Turkish pelagic gillnet fishery for swordfish and incidental catches in the Aegean Sea

Yıl 2012, Cilt: 18 Sayı: 2, 188 - 196, 01.08.2012

Okan Akyol Tevfik Ceyhan Mustafa Erdem

Öz

Abstract This study was carried out with 20 representative gill-netters based at the port of Sivrice and Sığacık from June 2008 to August 2010. The average length, gross tonnage (GT), machine power (hp) and number of personnel of the gill-netters were 10.4±0.6 m, 10.5±2.3 GT, 121.4±19.9 hp and 3.4±0.2 persons, respectively. Total length of all observed gillnets was reaching 339 km, ranged from 700 to 6000 m with average 2672 ±93 m. The mean CPUEs for swordfish by number and weight were calculated as 1.0 ±0.1 and 37.7 ±4.2 kg per km net, respectively. A total of 12 species, belongs to nine families were caught. The target species, swordfish had the highest ratio both in number (39.2%) and weight (73.1%) followed by Auxis rochei > Euthynnus alletteratus > Thunnus thynnus > Thunnus alalunga by number; Thunnus thynnus > Mola mola > Euthynnus alletteratus > Mobula mobular by weight. Biomass and number ratios of the non-target species to the target swordfish were 1:0.37 and 1:1.55, respectively. Four species, Caretta caretta, Dasyatis violacea, Mobula mobular, Mola mola were thrown back to the sea and the others were retained due to commercial value.

Anahtar Kelimeler

Key words: Aegean Sea, gillnet fishery, incidental catch, swordfish, Xiphias gladius

Kaynakça

• Akyol, O., Ceyhan, T. (2011) Turkish swordfish fishery. Col. Vol. Sci. Pap., ICCAT, 66(4): 1471-1479.
• Akyol, O., Erdem, M., Unal, V., Ceyhan, T. (2005) Investigations on driftnet fishery for swordfish (Xiphias gladius L.) in the Aegean Sea. Turk J. Vet. Anim. Sci. 29: 1225-1231.
• Akyol, O., Karakulak, F.S., Ceyhan, T., Dede, A. (2008) Driftnets, used in Turkish seas and the regulations. E.U. Su Ürünleri Dergisi 25: 153-157. (in Turkish).
• Anon. (2006) Turkish Fishery Regulation Circular (37/1) for Marine and Inland Commercial Fisheries in Fishing Season 2006-2008, T.C. TKB-KKGM, R.G. Sayı: 26269 Ankara, 108 pp. (in Turkish).
• Artuz, M.I. (1963) Contribution to the knowledge of the biology of the swordfish (Xiphias gladius L.) in the Sea of Marmara. Proc.Gen.Coun.Medit. 7: 459-471.
• De Metrio, G., Megalafonou, P. (1988) Catch, size distribution, growth and sex ratio of swordfish (Xiphias gladius L.) in the Gulf of Taranto. FAO Fish. Rep. No. 394, Rome, 91-102 pp.
• Deveciyan, K. (1926) Fish and Fisheries in Turkey. (original title: Pèche et Pècheries en Turquie, in French). Çeviri: Erol Üyepazarcı, 2006, Aras Yayıncılık, 2. Baskı, Nisan 2006, Istanbul, 574 pp. (in Turkish).
• Di Natale, A., Mangano, A., Maurizi, L., Montaldo, L., Navarra, E., Pinca, S., Schimmenti, G., Torchia, G., Valastro, M. (1993) Swordfish (Xiphias gladius L.) driftnet fishery in the Western Italian Seas: 1990-1991 Report. Col. Vol. Sci. Pap. ICCAT, 40: 184-193.
• Di Natale, A., Mangano, A., Navarra, E., Schimmenti, G., Valastro, M. (1995) Swordfish (Xiphias gladius L.) driftnet fishery in the Tyrrhenian Sea: 1992 Report. Col. Vol. Sci. Pap. ICCAT, 44: 236-241.
• Muus, B.J., Dahlstrom, P. (1974) Collins Guide to the Sea Fishes of Britain and North-western Europe. Wm. Collins Sons and Co. Ltd., 244 pp.
• Nedelec, C., Prado, J. (1990) Definitions and Classification of Fishing Gear Categories. FAO Fisheries Technical Paper 222 (Rev. 1): 92 pp.
• Onat, S. (1970) Pelagic fishes and their catching periods. Balık ve Balıkçılık Dergisi, EBK Yayınları, Đstanbul, 18: 39-40. (in Turkish).
• Ozturk, B., Ozturk, A.A., Dede, A. (2001) Dolphin by-catch in the swordfish driftnet fishery in the Aegean Sea. Rapp. Comm. int. Mer Medit. 36: 308.
• Tudela, S., Kai Kai, A., Maynou, F., El Andalossi, M., Guglielmi, P. (2005) Driftnet fishing and biodiversity conservation: the case study of the large-scale Moroccan driftnet fleet operating in the Alboran Sea (SW Mediterranean). Biological Conservation 121: 65-78.