Data about Loggerhead sea turtle (Caretta caretta L. 1758) in Patoku Lagoon, Albania

International Conference MarCoastEcos2012, Tirana, Albania, 25-28 April 2012

Published by: © Faculty of Natural Sciences of the University of Tirana, Albania

Printed by: Shtypshkronja “Julvin 2”, Tirana, Albania

PROCEEDINGS International Conference on Marine and Coastal Ecosystems (MarCoastEcos2012): increasing knowledge for a sustainable conservation and integrated management.

25 – 28 April 2012, Tirana, Albania

Cover photo: View from the coast of Sazani Island. Photo: Xhemal Mato.

Citation: Faculty of Natural Sciences of the University of Tirana. 2013. Proceedings of the International Conference on Marine and Coastal Ecosystems (MarCoastEcos2012): increasing knowledge for a sustainable conservation and integrated management. 25 – 28 April 2012, Tirana, Albania: 634 p.

The accuracy of findings, interpretations and presentations of the conference, expressed in this publication, are under the professional responsibility of the authors themselves.

Publication of the Proceedings was supported by the CEMSA Project “Consolidation of the Environmental Monitoring System in Albania”, EC, MEFWA, NEA.

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Oral presentations: Biodiversity and ecosystem functioning

International Conference MarCoastEcos2012, Tirana, Albania, 25-28 April 2012

DATA ABOUT LOGGERHEAD SEA TURTLE (CARETTA CARETTA L., 1758) IN PATOKU LAGOON, ALBANIA

protection and management of marine and coastal biodiversity in such areas would be of crucial importance. Improve the capacity to study and conserve biodiversity at the abovementioned sites, would help to ensure environmental sustainability.

1*

Enerit Saçdanaku, 2Idriz Haxhiu

Material and methods

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Departament of Biology, Faculty of Technical Sciences, University of Vlora ‘Ismail Qemali’, Albania 2 University Vitrina, Tirana, Albania * E-mail: eneriti@gmail.com

1. Study area

Abstract Data about loggerhead sea turtle (Caretta caretta L.,1758) conducted in Patoku area (Drini Bay, Western Albania) during 2008, within the project focused on the monitoring and conservation of important sea turtle feeding grounds in the Patoku area (2008-10), supported by MEDASSET. About 105 individuals were captured in total as bycatch in stavnike fish-traps and trawling operations in this area; all them were tagged, using Stockbrands titanium tags. Moreover, the relative data about morphometry and bioecology was assessed. About 95 individuals were tagged for the first time; 10 individuals were remigrants (tagged before 2008); while 16 individuals were recaptured within the same year. The largest number were captured in June (63 individuals) and only one in August and December, respectively. Based on morphometric size-classes, the largest number belonged to 60 cm class (46 individuals), while 2 individuals belonged to the 80 cm class. One of the most important morphometric aspects was the tail measurements: it is a simple technique, yet very important to show sexual differentiation in sea turtles.

Hence, almost the whole population captured (102 individuals) consisted of 19.6% male, 39.2% female and 41.2% undetermined. Most of individuals presented epibiontic flora (mainly green algae) and epibiontic invertebrates, Balanus spp. were common; Lepas spp. were occasional, gastropods and bivalves were relatively rare. It was concluded that Drini Bay is a regionally and nationally important habitat that is used by sea turtles for foraging, as a refuge and as part of a key migratory corridor between the Ionian and Adriatic Seas.

In the northernmost part of the Western Lowlands of Albania there is a lagoon at Patoku region [N41o38.191’; E019o35.327’]. This lagoon is part of Drini Bay, which is a shallow sea (maximum depth 47 m) with a sand and mud substratum dominated by bivalves and crabs. Five sedimentladen rivers enter the bay: Buna, Drini, Mati, Droja and Ishmi.

Keywords: Caretta caretta, morphometry, tagging, epibiontic, Patoku region.

