Hüseyin ÖZBİLGİN, Zafer TOSUNOĞLU, Celalettin AYDIN, Hakan KAYKAÇ, Adnan TOKAÇ

Selectivity of Standard, Narrow and Square Mesh Panel Trawl Codends for Hake (Merluccius merluccius) and Poor Cod (Trisopterus minutus capelanus)

The selectivity of 3 trawl codends, (1) a commercially used standard codend, (2) a narrow codend (100 meshes on its circumference instead of 200) and (3) a square mesh top panel codend, was tested for hake (Merluccius merluccius) and poor cod (Trisopterus minutus capelanus) between 8 and 24 October 2003, in the Aegean Sea. Data were collected using the covered codend technique, and analysed by means of a logistic equation with the maximum likelihood method. The results show that the commercially used standard codend (40 mm mesh size PE codends, 200 meshes on its circumference) retains all the hake that enter and releases only a few specimens of poor cod. The narrow codend has better selectivity than the standard codend (L50 = 14.28 cm for hake and 14.11 cm for poor cod). The selectivity of the square mesh top panel codend was higher than that of the narrow codend for hake (L50 = 15.25 cm), while it was similar for poor cod (L50 = 14.25 cm).

Anahtar Kelimeler:

Trawl selectivity, narrow codend, square mesh panel, hake (Merluccius merluccius), poor cod (Trisopterus minutus capelanus), Aegean Sea

Selectivity of Standard, Narrow and Square Mesh Panel Trawl Codends for Hake (Merluccius merluccius) and Poor Cod (Trisopterus minutus capelanus)

Keywords:

Trawl selectivity, narrow codend, square mesh panel, hake (Merluccius merluccius), poor cod (Trisopterus minutus capelanus), Aegean Sea,

