Argyll SMR

This section summarises the information from the Marine Protected Areas (MPAs) and intertidal and continental shelf habitats assessments from SMA2020. It also provides information from the relevant case studies relating to Priority Marine Features (PMFs), with a focus on habitats.  Further work is required to enable assessment at a regional scale for most species; this will be included in Scotland’s next marine assessment.

At a SMR/OMR scale for MPAs the focus is on the number of new MPAs, MPAs with new spatial management measures, and MPAs in which spatial management measures are in discussion, as well as recognising monitoring that has been undertaken between 2012-2018.  For the marine habitats, the focus is on interpreting the relevant intertidal and continental shelf habitat assessments – biogenic habitats, predicted extent of physical disturbance to the seafloor  (BH3) and intertidal seagrass beds.  For PMFs, a summary is provided of the changes in our understanding of the habitats of most relevance to the SMR, including changes in distribution and extent.

Marine Protected Areas

Progress in developing the Scottish MPA network

There are 23 MPAs in the Argyll SMR that contribute to the Scottish MPA network (see Table 1).  Some of these MPAs overlap completely or partially in terms of their spatial coverage and/or the features (habitats, species, etc.) they were set up to help conserve.  They are counted as separate MPAs because they have been established under different legislation which influences the way in which they are managed.  Also note that there are MPAs that straddle the boundaries between different SMRs / OMRs.  Where this is the case, these MPAs have been counted as contributing to the MPA network in all of the SMRs/OMRs in which they are present.  This means that the total number of MPAs in Scotland cannot be calculated through combining the SMR/OMR totals.  Please see the Marine Protected Area assessment which contains statistics for the Scottish MPA network as a whole.  

Table 1. Numbers of types of MPAs in the Argyll SMR that contribute to the Scottish MPA network, including number of new MPAs introduced since 2012.

Note that in December 2020 there were another three MPAs designated in this region in addition to those in the table above, comprising two SPAs (Coll and Tiree and Sound of Gigha) and one Nature Conservation MPA (Sea of the Hebrides).

Highlights from the various MPAs include:

The MPAs in the Argyll SMR protect a wide variety of features including benthic and intertidal habitats, fish, marine mammals, and birds.  Loch Sween MPA is home to a number of features including maerl beds, sublittoral mud and mixed sediment communities, and burrowed mud habitats. The surface of the latter habitats is dotted with the dome-shaped mounds of the volcano worm along with the burrow openings other animals including Norway lobsters and burrowing gobies.  Loch Sunart to the Sound of Jura MPA supports a resident population of flapper skate.  Skates are an ancient group of fish that first appeared in fossil records about 150 million years ago and the flapper skate is the largest extant skate in the world and can reach a length of 2.5 m and weigh over 100 kg.  Loch Creran SAC, situated at the northern end of the Firth of Lorn, is a typical fjordic sea loch. The site is particularly notable for biogenic reefs of the calcareous tube-worm Serpula vermicularis, which occur in shallow water around the periphery of the loch. This species has a world-wide distribution but the development of reef structures is extremely rare; Loch Creran is the only known site in the UK to contain living S. vermicularis reefs. The skerries, islands and rugged coastline of the South-east Islay Skerries SAC support a nationally important population of harbour seals. Gruinart Flats Ramsar site supports internationally important numbers of non-breeding light-bellied brent geese and Greenland barnacle geese. 

Progress in managing MPAs

The progress in implementing management for MPAs in the Argyll SMR is summarised in Table 2.  This includes information on where spatial management measures are in place and where they are under discussion.  It also includes information on the number of MPAs that have been monitored, whether by statutory bodies or through citizen science.

Table 2. Summary of progress in managing Marine Protected Areas in the Argyll SMR

Note that the spatial measures listed in the table are in addition to the protection provided as a result of consideration of activities/developments through licensing and consenting processes. Also, the monitoring of birds, mammals and habitats within SSSIs and SACs has been split out to reflect the different programmes of work.  These figures cannot be added together to provide a total number of SSSIs or SACs in which monitoring took place because of overlaps in coverage.  

Note that the Marine Conservation Order (MCO) for Loch Sunart to the Sound of Jura MPA provides benefits for the Duart Point Historic MPA.

The management measures for fishing activities in place for Loch Creran and Firth of Lorn SACs were replaced in 2015. A new Fisheries Order covers Loch Creran SAC and MPA, Loch Sween MPA and the Treshnish Isles SAC, whilst the Firth of Lorn SAC is now included under the Loch Sunart to the Sound of Jura Marine Conservation Order, which also covers the MPA of the same name. The management measures for fishing activities in the MPAs across Argyll SMR mainly focus on restrictions to demersal mobile gear but there are measures for static gear within Loch Creran because of the fragility of the serpulid reefs. A further measure for Moine Mhor SAC is under discussion.

