Scientia Marina, Vol 81, No 3 (2017)

Seasonal variation in mortality of red mullet (Mullus barbatus) escaping from codends of three different sizes in the Aegean Sea

F. Ozan Düzbastılar
Ege University, Faculty of Fisheries, Turkey

Michael Breen
Institute of Marine Research, Norway

Celalettin Aydın
Ege University, Faculty of Fisheries, Turkey

Hüseyin Özbilgin
Mersin University, Faculty of Fisheries, Turkey

Aytaç Özgül
Ege University, Faculty of Fisheries, Turkey

Ali Ulaş
Ege University, Faculty of Fisheries, Turkey

Gülnur Metin
Ege University, Faculty of Fisheries, Turkey

Benal Gül
İstanbul University, Faculty of Fisheries, Turkey

Altan Lök
Ege University, Faculty of Fisheries, Turkey


This study was performed off the southern coast of Yassıca Island in the Izmir Bay on the Turkish coast of the Aegean Sea to investigate the mortality of red mullet (Mullus barbatus, Mullidae) escaping through 40-mm square-mesh and 44- and 50-mm diamond-mesh codends attached to a conventional demersal trawl net. In total, 48 replicate experimental hauls were performed in the summer and winter of 2011 and 2012. Mean escape mortality for all hauls in winter (33.2%±6.51) was significantly higher (p<0.0001) than that in summer (26.5%±6.19). Furthermore, mortality was also highest among the smallest fish, particularly during winter. Irrespective of season, the escape mortality of red mullet was lowest from the 40-mm square-mesh codend (mean, 25.5%±4.58). These observations emphasize the importance of investigating the survival potential of escaping fish when considering the benefits of different selective devices in the management of a fishery.


escape mortality, bottom trawl, size-related mortality, seasonal variation, mesh size, mesh shape, Aegean Sea

Full Text:



Anonymous. 2008. The commercial fish catching regulations in seas and inland waters in 2008-2012 fishing period: circular No. 2⁄1 (2008/48) (in Turkish). Republic of Turkey, Minister of Agriculture and Rural Affair, General Directorate of Conservation and Inspection, Ankara.

Barton B.A., Schreck C.B. 1987. Metabolic cost of acute physical stress in juvenile steelhead. Trans. Am. Fish. Soc. 116: 257-263.<257:MCOAPS>2.0.CO;2

Breen M. 2004. Investigating of the mortality of fish escaping from towed fishing gears- a critical analysis. PhD thesis, Univ. Aberdeen, Scotland, 321 pp.

Breen M., Huse I., Ingólfsson O.A., et al. 2007. An assessment of mortality in fish escaping from trawl codends and its use in fisheries management. Quality of Life and Management of Living Resources Q5RS-2002-01603, 300 pp.

Broadhurst M.K., Kennelly S.J., Barker D.T. 1997. Simulated escape of juvenile Sand Whiting (Sillago ciliate, Cuvier) through square-meshes: effects on scale-loss and survival. Fish. Res. 32: 51-60.

Broadhurst M.K., Suuronen P., Hulme A. 2006. Estimating collateral mortality from towed fishing gear. Fish Fish. 7: 180-218.

Carscadden J.E., Frank K.T. 2002. Temporal variability in the condition factors of Newfoundland capelin (Mallotus villosus) during the past two decades. ICES J. Mar. Sci. 59: 950-958.

Cheung W.W.L., Watson R., Pauly D. 2013. Signature of ocean warming in global fisheries catch. Nature 497: 365-369. PMid:23676754

Chopin F., Arimoto T. 1995. The condition of fish escaping from fishing gears - a review. Fish. Res. 21: 315-327.

DeAlteris J.T., Reifsteck D.M. 1993. Escapement and survival of fish from the codend of a demersal trawl. ICES Mar. Sci. Symp. 196: 128-131.

Düzbastılar F.O., Özgül A., Aydın ?., et al. 2010a. A preliminary study on the survival of brown comber, Serranus hepatus (Actinopterygii, Perciformes, Serranidae), escaping from the codend of a bottom trawl. Acta Ichthyol. Piscat. 40: 27-36.

Düzbastılar F.O., Özbilgin H., Aydın C., et al. 2010b. Mortalities of fish escaping from square and diamond mesh codends in the Aegean Sea. Fish. Res. 106: 386-392.

Düzbastılar F.O., Aydın C., Metin G., et al. 2010c. Survival of fish after escape from a 40 mm streched diamond mesh trawl codend in the Aegean Sea. Sci. Mar. 74: 755-761.

Düzbastılar F.O., Lök A., Aydın C., et al. 2012. Investigating the survival of fish escaping from the codends of bottom trawls (in Turkish), TÜB?TAK Project No: 110O335, Final Rep. 174 pp.

EC. 2006. Council Regulation (EC 1967/2006) concerning management measures for the sustainable exploitation of fishery resources in the Mediterranean Sea, amending Regulation (EEC) No 2847/93 and repealing Regulation (EC) No 1626/94. Off. J.E.U. 409, 75 pp.

Gilman E., Suuronen P., Hall M., et al. 2013. Causes and methods to estimate cryptic sources of fishing mortality. J. Fish. Biol. 83: 766-803. PMid:24090548

He P., Wardle C.S. 1988. Endurance at intermediate swimming speeds of Atlantic mackerel, Scomber scombrus L., herring, Clupea harengus L., and saithe, Pollachius virens L. J. Fish. Biol. 33: 348-360.

