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Effect of the number of meshes in the protective bag circumference on size selectivity of demersal trawl codends
Author(s) -
Aydın C.,
Şensurat T.,
Özdemir Y.,
Tosunoğlu Z.
Publication year - 2014
Publication title -
journal of applied ichthyology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.392
H-Index - 62
eISSN - 1439-0426
pISSN - 0175-8659
DOI - 10.1111/jai.12413
Subject(s) - demersal zone , horse mackerel , hake , biology , shrimp , fishery , carapace , circumference , mackerel , zoology , statistics , mathematics , fishing , fish <actinopterygii> , geometry , crustacean
Summary This study investigated the effect of the number of meshes in the protective bag circumference on size selectivity of a demersal trawl codend. Circumferences of 50‐mesh ( NMPB 50) and 215‐mesh ( NMPB 215) protective bags rigged on the 44 mm diamond mesh codend were tested. Fishing experiments were carried out on the commercial trawler ‘Hapuloğlu’ between 20 and 27 August 2010, using a modified trawl net. Data were collected using the covered codend method and analyzed using the logistic equation with the maximum likelihood method. Mean selection curves were analyzed and compared using the between‐haul variations model. The mean L 50 values of NMPB 50 and NMPB 215 were, respectively, 16.4 ± 0.1 mm and 16.5 ± 0.1 mm carapace length for deep‐water rose shrimp, 10.7 ± 0.1 cm and 12.2 ± 0.1 cm total length for hake, and 16.0 ± 0.1 cm and 16.7 ± 0.1 cm total length for horse mackerel. In conclusion, increasing the number of meshes around the protective bag resulted in a 14% and 4% increase in the L 50 for hake and mackerel, respectively; however, these differences were not statically significant (P > 0.05).