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Marine Turtle Newsletter 32:6-8, © 1985

Marine Turtles in Greece and their Conservation

J. M. Sutherland
24 Chomeley Park, Highgate, London N6 5UE, England

Sea turtles have been observed in Greek waters by only a few biologists in this century (Mertens and Wermuth 1960; Ondrias 1968) but appear to have been common in Ancient times, for one of the first Greek coins bears the image of a marine turtle. There were practically no reports of nesting on the Greek shoreline until the recent discovery of a large breeding population on the island of Zakynthos in the Ionian Sea (Marinos 1977, 1981; Margaritoulis 1982). The only published record of possible nesting in Greece before this was by Mertens (1961), who observed a turtle on the southern shore of Corfu. In 1980 initial research was begun by the Council of Physical Planning and the Environment on the island of Zakynthos in conjunction with a World Wildlife Fund Project (No. 1822, Marinos 1981). Greek students from the Universities of Thessolonika and Athens have continued tagging turtles on one or two Zakynthos beaches (Margaritoulis 1983).

In 1983 I conducted a comprehensive survey of all the southern beaches of Zakynthos with the aid of a small grant from the World Wildlife Fund (UK). The survey revealed 5,411 emergences and some 2,460 nests on the seven main nesting beaches in the southern bay of Zakynthos. Daily results were obtained from all the beaches, from the beginning of the breeding season in June until the end of September. Only five days of emergence data were missed for the two main nesting beaches at Sekania; some of the other beaches were not covered so thoroughly (ca. 70% coverage over the same period). The two small beaches at Sekania represented about half the total number of emergences for the whole of Zakynthos. The data for missed days were estimated by averaging the number of emergences and nests recorded on previous and subsequent days. After each visit all tracks were obscured as much as possible and care was taken not to double-count tracks if a visit had not occurred on the previous day. Data are summarized in Table 1.

Table 1.Data summary for loggerhead sea turtle nesting on Zakynthos beaches, 1983.

The mean carapace length of the females was 81.2cm (N = 95; SD = 0.54); that of the hatchlings was 4.OOcm (N = 221; SD = 0.17). Mean clutch size was 114.4 eggs (N = 52; SD = 7.33) and incubation periods varied from 49 to 69 days (x = 57.5; N = 6; SD = 6.26). The number of hatchlings leaving the beach daily was recorded for 35 days (i.e., about half of the hatching period) and the total was estimated at about 70,000. This represents 25% of the eggs laid (estimated at 280,000 by multiplying 114.4 eggs per nest by 2,460 nests). Direct observation of nests by digging them up after the hatchlings had emerged produced an estimated mean hatching success of 70%, though there may well have been a bias towards choosing more successful nests by this method.

During September 1983 I surveyed Cephalonia (some 40 km north of Zakynthos) for nesting beaches and discovered both adult and hatchling tracks on a single beach at the southeastern tip of the island. In 1984 with the help of some students we surveyed three beaches (5 km) and estimated that 150 nests were laid (calculated from our observations during two months of the nesting season, by multiplying the average number of nests per night times the number o& nights in the season). In 1983 18 turtles were recorded nesting more than once in Zakynthos and 7 of these nested on different beaches, some of which were as much as l0 km apart. One of the turtles tagged on Zakynthos in 1982 also nested on Cephalonia in 1984.

There are a number of other areas in Greece where loggerheads may breed. Those that are known with any degree of certainty are: the Peloponnese coast from Kyparissa to Pyrgos, especially north of Kaiapha; Antirron, north of Patras; Killini; parts of Crete; southern Corfu; and Paros.

Environmental protection of marine turtles in Greece began with the Presidential Decree of July 1980, which prohibits the fishing of all species of sea turtle, the collection of hatchlings, and the destruction of their eggs. Another Presidential Decree of January 1981 gives a list of species which are to be protected in Greece, and includes all species of marine turtle. Marine turtles are not exploited for food in Greece, and the number of adults killed is low-usually the result of incidental capture in nets or damage by outboard engines. The percentage of eggs loss by flooding is also low due to the negligible Mediterranean tide and the predominantly calm waters in the area during the nesting season. The major conservation problem has been the increasing disturbance of the beaches by coastal development associated with tourism (MTN 19:14; 27:3). This situation has only become critical on one or two beaches (particularly Lagana on Zakynthos) and in the last year legislation has been passed preventing or restricting the construction of houses and hotels near the nesting beaches. However, there has been little attempt to explain the necessity of such legislation to the local people or to involve them in these proposals; nor have funds been provided to compensate those who have lost through this legislation.

Hirth, H. F. 1980. Some aspects of the nesting behavior and reproductive biology of sea turtles. Am. Zoïl. 20:507-523.

Marinos, P. 1977. Zakynthos, tourism and environment. MSc dissertation, Univ. Salford.

Marinos, P. 1981. On the distribution of sea turtles in Greek waters. MTN 19:13-14.

Margaritoulis, D. 1982. Observations on loggerhead sea turtle (Caretta caretta) activity during three nesting seasons (1977-1979) in Zakynthos, Greece. Biol. Conserv. 24:193-204.

Margaritoulis, D. 1983. The inter-nesting interval of Zakynthos loggerheads. pp- 135-144 In: Adaptations to Terrestrial Environments, N. S. Margaris, M. Arianoutsou-Faraggitati and R. J. Reiter, eds). Plenum Press, New York.

Mertens, R. 1961. Die Amphibian and Reptilien der Insel Korfu. Senk. Biol, 42:1-29.

Mertens, R. and H. Wermuth. 1960. Die Amphibien and Reptilien Europas (Dritte Liste). Frankfurt a-M., Waldemar Kramer.

Ondrias, J. 1968. Liste des amphibians et des reptiles de Grece. Biologia Gallo-Hellenica 1:111-135.