Fisheries Management Measures within Scottish Offshore Marine Protected Areas (MPAs) - Site Proposal Document

27. West of Scotland MPA

27.1 Description and background

The West of Scotland MPA (Figure 75) is 107,718 km² in size. The shallowest area within the MPA is approximately 400 m below sea-level and the deepest section is 2,500 m below sea-level. It covers a diverse marine landscape to the west of Scotland; from the steep gradient of the continental slope across the sediment plains of the Rockall Trough, to the slopes of George Bligh Bank and Rockall Bank, with two isolated seamounts (Anton Dohrn and Rosemary Bank). It is the geological and geomorphological features that define this marine landscape, with volcanic igneous rock protrusions forming the seamounts and the large banks at the western extent of the deep-sea marine reserve. Slide deposits are a characteristic feature along the Scottish continental slope, while other geomorphological and glacial remnant features (such as sediment wave fields, scour moats, turbidite accumulations, and iceberg plough marks) form the landscape of the seabed (Brooks et al., 2013).

The two seamounts (Rosemary Bank and Anton Dohrn) are protected as large-scale features of the deep-sea marine reserve and for the rich Seamount communities they support. The seamounts create a very different environment to the sedimentary plains of the Rockall Trough. The dynamic hydrographic environment surrounding the seamounts increases food availability to suspension feeders such as sponges and corals that colonise the seamounts. Many fish species such as Blue ling, black scabbard (Aphanopus carbo) and mesopelagic lantern fish (Lampanyctus sp.) are attracted to seamounts for feeding or spawning. The concentrations of fish and other prey species around seamounts also attracts larger predators and marine mammals such as Atlantic white-sided dolphin (Lagenorhynchus acutus) and sperm whale (Physeter macrocephalus), which have been observed in high numbers around these features (Clarke 2007, Macleod et al., 2003, Weir et al., 2001).

Further information can be found in the Site Information Centre.

27.2 Site Features

The West of Scotland MPA is designated for the following protected features:

• Burrowed Mud
• Deep sea sponge aggregations
• Coral gardens
• Cold-water coral reefs
• Offshore deep sea muds
• Offshore subtidal sands and gravels
• Seamount communities
• Blue Ling (Molva dypterygia)
• Leafscale gulper shark (Centrophorus squamosus) / Gulper shark (Centrophorus granulosus)
• Orange roughy (Hoplostethus atlanticus)
• Portuguese dogfish (Centroscymnus coelolepis)
• Round-nose grenadier (Coryphaenoides rupestris)

All of the protected biodiversity features (Figure 76) of the MPA are Priority Marine Features (PMFs); these are habitats and species considered to be of conservation priority in Scotland’s seas. In addition, eight features also listed as OSPAR Threatened and/or Declining habitats or species in the North-East Atlantic region, and five are classed as Vulnerable Marine Ecosystems (VMEs).

Deep-sea sponge aggregations, cold-water coral reefs and coral gardens are known as ‘habitat formers’. The physical structures they create provide an environment that other species can colonise, and they support a diverse community of associated species (OSPAR 2009, 2010 a and b). Sponges may also play a significant role in silicon regulation by providing a long-term sink for silicon (Maldonado et al., 2012, Tréguer and Rocha, 2013), while coral skeletons act as a long-term store of carbon (OSPAR, 2009).

The deep-sea marine reserve protects six deep-sea fish species (blue ling (Molva dypterygia), orange roughy (Hoplostethus atlanticus), leafscale gulper shark (Centrophorus squamosus) / gulper shark (Centrophorus granulosus), Portuguese dogfish (Centroscymnus coelolepis) and round-nose grenadier (Coryphaenoides rupestris)). Leafscale gulper shark and Gulper shark are presented as a feature complex due to difficulties in their identification. The MPA contains characteristic habitat for round-nose grenadier, leafscale gulper shark, gulper shark, and Portuguese dogfish. Round-nose grenadier are resident within the MPA, and this is one of only 17 locations globally where gulper shark has been reported. The MPA protects important aspects of these species' life-cycles, such as spawning areas (e.g. Large et al., 2010; Moura et al., 2014). There is limited understanding on the majority of these species, however, and further scientific research is required to assess the importance of the site for these species.

