ICES Journal of Marine Science · 1992 · 139 citations · 0 references
Mesh SizeEngineeringProfile ModificationAerospace EngineeringFishery ScienceSeafood IndustryMechanical EngineeringExtension LengthMechanical SystemsCod-end Extension LengthFishery ManagementMarine BiologyStructural MechanicsCod-end DiameterSelectivity Data
Recent studies indicate that cod‑end selectivity depends on cod‑end diameter, extension length, and mesh size. The study aimed to quantify how these three parameters affect selectivity by collecting data on cod, haddock, and whiting for cod‑ends with varying mesh sizes, extension lengths, and diameters. A linear model was fitted to the data, showing that mesh size and cod‑end diameter have stronger effects on selectivity than extension length, and the model was then used to estimate the selectivity of current gear configurations. The estimated gear selectivity was very low, with over 95 % of fish below the minimum landing size retained instead of the recommended 25 %.
Recent work has shown that the selectivity of cod-ends is dependent upon the diameter of the cod-end and the length of the extension piece to which it is attached, as well as the mesh size of the cod-end. To quantify the effects of these parameters, selectivity data for cod-ends with three different mesh sizes, extension lengths and diameters were collected for cod, haddock and whiting. A linear model was developed and fitted to these data.This showed that all three cod-end parameters had a significant effect on selectivity, and that over the range of cod-end parameters used, mesh size and cod-end diameter had a greater influence on selectivity than extension length. The model was used to estimate the selectivity of some current gears. These were found to be very unselective, with in most cases more than 95% offish of the minimum landing size being retained, rather than the recommended 25%.