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Öğe Age, Growth and Reproduction of the Thornback ray, Raja clavata (Linnaeus, 1758) in the Waters Off Gökçeada (the Northern Aegean Sea)(Springer Science and Business Media Deutschland GmbH, 2023) Yığın, Cahide Çiğdem; Cabbar, Koray; İşmen, Ali; Daban, İsmail Burak; Arslan İhsanoğlu, MukadderIn this study, the age, growth, maturity, and reproductive biology parameters of 262 Raja clavata, which were collected monthly from commercial trawlers off Gökçeada between February 2019 and February 2020, were estimated. The individuals comprise of 55.7% females and 44.3% males. The length of the females ranged between 23-84.2 cm (Disc width: 13.5-55.8 cm) and 11.2-74 cm (Disc width: 8-48.9 cm) for males. For age determination, age readings were performed on the vertebrae of 255 Raja clavata specimens (43.5% female, 56.4% male). The calculated von Bertalanffy growth parameters were estimated to be L∞= 93.04 cm, K=0.17 years-1, to=0.48 years for males, and L∞=102.46 cm, K=0.16 years-1, t0 =0.72 years for females. The minimum and maximum ages of the thornback rays ranged from 1 to 10 years. The first sexual maturity length of the population was measured to be L50 =57.7 cm in males, and L50 =66.1 cm in females.Öğe Age, Growth and Reproductive Biology of the Common Two-Banded Seabream (Diplodus vulgaris Geoffroy Saint-Hilaire, 1817) from the Northern Aegean Sea, Turkey(Springer International Publishing Ag, 2019) İşmen, Ali; Daban, Ismail Burak; Ihsanoglu, Mukadder Arslan; Yigin, Cahide Cigdem; Cabbar, Koray; Atak, SibelThe present study aims to describe population dynamics (age, growth, mortality and fecundity) of common two-banded seabream. Sampled individuals were obtained monthly between November 2017 and October 2018 directly from commercial fisherman in the Northern Aegean Sea. Ages were estimated from 327 otolith readings; the minimum and maximum ages observed were 1 and 8 years, respectively, corresponding to 13 and 29 cm total length (TL). The length-weight relationship was W = 0.0156*L-2.97 (R-2 = 0.92) for the whole population and isometric growth was detected. The growth parameters of Von Bertalanffy fitted to back-calculated size for age data were: L infinity = 30.69 cm, K = 0.20 and t(0) = -2.64 per year. The instantaneous rates of total mortality (Z) and natural mortality (M) were 0.86 and 0.47 per year, respectively. Rates of fishing mortality F and exploitation E were 0.39 and 0.35 per year, respectively. The spawning season extended from September to March and peaked in December. Total lengths at 50% maturity were 18.32 cm for males and 20.37 cm for females. Mean absolute fecundity (F) was 73,154 +/- 10,271 oocytes, ranging from 10,727 to 316,730.Öğe Age, growth and reproductive biology of the saddled seabream (Oblada melanura) in the North Aegean Sea, Eastern Mediterranean(Walter De Gruyter Gmbh, 2020) Daban, Ismail Burak; İşmen, Ali; Ihsanoglu, Mukadder Arslan; Cabbar, KorayThis study determines the length distribution, length-weight relationship, age, growth parameters, mortality rate, sex ratios, length at first maturity and reproduction of saddled seabream (Oblada melanura) collected monthly by fishermen around the Northern Aegean Sea between November 2017 and October 2018. The length-weight relationship was calculated as W = 0.0091 x L-3.11 (R-2 = 0.95) and positive allometric growth was found. The condition factor and GSI varied between 0.81-1.58 and 0.01-9.61, respectively. The spawning season extended from May to July and peaked in June. Total lengths at 50% maturity were 18.97 cm for males and 18.83 cm for females. Parameters of the von Bertalanffy growth equation were: L-infinity = 29.91 cm, K = 0.27 per year, t(0) = -0.82 year and age varied between 1 and 8. The instantaneous rates of total mortality (Z) and natural mortality (M) were 1.36 and 0.58 per year, respectively. Rates for fishing mortality F and exploitation E were 0.78 and 0.57 per year, respectively. The mean absolute fecundity (F) was 117 075 +/- 23 243 oocytes, ranging from 19130 to 470 132.