Short scientific article	UDK 597.315.6:591.9(262.53)
Received: 2014-05-08
STATUS OF ANGELSHARK, SQUATINA SQUATINA (ELASMOBRANCHII: SQUATINIFORMES: SQUATINIDAE) IN THE SEA OF MARMARA
Hakan KABASAKAL & Özgür KABASAKAL
Ichthyological Research Society, Tantavi Mahallesi, Mentesoglu Caddesi, Idil Apt., No: 30, D: 4, Umraniye, TR-34764 Istanbul, Turkey
E-mail: kabasakal.hakan@gmail.com
ABSTRACT
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.
Keywords: Angelshark, Squatina squatina, Sea of Marmara, status, endangered, protection
STATO DELL'ANGELO DI MARE, SQUATINA SQUATINA (ELASMOBRANCHII: SQUATINIFORMES: SQUATINIDAE), NEL MARE DI MARMARA
SINTESI
Il 4 gennaio 2014, una femmina di Squatina squatina e rimasta impigliata in una rete tramaglio, ad una profonditä di circa 50 metri. La lunghezza totale dell'esemplare era pari a 174 cm per circa 35 kg di peso. La recente singola cattura di S. squatina nella parte sud-orientale del mare di Marmara conferma la presenza temporanea della specie in questa piccola semichiusa regione marina. Tuttavia, la scarsitä di segnalazioni della specie nei registri di cattura della fauna ittica del mare di Marmara dal 2000, conferma la sua raritä nell'area marina studiata.
Parole chiave: angelo di mare, Squatina squatina, mare di Marmara, stato, specie in via di estinzione, protezione
INTRODUCTION
The angelshark, Squatina squatina (Linnaeus, 1758) is a temperate-water bottom-dwelling shark of the European and North African continental shelves, present on or near the bottom from the close inshore, littoral zone to at least 150 m depth (Ebert & Stehmann, 2013). Its distribution range extends from North Eastern and Central Eastern Atlantic coasts to the entire Mediterranean and Black Seas (Serena, 2005; Ebert & Stehmann, 2013). Presence of S. squatina has been well documented both in historical (Ninni, 1923; Deveciyan, 1926; Rhasis Erazi, 1942) and contemporary records (Ak^iray, 1987; Kabasakal, 2002, 2003; Kabasakal & Kabasakal, 2004); however, in a recent ichthyological survey of Turkey, S. squatina is considered as a severely declined shark in Turkey's seas (Fricke et al., 2007).
Although the occurrence of S. squatina in the Sea of Marmara is well-documented in historical records and in the ichthyological inventories of the last quarter of the 20th century, the paucity of the species in the fishing records since 2000 necessiates an update of its status in Marmaric waters. With this aim, in the present article, authors report a recent catch of S. squatina in the Sea of Marmara, which confirms the contemporary occurrence of the species in marmaric waters.
MATERIAL AND METHODS
Since 2000, S. squatina has been studied by members of the Ichthyological Research Society (IRS), as part
Fig. 1: Map showing positions in the Sea of Marmara where S. squatina specimens were caught: present specimen caught on 4 January, 2014 (^), the female caught in November 1995 (^) and the specimen of Squatina spp. harpooned in 1950's (^).
Sl. 1: Zemljevid z označenimi lokalitetami v Mar-marskem morju, kjer so bili ujeti navadni sklati (S. squatina): obravnavani primerek, ulovljen 4. januarja 2014 (^), samica, ulovljena v novembru 1995 (^) in harpunirani primerek sklata v petdesetih letih prejšnjega stoletja (^).
of an extensive survey of sharks occurring in Turkey's seas. The actions of the society have been supported by local fishermen and divers, who have helped researchers in reporting sightings and collection of by-caught specimens. In the framework of this collaboration, the authors were informed on the recent and seldom captures or sightings of S. squatina from the several parts of the Sea of Marmara. Identification and nomenclature of the present specimen is based on Serena (2005) and Ebert & Stehmann (2013). Total length (TL) was measured to the nearest 0.5 cm with a measurement tape, and the weight of the specimen was recorded by means of a scale at the fishmarket to the nearest 0.1 kg. Morphological characters of the present angel shark were examined at the fishing port on fresh specimen. Photographs of the examined specimen are kept in the archives of IRS and available for inspection on request.