During this assessment period the majority of the MPAs have been monitored at least once by the statutory bodies, and some have had multiple visits.  Monitoring has covered birds, fish, mammals and seabed habitats.  A partnership project – the Movement Ecology of Flapper Skate - between St Andrews University, Marine Scotland Science, and NatureScot has significantly improved the understanding of the flapper skate in the Loch Sunart to the Sound of Jura MPA.  This compliments the records collected by recreational anglers (see below).  Monitoring of seals continues to be undertaken via a collaboration between the Sea Mammal Research Unit and NatureScot.

Marine reefs, flame shell beds and burrowed mud are some of the protected features which are monitored through Seasearch surveys in the Firth of Lorn SAC, Loch Creran SAC, Loch Creran MPA and Loch Sween MPA. Recreational sea anglers play an important role in monitoring the flapper skate in the Loch Sunart to the Sound of Jura MPA through photograph submissions to SkateSpotter. Sightings data of harbour porpoise in the Inner Hebrides and the Minches SAC are recorded by the Hebridian Whale and Dolphin Trust (HWDT) and the Whale and Dolphin Conservation Shorewatch Sightings programme. Sightings data of minke whales and basking sharks in the Sea of the Hebrides MPA are collected through the HWDT, Basking Shark Scotland and the Marine Conservation Society’s Basking Shark Watch.

Information on MPA boundaries can be viewed in Marine Scotland’s NMPi. To find out more about specific MPAs, please visit NatureScot’s SiteLINK.  Detailed reports on habitat monitoring are referenced in Further reading – seabed habitat monitoring reports.

Intertidal and continental shelf habitats

SMA2020 contains three relevant habitat assessments: intertidal seagrass beds, subtidal biogenic habitats, and the predicted extent of physical disturbance to the seafloor.  The biogenic habitats assessment considered the status and trend of four marine habitats within Argyll SMR: horse mussel beds, flame shell beds, subtidal seagrass beds and serpulid aggregations. The assessment aimed to include maerl beds and blue mussel beds as well, but although these are present in the SMR, there were insufficient data for their inclusion.  Modelling work was also carried out to predict the extent of physical disturbance to the seafloor more generally.  Assessment of the status of intertidal seagrass beds could not be carried out in this SMR due to lack of relevant information.

Biogenic habitats

For the biogenic habitats as a whole, the status category assigned for SMA2020 was ‘Some concerns’ on the basis of recorded reductions in extent of flame shell, horse mussel and seagrass beds, as well as serpulid aggregations.

A loss in flame shell bed extent was recorded as the result of the disappearance of a bed at Port Appin with coverage of 40 ha during the years 2001 - 2006. Subsequent surveys in 2011 (Moore, Harries, & Trigg, 2012), 2015 (Cook, 2016) and from 2018 to 2019 (Heriot-Watt University, unpublished) have revealed shrinkage of the bed and eventually virtual extinction.  In Loch Creran known flame shell bed extent has increased from 18.5 ha in 2012 (Moore et al., 2013) to 35 ha in 2018 (Moore et al., 2020); however, the increase is likely to be due to the increase in spatial spread of survey sites rather than expansion of the habitat.

Declines in horse mussel density have been recorded on three beds in Loch Creran (with extent reduction also recorded at one of them) between 2005 (Moore et al., 2006) and 2018 (Moore et al., 2020). The scale of bed loss is unknown, although the previous extent of the bed is likely to have been small (based on the limited sampling intensity in 2005, Moore et al., 2006).  The total known habitat extent in Loch Creran has increased between 2005 and 2018, although this is due to wider sampling, as in the case of flame shell beds.  Surveys in 2019 by SNH and Marine Scotland (Williams, 2019; Moore, 2020) have revealed new beds off Gigha and in the Sound of Mull.

Complete subtidal seagrass bed loss is known to have taken place within the last 20 years in Loch Creran. There are no measures of bed extent for the habitat, but there are several records of its presence from 1883 - 2002.  A 2019 survey of the sea loch (Moore, unpublished) confirmed its absence.  Recent citizen science surveys have extended our knowledge of the distribution of the habitat elsewhere in the SMR, with new beds identified in 2019 in Loch Craignish by Seasearch and in 2020 in Loch Shuna by Narwhal Expeditions.

Within the Argyll SMR serpulid aggregations are only known to occur in Loch Creran, where they have formed bushy, well-developed reefs up to 75 cm in height and 1-2 m in diameter.  In 2005 the extent of the serpulid reef habitat was assessed at 108 ha (Moore et al., 2006). Most of the habitat appeared in good condition, albeit there was localised damage from demersal fishing, finfish and mussel farming, vessel moorings and organic pollution, although cessation of a major organic discharge had led to some recovery of the habitat (Moore et al., 2006). Condition monitoring in 2017 to 2019 revealed a marked deterioration in the status of the habitat, with widespread fragmentation of the reefs, loss of most of the larger structures and a loss of habitat extent of the order of 38 ha (Moore et al., 2020).    The cause of habitat deterioration is uncertain; however, it is considered most likely that it is part of a long-term natural cycle of degradation without compensatory replenishment (see Moore et al. (2020) for further details).

