data about loggerhead sea turtle (caretta caretta l. 1758) in patoku lagoon, albania

PROCEEDINGS

International Conference on Marine and CoastalEcosystems (MarCoastEcos2012):

increasing knowledge for a sustainable conservationand integrated management.

25 – 28 April 2012, Tirana, Albania

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

Proceedings2

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

Printed by:Shtypshkronja “Julvin 2”, 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 theInternational 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 authorsthemselves.

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

Oral presentations: Biodiversity and ecosystem functioning

Proceedings 65

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

1*Enerit Saçdanaku, 2Idriz Haxhiu

1Departament of Biology, Faculty of Technical Sciences, University of Vlora ‘Ismail Qemali’, Albania

2University Vitrina, Tirana, Albania

*E-mail: [email protected]

Abstract

Data about loggerhead sea turtle (Caretta caretta L.,1758) conducted in Patoku area (Drini Bay, WesternAlbania) during 2008, within the project focused on the monitoring and conservation of important seaturtle feeding grounds in the Patoku area (2008-10), supported by MEDASSET. About 105 individualswere captured in total as bycatch in stavnike fish-traps and trawling operations in this area; all them weretagged, using Stockbrands titanium tags. Moreover, the relative data about morphometry and bioecologywas assessed. About 95 individuals were tagged for the first time; 10 individuals were remigrants (taggedbefore 2008); while 16 individuals were recaptured within the same year. The largest number werecaptured in June (63 individuals) and only one in August and December, respectively. Based onmorphometric size-classes, the largest number belonged to 60 cm class (46 individuals), while 2individuals belonged to the 80 cm class. One of the most important morphometric aspects was the tailmeasurements: 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% femaleand 41.2% undetermined. Most of individuals presented epibiontic flora (mainly green algae) andepibiontic invertebrates, Balanus spp. were common; Lepas spp. were occasional, gastropods andbivalves were relatively rare. It was concluded that Drini Bay is a regionally and nationally importanthabitat that is used by sea turtles for foraging, as a refuge and as part of a key migratory corridor betweenthe Ionian and Adriatic Seas.

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

Introduction

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).

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 inAlbania. Focused studies have been carried out between 2002 – 2009. During this period, 1027individual of Caretta caretta were studied (75 of wich were found dead) and 18 individual ofChelonia mydas (Haxhiu, 2005, 2010).Loggerheads are considered endangered species and are protected by the International Unionfor the Conservation of Nature. Untended fishing gear is responsible for many loggerheaddeaths. 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 forthe turtles. Loss of suitable nesting beaches and the introduction of exotic predators have alsotaken a toll on loggerhead populations. Efforts to restore their numbers will require internationalcooperation since the turtles roam vast marine areas and critical nesting beaches are scatteredacross several countries. Their relatively high presence in Patoku region means that this areashows significant ecological importance, rich in habitats that can help in the conservation ofendangered migratory species (like marine turtles, etc.). Building knowledge and improving the


Proceedings66

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

Material and methods

1. Study area

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 (maximumdepth 47 m) with a sand and mud substratum dominated by bivalves and crabs. Five sediment-laden rivers enter the bay: Buna, Drini, Mati, Droja and Ishmi.

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

2. Stavnikes

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

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


Proceedings 67

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. Whenfish or turtles encounter the barrier they have three choices: to turn left, right, or to go back theway they came; an area they may have just foraged. Turning beachwards leads them intoshallower water, but any animals entering the traps’ reception area are guided into successivechambers; escape from these is difficult although not impossible.

3. Morphometric data

The curve carapace length (CCL) and curved carapace width (CCW) were measured and turtlesallocated into 10 cm size – classes (length - frequency distribution) based on their CCL e.g. 40cm 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 fromthe 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 theepidermal 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 plasticRototags (provided by RAC/SPA, Tunis). Suggett & Houghton (1998) provided evidence thatRototags can increase the risk of turtles becoming entangled in fishing gear, and so in this studywe used a single Stockbrand’s titanium tag (these tags lock into a closed u‐shape).

