Electronic Library
Project Database
Satellite Tracking
Flipper Tag Series
Bibliography Resource
Genetics Directory

French Chinese Portuguese Bahasa
Japanese Hindi Korean Vietnamese

Satellite tracking Estimated potential not yet realised?

Source: Douglas Hykle, IOSEA Coordinator

Photos: c/o WWF-Malaysia

This month’s IOSEA Profile – in the form of a commentary – concerns satellite tracking, which most people find inherently attractive; but it is as much about “information / knowledge management”, a subject that is probably rather less appealing to most turtle practitioners. It is unapologetically written from the latter perspective, rather than by someone with practical experience in deploying transmitters in the field or in analysing satellite telemetry data, for all its foibles.

I should point out from the outset that this article was in near final form when my attention was drawn to a highly informative paper by Godley et al. – ‘Satellite tracking of sea turtles: Where have we been and where do we go next?’ – first published online in the journal ‘Endangered Species Research’ in December 2007, and subsequently printed in January 2008. That paper, which covers the subject matter far more exhaustively, posed many of the same questions that have been on my mind, and reached a similar conclusion that appears at the end of this article. 


The seaturtle.org website provides an excellent introduction to satellite tracking of marine turtles for anyone who is interested. The topics covered there include:

(1) function, purpose, and getting started;
(2) cost (USD 3,000-6,000 or more per unit depending on data requirements, excluding monitoring costs);
(3) important caveats, such as relatively limited satellite coverage close to the equator, affecting precision/accuracy of data in tropical areas;
(4) benefits and drawbacks of the product ranges of the main (four) transmitter manufacturers; and
(5) descriptions and overview of the advantages and disadvantages of various attachment methods (i.e. glue, tether, harness, screws).

The seaturtle.org website also links to a “tagging bibliography” containing references to over 50 papers published since the early 1980s that cite the use of satellite telemetry in sea turtle research. (The bibliography appears not to have been updated recently, since it appears as Version 1.2, dated 10 February 2004. However, the literature cited in the Godley et al. (2008) paper includes numerous references to more recent papers of direct relevance, including approximately 35-40 papers that touch on the “IOSEA region” (that is to say: countries bordering the Indian Ocean, South-East Asia, and adjacent waters).

The most interesting aspect of Satellite Tracking section of the seaturtle.org website is the display of results from satellite tracking projects around the Indian Ocean and beyond. (The so-called “Satellite Tracking and Analysis Tool” or “STAT” is the subject of a separate paper by Coyne and Godley (2005), cited in the references at the end of this article.) There, one can view in near real-time the active tracks, as well as non-active tracks, of individual animals from their point of release to current location, either as static or animated maps. There is also a substantial archive of some 30 projects from the Indian Ocean / South-East Asia concerning animals whose transmitters have ceased sending signals for more than a month. Most of these date back only about 3-4 years; however there is one entry from the 2001-2003 period.

Godley et al. present an overview of the contents of more than 130 peer-reviewed papers of global distribution, including many pertaining to the IOSEA region, from 1994 to 2007. Most of these relate to projects that do not appear on the seaturtle.org website and therefore represent a complementary dataset not considered by the present article. In their more general survey, Godley et al. note that the Indian and Western Pacific oceans account for about 30% of the transmitters deployed on sea turtles in the world; that 82% of the studies undertaken cover only three species (Loggerhead, Green, and Leatherback); and that over 75% of the published tracking studies have featured adult females (and therefore under-represent males and juvenile turtles).

*  *  *  *  *

Now, to the real point of this paper.

While satellite telemetry can provide unparalleled insights into the sea turtle migration and behaviour, it is a relatively expensive undertaking with a lot riding on the back (figuratively speaking) of an individual animal. Results might be unobtainable or inconclusive for a number of reasons, including transmitter failure (eg. due to improper attachment, damage or other technical fault); infrequent data and/or data of limited precision or accuracy; as well as untimely death of the animal (eg. due to man-induced or natural factors).