RESULTS AND DISCUSSION
On 4 January 2014, a female specimen of S. squatina was entangled in trammel-nets, at a depth of about 50 m (Fig. 1). The specimen measured 174 cm in total length and weighed approximately 35 kg (Figs. 2A, B). The following characters are based on the present specimen: trunk is broad; origin of first dorsal fin is in line with pelvic fin rear extremity; 35 teeth were counted on the upper jaw and 42 on the lower jaw; simple tips were observed on nasal barbels and anterior nasal flaps are weakly fringed; a single triangular lobe is present on lateral head folds on each side; dorsal surface is very rough due to very sharp, hook-shaped and closely spaced dermal denticles; entire ventral surface is also covered with dermal denticles; patches of small thorns are present on snout and on interorbital space; dorsal surface is uniformly dark greyish brown with small blackish spots scattered on the background coloration, and ventral surface is whitish.
Maximum total length of S. squatina can reach up to 250 cm (Serena, 2005), and females are sexually mature at 126 to 167 cm (Ebert & Stehmann, 2013). According to Capape et al. (1990) females of S. squatina reaches sexual maturity at 128 cm in the Mediterranean Sea. Based on these facts and the total length of aforementioned female, it can be assumed that it was sexually mature. According to Capape et al. (1990), the duration of the reproductive cycle of species of the genus Squatina is probably 2 years. Same authors assumed that in adult females oocyte growth might span also a 2-year period. Capape et al. (1990) also reported a remarkably low fecundity (7 to 18 uterine ova or embryos) for S. squatina, based on pregnant females caught off Tunisia's coasts.
Basic data collected following the search of old literature, published documents, interviews with fisherman, as well as personal observations, revealed that S. squatina has historically occurred in Turkey's marine waters,
adult female was caught at a depth of 50 m in southern Sea of Marmara (Kabasakal, 2003; Fig. 2C).
Besides those records, the species has also been recorded along the Aegean and Mediterranean coasts of Turkey. S. squatina comprised 1.1 % of total number of elasmobranchs (n = 4632) caught in the seas of Turkey during an extensive survey of elasmobranchs carried out between 1995 and 1999 (Kabasakal, 2002). The same species represented 0.46 % of total shark catches (n = 1068) recorded during fishery surveys carried out between 1995 and 2004 in the northern Aegean Sea (Kabasakal & Kabasakal, 2004). In a recent survey of the Marmaric fish fauna, Keskin & Eryilmaz (2010) considered S. squatina as a rare shark in the Sea of Marmara.
The rarity of S. squatina in different parts of the Mediterranean Sea has been highlighted by several authors in recent literature on sharks of this area. According to Lipej et al. (2004), S. squatina, once common and abundantly caught in the Adriatic Sea, is now considered to be rare throughout the region. A preliminary analysis of MEDITS data shows clear evidence of decline for most sharks and rays, as well as the risk of localised extirpation for some species which in the past were considered common, among which S. squatina is comprised (Serena & Relini, 2006). According to Hadjichristophoru (2006), S. squatina is an occasional shark in waters off Cyprus. Moreover, S. squatina is considered to be a rare shark also off the Mediterranean coast of Israel (Golani, 2006). Ba^usta et al. (2006) reported that the angelshark is included in the list of main species rarely observed, endangered or protected in the Mediterranean. During a survey of abundances of demersal sharks conducted in Central Mediterranean Sea between 1994 and 2009
Fig. 2: Two specimens of S. squatina from the Sea of Marmara. (A) Dorsal view of the present female caught on 4 January, 2014, while it was displaying in the fish market; (B) anterior view of the present female; (C) female S. squatina caught in November 1995 (TL 87 cm; ♦ in Fig. 1), details of this specimen are given in Kabasakal (2003). Sl. 2: Primerka navadnega sklata (S. squatina) iz Mar-marskega morja. (A) Zgornji del samice, ulovljene 4. januarja 2014 in fotografirane na ribji tržnici; (B) sprednji del samice; (C) samica sklata, ujeta novembra 1995 (TL 87 cm; ♦ na sliki 1), podrobnosti o tej samici je podal Kabasakal (2003).
while a clear decline is obvious in recent decades. First account on the presence of the angelshark in the seas of Turkey was recorded by Ninni (1923; reported as S. angelus), in which the species was considered by the author as a common and abundant species of shark in the Sea of Marmara. In addition to Ninni's account, records of S. squatina have also been reported by Deveciyan (1926) and Rhasis Erazi (1942). Recently, a single sub-
Fig. 3: A large specimen of Squatina sp., harpooned by a free-diver off Selimpa^a coast (^ in Fig. 1), northern Sea of Marmara, in 1950's.
Sl. 3: Velik primerek sklata (Squatina sp.), ki ga je har-puniralpotapljač na dah v vodah obale Selimpa^a (^ na sliki 1), v severnem delu Marmarskega morja v petdesetih letih prejšnjega stoletja.
only one specimen of S. squatina was caught off Malta's coast in 2005. Ragonese et al. (2013) concluded that rarity of the species is now confirmed in that region.
