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Turtle Threats

 

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yewitnesses say that 30 years ago it was common to see hundreds of fresh turtle tracks each night on most of the beaches of the Turtle Islands. Indeed, historical records show that the Turtle Islands were famous at least until the middle of this century for the tremendous numbers of green turtles that nested there. In the early 1950s, Jose Domantay of the Bureau of Fisheries reported that there were relatively few turtles nesting on the islands of Great Bakkungan and Lihiman. At Taganak, however, he found that nesting occurred year round, with as many as 60 or more nestings a night especially in the months of July and August. He calculated that about 3,000 turtles nested every month on the islands.

Sadly, it has become rare in recent years to observe more than 30 turtles nesting in a single night on any of the islands, except at Baguan Island Marine Turtle Sanctuary (BIMTS), where about 100 clutches of eggs can be laid in a single night during the peak in the nesting season: from July to September. Since 1951, egg production on Taganak has declined by approximately 80% (Table 1).

Table 1. Egg production (number of eggs reported collected) on Taganak Island, Turtle Islands, Tawi-Tawi, Philippines, for the period August 8-September 11 during different years. Data from 1951 are from Domantay (1953) and those from the years 1984-1993 are from De Veyra (1994). For comparative reasons, data are presented for the specified 35-day period because the data for 1951 are available for this period only.

Year
EGG PRODUCTION
(number of eggs reported collected)
% REDUCTION from the 1951 value
1951
137,254
 
1984
22,135
83.87
1985
16,530
87.96
1986
30,133
78.04
1987
24,209
81.77
1988
41,596
69.69
1989
27,526
79.94
1990
15,515
88.70
1991
36,334
73.53
1992
18,401
86.59
1993
21,647
84.23

Green turtles need decades to reach sexual maturity. During this long period, they face many threats, both on beaches and in the ocean. There are many hazards that occur naturally, but the rapid decline of the turtle population in the Sulu Sea can be largely attributed to harmful human activities in the area. The turtles have survived countless natural threats and natural catastrophes through millions of years, but now people are pushing them closer than ever to the brink of extinction. Needless to say, only people can restore them to their old glory.

While in the ocean, adult green turtles have to avoid large predators such as sharks and killer whales. And even when they survive these predators and arrive after a long migration at the Turtle Islands to breed and nest, these adult turtles face still more threats. They may be caught by trawlers or long-lines, or destroyed by dynamite, before they even reach the beaches to lay eggs. The lights on the shore may scare them away and keep them from climbing up the beach. On the beach, huge logs may block their way, preventing them from finding a suitable place to dig a nest. Also, on some beaches covered with litter, they may not find room to nest.


The beaches on the Turtle Islands are often littered with huge logs, tree trunks and other debris. Sometimes the turtles can get over these obstacles but many times they are prevented by logs from reaching their nesting site. (PCP, file)

Even if the turtles have successfully laid their eggs, this does not guarantee that the baby turtles will survive, grow up to reproduce, and thus maintain the population. In many cases, the eggs are harvested by egg collectors soon after they are laid.


A female green turtle that has finished nesting, leaving her eggs on the beach to incubate for about two months. (Stuewe, Oct. 1998)


Though powerful, fast and graceful at sea, turtles are awkward and slow on land. In many places, people take advantage of this and catch and slaughter nesting turtles on the beach. In this respect, the green turtles that nest in the Turtle Islands are lucky - generally, Turtle Islands residents do not kill turtles. But there have been reports of people slaughtering gravid ("pregnant") turtles at sea to take their eggs.

It takes about two months for sea turtle eggs to hatch, and during that time the eggs are left unattended, as mother sea turtles do not protect their nests. So even if the eggs are not collected by people, their survival is still not assured because they face other threats. Monitor lizards, ghost crabs and even rats and ants can dig into the nests and devour the eggs. Once they hatch, the baby turtles, called hatchlings, must dig themselves out of the nest and make their way to the sea. While crawling on the beach toward the sea, they can be eaten by the same animals that dig into the nests, as well as by birds, dogs and cats. Inland lights disorient them, so they don't make it to the sea. Offshore, bright fishing lights attract them, drawing them to where there are concentrations of predatory fishes and fishing activities. Even just getting off the beach, across the reefs and out to sea can be a major ordeal for the hatchlings, because predatory fishes wait for them to cross the reef during their first swim.

Many of these typical turtle hazards are described in an illustrated comic book on turtle conservation produced by the World Wildlife Fund - Philippines. Copies are available upon request at kkp@wwf-phil.org.ph


The sea turtle conservation booklet, showing the turtle hazards puzzle on the back cover (left) and the front cover (right). (WWF-Philippines)

Trawlers
Many shrimp trawlers operate around the Turtle Islands. These boats drag large nets along the bottom, catching whatever gets in their way. Sometimes, sea turtles are trapped in the nets. Since turtles are air-breathing reptiles, they drown if they are dragged within the nets for several hours. They thus become part of the incidental catch (called by-catch) of the trawlers. Incidental catch is not well documented in the Turtle Islands, but former crew members report that as many as three turtles can be caught in a trawler's nets during a single night. What is more, the trawlers are not from the Turtle Islands, and most of them are not even from the Philippines.



Shrimp trawlers sometimes trap and drag sea turtles in their nets for several hours. The turtles drown and are usually thrown overboard as part of the trawlers' incidental catch. (PCP, file)


Many dead and decomposing male and female turtles are washed ashore each year on all the Turtle Islands, and there may be countless more out in the open sea that are never seen. (PCP, file)

The closer the trawlers are to the coastline, the greater is the chance that they will catch turtles. Most of the nesting green turtles spend months in the vicinity of the Turtle Islands, waiting for yet another clutch of their eggs to mature. Tracking studies indicate they stay within 40 km of the shore for at least a few months. Waiting to reproduce, these turtles are likely victims of trawling operations.

