A review of sea turtle nesting activity along the Mediterranean coast of Turkey

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Abstract

Many parts of the Turkish coastline are important nesting grounds for sea turtles. The aim of this study was to assess the present state of sea turtle populations along the coastline of Turkey, by evaluating research conducted at various nesting grounds from 1979 to 2000. The results of the evaluation indicate that the Turkish coastline is the most important nesting area for Chelonia mydas, and the third most important nesting area for Caretta caretta after Greece and Libya (if nesting estimates for Libya are correct) in the entire Mediterranean. The most important C. caretta nesting beaches in Turkey are Dalyan (11.9%), Kumluca (11.3%), Belek (27.9%), Kizilot, (8.9%) and Anamur (8.8%), while those for C. mydas are Kazanli (24.1%) and Akyatan (54.4%). These sites are classified as “Nesting Areas of 1st Degree Importance”. Annual mean nest numbers along the coastline of Turkey are estimated to be ca. 2000 for C. caretta and 650 for C. mydas. Assuming that each adult female sea turtle nests three times per season, the annual numbers of nesting females along the beaches of Turkey range between about 500 and 800 for C. caretta and 130 and 300 for C. mydas. Annual nesting densities along the 204 km beach strip, which includes 17 important nesting grounds in Turkey, were 11.3 nests/km for C. caretta and 19.2 nests/km for C. mydas.

Introduction

Loggerhead turtles (Caretta caretta) and green turtles (Chelonia mydas) nest regularly in the Mediterranean. Groombridge (1990) estimated the annual nesting female numbers in the Mediterranean as 300–400 for C. mydas and as 2000 C. caretta, while Kasparek et al. (2001) stated that the number of C. mydas females nesting annually in the Mediterranean is between 115 and 580. According to the “Red List of Threatened Species” published by the IUCN in 2000, Caretta caretta is “Not critically endangered but facing a very high risk of extinction in the wild in the near future”. The Chelonia mydas population in the Mediterranean is categorized as “Critically endangered as it is facing an extremely high risk of extinction in the wild in the immediate future”. Both species are also protected under the Bern Convention and CITES.

Important C. caretta nesting areas in the Mediterranean are found in Greece (Margaritouilis, 1998), Turkey (Geldiay et al., 1982, Baran & Kasparek, 1989, Laurent et al., 1999, Yerli & Canbolat, 1998b, Yerli et al., 1998), Libya (Laurent et al., 1995, Laurent et al., 1999) and Cyprus (Broderick & Godley, 1996, Demetropoulos & Hadjichristophorou, 1989), while other nesting grounds with a lower density are found in Tunisia (Laurent et al., 1990, Clarke et al., 2000), Syria (Kasparek, 1995) and Israel (Kuller, 1999). The most important nesting sites for C. mydas in the Mediterranean are generally situated in Turkey (Baran & Kasparek, 1989, Yerli & Demirayak, 1996, Yerli & Canbolat, 1998a, Yerli & Canbolat, 1998b, Yerli et al., 1998, Durmus, 1998, Gerosa et al., 1998) and Cyprus (Broderick and Godley, 1996).

Hathaway (1972) published the first study on sea turtles in Turkey, in which he mentioned the high probability of C. caretta and C. mydas nesting on Turkey’s beaches. Basoglu (1973) identified two C. caretta carapaces in the Izmir region and one in Koycegiz. However, the report did not provide sufficient information on the issue. Basoglu and Baran (1982) provided information on a C. caretta specimen in the Ege University Museum collection. The first detailed surveys on sea turtle populations (C. caretta and C. mydas) along Turkey’s beaches were conducted by Geldiay & Koray, 1982, Geldiay et al., 1982 and Geldiay, 1983, Geldiay, 1984. However, Geldiay et al. (1982) and Geldiay (1984) focused only on the beaches of Dalyan, Kumluca, Belek, Side and Alanya.

The first study after those of Geldiay and his team was conducted by Baran and Kasparek (1989), who identified 17 sea turtle nesting grounds throughout the Mediterranean and Aegean coasts of Turkey. They classified 13 of the nesting grounds as “beaches with a high density of nests” and four as “beaches with a lower density of nests”.

To date, there has only been one study (Yerli and Demirayak, 1996) conducted on nearly all of the sea turtle nesting grounds in Turkey to determine the population size for each site in the same nesting season. Other studies conducted on nearly all of the nesting grounds but in two different nesting seasons (in 1996 and 1998) are by Yerli & Canbolat, 1998a, Yerli & Canbolat, 1998b and Yerli et al. (1998). In addition to these, there have been a number of studies focusing on specific nesting grounds. Nevertheless, there has been no overall evaluation of these studies, nor any publication on the size of sea turtle populations in Turkey. The aim of this study is to state the importance of Turkey as a nesting site for the sea turtles of the Mediterranean, to determine the nesting potential of the sites along with their relative importance and to evaluate their current state.

Section snippets

Methodology

In this study, research on Turkey’s nesting grounds published in the form of articles, technical reports, books and theses, has been reviewed. The total nest numbers for each nesting ground found in these sources are given separately for C. caretta and C. mydas in the tables. Two different types of methodology were used in order to calculate the nest numbers given in the tables, which are grouped under “All Studies” and “Selected Studies”. For the calculations grouped under “All Studies”, all

Nesting sites

The first study to determine the sea turtle nesting grounds of Turkey was conducted between 1979 and 1982 (Geldiay, 1984). In this research, the Koycegiz, Fethiye, Kas, Finike, Kumluca, Kemer, Antalya, Serik, Side, Alanya, Gazipasa, Silifke, Mersin, Tuzla, Karatas and Yumurtalik regions of the Turkish Mediterranean coast were determined to be sea turtle nesting grounds. Of these regions, the Mersin, Tuzla, Karatas and Yumurtalik regions were recorded as important nesting grounds for C. mydas;

General status of nesting grounds and recommended strategies

Nesting grounds in Turkey face two major problems. Some beaches are exposed to tourism-related problems. In many areas, certain activities of the local people are also of concern, such as illegal sand removal and the use of heavy vehicles on the beach (Table 7). Nesting beaches where there is no human activity are exposed to relatively high predation rates.

The first concerns about sea turtle populations in Turkey started in the 1980s. In accordance with public awareness and international

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