On 17 January, marine biologist, National Geographic explorer, and Oceanswell Founder and Executive Director Dr. Asha de Vos shared images of an olive ridley turtle carcass discovered on Mount Lavinia Beach, stating that the specimen was bloated due to decomposition. However, the possible cause of death is unclear.
According to National Geographic, the olive ridley turtle is closely related to the Kemp’s ridley, with the primary distinction being that olive ridleys are found only in warmer waters, including the Southern Atlantic, Pacific and Indian Oceans, and that they are the smallest of the sea turtles.
Speaking with former University of Ruhuna Department of Oceanography and Marine Geology Head Dr. P.B. Terney Pradeep Kumara, he shared that these turtles are solitary creatures, preferring the open ocean, and that they migrate hundreds or even thousands of miles every year and come together as a group only once a year for the “arribada”, when females return to the beaches where they hatched and lumber onshore, sometimes in thousands, to nest.
Olive ridleys are said to have nesting sites all over the world, on tropical and subtropical beaches, and according to Dr. Kumara, Odisha, a state in Northeast India, hosts one of the world’s major annual mass-nesting events of marine turtles; hundreds of thousands of olive ridley turtles come ashore to nest each year on its shores.
Dr. Kumara shared that considering that olive ridleys do flock in the hundreds of thousands to beaches around the Bay of Bengal, they do at times nest in parts of Sri Lanka. Out of the eight species of sea turtles, five types nest in the shores of Sri Lanka, and the olive ridley is one of the five.
As for discovering a carcass, he said that what is notable here is that it was discovered in Mount Lavinia; carcasses of olive ridleys are a common site in the Mannar, Talaimannar areas as the carcasses often get washed ashore. He said that getting entangled in fishing nets is the biggest threat that marine turtles face in Sri Lankan waters, and that when Indian fishermen carry out fish trawling – which is a method of fishing that involves pulling a fishing net through the water behind one or more boats – marine turtles often get entangled in the trawl, which is the net used for trawling.
There has been a recent incident back in October 2020 where 10 olive ridley sea turtles washed ashore on the beaches of Colombo over a two-day period, leaving experts puzzled about the cause of death as the carcasses exhibited none of the injuries consistent with entanglement in fishing nets. At the time, it was speculated that the cause of death could be a number of variants, including a recent oil spill from the MT New Diamond crude carrier at the time, or blast fishing, which would explain the lack of external injuries.
Dr. Kumara also highlighted that the discovery of the specimen brings forth a very pressing issue of the dwindling sea turtle populations. He said that out of the five marine turtles known to nest on Sri Lankan beaches – the olive ridley turtle, green turtle (Chelonia mydas), loggerhead turtle (Caretta caretta), hawksbill turtle (Eretmochelys imbricata), and leatherback turtle (Dermochelys coriacea) – nearly for all, the population trend is declining rapidly. He said that it is imperative that we keep track of these changes in order to better address the matter.
Speaking with Dr. de Vos, she too noted the importance of reporting these incidents. She said that specimens that are dead or alive are data, stating that whatever data they at Oceanswell can collect of the species helps them build a more accurate picture of the species in the long term.
She added that they do not want these animals to die in vain and if the specimens are brought to their attention, then they are able to determine the cause of death and figure out ways to mitigate those factors; decide what they can do better. “For example, if animals are getting tangled up in fishing nets a lot, then we can decide if we have to build different fishing nets or come up with a mechanism where the animal can be set free without injury, etc.” she noted.
Finally, Dr. de Vos said that in allowing people to be a part of science, it must be realised that being a part of it does not depend on what degree you have. She added that what they wish to do is create a positive narrative. “Most people will never get to see these creatures and when they do unfortunately come up on shore, by reporting it, we can draw people’s attention and it is an opportunity to build interest.”
You can report such discoveries via info@oceanswell.org.
Photo by Dr. Asha de Vos
