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Gubili C.,University of Aberdeen | Gubili C.,Marine Biological Association of The United Kingdom | Bilgin R.,Bogazici University | Kalkan E.,Bogazici University | And 7 more authors.
Proceedings of the Royal Society B: Biological Sciences | Year: 2011

The provenance of white sharks (Carcharodon carcharias) in the Mediterranean is both a conundrum and an important conservation issue. Considering this species's propensity for natal philopatry, any evidence that the Mediterranean stock has little or no contemporary immigration from the Atlantic would suggest that it is extraordinarily vulnerable. To address this issue we sequenced the mitochondrial control region of four rare Mediterranean white sharks. Unexpectedly, the juvenile sequences were identical although collected at different locations and times, showing little genetic differentiation from Indo-Pacific lineages, but strong separation from geographically closer Atlantic/western Indian Ocean haplotypes. Historical long-distance dispersal (probably a consequence of navigational error during past climatic oscillations) and potential founder effects are invoked to explain the anomalous relationships of this isolated 'sink' population, highlighting the present vulnerability of its nursery grounds. © 2010 The Royal Society.

Status of the bramble shark, Echinorhinus brucus (Bonnaterre,1788), in the seas of Turkey has always been a point of debate until early 2000’s. With the addition of 7 recent records from the seas of Turkey, which constitues the 22.5 percent of the historical and contemporary records of the bramble shark from entire Mediterranean Sea, 31 individuals of E. brucus have been recorded from the entire region, and the record no. 7 of the present study is probably the most recently captured bramble shark, to date. Since 5 of the 7 recent records of E. brucus have been reported from the Sea of Marmara, special attention of research should be focused to this small inland sea to figure out whether this species has a localized population in this region or not. © 2014 University of Primorska. All rights reserved.

Extremely low number of records off Turkish coast from 1950’s to date confirmed the rarity of Cetorhinus maximus in Turkish waters. A specific scientific monitoring program accompanied by zooplankton surveys should be implemented as soon as possible to figure out the seasonal movements of C. maximus in the mentioned region to answer the question whether the occurrence of basking sharks in Turkish waters exhibits a seasonality and site fidelity or not? © 2013, University of Primorska. All rights reserved.

One hundred and fifty specimens of Hexanchus griseus (Bonnaterre, 1788) were caught by commercial fishing vessels in the seas of Turkey, between 16 July 1967 and 4 February 2013. Regarding the number of captured specimens per marine areas, the highest number of captures was recorded in the Sea of Marmara (90 specimens; 60%), followed by the Aegean (41 specimens; 27.3%), Mediterranean (15 specimens; 10%) and Black (3 specimens; 2%) seas. A single stranded individual was also recorded in the Çanakkale Strait. Regarding the number of recorded specimens it is obvious that the Sixgill Shark Data Bank of Turkey holds a significant number of H. griseus specimens caught in the eastern Mediterranean Sea, both reported in historical and contemporary studies. The sex ratio of the examined specimens of H. griseus is 1:2.61 in favour of females. Analysis of the fishing gear used for 72 of 150 examined sixgill sharks indicates that the most common fishing gear used to catch H. griseus is purse-seine, followed by several types of bottom fishing gear. Total length of the recorded specimens ranged between 50 and > 650 cm TL for both sexes; however, catches were dominated by two size groups, 250-350 cm and 350-450 cm TL, respectively. © 2013, University of Primorska. All rights reserved.

On 19 September 2014, a great white shark was incidentally caught by a stationary net set off Yeni Foça (38° 46′ 40″ N, 26° 53′ 40″ E), which was deployed for lobster fishing. The great white shark measured approximately 200 cm and weighed 40 kg. It was a juvenile male with uncalcified claspers, which were shorter than the pelvic fins. © 2015, University of Primorska. All rights reserved.

Kabasakal H.,Ichthyological Research Society
Marine Biodiversity Records | Year: 2011

A female great white shark, Carcharodon carcharias, was caught by a tuna hand-liner in the Bosphorus Strait, in late March 1968. Its total length was estimated to be 551 cm and precaudal length 433 cm. Carcharodon carcharias now seems to be extinct from the Sea of Marmara due to the decline of tuna populations in the Marmaric waters. Copyright © Marine Biological Association of the United Kingdom 2011.

In August 1998, a picture of a spinner shark, Carcharhinus brevipinna (Müller & Henle, 1839) was taken by an amateur group of divers at a depth of 3 m in Boncuk Bay (Gókova Bay, south Aegean Sea). Photographic evidence of this shark in Boncuk Bay contributes to our knowledge about the historical distribution of the species in Turkish waters. C. brevipinna is considered a very rare shark species in Turkish seas and needs immediate protection in Turkish territorial waters. The sighting of the spinner shark in the vicinity of a well-documented nursery ground of the sandbar shark, C. plumbeus, does not necessarily indicate a breeding ground for C. brevipinna in the studied area, as well; however, the possibility of a hypothetical nursery for the spinner shark in the Boncuk Bay area should be investigated in the future. © 2015, University of Primorska. All rights reserved.

Thirteen shark attacks were recorded in Turkey’s waters between 1931 and 1983. Ten out of the 13 attacks (76.9 %) occurred in the Sea of Marmara, and were followed by 2 attacks recorded in the Mediterranean and 1 attack in the Aegean Sea. In 7 attacks (53.8 %) targets were the fishing boats, of which 6 of them were boats of tuna handliners, while 6 attacks (46.2 %) were directly against humans. In 3 incidents (23.1 %) skin or scuba divers, who caught fish with a harpoon were attacked, while 3 attacks were against swimmers. Two attacks (15.3 %) were fatal. Large predatory sharks have been occurring in the vicinity of aquaculture cages, which are located along Turkey’s Aegean and Mediterranean coasts, as seen in the Güllük Bay incident; however, threats to public safety caused by the predator aggregations close to shorelines is still unknown. © 2015, University of Primorska. All rights reserved.

On 4 January 2014, a female specimen of Squatina squatina was entangled in trammel-net, at a depth of about 50 m. The specimen was 174 cm long (total length) and weighed approximately 35 kg. The recent single capture of S. squatina in the southeastern Sea of Marmara confirms the contemporary presence of the species in this landlocked small marine region; however, the paucity of the species in the fishing records of Marmaric fishes since 2000, confirms its rarity in the studied marine area. © 2014, University of Primorska. All rights reserved.

Kabasakal H.,Ichthyological Research Society
Mediterranean Marine Science | Year: 2010

During the last 58 years only 12 angular rough sharks have been recorded in Turkish waters. Rare captures of the species in the area indicate a need for immediate action to be taken for the conservation of O. centrina. To protect the habitat of O. centrina, strict regulations should be implemented regarding diving in the localities where angular rough sharks occur regularly. Protecting the habitat of the angular rough shark is an urgent need before subjecting O. centrina to 100% protection in the seas of Turkey.

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