Hüseyin Murat ÖZBİLGİN, Zafer TOSUNUĞLU, Adnan TOKAÇ, Gülnur METİN

Seasonal variation in the trawl codend selectivity of red mullet (Mullus barbatus)

Bu çalışmada Doğu Ege Denizi’nde 40 mm PE torba seçiciliğinin mevsimsel değişimi araştırılmıştır. Aynı torbanın seçiciliği, aynı gemi, av sahası, çekim hızı ve çekim süresi kullanılarak barbun için denenmiştir. İlkbahar (4-18 Nisan 2002), yaz (10-25 Temmuz 2002), sonbahar (26 Eylül-2 Ekim 2002) ve kış (22-23 Ocak 2003) mevsimlerinde 4 grup veri toplanmıştır. Veriler örtü torba tekniği kullanılarak elde edilmiş ve ‘En Yüksek Olabilirlik Yöntemi’ ile lojistik denklem kullanılarak analiz edilmiştir. Dört grup seçicilik eğrisi Fryer tarafından geliştirilen model kullanılarak karşılaştırılmıştır. Balığın kondüsyon faktöründeki mevsimsel değişimleri araştırmak amacıyla avdaki tüm boy aralığını kapsayacak şekilde alınan örneklerden boy ve ağırlık verisi toplanmıştır. Sonuçlar ilkbaharda hesaplanan L50’nin diğer mevsimlerdekinden belirgin derecede daha düşük olduğunu göstermektedir (P

Anahtar Kelimeler:

Ege Denizi, mevsimsel değişimler, Türkiye, su sıcaklığı

Barbun balığı (Mullus barbatus)’nın trol torba seçiciliğinde mevsimsel değişimler

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 L50 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.

Keywords:

