scholarly journals Investigation of the Effects of Hook Size and Bait Type on the Catch of Whiting, Merlangius merlangus (Linnaeus, 1758) (Gadidae) in Bottom Longline Fisheries of the Black Sea

2021 ◽  
pp. 72-77
Author(s):  
İsmet Balık
2015 ◽  
Vol 90 (3) ◽  
pp. 347-352 ◽  
Author(s):  
A. Özer ◽  
Y. Kornyychuk ◽  
T. Öztürk ◽  
V. Yurakhno

AbstractGyrodactylus alviga is a generalist species reported in many Black Sea fish species, but whiting is known to be its main host. It is the only monogenean parasite that has been reported so far on the skin, fins and gills of whiting Merlangius merlangus in the Black Sea. A total of 690 fish from Turkey and 423 fish from Russia were examined to detect parasites. Infection indices of prevalence, mean intensity and mean abundance values were calculated for length classes and sex of fish, as well as for the seasons. There is a gradual increase in infection indices in relation with increasing host length classes and there are higher infection indices on female fish. Furthermore, despite lower prevalence indices in spring and winter, higher parasite intensity values were determined in these seasons. It is concluded that larger fish provided more space and food for G. alviga, and female fish were more parasitized as they were more active in searching for food, which enables the parasite to switch between hosts. In addition, winter and spring were more appropriate for reproduction of G. alviga.


2013 ◽  
Vol 47 (4) ◽  
pp. 309-317 ◽  
Author(s):  
E. N. Skuratovskaya ◽  
V. M. Yurakhno ◽  
A. V. Zavyalov

Abstract Complex influence of infection by myxosporeans Myxidium gadi Georgevitsch, 1916; Ceratomyxa merlangi Zaika, 1966 and nematode Hysterothylacium aduncum (Rudolphi, 1802) on the morphophysiological and biochemical parameters of the Black sea whiting Merlangius merlangus euxinus (Nordmann, 1840) were studied. Significant decrease of spleenosomatic index and increase of hepatosomatic index in fish with average and high intensity of infection were found. The dependence of hepatic antioxidant enzyme activities on intensity of infection was observed. Increase of superoxidismutase, catalase, glutation-S-transferase activities in fish with average and high intensity of infection and decrease of peroxidase activity in specimens with average intensity of infection were shown.


2018 ◽  
pp. 26-37 ◽  
Author(s):  
Süleyman Özdemir ◽  
Hilal Söyleyici ◽  
Zekiye Birinci Özdemir ◽  
Uğur Özsandıkçı ◽  
Ferhat Büyükdeveci

2021 ◽  
Vol 22 (Special Issue) ◽  
Author(s):  
Ulgen Aytan ◽  
Fatma Basak Esensoy ◽  
Yasemen Senturk ◽  
Esra Arifoglu ◽  
Kaan Karaoglu ◽  
...  

The occurrence of micro- (<5 mm), meso- (5–25 mm) and macroplastics (>25mm) was investigated in seven commercial fish species of the Black Sea. Plastics were found in gastrointestinal track of all species analysed: Engraulis encrasicolus, Trachurus mediterraneus, Sarda sarda, Belone belone, Pomatus saltatrix, Merlangius merlangus and Mullus barbatus. A total of 352 plastic particles were removed from 190 individuals (29% of all individuals examined). The mean number of plastic particles per fish was 0.81±1.42 par.ind-1 (considering all fish analysed, n=650) and 2.06±1.09 par.ind-1 (considering only the fish that ingested plastic, n=190). The most common types of plastics were fibres (68.5%), followed by films (19%), fragments (11.9%), foams (0.3 %) and microbeads (0.3%). The most common plastic colour was black (39.3%) followed by blue (19.5%) and transparent (18.1%). The length of plastics ranged from 0.05 to 26.5 mm with an average of 1.84±2.80 mm. 93.2% of plastics were microplastics, 6.5 % as mesoplastics and 0.3% macroplastics. Plastic occurrence was higher in S. sarda (plastic in 70% of the analysed individuals) and lower in M. merlangus (plastic in 9% of the analysed individuals). The main synthetic polymers identified by Fourier-transform infrared (FTIR) spectroscopy were polypropylene (29.8%), polyester (17.5%), acrylic (15.8%), polyethylene (14%) and polystyrene (1.8%) and 21.1% of polymers were cellulosic. Results show that commercial fish of the Black Sea is contaminated by plastics. This might affect vital functions of fish and pose a risk to ecosystem and human health. The study contributes to a better understanding of the status of plastic pollution in the fish from different habitats of the Black Sea and provides baseline data to implement the Marine Strategy Framework Directive in the basin.


2013 ◽  
Vol 15 (1) ◽  
pp. 156 ◽  
Author(s):  
Y. CEYLAN ◽  
C. ŞAHİN ◽  
F. KALAYCI

The purpose of this study is to determine the amount of bycatch and discardfish caught by bottom trawlers used in the Black Sea coasts of Turkey anddiscard changes depending on the depth. The study was conducted during theSeptember 2009 – April 2010 fishing season. Twenty-one bottom trawleroperations were sampled and the catch composition was determined. A total of 26species were caught, which included 22 species of fish, 2 species of arthropods,1 species of gastropods and 1 species of bivalves. Two of these were targetspecies (Mullusbarbatus, Merlangius merlangus), while 25 species werediscarded including trash fish and specimens below the legal size. A total of2142.76 kg of biomass was caught during the operations, of which 53.99 % bycatch.The weighted discard rate was determined as 42.06% and two different groupswere identified in discards (T1: 10-57 m, T2: 72-118 m) based on the depth. Significantdifferences were identified between these depth groups (p<0.05). It was determined that the biomass (kg h-1),the evenness index (J) (p<0.05),the average species number and the species richness (D) (p<0.01) of the discards showed significant differences, but thatthe difference between species diversity (H) was negligible. No difference wasfound (p>0.05) between theecological parameters of landings.


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