SEA TURTLES IN NORTHERN ALBANIA: KEY RESULTS OF A THREE-YEAR RESEARCH PROGRAMME (2008-2010) Michael White1, Idriz Haxhiu2, Liza Boura1, Lily Venizelos1 1 MEDASSET - Mediterranean Association to Save the Sea Turtles, 1C Licavitou St., Athens, Greece. E-mail: medasset@medasset.org 2Herpetological Albanian Society, Tirana, Albania
Drini Bay
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Introduction During the three-year study (2008-2010) at Drini Bay in Northern Albania, 407 sea turtles were recorded as fisheries bycatch (402 Caretta caretta, 5 Chelonia mydas). The majority (99%) of turtles were captured in two ‘stavnike’ fish-traps (fixed-location poundnets); proving that this 30-km bay, which is rich in benthic fauna (e.g. bivalves & crabs), is an important nearshore foraging ground for loggerheads and more rarely for green turtles (White, Boura and Venizelos 2010, 2011)
Males: An unusually-high proportion (27%) of the turtles was male: adults (n=35); adolescents (n=77). When the adult and adolescent morphometrics were compared statistically there were highly-significant differences for CCL, CCW and the three tailmeasurements (see White et al. in prep).
Loggerhead in a Stavnike
Stavnikes are fixed location traps (90 ×10 m) set in shallow water (6-8 m)
Morphometric data
Comparison of CCL size-class ranges for males showed that there was a 12.5 cm overlap between the smallest adult (CCL = 68.5 cm) and the largest adolescent (CCL = 81.0 cm); it is not known how many years of growth this represents. The smallest male showing definite tail development was CCL 52.0 cm (White et al. 2011) Adult male’s tail
Short-tailed turtle
Adolescent male
Morphometrics
Females: Nesting has not been reported for Albania and thus it was more difficult to determine the size for maturity. By using CCL size-classes and, to a lesser extent, the tail measurements from the more-easily-recognisable males as a guide, short-tailed turtles were assumed to be female and categorised as: adult (CCL >70.0 cm); adolescent (CCL = 60-70 cm). This enabled another 160 turtles to be classified (adult=53; adolescent=107). A disadvantage of this approach was that the sex of the smallest size-classes remained unclear; these could be juveniles of either sex (White et al. in prep). Developmental habitat: Drini Bay is thus used as a developmental habitat: 69% of the captured turtles are not yet mature (77 adolescent males, 107 ‘assumed adolescent’ females and 98 uncategorised smaller animals) (White et al. in prep).
Juvenile C. mydas at Vlore (2009)
Table 1. CCL size-classes for turtles measured at Drini Bay (2008CCL 10)
Recaptures: Inter-annual recaptures showed that some turtles (n = 32) were at Drini in more than one year. This suggests that Drini bay is on a migratory route between the Ionian and Adriatic Seas; which is also reinforced by our telemetry study (see Oakley et al. poster). Their morphometric data enabled some incremental growthrates to be calculated; which also provided limited insight into the possible duration of adolescence and size-at-maturity. Interval between recaptures ranged from 9 to 84 months; CCL growth-rates for 26 loggerheads ranged between 0.0-4.9 cm/yr (Mean = 1.7 cm/yr; SD = ±1.4 cm/yr) (White et al. in prep). Turtles that were caught more than once in the same year (n = 54) demonstrate short-term residency; they were not expected to show significant growth between captures. None of the recaptured turtles had been tagged elsewhere (e.g. Greece or Croatia). International sightings Only two of the Project’s tags have been reported internationally: 1) A loggerhead turtle tagged and released from Patoku (16th June 2009) was seen by a diver in the Gulf of Sirte, Libya, November 2010 [tag # AL0045; CCL = 69.0 cm, adolescent male]. 2) A loggerhead tagged [tag # AL0127] and released from Patoku (31st July 2009) laid a nest at Sekania, Zakynthos, Greece (21/06/2011; ARCHELON pers. com.). At release CCL = 74.0 cm; ARCHELON reported CCL is now 77.5 cm; and they applied a 2nd tag [ZB752, plastic]. Therefore the incremental growth is 3.5 cm in almost two years (see White et al. in prep). This emphasises that sea turtles are migratory species and their protection requires multi-national co-operation. Albania had no sea turtle legislation, so to assist in this process MEDASSET has written a National Sea Turtle Management Strategy; which is now with the Albanian Government for review (see Boura et al. poster).
