An Assessment of the Nile Soft-shelled Turtle, Trionyx triunguis, in the Nile Delta and its Lagoons

AN ASSESSMENT OF THE NILE SOFT-SHELLED TURTLE, TRIONYX TRIUNGUIS, IN THE NILE DELTA AND ITS LAGOONS, EGYPT Mohamed Nada Commissioned by The Mediterranean Association to Save the Sea Turtles (MEDASSET) and supported by the British Chelonian Group

Abstract Very little data has been recorded on the presence of the Trionyx triunguis in Egypt during the last decades. A questionnaire survey was carried out in July 2002 among the Nile Delta fishermen and fishmongers to investigate whether there is any evidence of the species’ presence and population size in the area. According to the results the majority of the fishermen and fishmongers were unfamiliar with T. triunguis, which indicates that the species may have been extinct in the area for at least the last two decades.

Introduction a) General information on the Trionychidae The Nile soft-shelled turtle (Trionyx triunguis, ForskĂĽl 1775) belongs to the family Trionychidae (the soft shelled turtles) that has existed on earth for at least the last 100 million years (Meylan & Ganko 1997) and currently comprises about 300 described fossil species. Although these fossils have only been found in Australia and South America, 22 or 23 living species are found today all around the world (Meylan & Ganko 1997).

The soft-shelled turtles have a flat, leathery carapace reaching 95 cm in length. Their neck is long and mobile and their snout is tubular and elongated, adapted to reach the water surface for breathing while the body remains submerged. They are totally aquatic creatures, living in ponds, lakes and the lower course of rivers and laying their eggs on sandbanks and islands. Although T. triunguis is mostly known in brackish wetlands, there are many records of the species in the sea, especially during winter, which suggest that it spends part of its life cycle there (Kasparek 2001). The ability of soft-shelled turtles to

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tolerate salt water enabled them to colonise the southeast of Europe and the southeastern Mediterranean (Kasparek & Kinzelbach 1991; Flower 1933). The present distribution of T. triunguis extends from Mauritania and northern Namibia to Somalia and Egypt, and along the Mediterranean coast to Turkey. There have also been records from the Dodecanese archipelago, Greece (Demetropoulos & Ioannidis 2003; Taskavek et al.

1999). The main habitats of Trionyx in the Mediterranean are located in Turkey, Syria and Israel. In particular, Nahal Alexander in Israel is reported to support a dense population of the species and is considered to be the most important reproduction site (Taskavak et al. 1999; Kasparek & Kinzelbach 1991). Despite the wide geographic distribution of T. triunguis, the Mediterranean population is reported as highly threatened and on the verge of extinction as a result of fisheries interaction, intensive use of its habitats for water supply and irrigation, human predation and persecution, water pollution, destruction of nesting sites and disruption caused by boats (Kinzelbach 1986; Baran & Kasparek 1989) .The overall estimate has been argued not to exceed 500 adults (Kasparek & Kinzelbach 1991) varying in distribution from single or few sightings at sea (as in Greece) to a well-documented population in Turkey and Israel .

In an effort to conserve T. triunguis, it has been included in Appendix II of the Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention) in December 1996, and in Appendix III of The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) (Kasparek 2001). The Mediterranean population has also been listed as ‘Critically Endangered’ in the IUCN's Red Data Book (1996 and 2000) (Turtle and Tortoise Newsletter 2000; Kasparek 2001).

However, in spite of these conventions, it was reported that especially in Turkey no practical steps towards conservation of the species have been taken (MEDASSET 1998).

With regard to the Nahal Alexander population, the breeding potential there may be undermined by heavy pollution (Taskavak et al. 1999).

b) T. triunguis in Egypt Paleontological data on T. triunguis has been reported from the first Middle Pleistocene (750,000 years ago) fauna in Dakleh oasis in the Egyptian western desert (Churcher 1972

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& 1974; Churcher et al. 1999). Remains were also found in archaeological deposits dated to the Amratian era (3900 BC) (Fischer 1968 in: Kasparek & Kinzelbach 1991) and it is known that humans consumed soft-shelled turtle flesh at least as late as the 19th dynasty (Boessneck 1988). From then until the beginning of the 19th century there is no definite evidence that the author is aware of, regarding the presence of the T. triunguis in Egypt.

