A chronology of progression of recovery of a benthic community after scallop dredging: A case study in the Wester Ross MPA, Scotland

Scallop dredging is among the most damaging mobile bottom-towed fishing methods, impacting benthic habitats, community composition and structural complexity. While short-term effects are well documented, long-term recovery trajectories remain poorly understood due to the lack of undisturbed reference sites. In 2019, an isolated illegal dredging incident occurred within the Wester Ross Marine Protected Area (MPA), northwest Scotland—closed to scallop dredging since 2016—provided a rare opportunity to investigate recovery in a mixed-sediment habitat of known disturbance history. This study compared taxa diversity, abundance and community composition at the impacted site over five years to those of a nearby undisturbed control using diver and remotely operated vehicle (ROV)-based video surveys analyzed with the SACFOR (superabundant, abundant, common, frequent, occasional, rare) abundance scale. Surveys two and four weeks after dredging recorded fewer taxa at the impacted site, with the absence of key habitat-forming taxa such as hydroids and maerl. Early post-impact communities were dominated by opportunistic and scavenger species. By year three, some structurally important taxa, including hydroids and turf algae, had reappeared, indicating the progression of recovery, though maerl and multiple echinoderms remained absent. After five years, diversity and abundance were higher than in earlier surveys, but the community structure remained simplified, with persistent dominance by a limited number of taxa and an absence of habitat-formers, suggesting that the site has not yet recovered. This case study highlights the long-lasting impacts of a single dredging event and the need for robust MPA enforcement, habitat-specific recovery baselines and long-term monitoring to inform ecosystem-based fisheries management and policy.