Introduction Figure 1. Drini Bay (adapted by M. White)

There are four species of sea turtles documented from Albanian offshore waters:  Loggerhead turtle, Caretta caretta, is the most common (Zeko & Puzanov, 1960; Haxhiu, 1981, 1985, 1995, 1997, 1998, 2005, 2010)  The green turtle, Chelonia mydas, is rare (Zeko & Puzanov, 1960; Haxhiu, 1981, 1985, 1997, 1998)  Leatherback turtle, Dermochelis coriacea, very rare.  The hawksbill turtle, Eritmochelys imbricata, a special occasion in Albanian waters (Frommhold, 1959; Haxhiu, 2010).

2. Stavnikes One of the method used in this study was to monitor turtles that were caught incidentally by fisheries (i.e. ‘bycatch’); and in particular from a method of fishing that uses traps, which are known as ‘stavnikes’. Stavnikes are a type of fish‐trap, originating in Russia that arrived in Albania around 30 years ago, and were forgotten until about 2003; when the Patoku fishermen started to use them again (Haxhiu, 2010).

The first three species of marine turtle are exhibited in the Museum of Natural Science in Tirana.

Studies and publications on sea turtles in Albania are scarce (Zeko & Puzanov, 1960; Haxhiu, 1981, 1985, 1995, 1997, 1998; Haxhiu & Oruci, 1998; Haxhiu & Rumano, 2005; Haxhiu, 2010).

They concern sporadic observations and descriptive geographic distributions of turtles in Albania. Focused studies have been carried out between 2002 – 2009. During this period, 1027 individual of Caretta caretta were studied (75 of wich were found dead) and 18 individual of Chelonia mydas (Haxhiu, 2005, 2010).

Loggerheads are considered endangered species and are protected by the International Union for the Conservation of Nature. Untended fishing gear is responsible for many loggerhead deaths. Turtles may also suffocate if they are trapped in fishing trawls. Turtle excluder devices (TEDs) have been implemented in efforts to reduce mortality by providing an escape route for the turtles. Loss of suitable nesting beaches and the introduction of exotic predators have also taken a toll on loggerhead populations. Efforts to restore their numbers will require international cooperation since the turtles roam vast marine areas and critical nesting beaches are scattered across several countries. Their relatively high presence in Patoku region means that this area shows significant ecological importance, rich in habitats that can help in the conservation of endangered migratory species (like marine turtles, etc.). Building knowledge and improving the Proceedings

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Figure 2. Typical design of a stavnike fish‐trap (after I. Haxhiu)

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International Conference MarCoastEcos2012, Tirana, Albania, 25-28 April 2012

A long barrier net extends from the fish‐traps to the beach (Ishmi stavnike was 1800 m offshore, coordinates: [N41o36.198’; E019o33.349’]; Mati only 200 m, coordinates: [N41o38.512’; E019o34.126’]); the traps are constructed to allow entry from either side of the barrier net. When fish or turtles encounter the barrier they have three choices: to turn left, right, or to go back the way they came; an area they may have just foraged. Turning beachwards leads them into shallower water, but any animals entering the traps’ reception area are guided into successive chambers; escape from these is difficult although not impossible.

Results and discussion 1.

Distribution of individual (Caretta caretta) by month

In the following chart is shown the distribution of individual of C. caretta by month:

3. Morphometric data The curve carapace length (CCL) and curved carapace width (CCW) were measured and turtles allocated into 10 cm size – classes (length - frequency distribution) based on their CCL e.g. 40 cm size – class range: 40.0 – 49.9 cm et seq. (White, 2007).

As an indicator of the stage of sexual development, three measurements were recorded from the tail: a) Distance from posterior margin of plastron to midline of cloacal opening (Plas – clo) b) Total tail length (TTL) c) Distance from tip of tail to posterior margin of the carapace (+/- cara) As a very important elements in identifying the individual of turltes we have also counted the epidermal scales of the carapace (nuchal, coastal and marginal scales) as well as head scales (prefrontal and frontoparietal).

