STIMULATING articles in The Borneo Post by James Alin (April 17, 2014) and Rintos Mail (May 18, 2014) prompted me to write this.
In 2001, I landed ashore in Mayotte, in the Comoros group of islands, half way between Madagascar and Mozambique in the South-West Indian Ocean. Visiting the island’s volcanic crater-lake was a dream come true and then to be taken to a sandy beach for a swim in the warm sea was a delight.
My guide pointed to female turtle tracks through the sand and he reckoned that the turtles were nesting on the beach.
Quite suddenly and totally unexpectedly a mound of dry sand erupted as tens of little turtle hatchlings broke the surface and started to flip their way to the sea some 100 metres away.
Local children gently scooped them up in handfuls and ran to the sea to release these newcomers to their marine domain. An angry French tourist on the beach rushed over and asked whether I spoke English to converse with the children and tell them to leave nature to take its course!
Sadly she had not done her homework as these islanders spoke a form of French and had been helping the hatchlings in this manner for decades. The sheer delight on these children’s faces will remain with me forever.
It was frightening, however, to see from up to 20 metres offshore how many of these hatchlings were devoured by seabirds and further out to sea the shark fins were moving in a frenzy of feeding.
Against all natural hazards, sea turtles as a species have survived for more than a million years despite their chances from hatchling to maturity being less than one to 1,000. Even before they have a chance to hatch, monitor lizards often devour the eggs in the nests.
Loggerhead turtle hatchlings
I was told by a local conservationist that a turtle uses her front flippers to excavate dry sand, usually at night, to nest. Initially digging her body size pit, she then excavates deeper to create an egg chamber where she calmly lays her eggs.
Then facing the sea, she uses her rear flippers to fill in the egg chamber followed by front flippers scooping back the sand to hide her nest.
The incubation period of the eggs is up to two months. Researchers have found that warmer sand produces more female hatchlings and cooler sand more males. Very sadly, our very nature reduces the turtle population on our planet.
Turtles ingest, with disastrous consequences, plastic junk thrown overboard from ships and washed into the sea by our rivers.
Even if they manage to reach maturity, they can be accidentally caught in trawl or gill nets and by long-line fishing. As some turtle species enjoy crustaceans, they are trapped in crab and lobster pots.
Turtles are hunted for their highly prized meat and for ‘tortoise shell’ jewellery as well as for their perceived, but never proven, medicinal properties. Fresh turtle eggs are harvested and traded and this consumption is a threat to populations.
I have witnessed traders from across the border eagerly selling fresh turtle eggs from beneath their stalls to equally eager Malaysian purchasers at the Serikin Sunday morning market.
Sea turtles are divided into two families. The majority are the Cheloniidae, with shells covered by horny plates (scutes).
Only one species of the sea turtle family – the Dermochelyidae – has a leather-like skin, hence the Leatherback Turtle.
In Malaysia we can view, in various places, five of the seven types of sea turtle including the Green Turtle (Chelonia mydas), whose hatchlings I witnessed in the Comoros Islands.
The Green Turtle is totally herbivorous, feeding on seagrass beds and is the largest of the hard shelled turtles taking decades to reach sexual maturity. Female turtles of all species return annually to the same beach on which they were born to lay their eggs.
Olive Ridley Turtle
Each female Green Turtle lays clutches of around 125 eggs each time at two-week intervals during the laying season.
By comparison, the Hawksbill Turtle (Eretmochelys imbricata), exploited for its ‘tortoise shell’, lays three to five clutches of eggs with each cluster averaging 130 eggs. With its beak, it is initially a pelagic (shallow sea) fisher but as it develops, it dives deeper to feed off coral reef animals such as corals and sponges.
Confined mostly to subtropical and tropical areas, the Leatherback Turtle (Dermochelys coriacea) is the largest species nesting up to nine times each breeding season, laying a clutch of 100 eggs each time.
Wide ranging, it can withstand the relative coldness of temperate waters for it has a peculiar physiological capability, which allows it to maintain its body temperature up to 17 degrees Celsius above sea water temperature.
Last July, fishermen off the shores of South West Cornwall in the United Kingdow spotted these turtles. Leatherback turtles eat soft jellyfish almost exclusively.
Loggerhead Turtles (Caretta caretta) have large heads and powerful jaws used for crushing mollusc shells, crabs and lobsters, fish and shrimp. Whilst mostly found in coastal waters they are essentially benthic (sea bottom) feeders and are quite unlike the other species of turtle whose habitats vary from shallower to deeper waters in their lifetimes.
The most abundant and yet the most solitary of sea turtles, feeding on algae, crabs, lobsters, molluscs, fish and shrimps, is the Olive Ridley Turtle (Lepidochelys olivacea).
It is most susceptible to long-line and gill nets as it is found in coastal bays and river estuaries. With the youngest maturity age of all sea turtles at 15 years, it nests twice each year laying a clutch of 100 eggs each time.
What of the future of our sea turtles? The World Wildlife Fund has declared the very threats to the existence of sea turtles:
Hunting of turtles for meat, shells and eggs for religious ceremonies, costume jewellery, so-called medicine, and food.
The killing of turtles – despite being protected under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (Cites) agreement.
Habitat loss through coastal development, damage of coral reefs and seagrass, through coastal land clearance and the dredging of river estuaries plus chemical run off from the land into river systems from agricultural practices.
Climatic change resulting in even warmer sea temperatures, more severe storms and a gradual rise in sea level all combining to destroy turtle nesting beaches.
The Indian Ocean-South East Asian Marine Turtle (www.ioseaturtles.org) MoU came into effect in 2003 with its management plan.
Last June its website frankly stated that: “Owing to other development issues in the region, some countries lack the resources for the successful implementation of the MoU.”
I believe that the Sabah Wildlife Department and Sarawak Forestry Corporation have worked towards protecting this remarkable species through their rangers’ guardianship of turtles, their nests and eggs.
Whilst our knowledge of the migratory paths of sea turtles is still in its infancy despite turtle tagging, recent research by students at Swansea University, UK, have tracked using global positioning system (GPS) the longest voyage of a Green Turtle of 2,485 miles in the Indian Ocean.
All of us must pull together to ensure that these extraordinary sea creatures survive. We must ensure that we are not their predators.