Large Mesh Gillnets - a Complementary Tool to Standardized Multimesh Gillnets

The European Standard EN 14757 (“Water quality – sampling of fish with multimesh gillnets”, 2005) recommends gillnet mesh sizes that range from 5 to 55 mm (knot-to-knot) for standard monitoring of fish assemblages and suggests adding gillnets with larger mesh sizes if necessary. Our research showed that the recommended range does not provide a representative picture of fish sizes for larger species that occur in continental Europe. Thus, we developed a novel large mesh gillnet which consists of mesh sizes 70, 90, 110 and 135 mm (knot to knot, 10m panels) and estimated its size selectivity. From the data obtained by sampling with both standard mesh size and large mesh gillnets we describe selectivity curves for commonly observed species: bream (Abramis brama), carp (Cyprinus carpio), tench (Tinca tinca) and rudd (Scardinius erythrophthalmus). We also estimated an upper size threshold of 294mm, above which the mesh sizes 5 – 55 mm do not record bream representatively. Finally, we tested the recommended mesh size range by comparing its catch composition with that obtained during concurrent pelagic trawling. We demonstrate that the use of novel large mesh gillnets improves monitoring with standard mesh size gillnets in waters where larger fish specimens are expected.