Figure 76. Examples of features in the West of Scotland MPA showing a) gulper shark and coral gardens within the West of Scotland MPA ©University of Plymouth, University of Oxford, JNCC & BGS, 2016 and b) orange roughy (Hoplostethus atlanticus), corals and offshore sands and gravels ©University of Plymouth, University of Oxford, JNCC & BGS, 2016

27.3 Site Boundary

The boundary has been set in accordance with the boundary setting principles And all relevant documentation can be found on the West of Scotland JNCC site page.

The MPA boundary follows approximately the 800 m depth contour and extends to the edge of British Fisheries Limits out to 200 nautical miles. The West of Scotland MPA boundary excludes most of the existing MPAs within the Rockall Trough area. Although Anton Dohrn Seamount Special Area of Conservation (SAC) does fully overlap with the West of Scotland MPA, it remains an MPA in its own right. The top of Anton Dohrn Seamount falls out with the SAC boundary however and is encompassed by the West of Scotland MPA.

Confidence in the presence and extent of the protected features has been set out in the Data Confidence Assessment.

27.4 Conservation objectives

For Burrowed mud, Coral gardens, Cold-water coral reefs, Deep-sea sponge aggregations, Offshore deep-sea muds, Offshore sands and gravels, Seamount communities, Leafscale Gulper shark, Gulper shark, Orange roughy, Portuguese dogfish and Round-nose grenadier, the feature condition has been assessed by JNCC as being ‘Unfavourable’. For Blue ling, the feature condition has been assessed by JNCC as being ‘Favourable’

Conservation objectives set out the desired quality of the protected features within each Nature Conservation MPA. The conservation objectives for the features in the West of Scotland MPA are:

• so far as they are already at favourable condition, they remain in such condition; and
• so far as they are not already in favourable condition, they be brought into such condition, and remain in such condition.

The full conservation advice documents can be found on the JNCC website. This includes the formal conservation advice for the site, background information and the full conservation objectives.

27.5 Pressure from demersal mobile fishing gear

27.5.1 Habitats features

The species associated with seamount communities tend to be composed of erect and fragile species that are sensitive to physical disturbance, particularly deep-sea stony corals, gorgonians and black corals, sea anemones, hydroids and sponges (Clark et al., 2010; Clark and Tittensor, 2010).

Trawling can cause mortality to species by disturbance on the seabed or by bringing them to the surface resulting in a reduction in abundance (Kaiser & Spencer, 1996; Jennings & Kaiser, 1998; ICES, 2010). Recovery from such damage is estimated to be measured in decades, depending on the environmental conditions (Clark & Tittensor 2010; ICES, 2010).

Demersal mobile gears can reduce the long-term natural distribution of cold water coral reef, as well as impacting the structure and function of the habitat and the long term survival of its associated species. The passage of demersal mobile fishing gear may increase mortality of the coral by crushing, burying or wounding corals, increasing susceptibility to infection and epifaunal recruitment that may eventually smother corals (Fosså et al., 2002).

Studies on deep-sea sponge aggregations have found that trawling damages, displaces and removes sponges through direct physical impact, as well as from disturbed sediment resettling and causing smothering beyond the path of the trawl itself (ICES, 2007; ICES 2010; OSPAR, 2010a). Deep-sea sponges have some capacity for recovery from mild damage, but significant disturbance, damage or smothering may result in sponges being unlikely to survive (ICES, 2007; ICES 2010).

In general, the impact of demersal mobile gear on sand and gravel sediments is relatively well understood. In high energy locations (i.e. of wave and/or tide exposed) the associated fauna tend to be well adapted to disturbance and as a result are more tolerant of fishing-related disturbance (Dernie et al., 2003; Hiddink et al., 2006). In lower energy locations, such as muddy sands and sand in deep water (such as in the West of Scotland MPA), sediments tend to be more stable and their associated fauna less tolerant of disturbance (Hiddink et al., 2006; Kaiser et al., 2006). Stable gravels often support a ‘turf’ of fragile species which are easily damaged by trawling and recover slowly (Collie et al., 2005; Foden et al., 2010). Trawling and dredging tends to cause increased mortality of fragile and long lived species and favour opportunistic, disturbance-tolerant species (Eleftheriou & Robertson, 1992; Bergman & van Santbrink, 2000). Some particularly sensitive species may disappear entirely (Bergman & van Santbrink, 2000). The net result is benthic communities modified to varying degrees relative to the un-impacted state (Bergman & van Santbrink, 2000; Kaiser et al., 2006).

