Body shape and trawl cod end selectivity for nine commercial fish species

Tosunoğlu, Zafer; Özbilgin, Yeliz Doğanyılmaz; Özbilgin, Hüseyin

doi:10.1017/s0025315403008737

Cited by 45 publications

(59 citation statements)

References 2 publications

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“…Available studies have revealed differences in the demersal assemblages between these regions (Tsimenides et al 1991, Kallianiotis et al 2000, Labropoulou and Papaconstantinou 2000, Klaoudatos et al 2010 Thanks to increased research effort in the southern and northwestern region of the Aegean, information on the demersal fisheries and their impact on ecosystems has improved substantially (e.g. Petrakis and Stergiou 1997, Smith et al 2000, Labropoulou and Papaconstantinou 2004, Damalas and Vassilopoulou 2011, Maravelias et al 2012, Damalas et al 2010, Tosunoğlu et al 2003a, 2003b, Tokaç et al 1998. Similarly, demersal fish communities of the northeastern Aegean have also been studied and compared with other areas (Labropoulou and Papaconstantinou 2000, Keskin et al 2011a, 2011b.…”

Section: Introductionmentioning

confidence: 99%

Preliminary evaluation of landings and discards of the Turkish bottom trawl fishery in the northeastern Aegean Sea (eastern Mediterranean)

Keskin¹,

Ordines²,

Ateş³

et al. 2014

Sci. Mar.

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Summary: This short-term study on commercial discards was carried out in fishing grounds around Gökçeada Island in the northeastern Aegean Sea, a geographic area where fisheries information is rather limited. A total of 28 bottom trawls were performed between 70 and 410 m depth from December 2009 to February 2010. All the samples were collected on board a commercial trawler under commercial fishing conditions. A total of 3143 kg of biomass was caught in 28 valid hauls. Landings accounted for about 67% of the total catch while the remaining 33% was discarded. Fish species comprised 85% of the total catch and their composition could be divided into four main groups related to depth: shallow shelf (70 to 88 m), deep shelf (155 to 180 m), shelf break (196 to 276 m), and upper slope (307 to 410 m). Fish dominated the abundance and biomass of both landings and discards in all bathymetric strata. Echinoderms also accounted for a large proportion of the discards. Mean total catches varied between 78.4 kg/h on the shallow shelf and 38.1 kg/h on the shelf break with no differences in the landing biomass between groups, but with slightly higher discards over the shallow shelf. Taking into account the preliminary nature of the findings, based on a short-term analysis, the minimum mesh size and minimum landing size currently applied in the Turkish bottom trawl fishery are not sufficient to reduce discards and to protect juveniles of commercially important species in the northeastern Aegean Sea.Keywords: bottom trawl; catch composition; landings; discards; length-frequency; eastern Mediterranean. Evaluación preliminar de los desembarques y descartes de la pesquería de arrastre de fondo de Turquía en el mar Egeo nororiental (Mediterráneo oriental)Resumen: Este estudio a corto plazo sobre los descartes de la flota comercial de arrastre se llevó a cabo en las zonas de pesca alrededor de la isla Gökçeada en el noreste del mar Egeo, una zona geográfica en la que la información sobre las pesquerías es bastante limitada. Se realizaron un total de 28 pescas de arrastre de fondo entre 70 y 410 m de profundidad de diciembre 2009 a febrero de 2010. Todas las muestras se recogieron a bordo de un embarcación de pesca de arrastre siguiendo las mismas condiciones de pesca comercial. Se capturaron un total de 3143 kg de biomasa en 28 lances válidos. Los desembarques comerciales representaron alrededor del 67% de la captura total, mientras que el resto (33%) se descartó. El 85% de la captura total estuvo compuesta por especies de peces. La composición específica se pudo separar en cuatro grupos principales relacionados con la profundidad : la plataforma poco profunda (70 a 88 m), la plataforma profunda (155-180 m), el borde inferior de la plataforma (196 a 276 m) y el talud superior (307-410 m). Los peces dominaron la abundancia y biomasa tanto de los desembarques comerciales como de los descartes en todos los estratos batimétricos. Además los equinodermos también fueron un grupo importante de los descartes. La media de las capturas totales v...

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Section: Introductionmentioning

confidence: 99%

Preliminary evaluation of landings and discards of the Turkish bottom trawl fishery in the northeastern Aegean Sea (eastern Mediterranean)

Keskin¹,

Ordines²,

Ateş³

et al. 2014

Sci. Mar.

