Saving Paradise

Category: Marine life, Turtles | Date: Nov 16 2009 | By: savingparadise

No two individuals, even identical twins, have identical sets of fingerprints. For this reason fingerprints offer a reliable means of identification. They have played a huge role in the area of forensics providing accurate identification of criminals.

As it turns out, marks and patterns on certain marine animals are akin to human fingerprints and are unique to each individual. These marks are being put to good use, not to catch the criminals of sea world, but as a means of identification to help in conservation.

On Thursday 12 November, the Marine Conservation Society Seychelles, in collaboration with the Kelonia Marine Turtle Observatory in Reunion and Ministry of Environment organised a talk on how this form of identification is being utilsed for whale sharks and turtles. The talk, “using images to conserve endangered marine life” was delivered by David Rowat, MCSS, who is working with whale sharks in Seychelles  and Claire Jean from Kelonia working with turtles. As in humans where fingerprints develop at the embryonic stage and do not change, all indications in these marine animals are that marks are usually permanent with little change occurring over time.

According to Claire, Kelonia uses underwater photos of marine turtles head profiles for indetification. Their methodology consists of analyzing scale numbers and shape of both right and left profiles. Photos of these profiles are taken for each turtle. A database has been created to keep these photos. The matching of the new data with those in the database allows one to determine whether or not each marine turtle has been seen previously. Thanks to the participation of scuba divers and marine photographers, photos can be collected throughout the year in various sites.

Claire says photo ID can be used as an alternative or complimentary monitoring method. But she noted that current monitoring methods that use capture-mark-recapture techniques, require physical application of tags. Photo ID on the other hand is non-intrusive, less costly and less stressful. It is particularly useful in places where marine turtles cannot be caught and tagged and helps in situations where tags are lost. It also targets all turtles unlike the capture method, which mostly targets females and juveniles. It can be used in all habitats either at sea or one beaches. What it cannot be used for is measuring other parameters such as growth.

For whale sharks, researchers use photographs of the skin patterning behind the gills of each shark and any scars to distinguish between individual animals. Cutting-edge software supports rapid identification using pattern recognition and photo management tools. See whaleshark.org  for more information. David Rowat said that using this method between 2001-2009, 447 individual sharks have been identified in Seychelles. Fifty percent were re-sightings.

Picture via whalesharks.org

Both these projects rely on the contribution of pictures from people, and pictures come via tourists, scuba divers and others, allowing for public participation. They are asked to take good high resolution photos without obstruction, such as sand on turtles.  Identification however is done by trained people.The talk ended with an offer from Kelonia to conduct training for organizations involved in turtle monitoring in Seychelles.

Tags: Seychelles, Turtles, whale sharks

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Category: Cousin Island, Turtles | Date: Nov 10 2009 | By: savingparadise

It is that time of the year again and hawksbill turtles are making their annual pilgrimage to our shores to nest. The hawksbill breeds throughout Seychelles, peaking between mid-October and mid-January.  On Cousin Island, Conservation Officer Eric Blais reported an early appearance on August 8. Appearances are starting to pick up now and more turtles will arrive in November, December and January.

As numbers peak, so will monitoring. On a short visit to Cousin yesterday (9 Nov 2009), I took part in an afternoon monitoring exercise with Eric, David (Science Coordinator for Nature Seychelles), Mary (a volunteer helping with the turtle work) and Claire (from Kelonia) to see just what this means.

Cousin Island has one of the longest running monitoring programmes - started in 1972 - forming a core part of the wardens and volunteers work programs. Appearance dates and locations have to be recorded, with nesting beaches being patrolled several times a day. Metal tags with unique identification code, attached to the front flippers of each nesting turtle encountered help identify individual females returning to the beach each season.

Turtle emergences are recorded under four categories of behaviour: 1) “LAID” during which eggs were laid after digging one or more nests; 2) “Did Not Lay (DNL)” during which one or more nests were dug but no eggs laid; 3) “Half Moon (HM)”emergences during which digging did not occur although no disturbance factors were apparent; and 4) “Emergence Stopped by Obstacle (ESBO)” during which no digging occurred because the female was discouraged by obstacles on the beach.

After a short walk, we came across a female who had just begun to dig her pit. As I took covert pictures of her, my colleagues went about taking their data and doing their tagging. To my utter surprise Mary put her hand into the pit and with a counter in the other, began to tally the eggs as they came out.

