By-catch in the commercial beam trawl fishery for Rapa Whelk in the Black Sea

In this work, the by-catch was investigated in commercial beam trawls used in the rapa whelk (Rapana venosa) fishery, in trials at sea between September 1, 2015 and April 30, 2016. Four commercial boats using beam trawls were chartered and catch data was collected from a total of 87 hauls. Hauls were performed between 7.1–28.3 meters deep for a duration of 20–77 minutes and haul speed varied between 1.4 – 2.7 knots. A total of 28 by-catch species were identified, which amount in average to 11.4% of the total number of specimens in the by-catch. Two different groups were identified in the by-catch (G1: 7-18 m, G2: 19-26 m) according to depth. Although there is a reduction in the amount of by-catch for G2 group, no significant difference was found between groups (p>0.05). According to Generalized Additive Models (GAM) results, the variables affecting the by-catch amount were identified as fishing area, depth, haul duration, and amount of captured rapa whelk (p<0.01). In addition, a large proportion of immature individuals of striped venus clams (Chamelea gallina), blood cockles (Anadara kagoshimensis), Mediterranean mussels (Mytilus galloprovincialis) and wedge clams (Donax trunculus) were caught as by-catch during the study. Finally, the impact of commercial beam trawls on the demersal macrofauna is discussed

Influence of season, depth and mesh size on the trammel nets catch composition and discard in the Southern Black Sea, Turkey

YESILCICEK, TUNCAY/0000-0002-3236-8227WOS: 000335117700009The present study was conducted with trammel nets, which are intensively used in the Black Sea region, in order to investigate the influences of season, depth and mesh size on species composition and discard rates. in total, 27 species, belonging to 4 taxonomic groups (24 fish, 1 gastropod, 1 bivalve and 1 crustacean) were obtained. the percentage distribution of the total catch was 8.32% target species, 14.59% non-target landing and 77.09% discard. the discard rate of Mullus barbatus in the total catch was 0.61%. Among the total catch, Brachyura (22.74%) was the main group discarded, while the other important discard species were Rapana venosa (16.90%), Scorpaena porcus (13.71%) and Uranoscopus scaber (9.65%). the lowest and highest discard rates were found in spring and autumn, respectively. According to depth, the lowest discard rate was from depths > 30 m (37.5%) and the highest at depths 30 m depth groups (P 0.05).Scientific Research Fund of Recep Tayyip Erdogan University (RTEU-BAP)Recep Tayyip Erdogan University [2010.103.03.1]This study was supported by the Scientific Research Fund of Recep Tayyip Erdogan University (RTEU-BAP) with project number 2010.103.03.1. We are grateful to Yusuf Ceylan and boat owners for all of their cooperation and help during the data collection

DETERMINATION OF REPRODUCTIVE CHARACTERISTICS OF THE EUROPEAN CATFISH (SILURUS GLANIS L., 1758) IN BORCKA DAM LAKE

YESILCICEK, TUNCAY/0000-0002-3236-8227WOS: 000535839500016This study was carried out to determine the reproductive characteristics (sex ratio, gonadosomatic index, hepatosomatic index, reproductive period, fecundity, egg size, gonadal maturity stages and length at first maturity) of the European catfish (Silurus glanis L., 1758) for the first time in Borcka Dam Lake. A total of 26 fishing operations were performed monthly between February 2016 and November 2017 and totally 156 European catfish specimens (99 female and 57 male) were sampled. Total lengths of all samples varied from 20.6 cm to 145.0 cm, (68.3 +/- 2.214 cm), and body weights ranged from 56.33 g to 21452 g (3090.18 +/- 307.505 g). the sex ratio (Male: Female) was calculated as 1.0: 1.74 and this ratio was statistically different from the expected value 1.00:1.00 (P<0.05). the length at first maturity was estimated as 85.0 cm for females and 79.9 cm for males. the length and age of the smallest matured individual was 81.3 cm and 4 years in females and 78.3 cm and 3 years in males. the minimum mean monthly egg diameters were measured in May as 1.097 +/- 0.0273 mm, while the maximum mean egg diameters were measured in August as 2.554 +/- 0.0221 mm. the total fecundity was estimated between 30379 and 301356 (179043 +/- 335.320) number eggs. There was a strong positive relationship between total fecundity-total length and total fecundity-body weight. the reproductive period of the European catfish in the Borcka Dam Lake was from July to September and the spawning ended completely in September. the results of this study could be useful to help sustainable fisheries management of inland fisheries resources and to provide a scientific data to further studies, also implementation of conservation and control measures in Borcka Dam Lake on the Coruh River.Research Fund of the Recep Tayyip Erdogan University [2015.53001.103.03.08]We want to thank Prof. Dr. Cemalettin Sabin, Yusuf Ceylan, master students Yunus Dedeoglu and Erhan Ozttirk for their help during the samplings. Thanks are also extended to A. Muhtar Kiictiksonmez and Ali Ozttirk for their logistic support during the field studies at Borcka Dam Lake. This study was supported by Research Fund of the Recep Tayyip Erdogan University. Project Number: 2015.53001.103.03.08

