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Marine Turtle Newsletter 108:14-15, © 2005

Marine Turtle Newsletter-Online

Loggerhead Turtles in the Dalyan River, Mulğa Province, Turkey, 2004

Markus Keller
Aktionsgemeinschaft Artenschutz e.V., AgA, Tulpenstrasse 1, 70825 Korntal-Münchungen, Germany (E-mail: buero@aga-international.de)

The most common species of marine turtle in the Mediterranean Sea is the loggerhead turtle (Caretta caretta). It is well known that loggerhead turtles enter rivers and estuaries on a regular basis throughout the world. These marine turtles, especially juveniles and sub adults, use lagoons, estuaries and bays as feeding grounds (Dodd 1995) such as the Indian River Lagoon in Florida (Ehrhart 1983). In the Mediterranean, records of loggerhead turtles in the brackish water of the Neretva Delta, Croatia, in the freshwater of the Skadar Lake in Montenegro (Bolkay 1924) and Prokljan Lake near Šibenik, Dalmatia (De Luca et al. 1990) have been described.

As part of the Caretta Action Network (CAN) project 2004 of the Aktionsgemeinschaft Artenschutz e.V. (AgA) and Bund Deutscher Tierfreunde e.V. (BdT), Germany, an extended observation of surface activities of the Nile Soft-Shelled Turtle (Trionyx triunguis) in the Dalyan River was carried out. The river represents a typical brackish estuary with a strong vertical salinity gradient from an average of S = 3 ‰ on the surface to a maximum of S = 27 ‰ at a depth of 5 m. The wetlands (see fig 1), holding one of the biggest populations of T. triunguis in the Middle East (Bride 2004), are part of the Specially Protected Area (SPA) of Köyceğiz/Dalyan in the Mulğa province, Turkey and include Dalyan Beach, one of the important nesting sites of the loggerhead turtle in Turkey (Venizelos 1999).

During the observation period from May to July 2004, at least 2 different sub adult or adult loggerhead turtles were regularly seen near Dalyan town. Their average surface time for breathing was 3.5 seconds (n = 30). One turtle was regularly observed near the Dalyan River outlet. Loggerhead turtles have been previously documented feeding in the Ala Lake and the wetland system behind İztuzu beach (Venizelos 1999).

Because the fish gate (see fig 1) from the local fishing cooperation downstream from the observed section is closed most of the year, these loggerhead turtles are entrapped in the upper area of the Dalyan River and cannot freely move. In order to allow these turtles to follow their natural life cycle, migrating and reproducing, it would be necessary to relocate them behind the fish gate and this should be considered by the SPA authorities.


Figure 1. Map of the Dalyan estuaries between the Köyceğiz Lake and the Aegean Sea. The observed section of the river is marked as such. From there, the fish gates completely block access to the Aegean Sea for the observed loggerhead turtles.

Acknowledgements: I wish to thank Siegfried Weisel and all volunteers of the CAN project 2004 for their tireless work and assistance in the field. Many thanks to the Aktionsgemeinschaft Artenschutz e.V. and the Bund Deutscher Tierfreunde e.V. for their logistical and financial support.

BRIDE, I. 2004. Update Report on the Status of the Nile Soft-shelled Turtle, Trionyx triunguis, in Dalaman and Dalyan, Turkey. Report to the 24nd Meeting of the Standing Committee of the Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention). MEDASSET. pp. 9.

BOLKAY, S.J. 1924. Popis vodozemaca I gmizavaca koji se nalaze u bos.-herc. Zemaljskom muzeju u Sarajevu s morfološkim, biološkim zoogeografskim bilješkama. Spom. Srp. Kralj. Akad, Beograd
58:1-39.

DODD, C.K. 1995. Marine Turtles in the Southeast. In: E.T. LA ROE (Ed.): Our Living Resources. US Department of the Interior - National Biological Service, Washington D.C. pp. 121-124.
EHRHART, L.M. 1983. Marine Turtles of the Indian River Lagoon System. Florida Scientist 46:337-346.

DE LUCA, N., D. KOVAČIĆ & B. ĐULIĆ. 1990. Fauna vodozemaca, gmazova i sisavaca NP Krka. In: M. Kerovac (Ed.): Zbornik rad. Simp. NP Krka - stanje istraženosti i problemi zaštite ekosistema 3.- 5. Oct. 1989. pp. 523-550.

VENIZELOS, L. 1999. Conservation Status of Sea Turtles in the Northeastern Mediterranean: Three case studies. Contributions to the Zoogeography and Ecology of the Eastern Mediterranean Region 1:447-450.