Title: Effect of mesh size and twine type on gillnet selectivity of cod (Gadus morhua) in Icelandic coastal waters

Author(s): Jorge Raúl Faife
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Supervisors: Haraldur Einarsson


This report focuses on the selectivity of four mesh sizes of gillnets (6”, 7”, 8” and 9”) and two type of twine (monofilament and multifilament) on cod (Gadus morhua) conducted in two different areas in Icelandic waters. The data were collected in April 2001 as part of a spawning net survey of cod but not for examining selectivity. In this study a comparison of relative selectivity of mesh size and netting material was made for these nets in each area. The selection curves were estimated indirectly by using the Gamma model. This study has concluded that monofilament gillnets catch better than multifilament. The mean lengths of cod increased with mesh size of gillnet but the difference of netting material did not affect selection range. However the selection was affected by size distribution and abundance of cod. This approach emphasises that the process of catch such as wedging, snagging, and entangling should be considered in gillnet selectivity studies because it has been demonstrated that small mesh size of gillnet can catch large fish and large mesh size can catch small fish. 

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