Confidence in the SMA2020 subtidal biogenic habitat assessment is low.  Apart from serpulid aggregations, the extent of the habitats in the SMR is poorly understood.  Also, the relative importance of natural versus anthropogenic drivers of temporal change is inadequately known, although it does appear that anthropogenic factors are considered unlikely to be significant drivers in serpulid reef habitat loss.

Predicted physical disturbance to the seafloor

To assess physical disturbance to seafloor habitats SMA2020 employed a modelling approach which generates a map of predicted relative disturbance levels from demersal fishing activity on a scale of 0 (zero) to 9 (severe).  The map was produced by the combination of information on the distribution of habitats, the sensitivity of the habitats (and species present to varying degrees) and the fishing pressure from demersal trawling, dredging and seine netting.  Fishing pressure information was derived from Vessel Monitoring System (VMS) data from 2012 - 2016 and was categorised as either surface abrasion (disturbance of surface and upper layers of sediment) or sub-surface abrasion (disturbance to a depth of >3 cm).  The final predicted disturbance index utilises the greater of these two pressure values and for descriptive purposes has been categorised as no disturbance (0), low disturbance (1-4) and high disturbance (5-9).

It should be emphasised that this method does not measure disturbance to seabed habitats, but predicts relative levels of disturbance. These relative levels are dependent upon the accuracy of habitat data and sensitivity assessments.  Many of the habitat data are derived from modelling and there is a low level of confidence in its accuracy.  Geographical variation in the accuracy of the sensitivity information employed is likely to be great, being dependent upon the level and quality of information used locally.  A significant limitation of the method is that during the assessment period pressure data were only available for vessels >12 m, which has probably resulted in an underestimation of disturbance for the SMRs.

Twenty per cent of the seafloor of the Argyll SMR is predicted to experience no mobile fishery disturbance, which is the second highest figure for all SMRs (average 12%) (Figure 3).  The model predicts 44% of the seabed to suffer high disturbance, which is slightly below the average value of 50% for the SMRs.  Areas of high disturbance are concentrated to the west of Kintyre, between Jura and Mull, off the north and west of Mull and north west of Coll and Tiree.  This corresponds largely to the distribution of mud, with some areas of sand and, to the north of Mull, coarse sediment and also reflects very closely the distribution of subsurface abrasion levels.  With the exception of the Firth of Lorn Fisheries Order, which was enacted in 2007, the demersal fisheries prohibitions within the relevant MPAs commenced in 2016 and so will have had little effect on the assessment, which covered the period 2012-2016.

Figure 3.  Predicted physical disturbance to the seafloor in the Argyll SMR and prohibition areas for all mobile demersal fishing.  (Note that the prediction of physical disturbance covered the period 2012-2016 and so the fisheries prohibition relating to the relevant MPAs will have had little effect on this assessment.  The exception is the prohibition that has been in place for the Firth of Lorn since 2007.

Priority Marine Features and birds (non-PMF)

Overview of recorded PMFs and birds

The Argyll SMR supports a range of PMFs and breeding seabirds as well as wintering waterbirds (i.e. waders, estuarine waterfowl, seaduck and coastal water feeding birds) as detailed in Table 3. 

Table 3: Details of PMFs, seabirds, and wintering waterbirds found in the Argyll SMR

The Argyll SMR has a total of 56 PMF habitats and species, and 34 marine bird species.  There is a number of records of native oysters, including native oyster beds of which there are very few remaining in Scotland.  Pink sea fingers have a restricted distribution and there are only a few records from the whole west coast including the Firth of Lorn and the Sound of Mull. Basking sharks migrate to this SMR during the summer and can be seen feeding at the surface between June and October each year. They gather in large numbers, sometimes hundreds, and may remain within the SMR until late October before many head south for the winter or into deeper water.

Progress in understanding intertidal and continental shelf habitats listed as PMFs

Over the last 10 years there has been a change in emphasis of survey work in the region, with much of the earlier work by government agencies focused on obtaining an understanding of the distribution and conservation importance of habitats and species through detailed examinations of the sea lochs.  Over the 2012 - 2018 assessment period the focus has turned to improving understanding of PMF distribution and to the identification and subsequent monitoring of MPAs, as well as building up a broad understanding of habitat distribution to guide MPA boundary setting and checking that implemented management measures are effective.