Given the relatively important financial outlay on this investigative tool, one would hope that every effort is made to maximise the usefulness of, and knowledge that can be gleaned from, each and every deployment. In an ideal world, all of the tracking projects in and around the Indian Ocean would be well coordinated to make most efficient use of scarce resources – ensuring that real gaps in information were being addressed and avoiding duplication of effort. All of the projects with meaningful results would publish their findings in a timely manner, so that others could take account of them and hopefully learn from them. And anyone interested in telemetry work in and around the Indian Ocean could consult an online database and, with a few clicks of a mouse, obtain an overview of what has already been – and is currently being – done.

I would argue that, from a “knowledge management” perspective, we are not exploiting this amazing research tool to its full potential. Expensive transmitters are not necessarily being deployed with consideration given to work already carried out, or with a view to filling obvious information gaps that exist around the Indian Ocean. While we are some way from reaching the ideal described above, the underlying objective is not unrealistic.

The seaturtle.org website provides a convenient platform for presentation of ongoing satellite tracking research – indeed, it is probably the only one of its kind anywhere. It serves its intended purpose reasonably well, even if it is a bit of a challenge to get an overview focussed specifically on turtles in the Indian Ocean. (As visitors to seaturtle.org/tracking will note, information on turtle tracking projects is presently mixed in with projects on wood storks, sea lions and many other feathered/furry creatures. I understand, however, that plans are afoot to create a separate database for other non-turtle species.)

Beyond the interesting presentations on seaturtle.org, much more could and should be done to consolidate the metadata relating to projects already undertaken and to use this information for a more coordinated approach to planning future work. IOSEA is well-placed to make a modest contribution in this regard, at least with respect to the Indian Ocean and South-East Asia region. Perhaps this IOSEA initiative might then be replicated by others elsewhere.

The basic idea presented here is to make it easier to retrieve information on what satellite tracking work has already been conducted, in general terms, without referencing any of the specific location data or maps presented online or in other reports (in deference to the strict copyright restrictions under which people have supplied their data to seaturtle.org and other publications).

As a starting point, the following information has been compiled in a spreadsheet, the columns of which can be manipulated and sorted to make it easier to identify particular items of interest. The following headings have been used:

Country / area of initial deployment
Project title
Project team

No. of animals with transmitters attached
First deployment (Date)
Last signal (Date)
Longest signal (# days)
Shortest signal (# days)
Transmitter still active? (Y/N)
General indication of migration

Project archived? (Y/N)
Published paper available?

Information source: [S]eaturtle.org / [O]ther
Email contact

Overview of findings

Click to download / open the ‘Preliminary Spreadsheet of Satellite Tracking Projects relevant to the IOSEA Region'.

The information contained in the spreadsheet is, for the time being, necessarily incomplete. It contains no information on satellite tracking projects other than those listed on seaturtle.org and it goes back only as far as the seaturtle.org archive. It does not include projects that choose not to publish their results on seaturtle.org (but might possibly have presented them elsewhere) or those projects that never get around to publishing or presenting their results at all. As noted above, the results of most of the peer-reviewed projects cited by Godley et al. – arguably the most valuable in terms of their scientific rigour – do not appear on seaturtle.org.

Nevertheless, even with this rudimentary spreadsheet one can begin to get a better sense of what has transpired over the last five years or so. The information in the spreadsheet is current up to mid-January 2009; some data will have changed by the time this paper is published.

The projects reviewed cover all marine turtle species found in and around the Indian Ocean, except the Leatherback – omitting, for example, recent work from South Africa. In terms of country of deployment, Australia, Oman and Indonesia top the charts with a remarkable 85, 36, and 20 animals, respectively, fitted with transmitters in the time frame under consideration.

Altogether, nearly 50 projects that are reported separately provide information on the movements of about 190 animals fitted with satellite transmitters. (Godley et al. report on another 200+ animals, including approximately 90 Green turtles, 60 Leatherbacks, and 40 Loggerheads.) Among the projects reporting to seaturtle.org, there has been a gradual increase in the number deploying satellite tags between 2005 and 2008, ranging from 9 to 14 projects per year, with numbers peaking in 2008. About sixteen projects in eight countries were producing active data as of mid-January 2009.

