OCEAN AMBASSADORS

Migration Summary

 


What could have happened to...
TRIXIE, ANITA and LAILA, YUMI, HANI

(Migration summaries for three other Ambassadors tagged last March 2001 (besides Trixie) are not yet available. Click here for details of their movements.)

What they teach us



TRIXIE

Trixie was tracked for only about two weeks (March 11-25, 2001), during which time she produced a set of data locations that could reveal a wealth of information on the short-range habitats of green turtles and the threats they face as they navigate the waters around the Turtle Islands. Trixie was tagged on March 11 at about 1100 GMT on Selingaan Island in the Sabah Turtle Islands, after laying 113 eggs in her first nesting of the season.

Over the two weeks that we managed to track her, she produced four clusters of locations:

  1. Around the Turtle Islands until March 19, 1655 GMT;
  2. Towards Sandakan Harbour until March 21, 1353 GMT;
  3. Tracking south of Taganak until March 23, 2131 GMT; and finally
  4. Heading north away from the Turtle Islands until March 25, 1152 GMT

What could have happened to Trixie? Why did she suddenly go off the screen?

The following clues paint a possible scenario:

  1. From the time of tagging until March 19 1655 GMT, the location data we received were of the poor to fair quality, but this changed dramatically between March 19 and March 25, when the data stream consisted of mostly LC 0-3 locations, which indicated the transmitter was above the water surface for suspiciously long periods of time. At one point, the locations were so good and so dense they allowed us to calculate the speed of the movements -- 51 km between 21 locations from March 24 0829 GMT to March 25 1734 GMT, or 1.55 km per hour.
  2. Shortly after Trixie went off the air, we received the following message from WWF-Philippines: "On March 30, 2001 at 1100 GMT, one of our community partners from the Turtle Islands saw a dead turtle (headless) with some kind of device on its back floating in the waters near Langaan Island. Could this be Trixie? He tried to put the turtle on board his boat, but it was too heavy. He also tried, but failed, to take the device off the turtle's back, so he left the turtle where he found it and reported the matter to the local WWF staff."

This is what we think happened: Between the time of tagging and the time when the quality of location data improved dramatically, Trixie was apparently moving around the Turtle Islands, probably under her own steam. Sometime between March 19 and March 20, she could have been caught in a trawler's net, taken on board the boat (probably already dead) and placed on its deck. The boat then returned to Sandakan Harbour and stayed there for a day or so to refuel, replenish its supplies and dispose of its catch.

It's difficult to speculate what happened next. If we assume that there were currents going north from the Turtle Islands, Trixie could have been dumped into the sea the next time the trawler went out, probably on March 22 or March 23. By this time, the carcass could have already decayed and developed enough gas under the carapace so that, from March 24 to March 25, it could have been floating in the water, apparently moving north at the speed of the current (1.55 km/hour).

The above scenario, however, does not factor in the fisherman's report about a dead turtle with a device on its back. If that turtle was indeed PTT 10033, then a number of things in our scenario don't add up: The last transmission was on March 25; on the 30th, the fisherman reportedly found the dead turtle near Langaan Island, which is south of Trixie's last recorded location. How could Trixie reach Langaan Island from where it was last tracked? Why did the transmissions stop? Did the carcass at some point begin floating upside down?

If we factor in the report about the dead, headless turtle, we have to assume that the currents were moving south toward the Turtle Islands. In this case, the trawler could have dumped Trixie only after March 25 (when the last signal was received); the currents would then carry her southward to reach Langaan by March 30. She probably floated upside down after being thrown overboard, which explains why she suddenly went off the screen.

Still, more questions remain: Was Trixie indeed headless when found? Did the trawlers chop her head off (not a common practice)?

This much we do know: Despite a ban on commercial fishing in municipal waters (up to 15 kilometers from the shoreline), trawlers continue to operate around the Turtle Islands and pose a major threat to its turtle population. The location data generated by Trixie and the other Ocean Ambassadors also tell us that turtles go well beyond the 15-km limits of municipal waters during their nesting season. To protect turtles adequately from trawlers, therefore, the trawling ban must be fully enforced over a much wider area than the municipal waters. Earlier estimates indicate the turtles' habitats could stretch to a 40-km radius from Baguan Island, but recent data show even more extensive habitats.