The temporal sequence of records of all PMF habitats in Argyll SMR is provided in Table 4 and illustrated in Figures 4 and 5 based on inclusion in the Marine Recorder (2021) and GeMS (2021) databases, as well as identified additional sources.  Associated commentary, however, is restricted to PMFs for which the information has the potential to inform regional marine planning.  For example, some PMFs are excluded on the basis that they are very widely distributed and for which the records represent a small proportion of their likely distribution, such as several of the kelp habitats.

Table 4.  Temporal frequency of PMF habitat records within the Argyll SMR obtained from GeMS (2021), Marine Recorder (2021) and other sources.  The numbers of All records are given, as well as those from Citizen Science (CS) surveys alone.  *3579 records derived from the analysis of single video frames of serpulid aggregations are excluded.

Table 4 illustrates the increasing importance of citizen science records in raising our understanding of PMF distribution.  The proportion of such records has increased from 9% before 2012 to 29% in more recent years.

There has been modest progress in the improvement of knowledge of blue mussel bed distribution in the region (Figure 4).  Seasearch surveys from 2016 - 2018 have expanded the known distribution of a subtidal bed on rock in West Loch Tarbert and new subtidal and intertidal beds were recorded in 2012 in Loch Sween (ASML, 2014).

There has been a large increase in the number of burrowed mud records since 2011, although this has largely served to better define habitat extent within areas of existing, but often sparse, records (Figures 4 and 5).  Knowledge of the probable distribution of the habitat is also available from annual Nephrops burrow density surveys carried out by Marine Scotland from 2007 - 2016.  While Nephrops is also associated with several other habitat types, these data indicate that burrowed mud is likely to cover extensive areas of the seabed to the west of Kintyre, west of Mull and north of Coll and Tiree.  Recent surveys in Loch Linnhe (SEPA, unpublished) and Loch Sween (Moore et al., 2013) emphasize the importance of Loch Linnhe in supporting the PMF component biotope SS.SMu.CFiMu.SpnMeg.Fun, characterised by the tall seapen Funiculina quadrangularis, and the importance of Loch Sween in supporting the most extensive UK example of the component biotope SS.SMu.CFiMu.MegMax, characterised by the large mounds of the spoon worm, Maxmuelleria lankesteri.

Surveys over the period 2012 - 2019 have recorded losses in extent of seagrass and horse mussel beds and serpulid aggregations in Loch Creran, and the loss of a flame shell bed at nearby Port Appin (see the biogenic habitat assessment) ). Elsewhere, knowledge of the distribution of subtidal seagrass beds has been much improved, particularly in Loch Sween (Moore et al., 2013; Seasearch, unpublished).

There have been considerable recent gains in knowledge of the distribution of low or variable salinity habitats and tide-swept algal communities in the SMR, principally as a result of 2017 - 2019 Seasearch surveys of Lochs Creran, Etive, Linnhe and Sween and a 2019 Marine Scotland survey off Jura and Islay (Shucksmith, Shelmerdine, & Shucksmith, 2021).

Maerl is not particularly well-developed in the Argyll SMR, but post-2011 survey work by SNH and Marine Scotland have confirmed and mapped in detail dense maerl beds in Loch Sween (Moore et al., 2013) and identified new beds in the Sound of Islay (Shucksmith et al., 2021) and off Gigha (Williams, 2019), whilst a 2016 Seasearch survey recorded a rich bed off Ulva, west of Mull.  The few existing records of the related ‘maerl or coarse shell gravel with burrowing sea cucumbers’ PMF have also been supplemented by recent observations around Islay (Shucksmith et al., 2021) and Mull (Seasearch, unpublished).

Since 2011 information relating to the native oyster in the Argyll SMR has been expanded through a Marine Scotland/SNH distributional survey of oyster beds in Loch Sween (Moore et al., 2013) and 2018 Seasearch records of the species in West Loch Tarbert.

There is now a more detailed understanding of the distribution of ‘northern sea fan and sponge communities’ following recent Seasearch observations, particularly in the Firth of Lorn, and surveys by Marine Scotland and SNH around Jura (Shucksmith et al., 2021) and in the Sound of Mull (Moore, 2019).

The number of known sea loch egg wrack beds in the SMR has more than doubled since 2018, largely as a result of 2020 surveys by Narwhal Expeditions in Loch Sween and in the vicinity of Loch Shuna.

Figure 4.  Temporal pattern of records of selected PMF habitats for the Argyll SMR.

Figure 5.  Temporal pattern of records of burrowed mud PMF component biotopes for the Argyll SMR.

Trends and status of grey and harbour seals

Grey seal pup production at the major breeding sites such as the Treshnish Isles SAC is monitored biennially and has shown an increasing trend in numbers and their status is assessed as ‘few or no concerns’.  Harbour seal numbers are monitored on a rolling 4/5year cycle and have shown little or no change over the assessment period and their status is assessed as ‘few or no concerns’.