27.5.2 Mobile species features

In the 1990s, a targeted demersal otter trawl fishery for orange roughy occurred in deep water west of Scotland. However, in recent years, a zero Total Allowable Catch (TAC) was implemented for orange roughy in ICES Division area VI, which has effectively ended the fishery in this region. Demersal mobile gear may affect the presence and distribution of the orange roughy feature, due to the risk associated with accidental bycatch.

The long tapering tail of the roundnose grenadier is easily damaged after trawling (Priede, 2019; Simpson et al., 2011), suggesting that bycatch incidents can be fatal. The species was first targeted in the North Atlantic by deep-sea fishing fleets in the 1960s and landings peaked in the early 1970s, before declining sharply (Devine and Haedrich, 2008; Priede, 2019). Bycatch of roundnose grenadier most notably occurs in demersal trawl fisheries targeting Greenland halibut, (Reinhardtius hippoglossoides) and redfish, (Sebastes spp.), (Devine and Haedrich, 2008; Devine et al., 2006; Jørgensen et al., 2014). Although there is currently a zero TAC in place for roundnose grenadier within ICES area 6 demersal mobile gear may affect the presence and distribution of the roundnose grenadier feature, due to the risk associated with accidental bycatch.

Fisheries targeting blue ling during their spawning season have previously led to local depletions of aggregations. In 2009, a seasonal closure (1^st March to 31^st May each year) was introduced to protect spawning aggregations. Outside the spawning season blue ling is taken in mixed trawl fisheries (targeting shelf species such as saithe, hake, monkfish and megrim,(Lorance, 2020). Based on the evidence available, a precautionary approach is recommended as there is a risk that the presence and distribution of blue ling would be impacted if demersal mobile gear activity increases.

Due to their life history characteristics of very slow growth rates, late maturity, low reproductive potential, long intervals between litters and extreme longevity (Priede, 2019), deep-sea shark species are likely to be very slow to recover (exceeding 25 years), even if deep-water fisheries and all bycatch ceases. There are not known to be any measures that could mitigate the bycatch of sharks in commercial deep-water fisheries, therefore preventing mortality will be very difficult or impossible to achieve whilst fisheries continue in deep-water shark habitats (OSPAR, 2010c). Gulper shark, leafscale gulper shark and Portuguese dogfish have historically been landed as bycatch in the mixed deep-water bottom trawl fisheries targeting roundnose grenadier, blue ling, black scabbardfish and orange roughy off the west of Scotland (Priede, 2019). This resulted in significant population declines and the introduction of zero TAC for these species in 2010 (ICES WGEF, 2020). It is likely that demersal mobile gear will affect the presence and distribution of the gulper shark, leafscale gulper shark and Portuguese dogfish features due to the associated bycatch risk.

27.6 Pressure from pelagic gear (mobile species features)

Orange roughy is known to feed on bentho-pelagic prey (Gordon and Duncan, 1987) and the species can be caught by pelagic gear (ICES, 2020). Post-larval growth in orange roughy is thought to occur in the mesopelagic, with active foraging at 700-800m depth (Shephard et al., 2007). Spawning aggregations can also form into dynamic plumes, extending 200m off the seabed (Branch, 2001). Although there is a zero TAC in place for orange roughy, pelagic fishing gear may affect the presence and distribution of the species due to the associated bycatch risk at all life-stages.

Although the roundnose grenadier is typically a bottom-dwelling, demersal fish, there are records of the species being caught in pelagic nets fished at depths between 1,000-2,000m and 270-1,440m above the seafloor in the Denmark Strait (Haedrich, 1974). The species is known to feed on pelagic prey, which descends through the water column during their daytime diel vertical migration and concentrates at the sea floor (Mauchline and Gordon, 1991). Juveniles are also thought to feed bentho-pelagically (Priede, 2019). Although there is a zero TAC in place for roundnose grenadier, pelagic fishing gear may affect the presence and distribution of the species due to the associated bycatch risk at all life-stages.

