Browsing by Author "Bozaoglu, Adem Sezai"

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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.
Determination of Fishing Efficiency and Selectivity of Multifilament Trammel Nets in Pearl Mullet, Alburnus Tarichi (Güldenstädt, 1814), Fishing in Lake Van, Turkey
(Edp Sciences S A, 2023) Bozaoglu, Adem Sezai; Pala, Kemal
This study aimed to determine the selectivity of multifilament trammel nets in pearl mullet, Alburnus tarichi (Guldenstadt, 1814), and fishing in Lake Van (east of Turkey). In line with this objective, the multifilament trammel nets with 20, 22 and 24 mm mesh sizes were tested in trials. The current study was conducted between September 2019 and April 2020. Thirty-four fishing operations were conducted in the 40-60 m depth range. The "SELECT" method was applied to determine the selectivity parameters. According to the results, the lengths of the optimum catching using nets with 20, 22 and 24 mm mesh sizes were calculated as 20.76 cm, 22.07 cm and 24.11 cm, respectively. The highest average CPUE in weight was 24 mm (6.007 kg/ 100 m / day). Considering the data obtained in the present study, the best optimum catch length and CPUE values for pearl mullet fishing were determined in multifilament trammel nets with a 24 mm mesh size. In conclusion, this study suggests that using a 24 mm mesh size in a lake for pearl mullet fishing will benefit fish stocks and local fishermen.
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.
The Effects of Two Different Net Modifications on Reducing Discards in the Trammel Net Fishery for Prawn in Mersin Bay
(Walter de Gruyter Gmbh, 2023) Bozaoglu, Adem Sezai
The discarded species caught in prawn trammel nets damage the nets and cause a serious labor loss problem for fishers. In the present study, a 15 cm high greenhouse plastic film and a greenhouse shade cloth net were fitted between the lower parts of the nets and the lead collars to reduce discards in the trammel net fishery. The modified nets were tested in Mersin Bay with twenty-one fishing operations between September and December 2021. The results showed that, compared to commercial trammel nets, the nets equipped with greenhouse plastic film and greenhouse shade cloth did not significantly reduce the catch of the target species green tiger prawn (Penaeus semisulcatus). However, the total number of discards significantly decreased. The discard rates in the commercial net, greenhouse plastic film net, and greenhouse shade cloth net were 45%, 26%, and 22%, respectively. Furthermore, when the incomes from the nets' hauls were calculated, the net equipped with greenhouse garden film and the net equipped with greenhouse shade cloth generated 24.77% and 14.41% more profit than the commercial net, respectively.
First Record of Zebra Mussels (Dreissena Polymorpha Pallas, 1771) for Lake Aygir in Lake Van Basin
(Parlar Scientific Publications (p S P), 2020) Akkus, Mustafa; Sari, Mustafa; Bozaoglu, Adem Sezai
This study was conducted between the years 2017-2018 in Lake Aygir within the borders of Adilcevaz district of Bitlis Province, in Lake Van Basin. Zebra Mussel (Dreissena polymorpha Pallas, 1771) was firstly discovered in Lake Van Basin via this study. The drinking water requirements of the settlements around are met from Lake Aygir. Zebra Mussel, which was firstly discovered during the diving organized for the clogged drinking water pipes, is thought to have arrived at the lake six years ago. In this study, 456 mussels were examined, and the height-weight relationships of the mussels were determined together with their distribution areas within the lake through dives. The biggest height and weight values were found as 37.73 mm and 5.96 g. As the conclusion of the regression analysis, it was also noted down that there was an exponential relationship between the heights and weights of the mussels, and they demonstrated an allometric growth accordingly. Furthermore, it was discovered that the mussels spreaded over an area of 0.4 km(2). Finally, some possible ecological effects of Zebra Mussels (Dreissena polymorpha Pallas, 1771) in Lake Aygir and Lake Van Basin were evaluated, and some suggestions were made as solutions to the problem.
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.
The Socio-Economic Structure of Lake Van Fishery
(Parlar Scientific Publications (p S P), 2019) Bozaoglu, Adem Sezai; Yesil, Adiyet
The present study was conducted with 77 participants in the fishing ports of Lake Van which are located in Gevas, Dagonu, Edremit, Tatvan and citoren, between April-2016 and December-2017. A general evaluation related to trammel net fishermen in Lake Van district was done; accordingly, it was found out that 85% of them are from Van, while 15% of them are from Bitlis. The average number of crews for vessels was 2.34 +/- 0, 77, and the average for the age of fisherman was found out as 40,14 +/- 11, 37, respectively. The results of the education level items in the survey highlight that 62% of the fisherman graduated from primary school; 23% of them graduated from secondary school; 13% of them graduated from high school, and only 2% of them graduated from university. Regarding the marital status and their belongings, it was found out that 84% of the fishermen were found out to be married. By the time they were asked how they started this job, 29% of them claimed that they had a passion for lake, 26% of them preferred because of his father's occupation choices, and 45% of them preferred it because they were obligated to do this job. 55% of the participant fishermen pointed out that they wanted to give up this job, and 90% of them highlighted that they did not want their children to this job. According to the results, it was also found out that all of the fishermen had a second job. Particularly, when the season is closed, most of them work in building constructions as well as dealing with agriculture or animal husbandry. Last but not the least, the most important problems were identified as illegal fishing, gaining less money than expected with the fishery and the deficiency of port problems. Finally, this study is expected to shed light onto solutions of the abovementioned problems.