Öğe Biology of the thornback ray (Raja clavata Linnaeus, 1758) in the North Aegean Sea(De Gruyter Open Ltd, 2021) Cabbar, Koray; Yığın, Cahide ÇiğdemThe study deals with aspects of the population dynamics in the thornback ray (Raja clavata L., 1758), one of the most abundant cartilaginous fish caught in the North Aegean Sea. Females accounted for 73.08% and males 26.92% of all individuals. Total length of females and males ranged between 50.2 and 89.9 cm (disc width: 33.4-62.0 cm), and between 43.1 cm and 82.7 cm (disc width: 30.7-64.2 cm), respectively. Relationships between total length (TL) and total weight (TW), and between disc width (DW) and total weight (TW) were described by the equations: TW = 0.0041 TL3.10 and TW = 0.0178 DW3.03, respectively. Age data derived from vertebrae readings were used to estimate growth parameters using the von Bertalanffy function: L∞ = 101.71 cm, K = 0.18 y-1, t0 = -0.07 y for males and L∞ = 106.54 cm, K = 0.16 y-1, t0 = -0.28 y for females. The maximum age was 8 years for males and females. Total length at first maturity of males and females was 70.9 cm and 81.2 cm, respectively. Based on the gonadosomatic index and gonadal macroscopic observations, it was determined that the spawning period lasted throughout the year. Stomach content analysis showed that crustaceans (53.03% IRI) and teleosts (14.70% IRI) were the most preferred prey.Öğe Feeding Ecology of Thornback Ray, Raja clavata (Linnaeus 1758) in Gökçeada Island, Northern Aegean Sea, Turkey(Springer Science and Business Media Deutschland GmbH, 2022) Daban, İsmail Burak; Cabbar, Koray; Yığın, Cahide ÇiğdemThe dietary composition and nutritional alteration resulting from time and size of thornback ray, Raja clavata, were investigated in the present research. For this purpose, the individuals were obtained from the commercial bottom trawl vessels operated around Gökçeada Island, North Aegean Sea, Turkey between February 2019 and February 2020. The female:male ratio was found to be 1:0.79. The vacuity index was calculated for males, females and both individuals to be 5.8%, 4.7%, and 5.3%, respectively. The major food item groups were determined to be decapod crustaceans, teleost fish, and cepholopoda with IRI% (Index of Relative Importance) values of 77.72, 7.05, and 0.25, respectively. The best-represented food item was found to be Goneplax rhomboides. The prey types, abundance, and biodiversity were observed to change with the increasing lengths of R. clavata. The trophic level (TLw) of R. clavata was calculated to be 3.27, and it was observed that the TLw values were increased with the increasing individual length. The diet overlap was found to range from 40 to 49 cm and 50 to 59 cm TL in autumn and winter. The highest prey biodiversity was found in the length group of 70–85 cm TL and during spring. This study presents detailed findings on the feeding behaviour of R. clavata. In the future, food competition between the species should be monitored to develop a better understanding of the diet overlap. Thus, more comparisons should be conducted between the studies performed in varied geographical areas.Öğe Feeding habits of two skate species, Raja miraletus Linnaeus, 1758 and Dipturus oxyrinchus (Linnaeus, 1758) (Chondrichthyes, Rajidae), around the Gokceada Island (Northern Aegean Sea)(Ege Univ, Fac Fisheries, 2023) Cabbar, Koray; Yigin, Cahide CigdemThis study investigated the feeding habits of Raja miraletus Linnaeus, 1758 and Dipturus oxyrinchus (Linnaeus, 1758). For the purpose of this study, the specimens were obtained monthly from the commercial trawlers operating around the Gokceada Island in the Northern Aegean Sea between February 2019 and February 2020. A total of 29 (24 female and 5 male) brown rays (Raja miraletus) and 36 (20 female and 16 male) longnosed skates (Dipturus oxyrinchus) were captured. The total lengths of the R. miraletus specimens ranged between 24.0 cm and 53.9 cm, while the D. oxyrinchus specimens measured between 17.1 cm and 85.0 cm. Total length-weight relationships of R. miraletus and D. oxyrinchus specimens, respectively; W=0.0002TL(3.92) (R-2=0.97) and W=0.0007TL(3.43) (R-2=0.97) were calculated. The analysis of the stomach content of the specimens showed that crustacea were the primary and the most important prey group for R. miraletus (IRI% = 67.09), followed by teleosts (IRI% = 1.00) and cephalopods (IRI% = 0.45). The D. oxyrinchus specimens were determined to primarily feed on crustacea (IRI% = 74.3), followed by teleosts (IRI% = 6.50) and nematoda (IRI% = 0.40).