Some 23 projects achieved data transmissions lasting longer than six months; while ten reached the milestone of a year or longer – with some 50 individual animals transmitting data for at least a year. A relatively small number of projects – perhaps a half dozen or so – achieved transmission lengths of only 3 or 4 months.

Sponsorship for this satellite telemetry work has tended to come from three primary sources: federal government (particularly in Australia); corporate sector (eg oil and gas companies); nongovernmental organizations (such as WWF); and a variety of foundations.

This cursory review deliberately does not delve into what information might be gleaned from the various studies, for example in relation to inter-nesting habitat use within a single country. However, if one is interested in migration of animals from populations shared among a number of countries, several studies (eg. with animals originating from Indonesia, Kenya, Malaysia, Mozambique, Oman, Seychelles, Sri Lanka, United Arab Emirates, and Viet Nam) offer interesting examples of medium-long distance migration that span the territorial waters of several countries.


Independently, Godley et al. provide an informative overview of movements of animals of various species tracked in and around the IOSEA region, and attempt to identify some unifying patterns. In addition to presenting a useful compilation of satellite tracking research undertaken to date, Godley et al. do a valuable service by posing a number of very pertinent questions that go to the heart of whether or not sea turtle biology and conservation is benefitting enough from the substantial financial investment on satellite tracking research.

These questions (slightly modified/paraphrased below, followed by my succinct opinion) include the following:

(1) Should researchers and, especially, donors consider time-limited tenure over data before they are obliged to share the data on the global commons?  ... Yes

(2) Should managers and policy makers be prepared to make decisions on the basis of limited sample sizes of tracked animals?   ... Yes, in some instances

(3) Are tracking data simply one investigative strand that needs to be integrated with multiple lines of evidence to generate a synthetic understanding [of which policy actions need to be taken]? ... Yes

(4) Is the scientific community presenting results of satellite tracking research in a clearly understandable format and suggesting suitable management changes? ... Infrequently

(5) Notwithstanding the potential for satellite tracking to generate public awareness dividends, are we partaking in a 21st century version of Mrosovsky’s “tagging reflex”? [wherein satellite tracking has become affordable to more conservation programmes, thanks in part to support from “green-seeking” oil companies; and many turtles are tracked simply because the opportunity arises – without necessarily having a sound investigative objective in mind.]

... Possibly – and to the extent that seaturtle.org makes it easy for almost anyone with a satellite transmitter to generate spaghetti lines on a map, perhaps it is contributing to a trend that is not altogether productive.

The conclusion of Godley et al. (2008), with which I concur, is that “much of the tracking work to date has been funded and acted upon in such a manner that has so far failed to ensure translation of the research into tangible outputs and management benefits.”

Indeed, with respect to the last point, one might ask: are decision-makers even aware of much of the research that has already been undertaken – whether it be peer-reviewed findings or the simplified information presented on seaturtle.org?

In the context of the Indian Ocean – South-East Asia region, even with the helpful compilation prepared by Godley et al., and the useful facility provided by seaturtle.org, it is likely that only a small minority of interested researchers have a comprehensive picture of the considerable body of work conducted to date – let alone administrators and policy-makers with many other things on their plate.

It is precisely on this point that bodies such as IOSEA must shoulder some of the responsibility for promoting awareness of the vast amount of information on satellite tracking that is, or should be, in the public domain. This could be achieved by commissioning an even more in-depth analysis and presentation of existing data, for review by the IOSEA Advisory Committee, which in turn could be called upon to make concrete recommendations for follow-up research and management actions.

But to whom should these recommendations be addressed? Herein lies the challenge that lies ahead.

The IOSEA Marine Turtle MoU exists, not only to help coordinate the conservation activities of some 30 Signatory States around the Indian Ocean and South-East Asia, but also to provide a platform for other key actors to provide input, exchange information and, above all, to work more cooperatively towards common objectives. The MoU’s role as a “clearing-house” mechanism is, in my view, under-estimated and under-utilised by many projects/programmes that operate mostly independently, with little regard for what others have done or are doing in the field of marine turtle conservation.

