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    Density distribution and some biological properties of veined rapa whelk Rapana venosa (Valenciennes, 1846) populations in south central Black Sea
    (Cahiers De Biologie Marine, 2017) Gonener, Sedat; Ozsandikci, Ugur
    Rapana venosa is a gastropod species, which has an extremely high commercial importance for Black Sea ecosystem since 1940s and for Turkish fisheries industry since 1985. The study that aims to ensure sustainability of whelks, an alternative fisheries resource, was carried out in coast of South Central Black Sea between September and December 2015. Biological properties of veined rapa whelk populations were determined and density distribution maps of Rapana venosa and by-catch species were created from samplings collected with commercial dredges. According to the results, length, weight and condition factor values of Rapana venosa individuals obtained in Sinop region, were greater than those of obtained in Samsun region. Besides, the densities of Rapana venosa (5812 +/- 189 kg.km(-2)) and by-catch species (8.2 +/- 0.5 ind.haul(-1)) in Sinop were higher than those in Samsun (respectively, 4368 +/- 137 kg.km(-2) and 6.2 +/- 0.4 ind.haul(-1)).
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    Effectiveness of Pingers on the Harbour Porpoise Phocoena phocoena relicta Abel, 1905 (Cetacea: Phocoenidae) in Turkey as Revealed by Shore-based Observations
    (Inst Zoology, Bas, 2020) Ozsandikci, Ugur; Gonener, Sedat
    The aim of the present study was to assess the effectiveness of pinger devices on the Black-Sea harbour porpoises Phocoena phocoena relicta. The study was carried out in Sinop, Turkey. between 16 July and 22 October 2016. A buoy without a pinger device was placed and observations were carried out during 26 days (53.2 hour) throughout the control period. Subsequently. a pinger was placed on the buoy and 28 days (58 hour) of experiment period was performed. During the study, the average distances, closest observed approaches (COA) and frequency of porpoise sightings in the zone of vulnerability. a 100 m buffer around the buoy, have been calculated and compared between the two periods. According to this. the average distance increased from 775.35 +/- 38.96 m during the control period to 1536.05 +/- 81.33 m during the experiment period (p<0.05). Distances of COA were calculated for control and experiment periods, respectively, 443.86 +/- 94.18 m and 724.34 +/- 98.89 m. Porpoises entered the zone of vulnerability significantly more frequently during the experiment period as compared to the control period (p<0.05). Pingers used in the study were found to be effective on keeping porpoises away from the area. However. a possible habituation effect can be revealed depending on the long-term use of these devices.