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Progress in increasing knowledge on turtles in the Mediterranean

One of the reasons for updating the Action Plan was that much has happened in understanding turtles and their biology and conservation needs since the Action Plan was initially adopted in 1998. Knowledge and dissemination of information on turtles has been increasing rapidly in the last few years on a global basis. The more widespread application of up-to-date technologies and techniques in genetic research, satellite tracking etc as well as more work on more traditional research and conservation lines, in turtle biology and behaviour, have resulted in an unprecedented accumulation of knowledge. Such rapid progress inevitably makes mandatory a more frequent revision of conservation plans and programmes, if they are to stay abreast and take advantage of current knowledge. The accumulation of knowledge from different parts of the world is often applicable elsewhere and at all levels.

In the Mediterranean itself, much has happened since 1998 - but much remains to be done. There has been a proliferation of activities related to turtle conservation, both on land and more recently at sea. These now cover much of the Mediterranean and focus on most aspects of conservation, monitoring and research.

Three very successful Conferences on marine turtles in the Mediterranean have taken place (in Rome in 2001, at Kemer (Turkey) in 2005 and in Tunisia in 2008). These Conferences were jointly organised by the three Conventions operating in this field in the Mediterranean (the Barcelona, Bonn and Bern Conventions). Interest in marine turtles was such that in 2006 the International Sea Turtle Symposium (ISTS) was held in the Mediterranean for the first time (Crete, Greece).

Meetings of the Mediterranean specialists present in the annual Symposia of the ISTS are now held annually at each Symposium. In the years since 1998 much research and monitoring work has been done on Mediterranean marine turtles and many papers have been published not only in the Proceedings of the Mediterranean Conferences and the Sea Turtle Symposia but also in several scientific journals.

Key issues such as the genetic structure of the turtles in the Mediterranean and the degree of their isolation from the Atlantic populations is now a little better understood, though questions still persist. The use of nucleic and mitochondrial DNA (nDNA and mDNA) work, covering the paternal and maternal genetic makeup of turtles in the Mediterranean, has brought up new issues and has diversified information. The information available so far suggests a trickle of paternal genes into the Mediterranean green turtle gene pool – a trickle that was evidently large enough, on IUCN criteria, to lead of the conclusion that there is no genetically distinct green turtle Mediterranean “subpopulation”. This led to the delisting of the green turtles in the Mediterranean as Critically Endangered, pending of course further genetic work on these. The green turtles in the Mediterranean are now listed as Endangered, as are all green turtles globally. More work is obviously needed urgently in the Mediterranean, so that a better understanding of the genetic make up of turtles in this sea is achieved. Such work is now ongoing.

New information is now available on nesting areas. For example an important new nesting area for green turtles was found in Syria, while nesting sites of both species were found in Lebanon and have been monitored for some years. The nesting situation in Libya is now clearer and conservation activities have been developed; a comprehensive picture of nesting in that country is hopefully expected soon. Foraging areas are getting better known though again more work is needed to identify all the key areas for the species. Migration key passages are now also being studied through satellite tracking and other observation, though more data are needed to understand routes and identify critical passages.

The situation on incidental catches in fishing gear has also been focused on in several studies, as is the fate of the turtles incidentally caught. Research projects on fishing gear modification to reduce incidental catches are still few, though these will hopefully yield valuable results. Information has also been accumulating on the abundance of the Green and Loggerhead turtles in this sea. Inevitably estimates of populations and trends are based on numbers of nests on monitored beaches, extrapolated to females etc. Though there are well known problems with such a method it is still the main practical method of estimating abundance, provided that it is kept in mind that it does not take into consideration recruitment and hatchling/juvenile survival trends over the previous two or three decades.

Estimating populations at sea (e.g., from the air) remains an alternative to be explored. This could give real-time information on populations, though other complications may provide biases (e.g., “migrant” turtles from the West Atlantic).

Chapter 11 in the Smithsonian book the “Loggerhead Sea Turtles” summarises the information available at that time (2003) on this species in the Mediterranean. It was estimated that the number of nests in the Mediterranean ranges between 3,375 and 7,085 p.a. These were deemed to be minimum figures as they refer to monitored beaches only and do not cover adequately some areas (e.g., Libya) for which there were no comprehensive data. This chapter also summarises the knowledge available at the time, on migrations, stock structure, threats, conservation, public awareness etc. Red listing Regional Assessments for the three species in the Mediterranean, Leatherback, Green and Loggerhead turtles, were undertaken are ongoing. They aim at assessing the situation of these three species in this sea. The Leatherback Regional Assessment has already been completed, with the conclusion that this species was Data Deficient (DD) in this sea. The Regional Assessments have been undertaken under the auspices of the Mediterranean group of the Marine Turtle Specialist Group (IUCN/MTSG) and are being carried out for the IUCN Malaga Centre. The first drafts of the assessments for the loggerhead and green turtles are expected for the end of May 2007.