In 1775, when Fosk책l gave the first scientific description of T. triunguis (Testudo triunguis) he also noted that the species was rare in the Nile (Kasparek, 1999).

The first to confirm the presence of T. triunguis in Egypt in modern times was Flower (1933) but he acknowledged its rarity as a result of human predation. He only recorded four specimens scattered along the Nile river - from Kom Ombo (Aswan Province), the Giza province and the Ezbet Semada Saleh (in the al-Fayum basin). Rzoska (1976 in: Baha El Din & Salama, 1992) claimed that T. triunguis had been extinct from Egypt since the 1930s; however, in 1979, Sella (1981) recorded a skeleton on the seashore of Bardawill lagoon (Nile Delta) and in 1985, Kinzelbach (1986) encountered a small specimen surfacing in the Luxor district.

The most recent information is by Baha El Din & Salama (1992) who reported two sites where the species was recorded. The first was Lake Nasser, where they recorded two carapaces of a freshly killed T. triunguis and at least another five carapaces in display at the tourist market in Aswan. They also found that local fishermen were familiar with the species and described its nest, eggs and habits. The second record was a live specimen in El-Arish fish market, North Sinai, which had been caught in a fishing net in the Mediterranean off El-Arish.

Based on the information published in Baha El Din & Salama (1992) and Sella (1981), a questionnaire survey was organised during the summer of 2002 in order to examine in more detail whether fishermen and fishmongers along the Nile Delta were aware of the existence of T. triunguis in the area.

In addition the survey aimed to explore any

practices and cultural beliefs among the local community in relation to the species, i.e. human consumption, superstitions etc.

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Materials and methods a) The study area The Nile Delta is the outfall of the longest river of the world (6645 km) where it drains into the Mediterranean Sea. It covers an area of about 22,000 km2, the major cities being Alexandria, Port Said, Rosetta (Fig.1), Manzala, Damietta, Ras El Bar, Brullus and Baltim. The delta is of extremely high agricultural value and comprises one of the oldest intensely cultivated areas of the world. The northern coastal lagoons, within the Nile Delta, (Bardawill, Manzala, Brullus, Idku and Maryut) are considered one of the main fishing grounds in Egypt (Fig.1) with a surface area of about 200,000 hectares. A large number of small vessels and many fixed nets are used to exploit fisheries in the area (Theroux 1997). There has been a gradual decrease in the water quality of the river Nile towards the delta and the coastal plains as a result of the continuous discharge of pollutants and untreated domestic and industrial wastewater, and the increasing use of chemical fertilizers, herbicides and pesticides.

Figure 1. The Rosetta branch of the Nile.

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b) Target groups and survey tools Usually hidden in the muddy substrate of ponds and rivers, T. triunguis is renowned as a very elusive species. It was, therefore, considered that the first target group would be the fishermen as they are the most likely to encounter the species if it is still present in the delta area. They have good accessibility to several parts of the estuary and the incidence of by-catch as a result of their activities. The fish markets can also be a good source of information given the data published in Baha-El-Din & Salama (1992) and thus the fishmongers comprised the second target group for this survey.

Semi-structured interviews were used with both the fishermen and the fishmongers from different areas along the Nile Delta (see Figure 2 and Table). The main reason for choosing this methodology was to ensure that the questions were perfectly understood so that any illiterate individual would be able to participate and provide in-depth explanation of any question asked. A preliminary checklist questionnaire was used to ensure that those targeted were experienced enough for the scope of this survey: fishermen and fishmongers who had less than twenty years of experience in fishing and at the fish market respectively, were excluded from the targeted group sample.

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Figure 2. Map of surveyed area.

