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    External Morphology and Weight - Length Relationships (WLRs) of Harbour Porpoise, Phocoena phocoena (Cetacea: Phocoenidae) in the Black Sea
    (Central Fisheries Research Inst, 2020) Bilgin, Sabri; Kose, Ozay; Yesilcicek, Tuncay
    The present study summarized information on the morphometric characteristics and weight-length relationships (WLRs) of pregnant females, non-pregnant females and males of harbour porpoise, Phocoena phocoena (Linnaeus, 1758) along the Rize coast in the Black Sea, Turkey. A total of 68 harbour porpoises (31 males, 22 non-pregnant females and 15 pregnant females) were obtained as bycatch in the turbot gill net fisheries from April 2010 to July 2011. A total of 16 external morphological characteristics of the harbour porpoises were examined by Principal Component Analysis (PCA). The PCA results clearly showed that there is sexual dimorphism mainly in the general size between non-pregnant females and males and also pregnant females and males. The greatest body length in the sample was 142.0 cm for females and 128.0 cm for males. Weight-length relationships (WLRs) of harbour porpoise showed negative allometric growth characteristics (Pauly' t test, P<0.05). The slopes of the regression lines for males, non-pregnant females and pregnant females were significantly different from the isometric growth curve slope of 3 (Pauly' t test, P<0.001). Correlation coefficient (r) was significant for both sexes (P<0.05). These results will enable researchers, fishermen and fisheries management authorities to enhance the knowledge of harbour porpoises life history and ecology.
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    Incidental catches of endangered (Phocoena phocoena) and vulnerable (Delphinus delphis) cetaceans and catch composition of turbot bottom gillnet fisheries in the southeastern Black Sea, Turkey
    (Cahiers De Biologie Marine, 2018) Bilgin, Sabri; Kose, Ozay; Yesilcicek, Tuncay
    The present study summarizes information on the incidental catches of cetaceans and the catch composition of turbot bottom gillnet fisheries between March 2010 and September 2011 along the Rize coast in the southeastern Black Sea, Turkey. A total of 723 specimens (133 Scophthalmus maeoticus, 507 Raja clavata, 8 Squalus acanthias, 71 Phocoena phocoena, 4 Delphinus delphis) were recorded from 136 turbot gill net fishing operations. The 'danger index' or catch per unit effort (CPUE, individuals per km. day of netting) for cetaceans was 0.09 +/- 0.028 in 2010, 0.15 +/- 0.032 in 2011 and 0.13 +/- 0.023 overall for P. phocoena and < 0.003 overall for D. delphis. Monthly CPUE values for target S. maeoticus and non-target species R. clavata, and P. phocoena were similar in all years. An increasing CPUE trend between April and June was evident for target and non-target species in 2010 and 2011. The CPUE of P. phocoena was estimated highest in May as 0.18 +/- 0.088 in 2010 and in April as 0.26 +/- 0.086 in 2011. A similar pattern was evident for S. maeoticus and R. clavata. One-way ANOVA showed that no statistical significant difference of target and non-target species CPUE among 2010, 2011 and all data (P > 0.05). No new net damage due to cetacean interactions with the turbot gill nets was detected.
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    Length-Weight Relationships (LWRs) of target fish turbot, Scophthalmus maximus (Pleuronectiformes: Scophthalmidae) and non-target fish thornback ray, Raja clavata (Rajiformes: Rajidae) caught by turbot gill net fishery in the Black Sea, Turkey
    (Cahiers De Biologie Marine, 2018) Bilgin, Sabri; Kose, Ozay
    The present study was conducted to determine the length weight relationships (LWRs) of turbot, Scophthalmus maximus and thornback ray, Raja clavata caught by bottom turbot gill net in the Black Sea, Turkey and to compare the LWRs parameters of S. maximus and R. clavata from different geographical locality for contributing fisheries management of these two fish species in the Black Sea. The LWR of S. maximus samples collected from the Rize coast in the Black Sea highlighted that S. maximus showed isometric growth characteristics for female and combined data (Pauly's test, P > 0.05) and negative allometric growth for male (Pauly' t test, P < 0.05). The LWR of R. clavata showed that R. clavata has positive allometric growth characteristics for female and combined data (Pauly's test, P < 0.05) and isometric growth for male (Pauly's test, P > 0.05). In addition to this, to compare the estimations calculated from the present study with other studies, log (a) values were plotted against values of b, proved to be consistent with previous studies data for R. clavata and S. maximus. This study provides basic information on the LWRs both S. maximus and R. clavata populations, in support of sustainable fisheries management of these two fish species and especially of the sea coastal waters in the Black Sea, Turkey.
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    Testing two types of acoustic deterrent devices (pingers) to reduce harbour porpoise, Phocoena phocoena (Cetacea: Phocoenidae), by catch in turbot (Psetta maxima) set gillnet fishery in the Black Sea, Turkey
    (Cahiers De Biologie Marine, 2018) Bilgin, Sabri; Kose, Ozay
    Field experiments with Aquamark 100 and Aquamark 200 pingers were conducted in the bottom set gill net fishery for turbot in the Black Sea coast between March and June 2012. The aim of the experiment was to evaluate (i) the effectiveness of two types of pingers to reduce by catch rate of harbour porpoises, and (ii) the effects of pingers on the catches of the target fish species (Psetta maxima) and non-target fish species (Raja clavata, Suqualus acanthias and Trigla lucerna) in the turbot set gillnet fishery. A total of 246 specimens (95 P. maxima, 138 R. clavata, 8 P. phocoena, 4 S. acanthias and 1 T. lucerna) were caught during both Aquamark 100 and Aquamark 200 pingers trials. Catches of Psetta maxima and other fish species (Raja clavata, Suqualus acanthias and Trigla lucerna) were not affected by the sound of the pingers in the active nets. Catch of target P. maxima and non-target fish R. clavata were similar as were also for most caught species. 6 P. phocoena (2 in control and 3 in active nets with Aquamark 100) and 2 P. phocoena (1 in control and 1 in active nets with Aquamark 200) were caught in controls and active nets. There are no statistical differences between active and passive net catch per unit effort among the fish species and also cetaceans. As a conclusion, the acoustic signals clearly showed that these pinger types did not reduce by catch of harbour porpoise from the turbot gill net in the eastern Black Sea coasts, Turkey. The acoustic signals of both pinger types also did not affect the catch of target and non-target fish species.