View full text Add to dashboard Cite

show abstract

“…They estimated that fork lengths of the fish in age group I-II-III as 10.3, 13.4, and 15.4 cm, respectively. These values were converted to total length by using conversion formulation given by Tosunoğlu et al (2003b) and total lengths for age groups I, II, and III were calculated as 11.7, 15.2 and 17.5 cm, respectively. The populations entering to the codend in this study show a similar age distribution to the findings of Kınacıgil et al (2001).…”

Section: Discussionmentioning

confidence: 99%

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Özbilgin¹,

Tosunoğlu²,

Tokaç³

et al. 2011

Turk. J. Fish. Aquat. Sci.

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Seasonal changes in the selectivity of 40 mm PE codend were investigated in the Eastern Aegean Sea. Selectivity of the same codend was tested for red mullet (Mullus barbatus), by using the same vessel, fishing ground, towing speed and duration. Four sets of data were collected in spring (4-18 April 2002), summer (10-25 July 2002), autumn (26 September-2 October 2002) and winter (22-23 January 2003). Data were obtained by using covered codend technique, and analysed by using logistic equation with the maximum likelihood method. Four sets of selection curves were analysed and compared using the model developed by Fryer. To investigate the seasonal changes in the condition of the fish, length and weight data were collected from samples taken to cover the whole length range in the catch. Results show that estimate of L 50 in spring is significantly lower than those for other seasons (P<0.05). There is about 10% difference between the mean L 50 values of the best and the poorest seasons, summer (11.1 cm) and spring (10.1 cm), respectively. The L 50 values of autumn (10.8 cm) and winter (11.0 cm) lay between these two. Fish were in their best condition and the water temperature was at its highest point of the annual cycle in autumn. Balığın kondüsyon faktöründeki mevsimsel değişimleri araştırmak amacıyla avdaki tüm boy aralığını kapsayacak şekilde alınan örneklerden boy ve ağırlık verisi toplanmıştır. Sonuçlar ilkbaharda hesaplanan L 50 'nin diğer mevsimlerdekinden belirgin derecede daha düşük olduğunu göstermektedir (P<0,05). En iyi ve en düşük L 50 değerleri arasında, sırasıyla yaz (11,1 cm) ve ilkbahar (10,1 cm), yaklaşık %10'luk bir fark vardır. Sonbahar (10,8cm) ve kışın (11,0 cm) L 50 değerleri bu iki değerin arasında kalmaktadır. Sonbaharda balıklar en iyi kondüsyon faktöründe ve su sıcaklığı yıllık döngüsünün en yüksek değerindedir.Anahtar Kelimeler: Trol seçiciliği, örtü torba, Ege Denizi.

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“…Recent studies have shown that the selectivity of diamond mesh codend used commercially (nominal 40 mm or 44 mm diamond) by Turkish demersal trawlers is rather poor (Özbilgin & Tosunoğlu, 2003;Tosunoğlu, Özbilgin & Tokaç, 2003a;Tosunoğlu, Doğanyilmaz & Özbilgin, 2003b;Tokaç, Özbilgin & Tosunoğlu, 2004). Turkish Fisheries Regulations (TFR) allow trawlers to use a minimum of 40 and 44 mm codend diamond mesh size in the Black Sea and the remain Turkish waters, respectively.…”

Section: Introductionmentioning

confidence: 99%

Untitled

Ilkyaz¹,

Sensurat²,

Dereli̇³

et al. 2017

Turk. J. Fish. Aquat. Sci.

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This study investigated the selectivity of 90° turned meshes of 40 mm mesh size with 165 meshes around codend circumferences (40T1), 44 mm meshes size with 300 meshes around codend circumferences (44T1) and 44 mm mesh sizes with 150 meshes around codend circumferences (44T2). Experiments were carried out in the Kuşadası Bay of the Eastern Mediterranean, between 19 January and 29 March 2015 with commercial stern trawler. Selectivity data were collected using the covered codend method and analysed by means of a logistic equation with the maximum likelihood method. Individual hauls and mean selectivity parameter were estimated by using the CC2000 and EC-Modeller software, respectively. The mean 50% retention total length values (L50) and selection range (SR) were 12.7 cm and 2.3 cm for 40T1, 13.2 cm and 3.5 cm for 44T1 and 13.8 cm and 3.0 for 44T2, respectively. Significant differences were determined among the L50 values of the codends (between 40T1 and 44T2) (P<0.05). However, there are no statistical difference between the 40T1 and 44T1, 44T1 and 44T2 (P>0.05). On the other hand, L50 values of 40T1 and 44T1 are very close considered to the 13 cm length at first maturity size of the species.

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Body shape and trawl cod end selectivity for nine commercial fish species

Cited by 45 publications

References 2 publications

Preliminary evaluation of landings and discards of the Turkish bottom trawl fishery in the northeastern Aegean Sea (eastern Mediterranean)

Preliminary evaluation of landings and discards of the Turkish bottom trawl fishery in the northeastern Aegean Sea (eastern Mediterranean)

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