Protected areas for mobile marine species: consultation on proposals to designate four new Marine Protected Areas in Scottish waters

Southern Trench pMPA

Site description

Southern Trench pMPA is located on the east coast, and is proposed to protect minke whales, burrowed mud, fronts and shelf deeps. Fronts in the Southern Trench are created by mixing of warm and cold waters, which creates an area of high productivity, attracting a number of predators to the area. Minke whales are attracted by the fish species brought to the area by the fronts, as well as the abundance of sandeels in the soft sands. The site takes its name from the trench running parallel to the Moray coast. The trench is up to 250m deep and the soft mud on the floor are home to many species of mud-loving animals including Nephrops and crabs.

Conservation Objectives and Management Advice

The conservation objectives of this site are to conserve the features, meaning to keep the status of the features in favourable condition. This does not include where there is alteration of the feature through natural processes.

Burrowed mud is highly sensitive to physical disturbance and can be sensitive to pollution. The extent and distribution of the habitat should be conserved, as well as the structure and functions it provides. Also, the diversity, abundance and distribution of typical species should be conserved.

The management advice to reduce these pressures includes:

• Adoption of best practice to minimise the footprint of new developments; and
• Limit demersal mobile gear from burrowed mud habitat.

Minke whales are sensitive to underwater noise and also entanglement in fishing gear and collision with vessels. SNH also note the importance of sandeel as prey species of minke whale within the site. SNH advises that, in order to conserve minke whales, risk of injury and death should be minimised, access to resources within the site should be maintained, and supporting features should also be conserved.

The management advice to reduce these pressures includes:

• Use of best practice to reduce risk of boat collision;
• Reduce disturbance from noisy activities through best practice mitigation;
• Exclusion of drift and set net fishing gear, and no targeted fishing for sandeels;
• Further development and adoption of best practice to avoid entanglement in creel ropes;
• Use of best practice to reduce fishing bycatch; and
• Minimising impacts to sandeel habitat through appropriate siting of new developments.

Fronts could be sensitive to changes to tidal flow and seabed topography. Shelf deeps are not considered to be at significant risk from human activity. The geodiversity features, Quaternary of Scotland and submarine mass movement, are highly resistant to human pressures but have no recovery potential. SNH advises that, in order to conserve these features, the extent and distribution of the feature, functions and supporting processes of the features should be maintained. There is no management advice for fronts or shelf deeps.

Sustainability Appraisal

The SEA concluded that, under the intermediate management scenario, designation of the Southern Trench pMPA could have a minor beneficial impact on the environment and provide potential for future benefits. The limits on harbour and port activity would provide minor benefits and reduction in fishing effort would provide moderate benefits and potential for minor spill over benefits. There will be minor negative impacts from fishing displacement, but these will be outweighed by the benefits within the site. There is potential for cumulative environmental impacts due to the number of other protected areas and developments in the Moray Firth.

Table 6 shows the cost impacts from the Southern Trench pMPA for relevant sectors. The SEIA found that the total cost impacts, under the intermediate management scenario, could be £1.288 million in GVA impacts for commercial fisheries and £117,000 to all other sectors The economic impacts to commercial fisheries are attributed to the exclusion of mobile gear from 20% of burrowed mud habitat. The gear type most affected by this is demersal trawls for Nephrops. There are also high costs to the oil and gas, power interconnectors, and energy generation sectors under the upper scenario, which are caused by seasonal restrictions to surveying pipeline infrastructure in the Southern Trench pMPA.

Table 6: Quantified Economic Costs for the Southern Trench pMPA (£'000) costs discounted over assessment period (2019-2038), 2019 prices