Aegean Sea, seasonal variation, Turkey, water temperature,

PDF

___

Akyol, O., Tosunoğlu, Z. and Tokaç, A. 2000. Investigations of the growth and reproduction of red mullet (Mullus barbatus Linnaeus, 1758) population in the Bay of Izmir (Aegean Sea). Anadolu University Journal of Science and Technique, 1: 121-127.
Anonymous. 2008a. Fishery Statistics 2007. Turkish Statistical Institute, Printing Division, Ankara, Publication no. 3177, Ankara, 48 pp.
Anonymous. 2008b. Notification 2/1 Regulating Commercial Fishing (Notification Number 2008-48) (in Turkish). SUR-KOOP, Su Urünleri Kooperatifleri Merkez Birliği, Pozitif Matbaa, Ankara, 112 pp.
Çıra, E. 1999. Seasonal cod-end selectivity of traditional bottom trawl nets used in Aegean Sea (in Turkish). PhD thesis. İzmir: Ege University.
Ferretti, M. and Froglia, C. 1975. Results of selectivity experiments, made with different trawls, on more important Adriatic demersal fish. Quad. Lab. Tecnol. Pesca, 2: 3-16.
Ferro, R.S.T., Özbilgin, H. and Bren, M. 2008. The potential for optimizing yield from a haddock trawl fishery using seasonal changes in selectivity, population structure and fish condition. Fisheries Research, 94: 151–159. doi: 10.1016/j.fishres.2008.08.018
Fiorentini, L. and Leonori, I. 2002. The effects of mesh size and number of meshes around the codend on red mullet and hake selectivity. Tests in the Adriatic Sea made for the PREMECS EU Project: Development of predictive model of codend selectivity. ICES FTFB Working Group Meeting, 11, Sete-France. doi: 10.1093/icesjms/48.3.281
Fryer, R.J. 1991. A model of between-haul variation in selectivity. ICES Journal of Marine. Science, 48: 281-290.
Gurbet, R. 992. Selectivity of the bottom trawl nets on the red mullet (Mullus barbatus L.) fishery (in Turkish). PhD thesis. İzmir: Ege University.
Gurbet, R., Hoşsucu, H., İlkyaz, A.T. and Özekinci, U. 1997. The study on the comparison of selectivity of 40 and 44 mm mesh size in the trouser bottom trawls (in Turkish). In: B. Hoşsu (Ed.), Mediterranean Fisheries Congress, Izmir: 77-91.
He, P. 1993. Swimming speeds of marine fish in relation to fishing gears. ICES Mar. Sci. Symp., 196: 183-189.
Ilkyaz, A.T., Metin, C. and Kınacıgil, H.T. 1998. A computer program about the calculation of the selectivity parameters in towed fishing gear illustrated with covered codend method (L50 Version:1.0.0). Ege University, Journal of Fisheries and Aquatic Sciences, 15: 305-314.
Jukic, S. and Piccinetti, C. 1988. Contribution to the knowledge on the short and long-term effects of the application of 40 mm codend mesh size in Adriatic trawl fishery - eastern Adriatic coast. FAO Fishery Report. 394, Rome: 282-290.
Kınacıgil, H.T., İlkyaz, A.T., Akyol, O., Metin, G., Çıra E. and Ayaz, A. 2001. Growth parameters of red mullet (Mullus barbatus L., 1758) and seasonal cod-end selectivity of traditional bottom trawl nets in Izmir Bay (Aegean Sea). Acta Adriatic, 42: 113-123. doi:UDC: 551.465 (262.3-17)
Kınıkarslan, N. 1976. Research on Selectivity of Red Mullet (Mullus barbatus) in Trawl Codend Meshes (in Turkish). I.U. Hydrobiolgy Research Institution Publication 17, Istanbul, 12 pp.
Livadas, R.J. 1988. The selectivity of certain trawl cod-ends in Cyprus. FAO Fisheries Report No. 412, FIPL/R412, GFCM Technical consultation on stock assessment in the Eastern Mediterranean, Athens: 180-189.
Lök, A., Tokaç, A., Tosunoğlu, Z., Metin, C. and Ferro, R.S.T. 1997. The effects of different codend design on bottom trawl selectivity in Turkish fisheries of the Aegean Sea. Fisheries Research, 32: 149-156. doi:10.1016/S0165-7836(97)00048-9
Metin, G. 2005. Reproduction characteristics of red mullet (Mullus barbatus L., 1758) in Izmir Bay. Ege University Journal of Fisheries and Aquatic Sciences, 22: 225-228.
Özbilgin, H. 2002. Effect of temperature change on the maximum swimming speed of whiting, Merlangius merlangus (Linnaeus, 1758). Turkish Journal of Zoology, 26: 255-262.
Özbilgin, H. and Wardle, C.S. 2002. Effect of seasonal temperature changes on the escape behaviour of haddock, Melanogrammus aeglefinus, from the codend. Fisheries Research., 58: 323-331. doi:10.1016/S0165-7836(01)00394-0
Özbilgin, H. and Tosunoğlu, Z. 2003. Comparison of the selectivities of double and single codends. Fisheries Research, 63: 143-147. doi:10.1016/S0165-7836 (03)00005-5
Özbilgin, H., Tosunoğlu, Z., Metin, G. and Tokaç, A. 2005. Seasonal variation in trawl codend selectivity of annular sea bream (Diplodus annularis L., 1758). Turkish Journal of Veterinary and Animal Sciences, 29: 959-965.
Özbilgin, H., Ferro, R.S.T., Robertson, J.H.B., Holtrop, G. and Kynoch, R.J. 2006. Seasonal variation in trawl codend selection of northern North Sea Haddock. ICES Journal of Marine Science, 63: 737-748. doi: 10.1016/j.icesjms.2005.01.025
Özbilgin, H., Tosunoğlu, Z., Tokaç, A. and Metin, G. 2007. Seasonal variation in the trawl codend selectivity of picarel (Spicare smaris). ICES Journal of Marine. Science, 64: 1569-1572. doi: 10.1093/icesjms/fsm115.
Stergiou, K.L., Petrakis, G., Politou, C.-Y., Christou, E.D., Karkani, M., MacLennan, D.N. and Ferro, R.S.T. 1994. Selectivity of Square and Diamond Codends in Hellenic Waters. Final Report (Contract No. MED92/020, EC), Stergiou and Co., Athens.54 pp.
Stewart, P.A.M. 2001. A Review of Studies of Fishing Gear Selectivity in the Mediterranean. FAO, COPEMED, Rome, 75 pp.
Toğulga, M. 1976. Researches on biology and population dynamics of red mullet (Mullus barbatus Linne.) in the Bay of Izmir (in Turkish). MSc. thesis. İzmir: Ege Üniversitesi.
Tokaç, A. 2002. Studies on the improvement of bottom trawl selectivity in Aegean Sea. In: M. Paschen (Ed.), Contributions on the Theory of Fishing Gears and Related Marine Systems Rostock: 259-274.
Tokaç, A. and Tosunoğlu. Z. 1997. The importance of relationship between mesh shape and fish body form for trawl nets selectivity (in Turkish). In: B. Hoşsu (Ed.), Mediterranean Fisheries Congress, Izmir: 51-58.
Tokaç, A., Lök, A., Tosunoğlu, Z., Metin, C. and Ferro, R.S.T. 1998. Cod-end selectivities of a modified bottom trawl for three fish species in the Aegean Sea. Fisheries Research, 39: 17-31. doi:10.1016/S0165-7836(98)00172-6
Tosunoğlu, Z. 2000. Improving of red mullet (Mullus barbatus L., 1758) selectivity at conventional bottom trawl nets (in Turkish). Ege University. Journal of Fisheries and Aquatic Sciences, 17: 149-160.
Tosunoğlu, Z., Kaykaç, H. Aydın, C. and Tokaç, A. 1996. Bottom trawl nets used in fisheries researchs of the Aegean University, Faculty of Fisheries (in Turkish). Ege University, Journal of Fisheries and Aquatic Sciences, 13: 485-498.
Tosunoğlu, Z., Tokaç, A., Lök, A. and Metin, C. 1997. The comparison of effects on cod-end selectivity of different two techniques of covered cod-end method used in trawl selectivity experiments (in Turkish). Turkish Journal of Veterinary and Animal Sciences, 21: 449-456.
Tosunoğlu, Z., Özbilgin, H. and Tokaç, A. 2003a. Effects of the protective bags on the codend selectivity in Turkish bottom trawl fishery. Archive of Fisheries and Marine Research, 50: 239-252.
Tosunoğlu, Z., Özbilgin, Y.D. and Özbilgin, H. 2003b. Body shape and trawl codend selectivity for nine commercial fish species. Journal of Marine Biology Associations, 83: 1309-1313.
Wileman, D.A., Ferro, R.S.T., Fonteyne R. and Millar, R.B. (Eds.) 1996. Manual of Methods of Measuring the Selectivity of Towed Fishing Gears. ICES Coop. Res. Rep. 215, Copenhagen: 1-126.