2023 Lyell Centre Outer Hebrides Dredge Survey

Over the course of August 2023, both the Newhaven and N-Viro dredge gear were compared for abundance of king scallop (Pecten maximus) and bycatch retained, as well as the damage inflicted on the retained species. Trials took place in the Outer Hebrides, Scotland between Loch Maddy and Stuley Island. Replicate 30- minute hauls were conducted in two separate biotopes, one comprising mainly cobbles and stone whilst the other comprised of finer sediment and mud. The catch was sorted as king scallop, bycatch including invertebrates such as echinoderms and decapods, stones and other debris (primarily broken shells). Rocks and other debris (shells as example) were weighed (kg) as a total, as were the abundance of scallops collected separated by gear type and belly ring size. Each individual bycatch organism was weighed (kg), sized (mm) and assigned a damage score following a classification adapted from Jenkins et al. 2001. Scallops retained were measured and sorted into those of landing size and under the minimum landing size (<105mm). Each group was then weighed to provide the biomass per gear type and belly ring size.