Leafscale gulper shark are found at or near the seabed on continental slopes at depths of 230-2400 m, however the species has also been reported from the upper 1,250m of oceanic water, well above the seabed in ocean depths of around 4,000m (OSPAR, 2010e). Although there is a zero TAC in place for leafscale gulper shark, pelagic fishing gear may affect the presence and distribution of the species due to the associated bycatch risk at all life-stages.

Although there is no reliable information on migrations or the pupping grounds of gulper shark, pregnant females appear to segregate from the rest of the population along the outer edge of continental shelves and in canyons (Priede, 2019). This poses a greater risk for the species, as there is a risk of bycatch occurring when over a wider area. Although there is a zero TAC in place for Gulper shark, pelagic fishing gear may pose a risk to the presence and distribution of the species, due to the associated bycatch risk at all life-stages.

Portuguese dogfish are one of the deepest living sharks and are known to occur on or near the seabed, from 700 –1900m, in the area to the west of Scotland (Priede, 2019). There is evidence of the species exhibiting vertical migration and females are known to move to shallower waters to give birth (500-1000m), increasing risks of interactions with fisheries (Clarke et al., 2001; Girard and Du Buit, 1999; Moura et al., 2014; OSPAR, 2010f; STECF, 2006). Although there is a zero TAC in place for Portuguese dogfish, pelagic fishing gear may pose a risk to the presence and distribution of the species, due to the associated bycatch risk at all life-stages.

27.7 Pressure from demersal static fishing gear

27.7.1 Habitats features

No studies providing evidence of the effects of demersal static gears on Scottish seamounts were found, however impacts occurring on analogous vulnerable habitats and species, such as sponges and corals in Scottish waters are applicable (Muñoz et al., 2011). Impacts can arise from hooks, lines, nets and ropes becoming entangled with corals and other fragile species, including ‘plucking’ them from the seabed during hauling (Mortensen et al., 2005; Muñoz et al., 2011; OSPAR, 2010a). While the extent of damage caused by individual static gear fishing events is likely to be lower than that for trawling (Pham et al., 2014), the effect of cumulative damage may be significant.

The deep-sea sponge aggregation feature is considered to be sensitive to demersal static gear activity, notably because sponges may become caught or entangled in static gears and damaged on the seabed or brought to the surface. In certain conditions, for example during retrieval, static gears may move laterally across the seabed resulting in impacts (Sampaio et al,. 2012; Ewing and Kilpatrick, 2014). By-catch by demersal longliners of hexactinellid and demospongid sponges has been documented within the Northeast Atlantic (Muñoz et al., 2011) and in the Antarctic (Bowden, 2010). While the extent of damage caused by individual static gear fishing events is likely to be lower than that for trawling (Pham et al., 2014), the effect of cumulative damage may be significant.

Demersal static gears are likely to reduce the long-term natural distribution of cold water coral reef features, as well as impacting the structure and function of the habitat and the long-term survival of its associated species. The impacts are considered to be lower than for demersal mobile gear types (Pham et al., 2014), however impacts to habitats and biota may occur during certain conditions. For example, hooks, lines, nets and ropes entangle corals and may pluck them during hauling.

Evidence regarding the impacts of demersal static gear fishing on offshore deep-sea mud habitats is largely derived from studies on the effects of such activity on burrowed mud habitats. In general, the available research suggests that if fishing activity is low the direct impact on mud habitat is likely to be minimal and seabed structure is likely to be maintained in a slightly modified state (Eno et al., 1996; Kinnear et al., 1996; Eno et al., 2001; Adey, 2007). The impacts of repeated exposure to these types of fishing gear at high levels of fishing activity are less well understood (Eno et al., 2001; Adey, 2007).

27.7.2 Mobile species features

Orange roughy were only targeted using specialised bottom trawling techniques and are not commercially targeted with other gear types (FeAST, 2013), however, the species has also been recorded as bycatch in other fisheries. Although there is a zero TAC in place for orange roughy, demersal static nets may pose a risk to the presence and distribution of the species, due to the associated bycatch risk.

Although roundnose grenadier were previously only targeted using demersal mobile gears in the west of Scotland area, the species can be taken using gillnets (e.g. in Canada; Simpson et al., 2011). Although there is a zero TAC in place for roundnose grenadier, demersal static nets may therefore pose a risk to the presence and distribution of the species, due to the associated bycatch risk. As roundnose grenadier are not attracted to the odour of baits, they can only be caught by trawl (or nets, as discussed above), rather than longlines or traps (Priede, 2018).