Turtles were allocated into 10-cm size-classes (White 2007) based on their curved-carapace-length CCL (Mean CCL = 64.5 cm; see Table 1.). Laparoscopy was not available and so measurements of the external tail morphology were used instead as an indicator to ascertain the stage of development of secondary sexual characteristics: i.e. to determine if the animals were adult or adolescent. Three measurements were recorded from the tail ventrally (Casale et al. 2005, White et al. 2011): i) Distance from posterior margin of plastron to midline of cloacal opening (Plas-clo) ii) Total tail length (TTL) iii) Distance from tip of tail to posterior margin of the carapace (+/cara)
Photo: M Mitro
Green turtles Chelonia mydas Migrating green turtles were also captured in stavnikes (2008 = 1; 2010 = 3). Another C. mydas was in a net at Vlore, southern Albania. Two of the records in 2010 are for adolescent males: these have been reported as a new life-stage for the Adriatic Sea; thus extending the known range for this species (White, Boura & Venizelos in press). MEDASSET informed the Convention on Migratory Species (1979) to now include Albania as a range state for C. mydas
2010 2009 2008 Totals
20 30 3 1 0 0 4
40 6 7 2 15
50 60 33 60 30 54 27 46 90 160
70 80 90 42 8 152 40 5 137 21 2 98 103 15 0 387
Table 1 shows that the majority of turtles measured at Drini Bay are in the 50-70 cm size-classes (Mean CCL = 64.5 cm; SD = ±9.2 cm; CCL range = 30.0–84.5 cm; n = 387 turtles; eight records were Drini Bay is an important foraging Conclusion: data deficient due to carapace damage & are not included here). developmental habitat; and These findings may provide a better understanding of Smaller the life cycle and marine turtles were rare and (and included 2 of the migrating Chelonia formsthepart of aanimal migratory corridor movements for turtles in the Mediterranean Sea and offer the as basis forlarge moreturtles; mydas), were biggest had a CCL of 84.5 comprehensive legislative measures to be enacted in the particularly cm region, (data from White etfor al.between in prep). the Ionian and Adriatic the protection of sea turtle migratory corridors. Seas Literature cited: Casale P, Freggi D, Basso R, Argano R (2005) Size at male maturity, sexing methods and adult sex ratio in loggerhead turtles from Italian waters investigated through tail measurements. Herpetological Journal 15: 145-148. White M, Boura L, Venizelos L (2010) An overview of MEDASSET’s role in sea turtle research and conservation in Albania. Testudo 7(2): 43-54. White M, Boura L, Venizelos L (2011) MEDASSET’s three-year project: Monitoring an important sea turtle foraging ground at Patok, Albania. Lead researcher: Dr Michael White This research was undertaken within the MTN in press Project researcher & national coordinator: Prof. Dr. Idriz Haxhiu framework of MEDASSET’s sea turtle conservation programmes in the Research Assistants: Esmeralda Kararaj, Enerit Saçdanaku, Marina Mitro, Lazjon Petri, White M, Kararaj E, Mitro M, Petri L, Saçdanaku E, Trezhnjevna B, Përkeqi D, Boura L, Robinson P, Venizelos L (in prep) Possible population Mediterranean. Project reports & papers are Dhurata Perkeqi, Bekim Trezhnjevna, Vilma Piroli structure for sea turtles at Drini Bay: an important nearshore foraging ground in Albania available at www.medasset.org Management Team: Liza Boura, Prue Robinson Funded by: MEDASSET; Global Environment Facility/Small Grants Programme; Regional Activity Centre/Specially Protected Areas; United Nations Environment Programme-Mediterranean Action Plan; British Chelonia Group; Panton Trust, Spear Charitable Trust; J F Costopoulos Foundation … our deepest thanks to you all for supporting this very successful project. Thanks also to Dr Oguz Turkozan & team; David Oakley; Atef Ouerghi; Arian Gace; Tatjana Hema,& Anne Rowberry.