The effects of grid angle on a modified Nordmøre-grid in the Nordic Shrimp Fishery

A new version of the Cosmos grid, with tear-drop shaped bars to improve water flow, was tested simulating commercial conditions on a research vessel. The results show that the grid effectively released up to 72% of the unwanted fish, and at the same time maintained very low levels of shrimp loss. On average, the amount of shrimp lost reached 5.6%, expressed in weight. The grid was initially adjusted to work at an inclination angle of 36 °. However, significant improvements in the percentage of shrimp loss and the escape of unwanted fish were observed when the grid angle was modified. When lowered by 3 ° (to approximately 33 °) shrimp loss increased to 12.3% and the escape of fish reached 86%. Contrarily, when the grid angle was increased by 3 ° (up to 39 °), shrimp loss decreased on average to 4.2% and the escape of fish was reduced to 73%. The selectivity curves did not show any significant differences with the results obtained in earlier experiments.