Blue ling is landed as bycatch in Norwegian longline and gillnet fisheries targeting ling, tusk, and saithe (ICES, 2019). However, a high proportion of catches are discarded due to spoilage, as blue ling deteriorate very quickly, even with short-soak times, due to their soft-flesh. Blue ling are also caught both as a target species and as bycatch in longline fisheries, including around Rockall and the Hatton Bank (Clark, 2006; Gordon, 2003; ICES, 2020, 2019c, 2019b; Lorance, 2020). There is a risk that the presence and distribution of Blue ling would be impacted by demersal static gears, either as a target species or as bycatch.

Leafscale gulper shark, gulper shark and Portuguese dogfish were previously targeted in Scotland using gillnets or tangle net hybrids (Hareide et al., 2017; STECF, 2006). These fisheries have now ceased, however, bycatch still occurs and the long soak times and discards of nets from gillnet fisheries are known to increase bycatch mortality (Hareide et al., 2005). There is a risk that the presence and distribution of these species would be impacted by static nets, due to the associated bycatch risk.

Leafscale gulper shark, gulper shark and Portuguese dogfish has previously been targeted by longline fisheries, which resulted in a rapid decline in stocks (OSPAR, 2010e, 2010d). Although there is now a zero TAC in place, there remains a risk of accidental bycatch in longline fisheries and evidence shows that catch rates can be relatively high for these species. Therefore, the presence and distribution of these species may be impacted by static nets, based on this associated bycatch risk.

27.8 Levels of fisheries management considered

Table 50 provides a summary of the management advice set out against the various options that have been considered.

Table 50. Summary of fisheries management measures for the West of Scotland MPA

Fisheries management options considered for demersal mobile gear

No additional management: The conservation objectives would not be achieved for deep-sea sponge aggregations, coral gardens, cold-water coral reefs (including Lophelia pertusa reefs) or seamount communities. JNCC recommend that this level of management should not be applied in areas where these features occur.

There is a risk of not achieving the conservation objectives for all other features.

Reduce / limit pressures: The conservation objectives would not be achieved for deep-sea sponge aggregations, coral gardens, cold-water coral reefs (including Lophelia pertusa reefs) or Seamount communities.

This level of management would reduce, but not entirely eliminate, the risk of not achieving the conservation objectives for all other features.

Remove / avoid pressures: This is the only option that would not risk the achievements of the conservation objectives for deep-sea sponge aggregations, coral gardens, cold-water coral reefs (including Lophelia pertusa reefs) and seamount communities. JNCC recommend that this level of management should be applied in all areas where these features occur.

This level of management would reduce the risk of not achieving the conservation objectives for all other features to the lowest possible levels.

Fisheries management options considered for Pelagic gear

No additional management: This level of management is unlikely to prevent the achievement of the conservation objectives for blue ling (Molva dypterygia). There is very limited data on the impacts of pelagic gears on the remaining mobile species features, though some level of interaction may occur due to the life-histories of the species. Therefore, there is a risk of not achieving the conservation objectives for other mobile species features.

Reduce / limit pressures: There is very limited data on the impacts of pelagic gears on the mobile species features (except blue ling), though some level of interaction may occur due to the life-histories of the species. Therefore, this level of management is likely to reduce, but not entirely eliminate, the risk of not achieving the conservation objectives for mobile species features (except blue ling).

Remove / avoid pressures: There is very limited data on the impacts of pelagic gears on the mobile species features (except blue ling), though some level of interaction may occur due to the life-histories of the species. Therefore, this level of management is likely to reduce the risk of not achieving the conservation objectives for mobile species features (except blue ling) to the lowest possible level.

Fisheries management options considered for demersal static gear

No additional management: The conservation objectives would not be achieved for deep-sea sponge aggregations, coral gardens, cold-water coral reefs (including Lophelia pertusa reefs) or seamount communities. JNCC recommend that this level of management should not be applied in areas where these features occur.

With no additional management, there is a risk of not achieving the conservation objectives for all other features.

Reduce / limit pressure: The conservation objectives would not be achieved for deep-sea sponge aggregations, coral gardens, cold-water coral reefs (including Lophelia pertusa reefs) or seamount communities.

This level of management would reduce, but not entirely eliminate, the risk of not achieving the conservation objectives for all other features.

