Yazar "Akyol O." seçeneğine göre listele

Listeleniyor 1 - 20 / 51
  • Küçük Resim Yok
    Öğe
    Additional record of the Lessepsian Apogon queketti Gilchrist, 1903 (Osteichthyes: Apogonidae) from the Aegean Sea (Gökova Bay, Turkey)
    (Blackwell Publishing Ltd, 2015) Akyol O.; Ünal V.
    [No abstract available]
  • Küçük Resim Yok
    Öğe
  • Küçük Resim Yok
    Öğe
    Additional records of two lessepsian fish, Siganus Luridus and champsodon vorax from izmir bay (Aegean sea, Turkey) [Nuove segnalazioni di due pesci lessepsiani, Siganus Luridus e champsodon vorax, dalla baia di smirne (mar egeo, Turchia)] [Dodatni zapisi o pojavljanju dveh vrst lesepskih ribjih selivk, Siganus Luridus in champsodon vorax, iz izmirskega zaliva (egejsko morje, Turcija)]
    (University of Primorska, 2015) Akyol O.; Aydin İ.
    Two Lessepsian fish species, Siganus luridus (Siganidae) and Champsodon vorax (Champsodontidae) were reported for the second time from the Bay of Izmir, NE Aegean Sea and some morphometric and meristic characteristics of the specimens were also given. © 2015, University of Primorska. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Age, growth and mortality of Garfish, Belone euxini Günther, 1866 in the Central Black Sea, Turkey
    (University of Punjab (new Campus), 2019) Ceyhan T.; Samsun O.; Akyol O.
    A total of 986 garfish were collected from commercial fisheries, using encircling nets between October 2016 and December 2017 in Sinop, Central Black Sea. The length and weight distribution of all garfish samples ranged from 28.8 to 51.6 cm TL and from 26.6 to 177.2 g, respectively. Female: male ratio was 0.3:1. The LWR parameters (a, b, r 2 ) were computed as 0.0009 ± 0.50, 3.040 ± 0.32 and 0.902 ±0.40, respectively. The age of garfish was between 1 and 4 years. The estimated von Bertalanffy growth parameters with standard errors were L ? = 55.74 ±26.75 cm, K= 0.28 ±0.42, and t 0 =-1.68 ±2.02. Natural, fishing and total mortality of the garfish were 0.47, 0.69 and 1.16, respectively. The current study revealed that about 68% of the fish caught were of size smaller than the first maturity length. In addition, exploitation rate was found to be higher than optimum. On the other words, there is a fishing pressure on the garfish stock in the Black Sea due to absence of minimum landing size (MLS) of the garfish. Apart from direct fishing control measures aiming to reduce fishing mortality, the establishment of a MLS of 38cm that coincides with the length at first maturity would be also beneficial for the stock. Our results suggest that the garfish stock undergoes high levels of fishing pressure and the adoption of management measures is necessary. Copyright 2019 Zoological Society of Pakistan.
  • Küçük Resim Yok
    Öğe
    Capture of a bigeye thresher shark alopias superciliosus (Alopiidae) in turkish waters (eastern mediterranean sea) [Cattura di squalo volpe occhione alopias superciliosus (Alopiidae) in acque della turchia (mediterraneo orientale)] [Ulov velikooke morske lisice alopias superciliosus (Alopiidae) v turških vodah (vzhodno sredozemsko morje)]
    (Historical Society of Southern Primorska of Koper, 2020) Akyol O.; Ceyhan T.; Capapé C.
    The present paper reports a new capture of bigeye thresher shark, Alopias superciliosus (Lowe, 1839). To date, 9 specimens have been recorded in the area, suggesting that a viable population of this type of shark might be successfully establishing in the area, but other records are needed to confirm this hypothesis. The paper comments on the distribution of the species in the Mediterranean Sea, suggesting that it does not originate from this sea, but is probably a migrant species from the eastern tropical Atlantic or from the Indian Ocean. © 2020, Historical Society of Southern Primorska of Koper. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Capture of a New-born Shortfin Mako Shark Isurus Oxyrinchus (Lamniformes: Lamnidae), with Updated Records from the Turkish Marine Waters
    (Natural and Engineering Science, 2024) Akyol O.; Capape C.
