Comparison of monofilament and multifilament bottom trammel nets regarding catch efficiency and chondrichthyan bycatch in Çanakkale, Türkiye

Abstract This study aimed to evaluate the catch efficiency and chondrichthyan bycatch of monofilament and multifilament bottom trammel nets in the Çanakkale region, where small-scale commercial fishing is practiced intensively. The field trials of the study were carried out between September 2024 and March 2026. Within the scope of the study, a total of 8 units (800 m) of trammel nets were used. The trammel nets are equipped with a 42 mm inner mesh size, monofilament and multifilament materials and, have all other technical characteristics identical. 65 trials were carried out with these nets. The nets were deployed in the water for 36 hours in each trial. As a result of the trials, a total of 981 individuals and 622.3 kg of fish belonging to 20 species were captured. All species with economic value were classified as target, and other species without economic value were classified as discard. When the economic species caught in the nets were compared, multifilament trammel nets caught 1.22 times more than monofilament trammel nets. As a result of the statistical comparison, multifilament trammel nets caught more than monofilament trammel nets ( P < 0.05). In the discarded catch, monofilament trammel nets caught 1.62 times more than multifilament trammel nets. In addition, the ratio of priority conservation species within the total catch was calculated as 23.2% in monofilament trammel nets; this ratio was 12.5% in multifilament trammel nets. In the comparison made using repeated measures analysis of variance, the difference between them was found to be statistically significant ( P < 0.05). The study determined that the preference for monofilament material is not necessary for the nets used in the fishing of species such as cuttlefish, lobster, and scorpionfish in the region, and that multifilament trammel nets are more efficient than monofilament trammel nets in catching target species. Additionally, considering that a large part of the bycatch consists of conservation-priority chondrichthyan fish species, it was determined that the use of monofilament material in trammel nets is not suitable in terms of sustainable fisheries. It was established that the preference for multifilament trammel nets would enhance bycatch mitigation.