Remove / avoid pressures: This is the only option that would not risk the achievements of the conservation objectives for deep-sea sponge aggregations, coral gardens, cold-water coral reefs (including Lophelia pertusa reefs) and seamount communities. JNCC recommend that this level of management should be applied in areas where these features occur.

This level of management would reduce the risk of not achieving the conservation objectives for all other features to the lowest possible levels.

27.9 Other fisheries measures which apply to the site

A number of existing fisheries management apply to the West of Scotland MPA which provide protection for the features of the site. These are described below.

Under Regulation (EU) 2016/2336 it is prohibited for vessels to target, retain onboard, tranship, relocate, or land deep-sea sharks in ICES subareas 5 to 9 (this includes the full West of Scotland MPA area). In addition, it puts in place a ban on the use of bottom trawls below 800m depth across all UK waters. This prohibition applies across the area of the West of Scotland MPA where the depth falls below 800m.

Under Regulation (EU) 2019/1241 (as amended by S.I 2019/1312 and S.I. 2020/1542), fishing with bottom-set gillnets, entangling nets, and trammel nets below 200m is prohibited for the protection of deep-water shark species. However, there are derogations for the use of static nets between 200m and 600m, which are applicable in the shallower areas of the MPA to allow directed fishing for anglerfish and hake.

Under Regulation (EU) 2019/1241 a seasonal Blue ling closure is in place from 1st March to 31st May each year to protect spawning aggregations in specified areas along the edge of the Scottish continental shelf and at the edge of Rosemary Bank, imposing a catch restriction of < 6 tonnes per trip. The TAC for Blue ling in 2020 for ICES subareas 5b, 6, and 7 (which includes the full West of Scotland MPA are) was set at 11,150 tonnes (live weight). In 2021, the TAC has been reduced by 75% to 2,172 tonnes .

A precautionary TAC of 2,558 tonnes (per year live weight) for Roundnose grenadier was provided in 2019 and 2020 for ICES subregions 5b, 6 and 7. The TAC has been significantly reduced to 608 tonnes in 2021 and 0 tonnes in 2022 .

UK fishing vessels are prohibited from targeting, retaining onboard, transhipping, or landing Orange roughy in Union and waters of ICES subareas 1 to 10, which includes the full West of Scotland MPA area .

27.10 Proposed fisheries management and rationale

Table 51 and Figure 77 provide details of the proposed management approach and further explanation is provided below.

On the basis of available evidence, the seamount large scale features are considered unlikely to be impacted by fishing activities. As such, there is not considered to be any significant risks to the feature not achieving its conservation objective and so the feature has not been considered in the context of management measures.

The iceberg plough mark fields and bioherm reefs are considered sensitive to the pressures associated with fishing activities occurring within the MPA. However, as the iceberg plough mark fields geographically overlap with Offshore sands and gravels, and bioherm reefs geographically overlap with Seamount communities, Cold-water coral reefs, and coral garden features within the MPA, it is considered that there will be a similar perceived risk in terms of achieving the features’ conservation objectives, and the management measures presented for biodiversity features will also apply to geological and geomorphological features. As such, 13 iceberg plough mark fields and bioherm reefs have not been reported further in the context of the management options explored below.

The other geological and geomorphological features are considered to have a low sensitivity to the pressures associated with fishing activities taking place within the MPA. As such, there is not considered to be a significant risk to these features achieving their conservation objectives.

Fragile species found in seamount communities (such as corals and sponges) are amongst the most sensitive habitats to the impacts of all fishing gears. Removal of all demersal mobile and demersal static gear is the only approach that will further the conservation objectives for the coral gardens, cold water coral reefs, deep sea sponge aggregations, and seamount communities.

The mobile features of the site will benefit from the removal of demersal mobile and demersal static fishing gear, however there is insufficient evidence to support the management of pelagic gears to further the conservation objectives of these species.

The measures will contribute to the recovery of the OSPAR listed Threatened and/or Declining habitats and species; coral gardens, cold-water coral reefs, deep-sea sponge aggregations, seamount communities, leafscale gulper shark, gulper shark, orange roughy and Portuguese dogfish. They should also further progress towards Good Environmental Status in the Celtic Seas, particularly in relation to Descriptors 1 (biological diversity) and 6 (sea-floor integrity).