    The study reports on the capture of a new-born specimen of shortfin mako shark Isurus oxyrinchus Rafinesque, 1810 off Karantina islet coast, Urla, Izmir (north Aegean Sea). This specimen measured 761 mm in total length and weighed 2900 g. The historical and recent captures of the species in the area shows the presence of new-born, juvenile and adult males and females. The distribution of these specimens suggests the potential occurrence of a nursery ground in the same area. To preserve the extirpation of the species throughout the area where it finds favourable environmental parameters to live, a management plan should be conducted to ensure the establishment of a viable population in the Turkish marine waters. © 2024, Natural and Engineering Science. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Capture of a Rare Smoothback Angelshark Squatina oculata (Squatinidae) in Turkish Waters, with Updated Records from the eastern Mediterranean Sea
    (Natural and Engineering Science, 2023) Akyol O.; Çoker T.; Betül Toprak H.; Capapé C.
    The authors report on the capture of a specimen of smoothback angelshark Squatina oculata Bonaparte, 1840 from Turkish marine waters. The specimen measured 720 mm in total length and was caught by means of a commercial purse-seiner at a depth of 60 m. The species appeared to be sporadically caught in the area and the eastern Mediterranean Sea, however, the size diversity of recorded specimens shows the species still occurred in the region. Although the smoothback angel shark is listed as a protected species according to Turkish Marine Fisheries Act, a management plan should be integrated with local fisheries to preserve the species from extirpation throughout its distribution range in Turkish seas. © 2023, Natural and Engineering Science. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Catch per unit effort of coastal prawn trammel net fishery in izmir bay, aegean sea
    (Hellenic Centre for Marine Research, 2009) Akyol O.; Ceyhan T.
    Catch per unit effort (CPUE) data from the coastal trammel prawn net fishery was estimated from fishery-dependent surveys in Izmir Bay (Aegean Sea) during the 2004-2005 fishing season. Catches were sampled from 18 boats for a total of 170 landings, 60 landings from April to July (first period) and 110 landings from August to November (second period). The mean CPUEs were 2.56 ± 0.39 kg. 10 net unit-1 in the first period and 2.29 ± 0.20 kg. 10 net unit-1 in the second period, and not significantly different between periods (P>0.05).
  • Küçük Resim Yok
    Öğe
    Comparative body and otolith morphometrics of Mugilidae in Homa Lagoon (Izmir Bay, Aegean Sea)
    (2001) Akyol O.; Kinacigol H.T.
    Every species otoliths and body forms have characteristic shape and features. Because of that otoliths and body morphometrics are widely used in the systematic researches of the Teleost fishes. In the Homa Lagoon (Izmir Bay), of 5 members of the family Mugilidae, otolith characteristics are valued by using the Discriminant Analysis and it is found that the greatest similarity is observed among Liza aurata, Liza ramada and Chelon labrosus. The different groups are Mugil cephalus and Liza sallens. Body characteristics showed that L. sallens, L. aurata are the similar while C. labrosus and M. cephalus are different. Although the otoliths and body morphometrics of the family Mugilidae are In general similar ones, it is possible to distinguish the species according to the special body and otolith morphologies.
  • Küçük Resim Yok
    Öğe
    Consecutive repetition of lordosis-kyphosis in silverside Atherina boyeri Risso, 1810 collected from a wild population in Homa Lagoon, Izmir, Turkey
    (De Gruyter Open Ltd, 2017) Jawad L.; Akyol O.; Saglam C.
    The incidence of severe consecutive repetition of lordosis-kyphosis involving three flexions was reported in a specimen of the atherinid fish Atherina boyeri Risso. The values for the angles lay between the lines passing through the sides of the vertebral column and enclosing the curvatures, and the depth of the curvatures of the angles was obtained. Also, the ratio of the vertebral column to the fish total length of deformed and normal specimens of this species was calculated. Possible causes for these anomalies are discussed. © 2017 Archives of Polish Fisheries.