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 Albanianaddress, in order to reinforce the conservation message; fishermen thought that the Rototagshad been applied in Tunisia due to the RAC/SPA address marked on the tag. WhenRoto‐tagged turtles were recaptured, the plastic tags were removed and replaced with atitanium tag.


Proceedings68

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:

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 isseen 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 theprevious studies related to the distribution of C. caretta in this area (Haxhiu, 2005, 2007) wehave this view: in 2002 the largest number of individual resulted in September (50 individual); in2003 in May (71 individual); 2004 in July (24 individual); in 2005 in June (25 individual); 2006 inJune (15 individual).

2. Size – classes

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

Table 1. Number of loggerhead in each cm size – class of CCL.

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

CCL 40 50 60 70 80 Total

June 0 17 26 17 2 62July 2 10 20 4 0 36August 1 0 0 0 0 1

September 1 0 0 1 0 2

December 0 0 0 1 0 1

Total 4 27 46 23 2 102


Proceedings 69

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 cmsize – class (2 individual).

3. Head epidermal scales

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

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

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 neverless than 4. While to the other species Chelonia mydas this number is always 2. In this way thenumber 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 5prefrontal scales (which is normal), while the smallest number of individual have had 8prefrontal 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).


Proceedings70

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 thatthis 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 isbecause of some secondary characteristics features, as can be: males tail length; size andmorphology of carapace; the hole in the plastron or the development of nail in the front limbs ofa male individual. The most obvious feature to an adult male is the tail, which is too long andextend outside the carapace (see Figure 10).

Figure 10. The extended tail of an adult male loggerhead (left)A male individual of C. caretta (right)

While when we talk abuot an individual adult female, it can be easily traced because they havea short tail and in most cases the length of the tail does not extend out of carapace (see Figure11).


Proceedings 71

Figure 11. A female individual of C. caretta (left). Demonstration of morphological elementsor 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 itcan not be used as an element to determine their sex (Limpus, 1985; Wibbles, 1988). Indetermining 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 specialequipment (Wood et al., 1983; Limpus & Reed; Limpus, 1985). In this study we have classifiedthe individual of C. caretta into three groups regarding to their sex: Female, male andundetermined (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 taillength (TTL); Distance from tip of tail to posterior margin of the carapace (+/- cara) (see Figure11).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 itis seen in the following chart we have a dominance of female individual over the males andquite a large number of undetermined individual (juvenile).

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


Proceedings72

5. Epibionts

Epiobionts (epibiontic flora and epibiontic fauna) is very widespread in sea turltles (Oliverio etal., 1992). The individual of C.caretta were studied for the presence of epibionts. Most ofindividuals presented epibiontic flora (mainly green algae) and epibiontic invertebrates, Balanusspp. 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 (epibionticfauna and epibiontic flora) in a percentage of 48.6 % against them who were clean (withoutepibionts) in a percentage of 51.4 % (see Figure 13).

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 trawlingoperations in this area; all them were tagged, using Stockbrands titanium tags. About 95individuals 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 veryimportant 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 beconsidered as very important, because so far in Albanian coastline has not been found anynesting activity. Having these high percentage of female we can say that in the future Albaniancoastline 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 itis known males spend all their life-cycle on the sea and is very difficult to study them. As thedistribution and marine ecology of male turtles is poorly understood, this unusual assemblagecan be considered an important and highly-significant finding. We can say that Patoku lagoonmay be a male foraging and developmental habitat, as 19.60 % of all individual studied weremales.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 causeany damages to turtles, except of making their body a little havy for swimming. Thus, their arenot parazite to sea turtles, but they use the shell of these animals to fix on it and while turtlesare swiming in differents habitats they feeds.From the three year project was concluded that Drini Bay is a regionally and nationally importanthabitat that is used by sea turtles for foraging, as a refuge and as part of a key migratorycorridor between the Ionian and Adriatic Seas.