In the monumental work of Deveciyan (1926), the author reported that during the 1920's S. squatina was abundantly caught in Turkey's waters, particularly in June and July. Based on historical photographs of the species, now it is known that Squatina spp. has also been targeted by spearfishermen in Marmaric waters (Fig. 3). Serena (2005) considered S. squatina as a target species for demersal fishery in some parts of the Mediterranean. In addition to Serena's consideration, Bradai et al. (2006) reported that S. squatina is a regularly observed shark in Gulf of Gabes (Western Mediterranean). Contrary to the above statements, recent reports have pointed out a serious decline of angelshark populations in several parts of the Mediterranean (Lipej et al., 2004; Ba^usta et al., 2006; Golani, 2006; Hadjichristophoru, 2006; Serena & Relini, 2006; Ragonese et al., 2013); however, this decline does not mean that S. squatina was not caught. A similar trend in the decline of S. squatina catches has been observed in Bay of Biscay, where the annual catches of the species has been around 25,000 tons in 1850's off Arcachon coast and drastically declined to less than 300 kg in late 1990's (Quero, 1998).
According to FAO status evaluation for conservation and exploitation status of sharks and rays, S. squatina is categorized in B1, which means that it is a directly exploited or caught as bycatch species, that cannot be placed in any of the FAO status categories due to lack of data (Serena, 2005). Same author also stated that S. squatina is a vulnerable species in the entire Mediterranean. Regarding the status of the species in the seas of Turkey, S. squatina is a critically endangered shark in the aforementioned region, which is considered very sensitive to human activities (Fricke et al., 2007). Due to the severe decline of the species, Fricke et al. (2007)
also considered S. squatina as a high priority species for conservation action in Turkey's waters.
CONCLUSIONS
The recent single capture of S. squatina in the southeastern Sea of Marmara confirms the contemporary presence of the species in this land-locked 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. Due to life history parameters of S. squatina, such as low fecundity, long reproductive cycle (2 year) and large size at which females at sexual maturity (128 cm, which equals 51.2 % of reported maximum total length, 250 cm), this species is considered as highly vulnerable either to targeted or untargeted fisheries. Although, S. squatina is reported to be a high priority species for conservation action (Fricke et al., 2007), currently there are no regulatory measures regarding the fishing of the species implemented in the Turkey fisheries act. Therefore, immediate precautions should be taken for the release of specimens caught alive, such as the adult female of the present study, as a first step for the protection of S. squatina in the Sea of Marmara.
ACKNOWLEDGEMENTS
The authors wish to thank Mr. Bülent Kopuz who kindly and rapidly informed us of the capture of the female S. squatina and sent the photopraphs. Mr. Mark Taylor, an Istanbul based scuba instructor and underwater photographer, for kindly revising the English text. We are also indebted to Mr. Okan Ye^mil, an Istanbul based Scuba diver and collector of historical diving gears, for the photograph of the Squatina spp., seen in Figure 3. Special thank goes to our son Derin for his endless support and love.
STATUS NAVADNEGA SKLATA (SQUATINA SQUATINA) (ELASMOBRANCHII: SQUATINIFORMES: SQUATINIDAE) V MARMARSKEM MORJU
Hakan KABASAKAL & Özgür KABASAKAL
Ichthyological Research Society, Tantavi Mahallesi, Mentesoglu Caddesi, Idil Apt., No: 30, D: 4, Umraniye, TR-34764 Istanbul, Turkey
E-mail: kabasakal.hakan@gmail.com
POVZETEK
Četrtega januarja 2014 je bila na globini približno 50 m ujeta samica navadnega sklata fSquatina squatina) v trislojno stoječo mrežo. Primerek je meril 174 cm v dolžino in tehtal približno 35 kg. Novejši podatek o ujetju sklata v jugovzhodnem delu Marmarskega morja potrjuje prisotnost te vrste v tem majhnem in zaprtem morju. Kakorkoli že, maloštevilnost podatkov v ribiških zapisih kaže, da je vrsta v tem morju redka.
Ključne besede: navadni sklat, Squatina squatina, Marmarsko morje, status, ogrožena vrsta, varovanje
REFERENCES
Akfiray, F. (1987): Türkiye Deniz Baliklari Ve Tayin Anahtari, 2nd Edition. Publications of Istanbul University, no. 3490, Istanbul, 811 p.
Bafusta, N., Keskin, F. Serena & B. Seret (eds.) (2006): The Proceedings of the Workshop on Mediterranean Cartilaginous Fish with Emphasis on Southern and Eastern Mediterranean. Turkish Marine Research Foundation, Publication No. 23, Istanbul, Turkey.
