Review of changes to proposed fisheries management boundaries for Clyde Sea Sill MPA

Please note - The advice below was produced (May 2020) to assist the development of proposed management measures for fishing activity for MPAs and PMFs (11 most sensitive to bottom contact gear) outwith MPAs. Further considerations were made by Marine Directorate and the final proposed management measures being consulted upon in 2026 are available via Scottish Government’s website.

May 2020

Overview of proposed changes

A change to proposed fisheries management measures in the Clyde Sea Sill MPA (Figure 1) was suggested at a recent Marine Scotland (now Marine Directorate) led fisheries stakeholder workshop. The refinement relates to the management boundary in the nearshore area to the south-east of Sanda Island.

A modified boundary line has been developed that extends beyond the 30 m bathymetric contour in this part of the MPA to maintain protection of adjacent nearshore foraging habitats used by black guillemots (see Table 1 for details of protected features and management advice and Figures 2 and 3 for changes proposed).

The seabed habitat feature of the MPA affected by the proposed change to the management measures is 'Circalittoral and offshore sand and coarse sediment communities' (see the Detailed Assessment Against the Selection Guidelines document). This is a ‘representative’ feature comprising the following component biotopes:

• ‘Circalittoral coarse sediment’ (SS.SCS.CCS) and in particular ‘Mediomastus fragilis, Lumbrineris spp. and venerid bivalves in circalittoral coarse sand or gravel habitats’ (SS.SCS.CCS.[MedLumVen] - A5.14[2])
• ‘Offshore circalittoral coarse sediment’ (SS.SCS.OCS - A5.15)
• ‘Circalittoral fine sand’ (SS.SSa.CFiSa - A5.25)
• ‘Offshore circalittoral sand’ (SS.SSa.OSa - A5.27)

There are point and mapped polygon records of this habitat (the latter developed through an Scottish Natural Heritage (now NatureScot) research contract (Envision Mapping Ltd., 2014). There are two habitat polygons but these do not clearly differentiate the component biotopes and have therefore been combined for % analyses.

SNH management advice for the Clyde Sea Sill MPA.

Table 1a. Site features and conservation objectives.

Qualifying feature	Conservation objective
Black guillemot	Conserve
Circalittoral and offshore sand and coarse sediment communities	Conserve

 

Table 1b. Summary of fisheries management advice.

Feature	Mobile gear	Static gear	Other
Black guillemot	No management required	Remove / avoid pressures from set nets
Circalittoral and offshore sand and coarse sediment communities	Reduce / limit pressure from mobile / active gear (for hydraulic see Other)	No additional management	Reduce / limit all hydraulic methods (e.g. diver or vessel)
Fronts	No fisheries management is considered necessary for this feature of the MPA	No fisheries management is considered necessary for this feature of the MPA	No fisheries management is considered necessary for this feature of the MPA

In both Figures 2 and 3 the blue line is the previous draft fisheries management boundary (2019) and the green line shows the amended proposal (April 2020). Additional stakeholder discussions are envisaged in 2020/21 and these may result in further refinements.

Proportion of seabed habitat feature covered by the different management scenarios

The proportion of the seabed habitat protected feature encompassed by the original (2019) and revised (April 2020) management scenario is set out in Tables 2 and 3 below.

Table 2. Area of habitat (from predictive extent polygons) afforded protection from mechanical dredging under proposed fisheries management measures. Note under the management measures proposed 100% of the MPA would be protected from beam trawl, suction dredging and set nets. Demersal trawls or seines are permitted in the MPA (see Figure 1). Component biotopes not differentiated in predictive extent polygons. Dates indicated on each column refer to the dates of management boundaries for where dredging was prohibited.

Protected feature	Total area of habitat in MPA (ha)	2019 Area within boundary (ha)	2019 % of total habitat of MPA in management boundary	April 2020 Area within boundary (ha)	April 2020 % of total habitat of MPA in management boundary
Circalittoral and offshore sand and coarse sediment communities	39358.3	28481.5	72.4	28423.4	72.2

 

Table 3. Proportion of habitat points afforded protection from mechanical dredging under proposed fisheries management measures. Note under the management measures proposed 100% of the MPA would be protected from beam trawl, suction dredging and set nets. Demersal trawls or seines are permitted in the MPA (see Figure 1). Coverage of component biotopes of the protected habitat feature given in bold text.

Protected feature	Total no. of habitat points in MPA	2019 No. of points within boundary	2019 % of total points of MPA in mgmt. boundary	April 2020 No. of points within boundary	April 2020 % of total points of MPA in mgmt. boundary
Circalittoral and offshore sand and coarse sediment communities (all points)	29	15	51.7%	15	51.7%
Circalittoral coarse sediment’ (SS.SCS.CCS)	9	3	33.3%	3	33.3%
Offshore circalittoral coarse sediment SS.SCS.OCS	1	1	100%	1	100%
Circalittoral fine sand SS.SSa.CFiSa	18	10	55.6%	10	55.6%
Offshore circalittoral sand SS.SSa.OSa	1	1	100%	1	100%

Conclusions

Based on the habitat polygon data, an adequate proportion of the ‘Circalittoral and offshore sand and coarse sediment communities’ feature is encompassed within both the 2019 and 2020 Marine Scotland proposed fisheries management restrictions.

Whilst the polygon data is not broken down into the component biotopes of the broad MPA habitat, the point data provide an indication of the relative proportions of the components present in the site. It is important that these various components are protected within the management measures to ensure that the feature’s structure is conserved. The existing point data suggest that an adequate proportion of each of the component biotopes would be protected by both management proposals (ranging from 33.3% to 100%).

References

Envision Mapping Ltd. 2014. Predictive Mapping of MPA protected features within selected possible Nature Conservation MPAs in Scottish territorial waters using available datasets.