Effects of Depth, Season and Mesh Size on the Catch and Discards of Whiting (Merlangius merlangus euxinus) Gillnet Fishery in the Southern Black Sea, Turkey

YESILCICEK, TUNCAY/0000-0002-3236-8227WOS: 000348289800015In this study, factors (depth, season and mesh size) influencing the catch and discards of whiting (Merlangius merlangus euxinus) gillnet fishery on the Black Sea coasts of Turkey were investigated. A total of 19 species were identified and the target species, whiting (Merlangius merlangus euxinus), dominated 87.56% of the total catch and followed by red mullet (Mullus barbatus) with 6.32%. While 82.02% of the total catch had commercial value, 17.98% was discarded. the percentage of the discarded red mullet and whiting under MLS (<13 cm) were found to be 16.03% and 13.27%, respectively. the highest discard amount was observed in winter and the lowest one in summer. the discard rate was highest in the 55-74 m depth group and the 32 mm mesh size. One-way analysis of similarity (ANOSIM) showed that there were significant differences in the discard species compositions between spring and summer, as well as 32 and 40 mm, 32 and 44 mm mesh sizes (P<0.05). These results on the discard information in gillnet fishery can contribute to the literature on ecosystem-based sustainable fisheries management by highlighting relevant results on the protection of species and ecosystem.Scientific Research Fund of Recep Tayyip Erdogan University (RTEUSRF)Recep Tayyip Erdogan University [2010.103.03.1]This study was supported by the Scientific Research Fund of Recep Tayyip Erdogan University (RTEUSRF) with the project number 2010.103.03.1. We are grateful to Yusuf Ceylan and the boat owner for all of their cooperation and help throughout the data collection

External Morphology and Weight - Length Relationships (WLRs) of Harbour Porpoise, Phocoena phocoena (Cetacea: Phocoenidae) in the Black Sea

YESILCICEK, TUNCAY/0000-0002-3236-8227;WOS: 000486924400006The 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.Recep Tayyip Erdogan UniversityRecep Tayyip Erdogan University [BAP 2010.103.03.2]The authors thank fishermen Sami Akmermer, Kazim Akmermer Ugur Akmermer and Ahmet Kalkavan for their help during the field studies. This study was supported by the Recep Tayyip Erdogan University, Scientific Research Project (BAP 2010.103.03.2)

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

YESILCICEK, TUNCAY/0000-0002-3236-8227;WOS: 000455002200009The 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 0.05). No new net damage due to cetacean interactions with the turbot gill nets was detected.Recep Tayyip Erdogan University, Scientific Research Project [BAP 2010.103.03.2]The authors thank fishermen Sami Akmermer, Kazim Akmermer Ugur Akmermer and Ahmet Kalkavan for their help during the field studies and two anonymous referees for their suggestions and criticism that clearly improved an earlier version of this manuscript. This study was supported by the Recep Tayyip Erdogan University, Scientific Research Project (BAP 2010.103.03.2)

Biomonitoring of metal(oid)s in mining-affected Borcka Dam Lake coupled with public health outcomes