Bradai, M. N., S. Bechir, S. Enajjar & A. Bouain (2006): The Gulf of Gabes: a spot for the Mediterranean elasmobranchs. In: Ba^usta, N., Keskin, F. Serena & B. Seret (eds.): The Proceedings of the International Workshop on Mediterranean Cartilaginous Fish with Emphasis on Southern and Eastern Mediterranean. 14-16 October 2005, Istanbul, Turkey. Turkish Marine Research Foundation, pp. 107-117.
Capape, C., J. P. Quignard & J. Mellinger (1990): Reproduction and development of two angel sharks, Squa-tina squatina and S. oculata (Pisces: Squatinidae), off Tunisian coasts: semi-delayed vitellogenesis, lack of egg capsules, and lecithotrophy. J. Fish Biol., 37, 347-356.
Deveciyan, K. (1926): Peche et Pecheries en Turquie. Imprimerie de l'Administration de la Dette Publique Ottomane, Istanbul, 480 pp.
Ebert, D. A. & M. F. W. Stehmann (2013): Sharks, batoids and chimaeras of the North Atlantic. FAO Species Catalogue for Fishery Purposes, No. 7. FAO, Rome, 523 p.
Fricke, R., M. Bilecenoglu & H. M., Sari (2007): Annotated checklist of fish and lamprey species (Gnatho-stomata and Petromyzontomorphi) of Turkey, including a Red List of threatened and declining species. Stuttg. Beitr. Natkd. A Biol., 706, 1-169.
Golani, D. (2006): Cartilaginous fishes of the Mediterranean coast of Israel. In: Ba^usta, N., Keskin, F. Serena & B. Seret (eds.): The Proceedings of the International Workshop on Mediterranean Cartilaginous Fish with Emphasis on Southern and Eastern Mediterranean. 14-16 October 2005, Istanbul, Turkey. Turkish Marine Research Foundation, pp. 95-100.
Hadjichristophoru, M. (2006): Chondrichthyes in Cyprus. In: Ba^usta, N., Keskin, F. Serena & B. Seret (eds.): The Proceedings of the International Workshop on Mediterranean Cartilaginous Fish with Emphasis on
Southern and Eastern Mediterranean. 14-16 October 2005, Istanbul, Turkey. Turkish Marine Research Foundation, pp. 162-168.
Kabasakal, H. (2002): Elasmobranch species of the seas of Turkey. Annales, Ser. Hist. Nat., 12 (1), 15-22.
Kabasakal, H. (2003): Historical and contemporary records of sharks from the Sea of Marmara, Turkey. Annales, Ser. Hist. Nat., 13 (1), 1-12.
Kabasakal, H. & E. Kabasakal (2004): Sharks captured by commercial fishing vessels off the coast of Turkey in the northern Aegean Sea. Annales, Ser. Hist. Nat., 14 (2), 171-180.
Keskin, g. & L. Eryilmaz (2010): Fish fauna of the Sea of Marmara and Demersal Fish Assemblages. Proceedings of The Symposium of the Sea of Marmara. 25-26 September 2010, Istanbul, Turkey, pp. 289-311.
Lipej, L., A. De Maddalena & A. Soldo (2004): Sharks of the Adriatic Sea. Knjižnica Annales Majora, Koper, 253 p.
Ninni, E. (1923): Primo contributo allo studio dei pesci e della pesca nelle acque dell'impero Ottomano. Missione Italiana per l'Esplorazione dei Mari di Levante. Premiate Officine Grafiche Carlo Ferrari, Venezia, 187 p.
Quero, J.-C. (1998): Changes in the Euro-Atlantic fish species composition resulting from fishing and ocean warming. Ital. J. Zool., 65 (Suppl.), 493-499.
Ragonese, S., S. Vitale, M. Dimech & S. Mazzola (2013): Abundances of demersal sharks and chimaera from 1994-2009 scientific surveys in the Central Mediterranean Sea. PLoS ONE, 8 (9), e74865.
Rhasis Erazi, R. A. (1942): Marine fishes found in the sea of Marmara and in the Bosphorus. Rev. Fac. Sc. Univ. Istanbul, B, 7, 103-115.
Serena, F. (2005): Field identification guide to the sharks and rays of the Mediterranean and Black Sea. FAO Species Identification Guide for Fishery Purposes. FAO, Rome, 97 p.
Serena, F. & G. Relini (2006): Use of scientific campaigns (trawl surveys) for the knowledge of the sensitive habitats. A review of the MEDITS, GRUND and APHIA data with special attention to the Italian seas. In: Ba^us-ta, N., g. Keskin, F. Serena & B. Seret (eds.): The Proceedings of the International Workshop on Mediterranean Cartilaginous Fish with Emphasis on Southern and Eastern Mediterranean. 14-16 October 2005, Istanbul, Turkey. Turkish Marine Research Foundation, pp. 135-148.