Click here for more details about Trixie

View Trixie's raw satellite data, or go to the interactive animation showing her movements


ANITA and LAILA

August 14, 1999. We received a few, poor quality positions from Anita on July 19 and July 20, immediately after we tagged her on Selingan Island, Sabah Parks, Malaysia, and then... nothing.

Since she laid only 40 eggs on July 19, when she was tagged, there is a good chance that she returned to Selingan to nest again right after we tagged her, but we have been unable to verify this. It is still a mystery why her transmissions stopped so soon.


Laila goes back to sea with
a transmitter on her back
(A. Sia, 1999)

Laila stayed around Baguan for 2 weeks after tagging. Green turtles usually nest every two weeks during the nesting season -- could Laila have nested once more? Again this is a mystery.

What MIGHT have happened to either Anita or Laila? Was the antenna damaged by being wedged against hard objects? This is likely to happen, but NOT so soon after the transmitters are attached.

Was the transmitter damaged by the actions of the turtle? This can happen, but again, it is not likely so soon after the transmitters are attached.

Did the batteries give out? This happens, but NOT so soon after deployment.

Did some kind of electronic failure occur in the transmitter? There are cases of transmitters going "off line" for a few weeks or months, and then suddenly coming back on again. The mysteries of electronics.

Was the transmitter dislodged from the turtle? Hard to believe.

Was the turtle captured, and the transmitter destroyed by the person(s) who captured her? A sad senario, but definitely possible.

Maybe the turtle was caught underwater (in a net, say) and drowned, keeping the transmitter from the surface? Possible.

At this time, we can only speculate and hope that the turtles come back on-line soon. If anyone sees a turtle with a transmitter, please: inform us at
.

Read Laila and Anita's story

Click here for more details about Laila

View Laila's raw satellite data, or go to the interactive animation showing her movements


Click here for more details about Anita


YUMI

Yumi was tracked over a period of three and a half months. The transmitter was attached to her on 16th October 1998, and we received the first good quality position from her at 22:45 GMT on 22nd October (really the 23rd of October at 06:45 Philippine Time). This was an LC 1 quality position, which means that there is a 95% chance that the transmitter was inside a circle 1 km in diameter. From that date until 1st January at 00:25 GMT (08:25 Philippine Time) she stayed in the vicinity of the Turtle Islands. This is a period of about two and a half months, and we are surprised that she took so long to begin her migration back to feeding grounds. However, during this two-and-a-half-month period, Yumi may have made two excursions away from the Turtle Islands. On 23rd

November at 12:23 GMT (20:23 Philippine Time), there is a position at the southeast mouth of Labuk Bay, perhaps in the vicinity of Sibaung Island, Sabah. Then, on the 3rd of December at 12:05 GMT (20:05 Philippine Time), there is one position to the east of the Turtle Islands, out in the Sulu Sea, evidently not close to any islands or shoals. However, both of these apparent excursions away from the Turtle Islands are based on single positions, and in both cases the quality of the position is not good (LC 0 = no estimate of error was made), so we cannot be sure whether or not Yumi actually left the Turtle Islands between 16 October 1998 and 1 January 1999.

Her last good position in the Turtle Islands is on 1 January (LC 1) at 00:25 GMT (08:25 Philippine Time). On 2nd January at 10:11 GMT (18:11 Philippine Time), there is a position southeast of Turtle Islands which may be near Pearl Banks, at the southwest extreme of a chain of islands and shoals that extend from the Pangutaran Group. On 3rd January at 01:10 GMT (09:10 Philippine Time), there is another position a bit farther in the same southeasterly direction from the Turtle Islands. Then at 09:52 GMT (17:52 Philippine Time) on 3rd January she appears to suddenly have turned to the northeast and instead of heading towards the big island of Tawi Tawi, she seems to be heading towards the islands in the Pangutaran Group. She apparently keeps headed in that northeasterly direction, and on 6th January at 00:32 GMT (08:32 Philippine Time), we have a good position (LC 1) from north of the main island of Pangutaran. The exact route that Yumi took between the 1st and 6th of January is not certain, because none of the positions from this interval are good quality, they are all LC 0.


Yumi's route based on good quality ARGOS satellite positions

After the 6th of January, there are four more positions that we have plotted. On 11th January an LC 0 to the east-southeast; on 13th of January another LC 0, but to the northwest of Pangutaran; on 26th January at 23:16 GMT (really 27th January at 7:16 Philippine Time) an LC 3 nearly midway between Pangutaran and Basilan Island; and on 29th January an LC 0 not far from the position on the 26th. Because only the positions of 6th and 26th January are good quality (LC 1 and LC 3, respectively) we cannot be sure about the positions during the twenty-day interval while she was near Pangutaran Island.