The Philippine Fisheries Code of 1998 prohibits the use within municipal waters of active fishing gears, including trawls (the gear of choice of many operators of commercial fishing boats). Municipal waters extend up to 15 km from the coastline, but the municipality can issue an ordinance allowing commercial fishing boats to operate within 10.1-15 km from the shoreline in municipal waters more than 7 fathoms deep.


Patrol boat of the Philippine Navy (left) anchored off Taganak harbor. (Stuewe, Oct. 1998)

Actually, trawling does not have to be so devastating on turtles. Fisheries specialists have developed Trawling Efficiency Devices (also called Turtle Excluder Devices or TEDs). TEDs are installed in trawl nets, just before the "bag" or "cod end", and will deflect most turtles out before they get caught.

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Diagram of an otter trawl equipped with a TED

Long-line Fishing
There is a good market for shark fins in Sabah, and throughout much of Asia, so good that many fishermen at the Turtle Islands set "long-lines" for sharks. The hundreds of baited hooks on a single line may attract hungry turtles to the "easy bait". If a turtle is hooked and unable to come up to the surface to breathe, it will drown. Countless thousands of sharks are caught in long-lines each year just for their fins. The sharks are thrown back into the sea after the fins are cut off and they die from maiming and the removal of their means of swimming. Many species of sharks, dangerous or harmless, are now endangered.


A shark fisherman attaches bait to the dozens of hooks on his long-line in preparation for setting the line at sea. (Stuewe, Oct. 1998)


Shark fins being dried in the sun at Taganak, Turtle Islands. In most cases, the fin is all of the shark that is kept - the shark is thrown back into the sea, alive but severely wounded, to slowly bleed to death. (Stuewe, Oct. 1998)

Purse Seining and Night Fishing
The Philippine Fisheries Code of 1998 prohibits the use within municipal waters of "superlights" (bright lights employed by commercial fishing vessels to attract fish), because these lights give commercial fishers such high catch efficiency as to present unfair competition to fishers operating less efficient gear. Despite the ban, however, superlights are often used in municipal waters.

What is more, these lights brighten the horizon at night near many beaches in the Philippines, including the Turtle Islands, and for this reason, superlights have adverse effects on turtle populations. They may disturb the nesting process of the adult female turtles. Hatchlings are even more negatively affected, because they are attracted to the superlights, which draw them off course from their normal dispersal into the open ocean. Some hatchlings, if they are lucky, may just waste precious time and energy, but many meet concentrations of predatory fish, which are also attracted to the lights, or get caught up in fishing operations.

Beach Development
Population pressures also pose a threat to the turtles. These arise not only from the high human birth rate in the region, but also from an influx of human settlers to the Turtle Islands. Every year, problems of peace and order in Mindanao are driving more and more migrants in search of safer homes to the Turtle Islands. One fisherman who recently arrived on Boan said his fishing boat was stolen three times in the last few months, so he finally decided to pack up and come to the Turtle Islands, a relatively safer place. Many of the residents build their houses on the shores of the islands and keep their boats on the beach, thus reducing the area of sandy, undisturbed beach available for turtles to dig their nests. Also, the growing number of settlements is using more lights, which distract the nesting turtles and disorient the hatchlings.

The islanders themselves are now experiencing problems associated with population growth, such as reduced availability of safe drinking water and arable land to grow subsistence crops.


Beach development, such as this settlement on Taganak, Turtle Islands, poses a threat to sea turtles, typically by reducing the area of sandy, undisturbed beach available for the turtles to nest. (Stuewe, Oct. 98)

Egg collection
Collection and trade of turtle eggs is a tradition throughout the region. While egg collection is strictly prohibited at the Baguan Island Marine Turtle Sanctuary, 60% of the egg production in the five other Philippine Turtle Islands is legally harvested for local trade and consumption (Ministry of Natural Resources Administrative Order No. 33, Series of 1982). Egg traders, however, prefer to bring the eggs to Sandakan, Sabah, the most accessible market near the Turtle Islands. This is in violation of the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES), of which both Malaysia and the Philippines are Parties. The Joint Management Committee of the two-nation Turtle Islands Heritage Protected Area (TIHPA) is currently evaluating efforts to study the turtle egg trade to be able to implement a scheme that would reduce pressure on the turtle population.

Direct exploitation of turtles
The turtles have also been exploited for their meat. Domantay (1953) reported that, during the Japanese Occupation, a large number of turtles that nested on the Turtle Islands were killed to feed troops. Evidently, tens of thousands were slaughtered, with estimates ranging from 3,000 to 150,000.

These days, very few sea turtles are intentionally slaughtered on the islands, but the other threats that the turtles are facing will have to be countered if the population is to be restored to its former level. The drastic reduction in egg production that the PCP found several years ago is certain to be a result of the many threats that the turtles faced over the years, as well as the long-term effects of the rampant slaughtering of nesting females in the past and the very heavy exploitation of eggs that still occurs on the islands.

A single female green turtle can potentially lay thousands of eggs during her lifetime, so the loss of reproducing turtles is especially important for the future of the population. The full impact of such loss may not be seen for years, however. Turtles are an important component of our marine ecosystems and have great economic value. In the end, we may never know the price that we are paying for past indiscriminate exploitation.


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