4. Tagging The first turtle tagging project in Albania began at the end of 2002, using Dalton’s plastic Rototags (provided by RAC/SPA, Tunis). Suggett & Houghton (1998) provided evidence that Rototags can increase the risk of turtles becoming entangled in fishing gear, and so in this study we used a single Stockbrand’s titanium tag (these tags lock into a closed u‐shape).

Figure 4. Distribution of individual (Caretta caretta) by months

As it is shown from the chart the largest number of individual has resulted in June and July. It is seen that we have a disproposal in distribution between June and July and the other months.

This is because of stavnikes, wich have been working till the mid of August. Based on the previous studies related to the distribution of C. caretta in this area (Haxhiu, 2005, 2007) we have this view: in 2002 the largest number of individual resulted in September (50 individual); in 2003 in May (71 individual); 2004 in July (24 individual); in 2005 in June (25 individual); 2006 in June (15 individual).

2. Size – classes In the following table and chart is given the distribution of turtles by month, allocated into 10 cm size – classes (length - frequency distribution) based on their CCL e.g. 40 cm size – class range: 40.0 – 49.9 cm et seq. (White, 2007).

Table 1. Number of loggerhead in each cm size – class of CCL. CCL June July August September December Total

40

50

60

70

80

Total

0 2 1 1 0 4

17 10 0 0 0 27

26 20 0 0 0 46

17 4 0 1 1 23

2 0 0 0 0 2

62 36 1 2 1 102

Figure 3. Stockbrand’s titanium tag, put on the flipper of the turtle (Photo M. White)

The first titanium tag was applied in July 2008; these tags were marked with an Albanian address, in order to reinforce the conservation message; fishermen thought that the Rototags had been applied in Tunisia due to the RAC/SPA address marked on the tag. When Roto‐tagged turtles were recaptured, the plastic tags were removed and replaced with a titanium tag.

Figure 5. General distribution of individual of C. caretta by size – class for 5 months (June, July, August, September, December) Proceedings

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International Conference MarCoastEcos2012, Tirana, Albania, 25-28 April 2012

From the above table and chart it is clearly seen that the largest number of individual of C. caretta belongs to 60 cm size – class (46 individuals), while the smallest number to the 80 cm size – class (2 individual).

3. Head epidermal scales As a very important elements in identifying the individual of turltes we have also counted the epidermal scales of head (prefrontals and frontoparietals). The following charts shows the distribution of individual related to the number of prefrontal and frontoparietal scales:

Figure 8. Distribution of individual by the number of frontoparietals scales

In frontoparietals scales we have included all those scales that touch the parietal (see Figure 6).

There is a certain number of these scales in Caretta caretta. From the Figure 8, it is seen that this number varies from 9 – 15 frontoparietals and the mode is 12 with 35 individuals.

4.

Determination of sex

The sex of marine turtles can be determined easily in mature individuals (adults). This is because of some secondary characteristics features, as can be: males tail length; size and morphology of carapace; the hole in the plastron or the development of nail in the front limbs of a male individual. The most obvious feature to an adult male is the tail, which is too long and extend outside the carapace (see Figure 10).

Figure 6. Demonstration of head scales (Photo: I. Haxhiu)

Figure 10. The extended tail of an adult male loggerhead (left) A male individual of C. caretta (right) Figure 7. Distribution of individual by the number of prefrontal scales

Regarding to the prefrontal scales in C. caretta their numbers is always 4 or more, but never less than 4. While to the other species Chelonia mydas this number is always 2. In this way the number of prefrontal scales it is used as a taxonomic element for the identification of species.

Form the chart (Figure 7), it is seen that the largest number of individual have had 4 and 5 prefrontal scales (which is normal), while the smallest number of individual have had 8 prefrontal scales (this is very rare).

While for the identification of individuals within the species we have been focused on the shape, size and number of frontoparietals scales (photo – recognition, White, 2006).