Nonetheless, taken together, the good and moderate quality positions show a route which left the Turtle Islands on 1 January, heading southeast until reaching the Pangutaran Group. Then Yumi appears to have changed direction nearly 90 degrees, heading northeast, and arriving at the north of Pangutaran Island five days after leaving the Turtle Islands. If she followed the "dogleg" route from southeast to northeast, this would be a distance of about 278 km; if she went in a straight line from Turtle Islands directly to Pangutaran, this would be about 252 km. Either way, she covered a large distance in five days!

Nearly three weeks after reaching Pangutaran, she appears to have headed off toward the east and Basilan Island, when her transmitter failed. Where she was ultimatedly headed, we do not know, but it is possible that she was destined for a much farther destination to the northeast, somewhere in the main Philippine Islands, where many other green turtles tagged in the Turtle Islands have been recovered.

Click here for more details about Yumi

View Yumi's raw satellite data, or go to the interactive animation showing her movements


HANI

Hani, the turtle fitted out with a satellite transmitter on 17 October 1998, remained in the vicinity of the Turtle Islands for more than a month. On 18 November there is a position southeast of the Turtle Islands, near Benrinnes Reef. This is not a good quality position (LC 0), but on 19th November at 23:14 GMT (really 20th November at 7:14 Philippine Time) and again on 22nd November at 00:09 GMT (8:09 Philippine Time), there are two good quality positions showing that Hani was to the east of the area where she had spent most of the time earlier. (The positions are LC 2 and LC 3, respectively, meaning that the 95% error around the point is a circle with a radius of only 350 m for LC 2, and 150 m for LC 3).

Finally, between the 22nd and 23rd of November Hani apparently set off to the southeast, moving a remarkable distance of about 156 km. Since her position at 00:09 GMT (8:09 Philippine Time) on 22 November is good quality (LC 3), we are convinced that she was just east of the Turtle Islands at that time.

Her next good position (LC 2) was at 10:01 GMT (18:01 Philippine Time) on 23rd November, so we are also pretty sure that she was approaching the island of Tawi Tawi at that time. The position indicates that she had gone past the southwestern end of the chain of shoals extending from the Pangutaran Group. By 26th November, at 18:54 GMT (really 27th November at 02:54 , Philippine Time) she was off the northeast of the Tawi Tawi Island Group, south of Sugbai Passage. She stayed in this general area until at least 31 December when we received the last good quality position from her (LC 2). However, we did continue to receive poor quality positions until January 24, 1999.


Hani's route based on good quality ARGOS satellite positions

Hani seems to have made a very fast migration from Turtle Islands to Tawi Tawi, and then to have spent at least a month at Tawi Tawi. This may be the area where she will stay feeding and resting until she migrates back to the Turtle Islands in a couple of years. But she may also have set off again on a longer migration, perhaps into Indonesia, or perhaps into the main Philippine Islands. We just do not know what happened after the transmissions stopped.


Click here for more details about Hani

View Yumi's raw satellite data, or go to the interactive animation showing her movements


What they teach us

The location data we have show us that each nesting season, our Ocean Ambassadors stay around the Turtle Islands for a period of months. Those that we have managed to track through at least part of their migration from the Turtle Islands show the remarkable ability to move hundreds of km in just a few days. Although they go in different directions, they seem to stop for at least a few weeks at a specific area near an island group, which is likely rich in seagrass and thus serves as their foraging area.

It is possible that our Ocean Ambassadors will continue their migration to more distant places, but, since reefs and seagrass beds are abundant and extensively distributed in Sulu Sea and food is pretty much available within a relatively short distance between known turtle breeding and possible foraging areas, it is just as likely that they are in fact "residents" of Sulu Sea.

In any case, our Oceans Ambassadors have shown us that for a critical part of their lives they live and breed in the transfrontier Turtle Islands Heritage Protected Area. After a period of months, some of them pass through the southwestern end of the Sulu Sea, heading off deeper into Philippine waters, or on the edge of the Celebes Sea. For these Ocean Ambassadors to live and prosper, they will need the care and protection of people in at least Malaysia, the Philippines and Indonesia. If you have the fortune to see one of these amazing animals, remember that -- without talking -- they are telling us that we all must care for the oceans.


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