Proceedings 73

References

Haxhiu, I. (1979). Percaktues i Reptileve te Shqiperise. Shtepia Botuese e Librit Universitar. Tirane.1 – 144.

Haxhiu, I. (1980). Rezultate te studimit te reptileve ne vendin tone. Disertacion.‐ Biblioteke Kombetare,Tirane. 1‐102.

Haxhiu, I. (1981). Emertime popullare te zvarranikeve ‐ Studime Filologjike. (4): 209‐ 217.

Haxhiu, I. (1985). Rezultate te studimit te breshkave ne vendin tone (Rendi Testudines) . Bul Shkenc.Nat. (2): 54‐60.

Haxhiu, I. (1995). Results of studies on the Chelonians of Albania. Chelonian Conservation and Biology.,Florida – USA. (1). Nr. 4 : 324‐327.

Haxhiu, I. (1998). The Reptilia of Albania: species composition, distribution, habitats. Bonn Zool. Jb.Syst. (121): 321‐334.

Haxhiu, I., Rumano, M. (2005). Conservation project of sea turtles in Patok, Albania. ProceedingsSecond Mediterranean Conference on Marine Turtles. Kemer. 87-90.

Haxhiu, I., (2010) Albania Pp. 5-28 in Casale, P. D. Magritoulis (Eds) 2010. Sea turtles in theMediterranean: Distribution, threats conservation priorities. Gland, Swizerland: IUCN. 296.

Haxhiu, I. (1998). The Reptiles of Albania: Species compositions, distribution, habitats. Bonn, zool. Beitz.(48): 35-37.

Limpus, C. J. (1985). A study of loggerhead sea turtle, C. caretta in eastern Australia. Ph.D. disertation.Univ. Queensland, Brisbane, Australia.

Oliverio, M., Gerosa, G., Cocco, M. (1992). First record of Pinctada radiata (Bivalvia, Pteriidae) epibionton the loggerhead sea turtle Caretta caretta (Chelonia, Cheloniidae). Boll. Malacol.( 28): 149-152.

Suggett DJ, Houghton JDR (1998) Possible link between sea turtle bycatch and flipper tagging in Greece.Marine Turtle Newsletter 81: 10‐11.

White, M. G. (2007). Marine ecology of loggerhead sea turtles Caretta caretta (Linnaeus, 1758) in theIonian Sea: Observation from Kefalonia and Lampedusa. Ph.D. Thesis, University College Cork,Irleand. 300.

White, M. (2006). Photo‐recognition: a technique used to identify individual loggerhead turtles in themarine environment. In: Frick, M., A. Panagopoulou, A.F. Rees and K. Williams (Eds.), Book ofAbstracts. Twenty‐Sixth Annual Symposium on Sea Turtle Biology and Conservation. InternationalSea Turtle Society. Crete, Greece. 376.

White, M., Haxhiu, I., Kararaj, E., Mitro, M., Petri, L., Saçdanaku, E., Trezhnjevna, B., Boura, L.,Grimanis, K., Robinson, P., Venizelos, L. (2010). Monitoring and Conservation of Important SeaTurtle Feeding Grounds in the Patok Area of Albania 2008‐2010. Project Report.

Wood , J. R., Wood, F.E., Critchley, K.H., Wildt, D.E., Bush. M. (1983). Laparoscopy of the green seaturtle. British Journal of Herpetology. (6):323-327.

Zeko, I., Puzanoi, V., (1960). Nje breshke oqeanike ne bregdetin tone [An oceanic turtle in our seaside].Buletini I Shkencave Natyrore [Bulletin of Natural Sciences]. (4): 145-146.


Proceedings74

data about loggerhead sea turtle (caretta caretta l. 1758) in patoku lagoon, albania

Documents