  • Küçük Resim Yok
    Öğe
    Diet composition of adult twaite shad (Alosa fallax) in the Aegean Sea (Izmir Bay, Turkey)
    (2012) Ceyhan T.; Akyol O.; Sever T.M.; Kara A.
    Specimens of twaite shad, Alosa fallax were sampled from commercial purse seiners and trammel netters in Izmir Bay during November and December 2007. A total of 287 prey items from 14 taxa from 208 stomachs were recorded. The primary food of twaite shad was found to be fish, especially anchovy Engraulis encrasicolus, which was the most frequent (%F = 66.11) and abundant (%N = 63.64) prey item, and also had the highest percentage by weight (%W = 81.91). Decapoda, Isopoda, Ostracoda and Copepoda (Calanus spp., Candocia armata, Temora stylifera from Calanoida and Corycaeus spp. from Cyclopodia), were recorded occasionally with low values for all indices. The study showed that in the Aegean Sea Alosa fallax is a predator of small pelagic fish, E. encrasicolus, A. boyeri, S. pilchardus, and some crustaceans. Benthopelagic P. acarne and demersal S. hepatus were first recorded in diet of twaite shad. © 2011 Marine Biological Association of the United Kingdom.
  • Küçük Resim Yok
    Öğe
    Distribution of blackchin guitarfish Rhinobatos cemiculus E. Geoffroy Saint-Hilaire, 1817 (Elasmobranchii: Rhinobatidae) with first records from İzmir Bay (Turkey, northeastern Aegean Sea)
    (Turkiye Klinikleri Journal of Medical Sciences, 2014) Akyol O.; Capapé C.
    Blackchin guitarfish, Rhinobatos cemiculus, is rather abundantly captured in the eastern tropical Atlantic, especially off Senegal and Mauritania. In the Mediterranean western basin, R. cemiculus is unknown at present off the European shore but is rather frequent off southern areas; conversely, the species occurs throughout the eastern basin. Two large specimens recorded for the first time in İzmir Bay, northern Aegean Sea, are reported and described in this note. These findings constitute the northernmost records of R. cemiculus in both the Aegean Sea and the Mediterranean Sea, and they significantly extend the species' distribution known to date. © TÜBITAK.
  • Küçük Resim Yok
    Öğe
    The effect of the lunar phase on the catch per unit effort (CPUE) of the Turkish swordfish longline fishery in the eastern Mediterranean Sea
    (Scientific Society of Szczecin, 2018) Ceyhan T.; Tserpes G.; Akyol O.; Peristeraki P.
    Background. The swordfish, Xiphias gladius Linnaeus, 1758, is a pelagic and highly migratory species distributed in the Atlantic, Indian, and Pacific oceans as well as in the Mediterranean Sea. Swordfish fishing has been carried out in the Mediterranean with longlines, gillnets, harpoons, and traps since the Roman times. Although information is available on the influence of the lunar phase on the catch per unit effort (CPUE) for the swordfish longline fishery in the Atlantic and Pacific oceans, the data concerning the Mediterranean is rather limited. The aim of this study was to examine the relation between the lunar phase and the swordfish CPUE, based on data from Turkish longline fisheries, targeting swordfish in the eastern Mediterranean during the 2008–2016 fishing seasons. Material and methods. We monitored randomly the daily fishing activity of longliners based at the ports of Fethiye and Özdere during 2008–2016. A total of 86 surveying operations were carried out, including 79 in the area between Fethiye and Alanya, the remaining ones were in Özdere in the southern Aegean coasts along the eastern Mediterranean Sea. The effect of the lunar phase on the swordfish catch rates, expressed in terms of kg · 1000 hooks–1, was examined by means of the Generalized Additive Modelling (GAMs) techniques. Results. The observed CPUE rates ranged from 0 to 700 kg · 1000 hooks–1. The mean swordfish CPUEs in the dark and light periods of the lunar cycle were equal to 178.10 ± 19.01 and 175.27 ± 19.56 kg · 1000 hooks–1, respectively. Although no significant differences among phases of the Moon were found (P > 0.05), CPUEs differed significantly between years (P < 0.05). Conclusion. It seems that the mechanism linking swordfish CPUE variations with the lunar cycle involves several factors, making difficult the identification of direct relations. Further studies are needed to better clarify the impact of the lunar phase on the longline gear, considering also additional parameters, such as light transition, prey abundance, physico-chemical characteristics of the marine environment, and the soak time of the gear. © 2018, Scientific Society of Szczecin. All rights reserved.