Öğe Kuzey Ege denizindeki dikenli vatoz Raja clavata (Linnaeus, 1758)'nın bazı biyolojik özellikleri(Çanakkale Onsekiz Mart Üniversitesi, 2018) Cabbar, Koray; Yığın, Cahide ÇiğdemBu çalışmada, Kuzey Ege Denizi'nden 104 adet Raja clavata bireyinin boy-frekans dağılımı, toplam boy-toplam ağırlık ve disk genişliği-toplam ağırlık ilişkileri, cinsiyet oranları, yaş, büyüme, üreme ve beslenmesi araştırılmıştır. Toplam çalışılan bireyin %73,08'ni dişiler, %26,92'ni erkekler oluşturmuştur. Cinsiyet oranı, D:E 2,71:1 olarak belirlenmiştir. Dişilerde toplam boy 50,2 cm ve 89,9 cm (Disk genişliği; 33,4 cm?62,0 cm) arasında iken, erkeklerde 43,1 cm ile 82,7 cm (Disk genişliği; 30,7 cm?64,2 cm), arasında değişmiştir. Toplam boy (TL)-toplam ağırlık (TW) ve disk genişliği (DW)-toplam ağırlık (TW) ilişkileri sırasıyla, TW=0,0041TL3,10, r2=0,93 and TW=0,0178DW3,03 denklemleriyle tanımlanmıştır. Omur okumalarından elde edilen yaş verileri, von Bertalanffy büyüme parametrelerinin hesaplanmasında kullanılmıştır: Erkekler için, L?=101,71 cm, K=0,18 y-1, t0=?0,07 y ve dişiler için, L?=106,54 cm, K=0,16 y-1, t0=?0,28 y. Maksimum yaş erkekler ve dişiler için 8'dir. İlk eşeysel olgunluk boyu erkekler ve dişiler için sırasıyla, 70,9 cm ve 81,2 cm'dir. Gonadosomatik indeks ve gonadların makroskopik gözleminden, yumurtlama peryodu tüm yıl boyunca sürmektedir. Mide içeriği analizlerinde en çok tercih edilen türlerin krustase (%53,03 IRI) ve kemikli balıklar (%14,07 IRI) olduğu tespit edilmiştir. Anahtar sözcükler: Raja clavata, Dikenli Vatoz, Yaş, Büyüme, Üreme, Beslenme, Ege Denizi.Öğe Length-Weight Relationships of Elasmobranch Species From Gokceada Island in the Northern Aegean Sea(Springer Science and Business Media Deutschland GmbH, 2021) Cabbar, Koray; Yığın, Cahide ÇiğdemLenght – weight relationships (LWRs) were estimated for eight elasmobranchs (five sharks and three batoids) off the Gökçeada Island, Northern Aegean Sea. All specimens were collected by commercial bottom trawl at depths ranging from 120–400 m between February and November 2019. A total of 2991 individuals (1143 Scyliorhinus canicula, 110 Scyliorhinus stellaris, 795 Galeus melastomus, 575 Etmopterus spinax, 48 Squalus acanthias, 255 Raja clavata, 29 Raja miraletus, 36 Dipturus oxyrinchus) were sampled and studied. Results showed that most species had positive allometric growth and the values of parameter b ranged between 2.93 and 4.01. Furthermore, five shark (Mustelus asterias, Mustelus mustelus, Centrophorus granulosus, Hexanchus griseus, Oxynotus centrina) and eight batoid species (Dasyatis pastinaca, Gymnura altavela, Pteromylaeus bovinus, Leucoraja naevus, Rostroraja alba, Myliobatis aquila, Torpedo marmorata, Tetronarce nobiliana) were described, yet because they amounted to less than ten, only their respective descriptive statistics were determined.Öğe Müsilajın Çanakkale Boğazı’nda Dağılım Gösteren Posidonia oceanica Çayırlarına Etkisi(2023) Ak, İlknur; Yığın, Cahide Çiğdem; Ayaz, Adnan; Altınağaç, Uğur; Öztekin, Alkan; Şen, Yusuf; Cabbar, Koray2021 yılı içerisinde Marmara Denizi ve Türk Boğazlar Sistemlerinde, su sıcaklığına bağlı olarak birincil üretimde önemli rol oynayan mikro alglerin aşırı çoğalması sonucunda hücre dışı polisakkaritlerden oluşan Müsilaj adı verilen bir olay meydana gelmiştir. Gerçekleştiği alanın büyüklüğü ve etkilenen canlı topluluklarının sayısı dikkate alındığında ülkemiz denizel alanlarında gerçekleşen en büyük çevre felaketi olarak tarihte yerini almıştır. Bu nedenle Çanakkale Boğazı’nda dağılım