Browsing by Author "Eryasar, Ahmet Raif"

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Are Cloth Tarpaulin Mounted Nets Effective for Discard Reduction in Trammel Nets
(Central Fisheries Research inst, 2021) Eryasar, Ahmet Raif; Ceylan, Yusuf; Ozbilgin, Huseyin; Bozaoglu, Adem Sezai
Discarding is a significant problem due to net damage and labour loss in trammel net fisheries. In this study, the effects of 15, 25, and 35 cm high cloth tarpaulin rigged between the lead line and the net were investigated in reducing the discard amount of trammel nets for red mullet (Mullus barbatus) in the south-eastern Black Sea. During the study, twenty fishing trips were carried out on-board a commercial vessel between May 11 and June 20, 2018. Results showed that there were no significant differences in the amount of discards between the commercial and experimental nets (P>0.05) However, cloth tarpaulin mounted nets (CTMN) were found to be significantly successful to reduce the amount of shore crab (Liocarcinus depurator) and the veined rapa whelk (Rapana venosa) (P<0.05). Although it is insignificant, a decline of capture was also observed in the amount of target species in CTMN compared to the commercial net (CN). Finally, the advantages and concerns of this gear modification, and potential reasons for the reduction of target and discard species are discussed.
The Effect of Codend Circumference on Selectivity of Hand-Woven Slack Knotted Codend in the North Eastern Mediterranean Demersal Trawl Fishery
(Central Fisheries Research inst, 2014) Eryasar, Ahmet Raif; Ozbilgin, Huseyin; Gokce, Gokhan; Ozbilgin, Yeliz Doganyilmaz; Saygu, Ismet; Bozaoglu, Adem Sezai; Kalecik, Ebrucan
Poor selectivity and high discard rate of hand-woven slack knotted codend is a serious problem for north eastern Mediterranean demersal fish stocks. This study investigates the effect of codend circumference on bottom trawl selectivity for red mullet (Mullus barbatus), bogue (Boops boops), goldband goatfish (Upeneus moluccensis), Randall's threadfin bream (Nemipterus randalli) and picarel (Spicara smart's). A total of 18 valid hauls were conducted using covered codend method between 08 October and 26 December 2012 in Mersin Bay. Results show that selectivity of commercially used standard codend (300 meshes around its circumference) is rather poor and the narrow codend (150 meshes around its circumference) significantly increases selectivity for tested species. However, it is not selective enough to avoid the individuals of five commercial species under the MLS or FMS.
Selectivity of Monofilament Gillnets With Different Mesh Sizes Used in Fishing of Pearl Mullet, (Alburnus Tarichi (Guldenstadt, 1814)) in Lake Van
(Ege Univ, Fac Fisheries, 2023) Akkus, Mustafa; Bozaoglu, Adem Sezai; Eryasar, Ahmet Raif
This study was carried out between September 2020 and March 2021 to determine the selectivity of monofilament gillnets used in pearl mullet, Alburnus tarichi (Guldenstadt, 1814), fishing in Lake Van. The SELECT method was applied to determine the selectivity. The best model for the selectivity of monofilament gillnets used in pearl mullet fishing was determined as the log-normal model. The optimum catch lengths of monofilament gillnets with 20, 22 and 24 mm mesh sizes were calculated as 21.69 cm, 23.84 cm and 26.01 cm, respectively. Catch per unit effort was determined as 10.03 kg/90 m/day at 20 mm, 15.91 kg/90 m/day at 22 mm and 12.99 kg/90 m/day at 24 mm. The average catch per unit effort was determined as 151 unit/90 m/day at 20 mm, 151 unit/90 m/day at 22 mm, and 110 unit/90 m/day at 24 mm. According to the results of optimum catch length and daily average catch per unit effort, using monofilament gillnets with 22 mm mesh size was more convenient for sustainable pearl mullet fishing in Lake Van.
Size Selectivity of Hand and Machine Woven Codends and Short Term Commercial Loss in the Northeastern Mediterranean
(Elsevier Science Bv, 2015) Ozbilgin, Huseyin; Eryasar, Ahmet Raif; Gokce, Gokhan; Ozbilgin, Yeliz Doganyilmaz; Bozaoglu, Adem Sezai; Kalecik, Ebrucan; Herrmann, Bent
Poor selectivity of demersal trawls targeting fish, crustaceans and cephalopods in Mersin Bay, Turkey, (and more broadly for most Mediterranean demersal trawlers) is a significant concern. The majority of the boats working in the Mersin Bay trawl fishery use traditional gears with 44mm mesh size hand-woven slack knotted codends in which approximately 50% of the catch by weight and 70% by numbers are discarded. The present study compares size selectivity of a commonly used hand-woven codend and three alternative machine woven codends (40 mm square mesh; 44 mm and 50 mm diamond mesh) for seven commercial species: red mullet (Mullus barbatus); brushtooth lizardfish (Saurida undosquamis); common pandora (Pagellus erythrinus); goldband goatfish (Upeneus moluccensis); Randall's threadfln bream (Nemipterus randalli); green tiger prawn (Penaeus semisulcatus); and speckled shrimp (Metapenaeus monoceros). A total of 87 hauls were conducted using a covered codend method in 2011. Short term commercial loss for 31 marketed species resulting from switching from the commercial codend to each alternative codend, was estimated. Results show that size selectivity of the commercial codend is rather poor for almost all the marketed species. The 40 mm square mesh codend is the best alternative for the majority of the marketed species in terms of releasing juveniles. We estimate a commercial loss of 17% in landing values if this codend is used. (C) 2014 Elsevier B.V. All rights reserved.