  • Küçük Resim Yok
    Öğe
    First record of a Lessepsian migrant, Pomadasys stridens (Actinopterygii: Perciformes: Haemulidae), from the Aegean Sea, Turkey
    (Scientific Society of Szczecin, 2016) Akyol O.; Ünal V.
    A new record of a Lessepsian migrant, the striped piggy, Pomadasys stridens (Forsskål, 1775), in Turkish waters is reported herewith. The specimen was captured off the Akyaka coast in Gökova Bay, SE Aegean Sea and measured 130 mm in total length. Other measurements and counts are also provided, as well as the list of other Mediterranean records. This finding constitutes the fist record of this fish from the Aegean Sea and the third record from Turkish marine waters. It is also the northernmost report of this species in the Eastern Mediterranean Sea. © 2016, Scientific Society of Szczecin. All Rights Reserved.
  • Küçük Resim Yok
    Öğe
    The first record of a mangrove red snapper, Lutjanus Argentimaculatus (Actinopterygii: Perciformes: Lutjanidae), from the aegean sea (gulf of Izmir, Turkey)
    (Scientific Society of Szczecin, 2019) Akyol O.
    A specimen of Lutjanus argentimaculatus (Forsskål, 1775) was caught on 4 October 2018 by a commercial gillnet fishery from shallow waters of the Gulf of Izmir, northern Aegean Sea, at a depth of 8 m. The presently reported study constitutes the first record of the mangrove red snapper for the Aegean Sea but also the third record for the Mediterranean Sea. © 2019, Scientific Society of Szczecin. All rights reserved.
  • Küçük Resim Yok
    Öğe
    First record of an indo-pacific gaper, champsodon vorax (Actinopterygii: Perciformes: Champsodontidae), from the aegean sea, turkey
    (Scientific Society of Szczecin, 2015) Aydin İ.; Akyol O.
    A specimen of Champsodon vorax Günther, 1867, of 113 mm SL, was caught on 6 September 2014 with a bottom trawl from the entrance of the Bay of Izmir, north-eastern Aegean Sea at a depth of 65 m. The presently reported study constitutes the first record for the Aegean Sea but also the fourth record for the Mediterranean Sea. The specimen described in this paper is the largest individual reported to date from the Mediterranean. As it is evident from the spatial dynamics of all successive records of C. vorax in the Mediterranean this gaper seems to be a rapidly expanding species. It disperses both westwards and northwards. © 2015 Scientific Society of Szczecin. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Fish by-catch species from coastal small-scale shrimp trammel net fishery in the Aegean Sea (Izmir Bay, Turkey)
    (2008) Akyol O.
    Fish by-catch from coastal small-scale shrimp trammel net fishery was estimated from fishery-dependent surveys in Izmir Bay (Aegean Sea), Turkey, during the 2004 and 2005 fishing seasons. Sampling data were obtained from 170 observations onboard 18 commercial fishing vessels. Fifty-two species belonging to 31 families of fish, including cephalopods, constituted the by-catch. Diplodus annularis was the most abundant by-catch species followed by Loligo vulgaris > Sepia officinalis > Mullus barbatus > Boops boops > and Solea vulgaris. The estimated total ratio of fish by-catch to shrimp was 1 : 1.09 kg. © 2008 Blackwell Verlag.
  • Küçük Resim Yok
    Öğe
    Fishing near sea-cage farms along the coast of the Turkish Aegean Sea
    (2010) Akyol O.; Ertosluk O.
