Zafer Tosunoğlu, Gökhan Gökçe, Nazlı Kasapoğlu

An adapted slipping process to exclude jellyfish in the Sea of Marmara purse seine fishery

Excluding the jellyfish from the bunt-end is a common slipping process used in the Sea of Marmara purse seine fishery. For this aim, a sheet of netting piece, larger mesh size and thicker diameter, is rigged on the bunt-end of the purse seine net. The jellyfish mass on the netting piece are slipped by rolling over the headline (floating line) after partially hauling or drying-up the net while it is still in the water. In this study, the catch amount of this slipping was roughly estimated with the introduction of the slipping process only used by the purse seiners in the Sea of Marmara. There were eight successful purse seine operations conducted between 8 and 11 September 2018 in depth ranged 77 to 677 m. The percentage of landed species versus to jellyfish varied between 23% and 85%. The mean landed anchovy amount is 4379 (±3756.6) kg for per operation. The mean slipped amount of jellyfish is 3812.5 (±2404.4) kg. However, both anchovy (99.8%) and jellyfish (96.3%) are the vast majority species that landed and slipped, respectively. In the operations totally 100 boxes of anchovy (1180 kg) unintentionally was slipped with the jellyfish. In addition, two sharks with larger size were slipped to the sea as alive over the floating line of the net. Although slipping practised rarely in Turkey, all the purse seiner in the Sea of Marmara have to use the adapted slipped process to get rid of jellyfish. However, there are no records and scientific findings regarding slipped amount of the jellyfish. For this reason, this study is important to presented preliminary results regarding amount of the jellyfish. In conclusion, this study is extended completely the Sea of Marmara practised to understand the dimensions of jellyfish amount and slipping process.

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Breen, M., Isaksen, B., Ona, E., Pedersen, A. O., Pedersen, G., Saltskår, J., Svardal, B., Tenningen, M., Thomas, P. T., Totland, B., Øvredal, J. T. & Vold, A. (2012). A review of possible mitigation measures for reducing mortality caused by slipping from purse-seine fisheries. ICES CM 2012/C: 12.
Daskalov, G. M., Grishin, A. N., Rodionov, S. & Mihneva, V. (2007). Trophic cascades triggered by overfishing reveal possible mechanisms of ecosystem regime shifts. Proceedings of the National Academy of Sciences, 104: 10518-10523.
Handegard, N. O., Tenningen, M., Howarth, K., Anders, N., Rieucau, G. & Breen, M. (2017). Effects on schooling function in mackerel of sub-lethal capture related stressors: Crowding and hypoxia. PLoS ONE, 12(12): e0190259. https://doi.org/10.1371/journal.pone. 0190259
Huse, I., & Vold, A. (2010). Mortality of mackerel (Scomber scombrus L.) after pursing and slipping from a purse seine. Fisheries Research, 106: 54-59. https://doi.org/10.1016/j.fishres.2010.07.001
İşinibilir, M. & Yılmaz, İ. N. (2016). Jellyfish species in the Sea of Marmara (pp. 390-400). In E. Özsoy, M. N. Çağatay, N. Balkıs, N. Balkıs, B. Öztürk (Eds.), The Sea of Marmara: Marine Biodiversity, Fisheries, Conservation and Governance. Istanbul: Turkish Marine Research Foundation (TUDAV), Publication No. 42.
Lockwood, S. J., Pawson, M. G. & Eaton, D. R. (1983). The effects of crowding on mackerel (Scomber scombrus L.) - Physical condition and mortality. Fisheries Research, 2: 129-147. https://doi.org/10.1016/0165-7836(83)90114-5
Marçalo, A., Breen, M., Tenningen, M., Onandia, I., Arregi, L. & Gonçalves, J. M. S. (2019). Mitigating slipping-related mortality from purse seine fisheries for small pelagic fish: case studies from European Atlantic waters (pp. 297-318). In S. S. Uhlmann, C. Ulrich, S. J. Kennelly (Eds), The European Landing Obligation. Switzerland: Springer Nature.
Marçalo, A., Guerreiro, P. M., Bentes, L., Rangel, M., Monteiro, P., Oliveira, F., Afonso, C. M. L., Pousão-Ferreira, P., Benoît, H. P., Breen, M., Erzini, K. & Gonçalves, J. M. S. (2018). Effects of different slipping methods on the mortality of sardine, Sardina pilchardus, after purseseine capture off the Portuguese Southern coast (Algarve). PLoS ONE, 13(5): e0195433. https://doi.org/ 10.1371/journal.pone.0195433
Marçalo, A., Marques, T. A., Araújo, J., Pousão-Ferreira, P., Erzini, K. & Stratoudakis, Y. (2010). Fishing simulation experiments for predicting the effects of purse-seine capture on sardine (Sardina pilchardus). ICES Journal of Marine Science, 67: 334-344. https://doi.org/ 10.1093/icesjms/fsp244
Marçalo, A., Mateus, L., Duarte Correira, J. H., Serra, P., Fryer, R. & Stratoudakis, Y. (2006). Sardine (Sardina pilchardus) stress reactions to purse seine fishing. Marine Biology, 149: 1509-1518. https://doi.org/ 10.1007/s00227-006-0277-5
Mitchell, R. W., Blight, S. J., Gaughan, D. J. & Wright, I. W. (2002). Does the mortality of released Sardinops sagax increase if rolled over the headline of a purse seine net? Fisheries Research, 57: 279-285. https://doi.org/10.1016/ S0165-7836(01)00354-X
Stratoudakis, Y. & Marçalo, A. (2002). Sardine slipping during purse-seining off northern Portugal. ICES Journal of Marine Science, 59: 1256-1262. https://doi.org/10.1006/ jmsc.2002.131
Tenningen, M, Vold, A. & Olsen, R. E. (2012). The response of herring to high crowding densities in purse-seines: survival and stress reaction. ICES Journal of Marine Science, 69: 1523-1531. https://doi.org/10.1093/icesjms/ fss114
Tosunoğlu, Z. & Kasapoğlu, N. (2019). Slipping practises in Turkish purse seine fishery. Proceedings of the International Biodiversity and Ecology Sciences Symposium, Turkey pp. 82-85.
TurkStat. (2018). Fisheries statistics 2017 (in Turkish). Ankara: Turkish Statistic Institution.
Watson, R., Revenga, C. & Kura, Y. (2006). Fishing gear associated with global marine catches. I Database development. Fisheries Research, 79: 97-102. https://doi.org/10.1016/j.fishres.2006.01.010
Yıldız, T. & Karakulak, F. S. (2016). Traditional fishing in the Sea of Marmara: from the past to the present (pp. 697- 709). In E. Özsoy, M. N. Çağatay, N. Balkıs, N. Balkıs, B. Öztürk (Eds.), The Sea of Marmara: Marine Biodiversity, Fisheries, Conservation and Governance. Istanbul: Turkish Marine Research Foundation (TUDAV), Publication No. 42.
Yüksek, A. (2016). Biodiversity of Sea of Marmara and the affecting factors (pp. 570-580). In E. Özsoy, M. N. Çağatay, N. Balkıs, N. Balkıs, B. Öztürk (Eds.), The Sea of Marmara; Marine Biodiversity, Fisheries, Conservation and Governance. Istanbul: Turkish Marine Research Foundation (TUDAV), Publication No. 42.