Terzi, Ertugrul/0000-0003-2811-6497; YESILCICEK, TUNCAY/0000-0002-3236-8227; Gedik, Kenan/0000-0001-8244-6935WOS: 000437339700017Due to increased anthropogenic activities, the aquatic environment is exposed to pollutants much more than ever. These pollutants go into the food chain and can pose a health risk to human. Correlatively, Borcka Dam Lake, Turkey has been affected by mining activities since decades. in the present study, therefore, Cu, Pb, As, Zn, Mn, Cd, Cr, and Se concentrations in water, sediment, and different tissues (muscle, gill, liver) of 11 fish species sampled from the lake were analyzed regarding metal(oid)s pollution and potential human health risk through fish consumption. the metal(oid) concentrations in the water were below the limit values recommended by USEPA for aquatic life criteria but sediments were heavily polluted by As, Cu, Pb, and Zn based on Sediment Quality Guideline. the lowest metal(oid) values among tissues for all fish species were determined in muscle (p < 0.05) which was lower than the limits for human consumption declared by European Union Regulation. Target Hazard Quotient and Hazard Index used non-cancer risk estimate which was lower than 1. in the view of these results, the consumption of fish caught from the Borcka Dam Lake may not pose a potential risk to human.Research Fund of Recep Tayyip Erdogan UniversityRecep Tayyip Erdogan University [FBA-2016-670]This work was funded by the Research Fund of Recep Tayyip Erdogan University (Project Number: FBA-2016-670)

Life-History Traits of the Black Scorpionfish (Scorpaena porcus) in Southeastern Black Sea

YESILCICEK, TUNCAY/0000-0002-3236-8227WOS: 000455896800004Scorpaena porcus is one of the most important members of rock and reef community in the Black Sea. the present study aimed to investigate the bio-ecological properties of 5. porcus in the Eastern Black Sea. the growth, age, and sex compositions, feeding and reproduction biology of 1061 individuals were examined. the total length of the individuals ranged between 6.7 and 25.5 cm. the observed age ranged up to 8 years in both the sexes; the oldest individual both in males and females was 8 years of age. the von Bertalanffy growth function parameters in the samples were L-infinity=22.15 cm, k=0.287, t(0)= -1.577 (year) and W-infinity=238.14 g. the sex ratio (male/female) was 1/1.13. S. porcus fed most frequently on fish and decapods in all seasons. the reproduction period was identified to be between June and October, as evident by GSI values and macroscopic and histological analysis of gonads. Hydrated oocytes first appeared in June on the histological examinations; however, the atresia was highest in October. in conclusion, the study identified S. porcus as a new target species and the studied bio-ecological characteristics are expected to be important in developing an optimal strategy for fishery stock management

Biomonitoring of metal(oid)s in mining-affected Borcka Dam Lake coupled with public health outcomes

Terzi, Ertugrul/0000-0003-2811-6497; YESILCICEK, TUNCAY/0000-0002-3236-8227; Gedik, Kenan/0000-0001-8244-6935WOS: 000437339700017Due to increased anthropogenic activities, the aquatic environment is exposed to pollutants much more than ever. These pollutants go into the food chain and can pose a health risk to human. Correlatively, Borcka Dam Lake, Turkey has been affected by mining activities since decades. in the present study, therefore, Cu, Pb, As, Zn, Mn, Cd, Cr, and Se concentrations in water, sediment, and different tissues (muscle, gill, liver) of 11 fish species sampled from the lake were analyzed regarding metal(oid)s pollution and potential human health risk through fish consumption. the metal(oid) concentrations in the water were below the limit values recommended by USEPA for aquatic life criteria but sediments were heavily polluted by As, Cu, Pb, and Zn based on Sediment Quality Guideline. the lowest metal(oid) values among tissues for all fish species were determined in muscle (p < 0.05) which was lower than the limits for human consumption declared by European Union Regulation. Target Hazard Quotient and Hazard Index used non-cancer risk estimate which was lower than 1. in the view of these results, the consumption of fish caught from the Borcka Dam Lake may not pose a potential risk to human.Research Fund of Recep Tayyip Erdogan UniversityRecep Tayyip Erdogan University [FBA-2016-670]This work was funded by the Research Fund of Recep Tayyip Erdogan University (Project Number: FBA-2016-670)