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Tokaç, A., Lök, A., Tosunoğlu, Z., Metin, C., Ferro, R.S.T.: Cod- end selectivities of a modified bottom trawl for three fish species in the Aegean Sea. Fish. Res., 1998; 39: 17-31.
Özbilgin, H., Tosunoğlu, Z.: Comparison of the selectivities of double and single codends. Fish. Res., 2003; 63: 143-147. 3. Tosunoğlu, Z., Özbilgin, H., Tokaç, A.: Effects of the protective bags on the codend selectivity in Turkish bottom trawl fishery. Arch. Fish. Mar. Res., 2003; 50: 239-252. 4. Tosunoğlu, Z., Özbilgin, Y.D., Özbilgin, H.: Body shape and trawl codend selectivity for nine commercial fish species. J. Mar. Biol. Assoc. UK, 2003; 83: 1309-1313.
Tokaç, A., Özbilgin, H., Tosunoğlu, Z.: Effect of PA and PE material on codend selectivity in Turkish bottom trawl. Fish. Res., 2003; 67: 317-327. 6. Tokaç, A.: Studies on the improvement of bottom trawl selectivity in Aegean Sea. Contributions on the Theory of Fishing Gears and Related Marine Systems, Rostock. 2002; 259-274. 7. Stewart, P.A.M.: A review of studies of fishing gear selectivity in the Mediterranean. FAO, COPEMED. 2001.
Devlet İstatistik Enstitüsü: Su Ürünleri İstatistikleri 2001. T.C. Baflbakanlık Devlet İstatistik Enstitüsü, Ankara. 2003. 9. Tarım ve Köyiflleri Bakanlığı: Denizlerde ve içsularda ticari amaçlı su ürünleri avcılığını düzenleyen 2002-2004 av dönemine ait 35/1 numaralı sirküler. T.C. Tarım ve Köyiflleri Bakanlığı, Koruma ve Kontrol Genel Müdürlüğü, Ankara. 2002.
Politou, C.Y., Papaconstantinou, C.: Population biology of Trisopterus minutus capelanus (Gadidae) from the eastern coast of Greece. Cybium, 1991; 15: 69-81.
Robertson, J.H.B., Stewart, P.A.M.: A comparison of size selection of haddock and whiting by square and diamond mesh codends. J. Cons. Int. Explor. Mer., 1988; 44: 148-161.
Reeves, S.A., Armstrong, D.W., Freyer, R.J., Coull, K.A.: The effects of mesh size, cod-end extension length and cod-end diameter on the selectivity of Scottish trawls and seines. ICES J. Mar. Sci., 1992; 49: 279-288.
Tosunoğlu, Z., Özbilgin, Y.D., Özbilgin, H.: Determination of the appropriate hanging ratios to ease the escape of juvenile red mullet (Mullus barbatus L., 1758) and annular sea bream (Diplodus annularis L., 1758) from trawl codend. Turk. J. Vet. Anim. Sci., 2003; 27: 1193-1199.
Petrakis, G., Stergiou, K.I.: Size selectivity of diamond and square mesh codends for four commercial Mediterranean fish species. ICES J. Mar. Sci., 1997; 54: 13-23.
Campos, A., Fonseca, P.: Selectivity of diamond and square mesh cod ends for horse mackerel (Trachurus trachurus), European hake (Merluccius merluccius) and axillary sea bream (Pagellus acarne) in the shallow groundfish assemblage off the south-west coast of Portugal. Sci. Mar., 2003; 67: 249-260.
Campos, A., Fonseca, P., Henriques, V.: Size selectivity for four fish species of the deep groundfish assemblage off the Portuguese southwest coast: evidence of mesh size, mesh configuration and cod end catch effects. Fish. Res., 2003; 63: 213-233.
Robertson, J.H.B., Ferro, R.S.T.: Mesh selection within the cod- end of trawls. The effects of narrowing the cod-end and shortening the extension. Scot. Fish. Res. Report No 39: 1988.
Broudhurst, M.K., Kennelly, S.J.: Effects of the circumference of codends and a new design of square-mesh panel in reducing unwanted by-catch in the New South Wales oceanic prawn-trawl fishery, Australia. Fish. Res., 1996; 27: 203-214.
Lök, A., Tokaç, A., Tosunoğlu, Z., Metin, C., Ferro, R.S.T.: The effects of different cod-end design on bottom trawl selectivity in Turkish fisheries of the Aegean Sea. Fish. Res., 1997; 32: 149- 156.
Tokai, T.: Maximum likelihood parameter estimates of a mesh selectivity logistic model through SOLVER on MS-Excel. Bull. Jpn. Fish. Oceanog., 1997; 61: 288-298.
Wileman, D.A., Ferro, R.S.T., Fonteyne, R., Millar, R.B. (eds.): Manual of Methods of Measuring the Selectivity of Towed Fishing Gears. ICES Cooperative Research Report, No. 215, Copenhagen. 1996.
Fryer, R.J.: A model of between-haul variation in selectivity. ICES J. Mar. Sci., 1991; 48: 281-290.
Ferretti, M., Froglia, C.: Results of selectivity experiments, made with different trawls, on more important adriatic demersal fish. Quad. Lab. Tecnol. Pesca, 1975; 2: 3-16.
Gurbet, R.: Farklı dip trol ağlarının seçiciliği üzerine arafltırma. E.Ü. Arafltırma Fon Saymanlığı, 1990/SUFA/003 Nolu Proje, Bornova-İzmir. 1993.
Gurbet, R., Hoflsucu, H., İlkyaz, A.T., Özekinci, U.: Dip trollerinde 40 ve 44 mm ağ gözü uzunluğuna sahip pantolon tipi torbalarda seçiciliğin karflılafltırması üzerine arafltırma. Akdeniz Balıkçılık Kongresi, İzmir. 1997: 77-91.
Fiorentini, L., Leonori, I.: The effects of mesh size and number of meshes around the cod-end on red mullet and hake selectivity. Tests in the Adriatic Sea made for the PREMECS EU Project: Development of predictive model of cod-end selectivity. ICES FTFB Working Group Meeting, Sete. 2002.