Those who fulfilled the requirements of the preliminary checklist were asked to identify the pictures of T. triunguis, the loggerhead (Caretta caretta) and the green turtle (Chelonia mydas) and whether they were able to differentiate between them. A different set of questions was then applied to the fishermen and the fishmongers: for the fishermen, the main questions attempted to explore the circumstances under which they see or catch T. triunguis and how often it happens, whereas the fishmongers were asked about the cultural beliefs and practices related to T. triunguis.

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Table. Survey sample of fishermen and fishmongers along the Nile Delta.

Area

Number of fishermen that Number of fishmongers participated in the survey that participated in the survey Edfena 12 Rosetta 14 11 (fish market) Damietta 8 9 (fish market) Village near Bardawill Lake 21 Bardawill Lake 11 Manzala Lake 14 Brullus Lake 15 Idku Lake 11 El-Maadia fishmarket 16 Maryut Lake 22 Total 128 36 Results Only two fishermen, both from Bardawill Lake, were able to identify T. triunguis: the first mentioned that he caught it in his net 25 years ago. The other fisherman reported that in his 35 years of experience in fishing in the lake, it was extremely rare to find any of them, adding that in the last twenty years he had not seen any. However, fishermen were very familiar with both the loggerhead (Caretta caretta) and the green turtle (Chelonia mydas) and almost 100% of them were able to identify the two species. Twenty seven fishermen, 11 from Rosetta, 8 from Damietta and 8 from Bardawill, mentioned that they occasionally catch them in their nets off the coast and that the catching rate has decreased in recent years. A report of a fisherman in Damietta suggests that what was probably a leatherback (Dermochelys coriacea) was caught in 1999.

Results from the fishmonger group were similar: no one reported having ever seen Trionyx in the market or elsewhere but they all confidently identified the loggerhead and the green turtles. They added that marine turtles were rarely displayed in the market since there is no local demand for their meat, so if a turtle is caught it is sent to the fish market of Alexandria. It was also reported that in recent years marine turtles are rarely sold as a result of law enforcement regarding its illegal trade.

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Discussion and conclusion The results of this survey together with the records by Sella (1981) and Baha-El-Din & Salama (1992), suggest that if any T. triunguis still survives in the Nile Delta, then it would most likely be found within Bardawill Lake. This should be seen, however, as very unlikely, as even the fishermen who admitted having encountered the soft-shelled turtle within the Nile Delta dated this event back at least 20 years. It remains to be seen whether Lake Nasser, reported in Baha-El-Din & Salama (1992) as “the main stronghold” of the species “in Egypt today”, still supports a population.

A very positive finding was the reported decrease in the illegal trade of the sea turtles at the Delta fish markets especially after a long history of lack of enforcement of the regulations. The report by the fishermen of a decrease in numbers of turtles caught may indicate that the populations visiting Egypt are decreasing. It is recommended here that further research should be carried out in order to identify the main source rookery for marine turtles visiting Egypt, and the threats it may be facing.

The fisherman’s description of the leatherback turtle in Damietta, in addition to the three unpublished incidents this author has documented in Alexandria’s fish market and from the local fishermen between 1999 and 2002, illustrate that the geographic distribution of the leatherback in the Mediterranean may be extended to Egypt.

Acknowledgements This assessment was made possible thanks to the support of MEDASSET and funding from the British Chelonia Group. I would like to thank Mr Bob Langton, BCG Conservation Officer, and Lily Venizelos, President of MEDASSET, for encouragement and background work in carrying out this project. Special thanks are due to Dr Max Kasparek, MEDASSET Scientific Adviser, for his invaluable information, and my sincere thanks go to Ms Kelly Papapavlou for scientific advice and proof reading.

Finally, thanks to all the Egyptian fishermen for their cooperation and for providing information.

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Meylan, P. A. & Ganko, E. (1997). Trionychidae: the soft-shelled turtles. http://www.eckerd.edu/turtles/polycryptodira/Trionychidae/trionychidae.html accessed 18 August 2002.

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