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Öğe Effect of twine thickness on selectivity of gillnets for bogue, Boops boops, in Turkish waters(Natl Centre Marine Research, 2011) Ayaz, A.; Altinagac, U.; Ozekinci, U.; Ozen, O.; Altin, A.; Ismen, A.To investigate the effect of twine thickness on the selectivity of multifilament gillnet targeting bogue, Boops boops L., four different stations were sampled between March and November 2008 in the North Aegean Sea. Gillnets with 22, 23, and 25 mm nominal mesh size (bar length) each having two different twine thicknesses (approximately 0.45 mm and 0.54 mm empty set) were applied for this purpose. The deviances from the SELECT method revealed that lognormal models provided the best fits for both of the twine thicknesses. Results from the two-way ANOVA analyses revealed that the mean total lengths increased with the mesh size (F = 87.36; df = 2; P < 0.0001) and decreased with the twine thickness (F = 46.12; df = 1; P < 0.0001). The 22 mm mesh size net (0.45 mm empty set) captured significantly larger fish than the 23 mm mesh size net (0.54 mm empty set), probably due to the higher elasticity and flexibility of the thinner twine. Thus, fisheries' managers should take into consideration twine thickness while advising mesh size regulations in gillnet fisheries.Öğe Fishing gear losses in the Gokova Special Environmental Protection Area (SEPA), eastern Mediterranean, Turkey(Wiley-Blackwell, 2010) Ayaz, A.; Unal, V.; Acarli, D.; Altinagac, U.P>This two-stage study was designed to determine the types and quantities of lost fishing gear and their distribution in the Gokova Special Environmental Protection Area (SEPA), eastern Mediterranean Sea. The study was carried out in approx. 15% of the total Gokova SEPA (7000 hectares), where traditional fishing is intensive. In the first phase of the study, the owners of all fishing boats (about 67% of the local fishermen in Gokova SEPA, n = 56) were interviewed using a structured questionnaire. In the second phase, diving surveys were conducted at 14 locations to locate and identify lost fishing gear, estimate the extent of the loss, and deduce the coherence between the diving survey and the questionnaire data. The questionnaire results showed that 0.84% of gillnets, 3.41% of trammel nets, and 79.2% of longlines were lost during 2007 and that the major cause of gear loss was snagging on bottom structures. In the diving surveys, 22 600 m2 (2.26 hectares) of the bottom area were scanned, and an estimated 157 m of gill and trammel nets and 36 280 m of longline nets were located per hectare in the observed area. Moreover, at diving locations D1 and D2, lost trammel and gill nets were 'ghost fishing', suggesting that these lost gear should be removed from the ecosystem. A retrieval project coordinated by universities, fishery cooperatives, and NGOs might help accelerate efforts towards the removal of this lost gear.Öğe Length-weight relationships for ten shark species from Saros Bay (North Aegean Sea)(Wiley, 2009) Ismen, A.; Yigin, C. Cigdem; Altinagac, U.; Ayaz, A.P>Length-weight relationships are presented for ten shark species sampled with a commercial trawl vessel at depths ranging from 5 to 500 m between March 2005 and June 2008 in Saros Bay, Turkey. The values of the exponent b of the length-weight relationships ranged from 2.6816 to 3.6060.Öğe Weight-length relationships of 63 fish species in Saros Bay, Turkey(Blackwell Publishing, 2007) Ismen, A.; Ozen, O.; Altinagac, U.; Ozekinci, U.; Ayaz, A.Weight-length relationships are presented for 63 fish species sampled with a commercial trawl vessel at depths ranging from 28 to 370 m between February 2005 and April 2006 in Saros Bay, Turkey. Saros Bay was closed to trawl fishery in 2000, thus, most of the demersal fish species sampled were relatively undisturbed.
