaro, and published on The Public Library of Science blog PLOS One confirms that there are reasons for alarm. Researchers compared the immune activity and body condition of 60 tagged sea lions in uninhabited Santa Fe island with those of inhabited San Cristóbal. They found that the immune systems of the sea lions that lived in town were more active and that the pups had higher levels of antibodies, thinner skin folds and lower weight.
In a press statement Dr. Paddy Brock, author of the paper, says: “A tell-tale sign of an unhealthy sea lion is a thinner than normal layer of blubber, which is what we saw in the sea lions on San Cristobal. This was all the more notable as we didn’t notice these patterns in sea lions on Santa Fe, where they live without the presence of people or pets.
“”The immune systems of San Cristobal sea lions were more active, perhaps indicating a threat of infectious disease, which could mean human activity is increasing the chance of potentially dangerous diseases emerging in the Galapagos sea lion,” Dr Brock added.
Although Ecuador has laws designed to protect the unique fauna of the Galapagos there is no effective control over the proliferation of pets. On the malecón of Baquerizo Moreno, one can see many dogs sharing space with the sea lions and sometimes chasing them. A long time Galápagos resident who did not want to be identified told how he witnessed packs of dogs attacking the sea lions.
This increases the risk of new diseases spreading to local species. Furthermore, there is sewage contamination in the bay where the sea lions live and this increases their exposure to human germs and bacteria.
The Zoological Society of London, the Galapagos National Park and the other collaborators pledge to continue to address the threats faced by the Galapagos sea lion by carrying out further research.