    This study reports on the yield of commercially important species captured intentionally around and under fish-cage farms using specific types of gear from both sea-cage farmers and artisanal fishermen, and to identify the species composition of these catches. The 2004-2008 research was carried out in 21 fish farms, randomly chosen along the coast of Izmir Province on the Aegean Sea. A total of 91 persons were interviewed, including directors, fishers from the fish farms and artisanal fishermen. The technical characteristics of a special trap used by some fish farmers were diagramed. Total wild fish catch quantities as well the species raised in the sea-cages were recorded. A total of 34 finfish and four invertebrate species were identified from the sea-cage farm fishery. Eight fish species according to the descending quantities raised were bogue (Boops boops), grey mullet (Mugil spp.), blackspot seabream (Pagellus bogaraveo), salema (Sarpa salpa), common two-banded seabream (Diplodus vulgaris), annular seabream (Diplodus annularis), striped seabream (Lithognathus mormyrus) and gilthead seabream (Sparus aurata). Mean quantities of wild fish caught from 2004 to 2008 in a sampled farm were 13 998 ± 210, 34 434 ± 482, 30 116 ± 529, 27 893 ± 429, and 32 366 ± 808 kg, respectively. There were significant differences between fish amounts and years (P < 0.05). © 2009 Blackwell Verlag, Berlin.
  • Küçük Resim Yok
    Öğe
    Food composition of whiting merlangius merlangus, captured around the sea-cage fish farms in ordu, south-eastern black sea
    (Cambridge University Press, 2019) Şensurat-Genç T.; Akyol O.; Özgül A.; Özden U.
    The food composition of whiting, Merlangius merlangus, caught around the sea-cage fish farms off the coast of Perşembe, was analysed and compared with the diet of whiting from a control site off the coast of Fatsa (Ordu Province, south-eastern Black Sea). A total of 815 stomach samples were collected during the study, and of these, 195 (23.9%) were empty. According to the percentage of relative importance index (IRI%), pellet food (47.8%) and Annelida (25%) were the main prey groups of whiting in the sea-cage fish farms area, while unidentified teleost (85.3%) and Engraulis encrasicolus (8.2%) were dominant in the control site. The other prey groups in both areas were Crustaceans (Mysidae, Amphipoda, Upogebia sp.), Sprattus sprattus and Gobius spp. Seasonally, pellet food was the most consumed food in all seasons, but Mysidae was the first preference of whiting around the sea-cage fish farms in spring. In the control site, unidentified teleost was the first preference in all seasons, except winter, where E. encrasicolus was the first choice, followed by crustaceans and S. sprattus in winter. Bray-Curtis analysis shows that seasonally, there is no significant difference in the sea-cage fish farms, while there is significant difference in the control site, and two-dimensional nMDS of IRI% revealed a clear separation between both sites. SIMPER analysis revealed that the most contributing factors to the differences between seasons were pellet food in the sea-cage fish farms, and E. encrasicolus in the control site. © Marine Biological Association of the United Kingdom 2019.
  • Küçük Resim Yok
    Öğe
    The gathering of predators around the sea-cage fish farms in the Aegean Sea
    (Station Biologique de Roscoff, 2020) Ceyhan T.; Akyol O.; Demir-Sağlam Y.; Şen H.; Özgül A.; Düzbastilar F.O.
    A total of 48 randomly selected fish farms from the coasts of Izmir and Muğla, Aegean Sea, were visited to face-to-face interviewing with fish farmers in the sea-cage fish farms between July 2015 and July 2017. Data were collected concerned mainly the following two aspects in the area: (i) actual problems on the sea-birds and other predators such as sharks, dolphins, monk seals, fishes; (ii) interactions between sea-cages and predator attacks. Around the sea-cage fish farms, 3 sea birds, Phalacrocorax carbo, Egretta alba and Larus michahellis, 2 marine mammals, Tursiops truncatus and Monachus monachus, 3 fish species, Pomatomus saltatrix, Thunnus thynnus and Prionace glauca, and one sea turtle, Caretta caretta, were declared as predators. The cormorant P. carbo had the highest ratio (24.3%) for being seen as a potential problem by fish farmers, followed by T. truncatus, T. thynnus and M. monachus. Great white egret, yellow-legged gull and cormorant were continuously observed by fish farmers. Seasonally, there were significant different incidences of the species (p < 0.05). Monk seal and bluefish were observed continuously, while blue shark had only been appeared during the collecting dead fish around the sea-cage fish farms. © 2020 Station Biologique de Roscoff. All rights reserved.