This issue goes beyond the immediate need to better coordinate satellite tracking research; but addressing this particular problem may provide an opportunity to bring more collaborators into the IOSEA fold. Needless to say, it will be one of many issues discussed at the forthcoming IOSEA Strategic Planning Session being organised in Brisbane on 13-14 February 2009.

Next steps

It is impossible to know exactly many Indian Ocean – South-East Asian projects might be missing from this review, together with the 30 or so ‘IOSEA region’ projects described in Godley et al. (2008). We know that this initial compilation misses some of the telemetry work done in Australia in the 1990s; much of the work done in South-East Asia under SEAFDEC and SEASTAR auspices; as well as some of the recent work done on Leatherbacks in South Africa, Indonesia and Papua New Guinea, as well as Olive Ridleys in India.  Based on the numbers at hand, a rough estimate of 500 animals tracked in and around the Indian Ocean and South-East Asia over the last couple of decades would probably not be too far off the mark - a rather impressive figure!

Hint: There’s a nice project just waiting for someone to conduct an exhaustive search of the literature and other sources to try to arrive at a list that is say, 90-95 percent, complete; and another even more interesting exercise to carry out a thorough analysis of the data to serve as a basis for policy recommendations.

It would not take much to scale up from the rudimentary spreadsheet we have prepared to a simple database that would allow for more sophisticated searches of the metadata pertaining to the IOSEA region. For instance, one could query the metadatabase to: “Produce a listing of all projects with hawksbill releases from countries X, Y, and Z between 2004 and 2006” OR “Show all sponsors of satellite tracking work over the last 5 years” OR “List all projects with any track that lasted at least 180 days.” The Secretariat aims to develop this database application over the coming months, as a new element of the IOSEA website.

The logical next step would be to populate the database, once it has been established, with additional IOSEA-region projects not recorded by seaturtle.org (incorporating, in particular, those cited by Godley et al.) -- perhaps beginning with an online search and moving progressively to other harder-to-access sources (eg. from published and unpublished literature, and personal contacts).

Finally, if users find the finished application useful and if there were interest in mining the data more deeply for research and policy planning purposes, perhaps closer linkages could be forged with seaturtle.org and the original data providers to permit the compilation of other basic parameters; and to facilitate updating of the ever-changing information.

*  *  *  *  *

Hopefully, this Profile of the Month will stimulate more interest in exploiting the full potential of the significant investment already made in this evolving technology. It doesn’t take much imagination to consider some of the possible uses and applications of this work – for instance, identifying important migration corridors for marine turtle populations; overlaying tracks with known areas of concentrated fishing effort; identifying areas that might benefit from temporal or spatial regulation of fishing effort and/or creation of protected areas; and most importantly, obtaining a holistic view of turtle migration by combining satellite tracking information with available data from tag returns, as well as climate and oceanographic datasets. We hope that this contribution from IOSEA is a first step towards achieving that goal in the Indian Ocean and South-East Asia region.

Douglas Hykle
IOSEA Coordinator
February 2008

A final word of thanks to Dr. Mark Hamann for commenting on an earlier draft of this article, and for drawing attention to the paper by Godley et. al, which is worth a read if you have not already seen it.

PS: Please visit the IOSEA Message Board to see a note from Micheal Coyne, seaturtle.org, announcing the availability of GoogleEarth 5, with a link to an improved interface for the Wildlife Tracking Tool.


Godley BJ, Blumenthal JM, Broderick AC, Coyne MS, Godfrey MH, Hawkes LA, Witt MJ (2008). Satellite tracking of sea turtles: Where have we been and where do we go next? Endangered Species Research 4: 3-22.

Coyne MS, Godley BJ (2005). Feature Article: Satellite Tracking and Analysis Tool (STAT): An Integrated System for Archiving, Analyzing and Mapping Animal Tracking Data. Marine Ecology Progress Series 301: 1-7.

UNEP © IOSEA Marine Turtle MoU Secretariat, c/o UNEP Regional Office for Asia and the Pacific,
United Nations Building, Rajdamnern Nok Avenue, Bangkok, 10200, Thailand
Tel: + (662) 288 1471 ; Fax: + (662) 288 3041 / 288 1029; E-mail: IOSEA Secretariat