SARF036: A review and assessment of the effects of marine fish farm discharges on Biodiversity Action Plan habitats 

Start Date: 01/05/2007
End Date: 30/04/2009 
Main Contractor(s): Scottish Association for Marine Science
Other Sponsor(s):  

Objectives

Phase 1. A comprehensive literature review to consider both published and 'grey' sources viz. the impacts of fish-farming on BAP habitats.

Phase 2. Construct a ArcGIS database that combines existing habitat databases. Interogate the database to determine the most commonly occurring interaction between fish-farms and BAPS.

Phase 3. Establish the distance/sedimentation rate effect on the abundance, and qualitative measures such as size, of a range of habitats with a focus on deep-water mud species such as the seapens Funiculina quadrangularis, Pennatula phosphorea and Virgularia mirabilis and burrowing crustacea and anemones such as Nephrops norvegicus and Pachycerianthus multiplicatus respectively.

Summary

Fish-farming is a significant employer in Scotland, particularly in remote rural areas where it makes a considerable contribution to rural economies. However, fish-farming has a number of impacts on the receiving environment and, consequently, operations are only permitted following extensive consultation with a variety of stakeholders including those with statutory responsibilities, such as SNH, to protect the marine environment. Sheltered sea-lochs have been favoured by fish-farmers as they offer high water quality in a relatively protected environment. Such sheltered waters also host unique biotopes including 'deep-water muds' and 'Modiolus beds'. These habitats are associated with high biodiversity and were designated as 'Biodiversity Action Plan' habitats (BAPs) following the UK's adoption of the Convention on Biological Diversity. In Scottish coastal waters these habitats also include maerl beds, Sabellaria reefs, seagrass beds, serpulid reefs, sheltered muddy gravels, sublittoral sands and gravels, and Limaria hians and Ostrea edulis beds. The purpose of Phase 1 of the proposed research is to thoroughly review the likely impacts of fish-farming activity on all BAP habitats. Scottish coastal waters have been variously mapped over the last few decades with the information being stored in an assortment of forms. Geographical information systems (GIS) allow various sources of information to be collated into a single map allowing a more informed and holistic interpretation of the area. The purpose of Phase 2 of the proposed research is to collate all relevant data into a single GIS package and interogate it with respect to the overlap between fish-farms and BAP habitats. Fish-farming impacts stem, primarily, from the release of particulate matter (faeces and uneaten food) into the water column. This material is dispersed around the farm with a substantial proportion settling on the seabed. The organic enrichment that is associated with build-up of this waste material has a profound effect on the benthos being associated with a decrease in species diversity and the superabundance of opportunistic species. Whilst the impact of fish-farming on benthic infauna is well understood much less is known about their impacts on larger sessile or motile species primarily as a consequence of the logistical problems of sampling larger, occasionally motile and widely dispersed organisms. The purpose of Phase 3 of the proposed research is to evaluate the impact of fish-farming activity on the megabenthos using a drop-down video camera.