gösteren deniz çayırlarının bu olaydan sonra durum tespiti önem taşımaktadır. Çalışma kapsamında Çanakkale Boğazı, Dardanos mevkiinde dağılım gösteren P. oceanica çayırlarının mevcut durumu belirlenerek, fenolojik ve lepidokronolojik çalışmaları yapılmış ve BiPo indeksine göre “Ekolojik Kalite oranları” belirlenmiştir. Çalışma sonucunda son sekiz yılda Dardanos bölgesinde dağılım gösteren deniz çayırı alt limitinin yaklaşık 1,4 m gerileyerek 15,6 m derinliğe kadar dağılım gösterdiği tespit edilmiştir. Ayrıca 2014 yılında deniz çayırlarının alt limit sınırlarında yeşil alglerden Caulerpa racemosa yoğun olarak dağılım gösterirken gerçekleştirdiğimiz çalışmada alt limit sınırlarında Ceremiales takımına ait kırmızı alglerin varlığı dikkat çekmiştir. BiPo indeksine göre elde edilen ekolojik kalite oranları 0,30- 0,20 arasında değişim göstermiştir. Çalışma sonucunda, bu indekse dayanarak Dardanos bölgesindeki P. oceanica çayırlarının müsilaj olayından sonra durumu \"kötü\" olarak belirlenmiş olup bu bölgedeki çayırların korunması yönelik eylem planlarının oluşturulması önem arz etmektedir.Öğe New Occurrence of Atlantic Tripletail, Lobotes surinamensis (Bloch, 1790) from the Turkish Part of the Aegean Sea, with Biological Notes(2021) Daban, İsmail Burak; Cabbar, KorayA new record of Lobotes surinamensis (Bloch, 1790) around Saros Bay, North Aegean Sea is presented, based on a single hermaphrodite specimen with detailed biological information. On 12 June 2018, the specimen was captured by fishermen with gillnets at a depth of 25 m. Sex, age, and stomach content were determined. This new record proves the Northernmost distribution of the species in the Turkish part of the Aegean Sea.Öğe Reproductive biology of Penaeus kerathurus (Forskal, 1775) (Decapoda: Penaeidae) in the Sea of Marmara, Turkey(De Gruyter Open Ltd, 2021) Arslan İhsanoğlu, Mukadder; Daban, İsmail Burak; İşmen, Ali; Cabbar, Koray; Yığın, Cahide ÇiǧdemOne of the economically important species is Penaeus kerathurus (Forskål, 1755), which is widespread in the Mediterranean ecosystem. This paper presents results of research on reproductive biology of Penaeus kerathurus in the Sea of Marmara. A total of 1404 specimens were dissected to determine the maturity stages, reproduction time, and length at first reproduction. The female-to-male ratio was 1:0.9. A high percentage of mature females was determined in April, May and July. Moreover, the value of the gonadosomatic index (GSI) decreased after July. The spawning period was observed between April and July, and its intensity increased in July. The carapace length at first sexual maturity was determined to be 39 mm.Öğe THE LIVER LIPID FATTY ACID COMPOSITION OF TWO CARTILAGINOUS FISH, THE THORNBACK RAY (Raja clavata) AND THE COMMON SMOOTH-HOUND (Mustelus mustelus)(2019) Yığın, Çiğdem Cahide; Çakır, Fikret; Cabbar, Koray; Kızılkaya, Bayram; Ormancı, Hasan Basri; Öztekin, Alkan; Özüdoğru, YelizWe have evaluated the fatty acid composition of the livers from two cartilaginous fish species Rajaclavata (thornback ray) and Mustelus mustelus (common smooth-hound) caught off the NorthernAegean Sea. While there was generally little variation between species, Mustelus mustelus indicated low saturated (SFA) in summer (29.61%), in spring (32.57%), in autumn (30.07%) and inwinter (31.81%) and high polyunsaturated fatty acid (PUFA) in summer (40.35%), in spring(36.50%), in autumn (30.21%) and in winter (27.26%) levels. The dominant fatty acids were palmitic acid (C16:0), oleic acid (C18:1 (n-9)), eicosapentaenoic acid (EPA; C20:5 (n-3)), and docosahexaenoic acid (DHA; C22:6 (n-3)) in both cartilaginous fish species in all seasons. The ratioof DHA/EPA with respect to the total of fatty acids in livers oils was ranged from 2.66% to 4.44%for Mustelus mustelus and 2.89% to 4.46% for Raja clavata. The n:3/n:6 ratio of thornback raywas higher compared to smooth-hound shark in all seasons. The liver oil of R. clavata and M.mustelus represent a valuable source of omega-3 PUFA that can be used for human and animalnutrition.