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While when we talk abuot an individual adult female, it can be easily traced because they have a short tail and in most cases the length of the tail does not extend out of carapace (see Figure 11).

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5. Epibionts Epiobionts (epibiontic flora and epibiontic fauna) is very widespread in sea turltles (Oliverio et al., 1992). The individual of C.caretta were studied for the presence of epibionts. Most of individuals presented epibiontic flora (mainly green algae) and epibiontic invertebrates, Balanus spp. were common; Lepas spp. were occasional, gastropods and bivalves were relatively rare.

For all the individual studied has resulted that they were overloaded with epiobionts (epibiontic fauna and epibiontic flora) in a percentage of 48.6 % against them who were clean (without epibionts) in a percentage of 51.4 % (see Figure 13).

Figure 11. A female individual of C. caretta (left). Demonstration of morphological elements or sex determination to an adult male (right)

The difficulty in determining the sex of individuals stands to those who are sexually unmatured (Juveniles). This is because the length of the tail to the juvenile is not enough developed and it can not be used as an element to determine their sex (Limpus, 1985; Wibbles, 1988). In determining their sex are used other methods that are not based on morphological elements.

One of the methods can be direct observation of the gonads, through examination with special equipment (Wood et al., 1983; Limpus & Reed; Limpus, 1985). In this study we have classified the individual of C. caretta into three groups regarding to their sex: Female, male and undetermined (juvenile). For this we are based mainly on these morphological elements: Distance from posterior margin of plastron to midline of cloacal opening (Plas – clo); Total tail length (TTL); Distance from tip of tail to posterior margin of the carapace (+/- cara) (see Figure 11).

Based on this classification has resulted that 41.17 % were female, 19.60 % male and 39. 21 % undetermined (juvenile). In the following chart is given this distribution of individual by sex. As it is seen in the following chart we have a dominance of female individual over the males and quite a large number of undetermined individual (juvenile).

Figure 12. Distribution of individual of C. caretta by sex given in percentage

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Figure 13. An individual of C. caretta overloaded with epibionts (Photo: I. Haxhiu)

Conclusions About 105 individuals were captured in total as bycatch in stavnike fish-traps and trawling operations in this area; all them were tagged, using Stockbrands titanium tags. About 95 individuals were tagged for the first time; 10 individuals were remigrants (tagged before 2008).

Remigrants referres to previously‐tagged turtles captured inter‐annually. This is a very important data because it shows that Albania is part of their migratory routes.

Turtles that were caught more than once in the same field‐season were referred to as ‘recaptures’. In our stduy resulted that 16 individuals were recaptured within the same year (2008). This data shows that this area could be a foraging habitat for those animal.

From this study resulted that 41.17 % were female, 19.60 % male and 39. 21 % undetermined (juvenile). As it is seen we have quite a large number of female individual. This data can be considered as very important, because so far in Albanian coastline has not been found any nesting activity. Having these high percentage of female we can say that in the future Albanian coastline can be a potential nesting habitat for Caretta caretta.

The distribution and lifestyle of male turtle is not as well known as that of females, because as it is known males spend all their life-cycle on the sea and is very difficult to study them. As the distribution and marine ecology of male turtles is poorly understood, this unusual assemblage can be considered an important and highly-significant finding. We can say that Patoku lagoon may be a male foraging and developmental habitat, as 19.60 % of all individual studied were males.

In this study almost half (48.6%) of infividual of C. caretta were overloaded with epibionts (epibiontic fauna and flora). The most important is the fact that these epibionts does not cause any damages to turtles, except of making their body a little havy for swimming. Thus, their are not parazite to sea turtles, but they use the shell of these animals to fix on it and while turtles are swiming in differents habitats they feeds.

From the three year project was concluded that Drini Bay is a regionally and nationally important habitat that is used by sea turtles for foraging, as a refuge and as part of a key migratory corridor between the Ionian and Adriatic Seas.

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