ICES. 2005. Joint report of the Study Group on Unaccounted Fishing Mortality (SGUFM) and the Workshop on Unaccounted Fishing Mortality (WKUFM). ICES CM 2005/B: 08.

ICES. 2014. Report of the Workshop on Methods for Estimating Discard Survival (WKMEDS), 17-21 February 2014, ICES HQ, Copenhagen, Denmark. ICES CM 2014/ACOM: 51. 114 pp.

Ingólfsson O.A., Soldal A.V., Huse I., et al. 2007. Escape mortality of cod, saithe, and haddock in a Barents Sea Trawl Fishery. ICES J. Mar. Sci. 64: 1836-1844.

Kınacigil H.T., ?lkyaz A.T., Akyol O., et al. 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 Adriatica 42: 113-123.

Lehtonen E., Tschernij V., Suuronen P. 1998. An improved method for studying survival of fish that escape trawl-codend meshes. Fish. Res. 38: 303-306.

Lowry N., Sangster G.I., Breen M. 1996. Codend selectivity and fish mortality. European Commission Study Contract No. 1994/005, Brussels, EC, Final Report.

Lök A., Metin C., Özbilgin H., et al. 2002. Survival ratios of red mullet (Mullus barbatus) and annular sea bream (Diplodus annularis) after escaping from trawl codend in the Eastern Aegean Sea. ICES CM 2002/V:08.

Main J. Sangster G.I. 1988. A report on an investigation to assess the scale damage and survival of young fish escaping from a demersal trawl. Scottish Fish. Res. Rep. No. 3/88.

Main J., Sangster G.I. 1990. An assessment of the scale damage to and survival rates of young fish escaping from the codend of a demersal trawl. Scottish Fish. Res. Rep. 46: 1-90.

McCullagh P., Nelder J. 1999. Generalized Linear Models. Second Edition. Chapman and Hall/CRC, London. PMCid:PMC1115599

Metin C., Tokaç A., Ula? A., et al. 2004. Survival of red mullet (Mullus barbatus L., 1758) after escape from a trawl codend in the Aegean Sea. Fish. Res. 70: 49-53.

Metin C., Özbilgin H., Tosuno?lu Z., et al. 2005. Effect of square mesh escape window on codend selectivity for three fish species in the Aegean Sea. Turk. J. Vet. Anim. Sci. 29: 461-468.

Özbilgin H., Wardle C.S. 2002. Effect of seasonal temperature changes on the escape behaviour of haddock, Melanogrammus aeglefinus, from the codend. Fish. Res. 58: 323-331.

Özbilgin Y.D., Tosuno?lu Z., Özbilgin H. 2006. By-catch in a 40 mm PE demersal trawl codend. Turk. J. Vet. Anim. Sci. 30: 179-185.

Özbilgin H., Tosuno?lu Z., Tokaç A., et al. 2011. Seasonal variation in the trawl codend selectivity of red mullet (Mullus barbatus). Turkish J. Fish. Aquat. Sci. 11: 191-198.

Petrakis G., Stergiou K.I. 1997. Size selectivity of diamond and square mesh cod- ends for four commercial Mediterranean fish species. ICES J. Mar. Sci. 54: 13-23.

R Development Core Team. 2007. R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Version 2.6.1. Vienna, Austria.

Ricker W.E. 1973. Linear regressions in fishery research. J. Fish. Res. Board of Canada 30: 409-434.

Sacchi J. 2008. The use of trawling nets in the Mediterranean. Problems and selectivity options. Options Mediterranean's, Series B, No: 62: 87-96.

Sangster G.I., Lehmann K., Breen M. 1996. Commercial fishing experiments to assess the survival of haddock and whiting after escape from four sizes of diamond mesh codends. Fish. Res. 25: 323-345.

Sardà F., Bahamon N., Molí B., et al. 2006. The use of a square mesh codend and sorting grids to reduce catches of young fish and improve sustainability in a multispecies bottom trawl fishery in the Mediterranean. Sci. Mar. 70: 347-353.

Soldal A.V., Engås A. 1997. Survival of young gadoids excluded from a shrimp trawl by a rigid deflecting grid. ICES J. Mar. Sci. 54: 117-124.

Sparre P. 1987. Introduction to tropical fish stock assessment (Part 1. Manual). FAO Fish. Tech. Pap. 101 Suppl. 2: 1-114.

Suuronen P. 2005. Mortality of fish escaping trawl gears. FAO Fish. Tech. Pap. 478: 72 pp.

Suuronen P., Erickson D.L., Orrensalo A. 1996a. Mortality of herring escaping from pelagic trawl codends. Fish. Res. 25: 305-321.

Suuronen P., Lehtonen E., Tschernij V., et al. 1996b. Skin injury and mortality of Baltic cod escaping from two codends equipped with exit windows. Arch. Fish. Mar. Res. 44: 165-178.

Suuronen P., Lehtonen E., Jounela P. 2005. Escape mortality of trawl-caught Baltic cod (Gadus morhua) - the effect of water temperature, fish size and codend catch. Fish. Res. 71: 151-163.

Wileman D.A., Sangster G.I., Breen M., et al. 1999. Roundfish and nephrops survival after escape from commercial fishing gear. Final Report, EC Contract FAIR-CT95-0753, Brussels. PMCid:PMC1220640

Copyright (c) 2017 Consejo Superior de Investigaciones Científicas (CSIC)

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Contact us

Technical support