Scallop fishing in the Firth of Lorne Marine SAC: Review of Scientific Literature.

Beth Leslie, Richard L. Shelmerdine

Research output: Book/ReportCommissioned report


The Firth of Lorn SAC is a large and complex site with some of the best examples of rocky reef in Europe. Scallop dredging has been carried out in the area since the 1960’s and it has been suggested that there is potential for this fishing activity to impact on the designated features of the site (the rocky reef). This report reviews the available literature on the impacts of scallop dredging with reference to the Firth of Lorn SAC. Due to the scarcity of research on the impacts of dredging on rocky reefs, the report considers the impact of scallop dredging on other seabed types and also looks at the impacts of other types of mobile gear in order to draw comparisons. The review examines the direct impacts of dredging on the seabed and its associated communities; physical, biological, ecological and chemical. It examines the potential for indirect impacts on the designated features through sedimentation following dredging and by discarding onto the qualifying habitat. The potential for fishing activity to have cumulative impacts on the designated features is examined in both the short and long term, and the potential for post impact recovery is also reviewed. These findings are related to the sensitivity of species and biotopes found within the Firth of Lorn SAC.

The main findings of the report are:
• Scallop dredging has the potential to impact on the designated features in the Firth of Lorn.
• The areas in which impacts are most likely to occur are at boundaries between scallop grounds and reef features, patches of sediment surrounded by reef, and cobble habitats.
• The potential direct effects, due to contact with the dredge, include physical disruption to the substrate and the associated biota, changes in population and trophic structure, and chemical changes to the substratum.
• The potential indirect effects, due to sedimentation, include the disruption of settlement of flora and fauna onto the reef, and reducing the availability of light, smothering, and abrasion of existing organisms. There is also potential for discarding onto the designated features.
• The scale of these impacts are also related to the frequency and intensity of fishing activity, and a review of the fishing activity within the SAC will help to indicate if there is the potential for cumulative impacts on the designated features.
• The post impact recovery following dredging will also depend on the frequency and intensity of the fishing activity, but will also be affected by the biology of the species affected.
• Areas with a high level of natural disturbance are likely to have lesser impacts and be able to recover more quickly than areas with low levels of natural disturbance.
• A key area for future work is to identify the full extent of the designated features with respect to the fishing activity within the site.
Original languageEnglish
PublisherScottish Natural Heritage
Commissioning bodyScottish Natural Heritage
Number of pages91
Publication statusPublished - 16 Mar 2007


  • Scallop dredging
  • Fishing impacts
  • Trawling
  • Rocky reefs
  • Disturbance
  • Sedimentation


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