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    Determination of catch eficiency and lenght composition of anchovy (Engraulis encrasicolus L., 1758) caught by midwater trawl during nihgt in the Black Sea
    (Ege Univ, 2006) Ozdemir, Suleyman; Erdem, Yakup; Satilmis, Hasan Huseyin; Ozdemir, Zekiye Birinci
    The aim of this study is to determine catch amount and size composition of anchovy in pelagic trawl along night time that carried out at fishing season 2005-2006 in Black sea. Night time was divided 3 periods as 17:00-20:00, 21:00-00:00 and 01:00-04:00, and was performed 6 tows for each period. Total 138 180 kg fish was fishing along study, I. period II. period and III. period 34 560 kg, 66 360 and 37 260 kg respectively. Mean size of all fishes caught 10,19 +/- 0,03 cm were determined, I. II. and III. period 10,26 +/- 0.05 cm; 9,89 +/- 0,04 cm and 10,42 +/- 0,09 cm respectively. Difference between Catch efficiency and mean size for fishing operation was done at different time periods was significantly (p<0,05). Change of school structure and movements showed in anchovy fishing by midwater trawl and depend on that be variation especially in catch efficiency and size composition were determined. Besides although decreasing of catch efficiency is at sun set and dawn due to there is less saturation on the net, more size fishes as to midnight fishing in these periods could be saying.
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    Effects of square mesh panels position of bottom trawls on by-catch bluefish Pomatomus saltatrix (Linnaeus, 1776) selectivity in the Southern Coast of the Black Sea, Turkey
    (Cahiers De Biologie Marine, 2014) Ozdemir, Suleyman; Erdem, Yakup; Erdem, Ercan; Ozdemir, Zekiye Birinci
    The selectivity parameters for by-catch bluefish Pomatomus saltatrix caught by demersal trawl, a nominal 40 mm diamond mesh size codend outfitted with square mesh escape panels, was determined on the southern coast of the Black Sea. Square mesh panels of nominal 36 mm were evaluated in two separate combinations: left-right and middle on the codend. The 50% retention lengths (L-50) and selection ranges of left-right (SDS), middle (DSD) combinations and control codend for blue fish were estimated to be 13.03 and 3.82 cm, 12.91 and 3.71 cm, 12.49 and 3.68 cm respectively. The L-50 value of SDS and DSD codend were comparable with the L-50 value of the control codend; however, the control codend value was rather low. The values of SDS and DSD codend weren't very close to MLS of the bluefish (20 cm). For this reason, more than 36 mm square mesh panels can be used alternatively, instead of the 36 mm square mesh panel on the codends for the fishery of the bluefish and higher size selectivity can be obtained. However, it may not be successful fisheries when considering the minimum landing size for dominant species (whiting Merlangius merlangus (Linnaeus, 1758) and red mullet Mullus barbatus ponticus (Essipov, 1927), 13 cm) in the Black Sea trawl fishery. These results show that increasing the size selectivity in a multi-species trawl fishery using a single position or square mesh size is quite difficult. Furthermore, square mesh panel codends were more selective than diamond mesh codend (p < 0.05). Differences between left-right (SDS) position and middle (DSD) position were no significant (p > 0.05) for the square mesh panel codend. Although the left-right (SDS) combination had a higher total area than the other combination (DSD) with square mesh in the middle and was preferable for bluefish.
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    Food composition and distribution of Gelatinous Macrozooplankton in the Southern Black Sea
    (Natl Inst Science Communication-Niscair, 2018) Ozdemir, Zekiye Birinci; Erdem, Yakup; Bat, Levent
    Food composition and distribution of gelatinous macrozooplankton (Aurelia aurita and Mnemiopsis leidyi) were determined during this study. Dominant main food of A. aurita and M. leidyi were found Copepoda (41.7% and 31.6%) and Bivalvia (16.3% and 27.6%) according to numerical occurrence. While the numerical and frequency rates of fish eggs and larvae in the A. aurita food composition were 0.8% and 1.5%, respectively. These values were determined as 0.9% and 1% for M leidyi. Zooplankton was found as feeding preferences of A. aurita and M. leidyi in terms of food composition. Seasonal differences have been observed in biomass and abundance of species. Highest abundance and biomass were 16.67 n.m(-2) and 124.17g.m(-2) for A. aurita, 51 n.m(-2) and 82.5 g.m(-2) for M leidyi, and 2.5 n.m(-2) and 17.29 g.m(-2) for B. ovata. M. leidyi showed correlation with temperature (p<0.05).
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    Monthly monitoring of length-weight relationships of allis shad (Alosa immaculata Bennett, 1835), horse mackerel (Trachurus mediterraneus Steindachner, 1868) and sprat (Sprattus sprattus Linnaeus, 1758) from the Southern Black Sea, Turkey
    (Cahiers De Biologie Marine, 2015) Ozdemir, Suleyman; Erdem, Ercan; Ozdemir, Zekiye Birinci; Aksu, Hakan
    Length-weight relationships are presented monthly for allis shad (Alosa immaculata), horse mackerel (Trachurus mediterraneus) and sprat (Sprattus sprattus) sampled with a commercial pelagic trawl vessel at depths ranging from 20 to 80 m between October 2008 and May 2009 in Black Sea, Turkey. The mean monthly values of the exponent b of the length-weight relationships ranged from 3.043 to 3.658 for allis shad, from 3.016 to 3.357 for horse mackerel and from 2.813 to 3.253 for sprat. Taking into account monthly confidence intervals, the length-weight relationships generally indicated a positive allometric growth in allis shad but an isometric growth in February, April and May 2009; it indicated a positive allometric growth in horse mackerel except in November and December 2008 (isometric growth), whereas it denoted isometric growth in sprat in October 2008, negative allometric growth from November 2008 to February 2009, isometric growth again in March 2009 and positive allometric growth in April and May 2009. Results showed that b value of allis shad, horse mackerel and sprat varied with season in the Black Sea.
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    Some population parameters of Mnemiopsis leidyi A. Agassiz, 1865 (Ctenophora: Lobata) in Sinop coasts of the Black Sea
    (Ege Univ, Fac Fisheries, 2020) Ozdemir, Zekiye Birinci; Erdem, Yakup; Bat, Levent
    Some population parameters of gelatinous macrozooplankton species, Mnemiopsis leidyi, were studied in the present study carried out from January 2008 to December 2008 along the coasts of Sinop in the Black Sea. A total of 980 M. leidyi specimens were measured and weighed. The estimated average length and weight of the species were 3.2 +/- 0.060 cm and 7.3 +/- 0.250 g, respectively. The observed maximum and minimum lengths were 10.8 cm and 0.2 cm. The maximum and minimum weights measured were 63 g and 0.1 g. The length-weight relationship equation for M. leidyi was determined to be W = 0.7905L(1.6406) .