A female turtle crawls out of the sea and using her front flippers drags herself up to the beach to a suitable nest site. There, she digs a pit with her front flippers and then excavates a vertical egg chamber with her hind flippers in which she lays her eggs. Eggs can be as many as 250. Mary counted 210 eggs for this one! Afterwards, the turtle used her hind legs to cover up the nest with sand and returned to sea.

It will take close to sixty days for the eggs to hatch and two or more days for the baby turtles to get to the surface. The babies will emerge as a group and - usually at or after dusk - head towards the sea attracted by the reflection of the moon on the water. But they face a number of challenges. Once hatched, babies are a favorite food for ghost crabs, birds and fish. Baby turtles could also be affected by beach lighting, which can cause them to head inland rather than out to sea. On Cousin, lights are of low wattage and screened from all nesting beaches.

As I left Cousin, I reflected on the work ahead for these hardworking people. Things will certainly get very busy soon. But thankfully, the collection of data will be increasingly efficient due to new technology and data analysis techniques that are being introduced.

Tags: Cousin Island, hawksbill turtle, monitoring

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Category: Cousin Island, Seabirds | Date: Nov 04 2009 | By: savingparadise

This post was contributed by Michelle Kappes and Kevin Coustaut, Laboratoire d’Ecologie Marine at the Université de la Réunion.

Shearwaters, like most seabirds, spend most of their lives at sea.  In order to learn about where shearwaters go when they are away from their breeding colonies, Dr. Matthieu Le Corre from the Université de la Réunion has begun a research program to deploy miniaturized electronic tags on wedge-tailed shearwaters (Puffinus pacificus) at sites throughout the western Indian Ocean.  These tags, or geolocators, collect data on light level that can be used to determine the position of the bird at sea.  Basically, the time of local noon is used to determine longitude, and latitude is estimated by local day length.  The tags are attached to a metal ring on the bird’s tarsus using a plastic zip-tie (see photo).  The tags also have a salt-water switch, and due to their placement, we can determine when the shearwaters are in flight and when they are resting or foraging on the sea surface.  By taking advantage of this technology, we can begin to get a picture of how these wide-ranging seabirds behave during their foraging trips to sea.

Wedge-tailed shearwater with geolocator © Michelle Kappes

Also using geolocators, recent work by Catry et al. (2009) demonstrated that 9 wedge-tailed shearwaters breeding on Aride Island remained close to the colony when raising chicks, and later dispersed up to 3,500 km to the central Indian Ocean Basin during the non-breeding period.  Last year, members of Dr. Le Corre’s research team recovered 6 geolocators from wedge-tailed shearwaters deployed at Cousin Island.  Preliminary analysis suggests that shearwaters from Cousin Island disperse further east during the non-breeding period than those from Aride Island.  However, a larger sample size will be necessary to confirm colony-specific differences in foraging behavior.

During 14-29 September 2009, we deployed 24 geolocators on wedge-tailed shearwaters breeding within St Joseph Atoll, Amirantes group, and 24 geolocators on shearwaters breeding at Cousin Island.  Field work is planned to deploy similar numbers of geolocators at sites on Réunion Island, as well as off Mauritius and Madagascar.  This will be the first attempt to simultaneously study the at-sea behavior of this seabird species across a broad range of breeding sites.

Ultimately, these data will help us answer questions such as: do wedge-tailed shearwaters breeding at different sites in the western Indian Ocean travel to similar locations at sea?  Are there specific ocean habitats that are of particular importance for this species?  Areas of the ocean that are important to shearwaters may be important for other marine species as well, so these data could be used to help identify marine Important Bird Areas and possibly oceanic Marine Protected Areas.

Shearwater in burrow on Cousin Island © Conor Jameson

However, as the geolocators store these data on-board, we won’t be able to answer these questions until we recover the tags at the end of the breeding season.  This may prove trickier than it sounds because once shearwater chicks reach about a week in age, adults only return to the colonies for brief periods to deliver meals to their chicks.  So we may have to wait until the next breeding season starts in 2010 to recover these tags and unlock the secrets of where these different populations of shearwaters spend their time at sea!

Tags: Cousin Island, Seabirds, wedge tailed shearwater

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