Draft Fisheries Assessment – Anton Dohrn Seamount SAC: Fisheries management measures within Scottish Offshore Marine Protected Areas (MPAs)

3. Part B Assessment – Fisheries Assessment

3.1 Fisheries Assessment Overview

Part B of this assessment meets the requirements for an appropriate assessment under Article 6(3) of Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora (the Habitats Directive) and Regulation 28 of the Conservation of Offshore Marine Habitats and Species Regulations 2017.

The fishing activities and pressures identified in Part A, at the levels identified in the relevant date range, which have been included for assessment in Part B are demersal trawl. The only pressures associated with these fishing activities that have been included in Part B are:

• abrasion/disturbance of the substrate on the seabed,
• penetration and/or disturbance of the substrate below the surface of the seabed, including abrasion,
• smothering and siltation rate changes,
• removal of target species and
• removal of non-target species.

3.2 Fisheries Activity Descriptions

3.2.1 Existing fisheries management within Anton Dohrn Seamount SAC

The Anton Dohrn Seamount SAC ranges from between 600-800 m down to approximately 2400 m. Since 2007, the deployment of gill nets and entangling nets has been prohibited at depth over 600 m.

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. Regulation (EU) 2016/2336 (as amended by S.I 2019/753) prohibits the use of bottom trawls below 800 m. As the majority of the site falls below 600 m - 800 m (see Figure 1), there is only a small proportion of the site open to demersal trawling activity, or deployment of aforementioned nets.

3.2.2 Fishing activity with Anton Dohrn Seamount SAC

The Anton Dohrn Seamount SAC lies across four ICES rectangles (44D8, 44D9, 43D8 and 43D9) in the North Atlantic. The only gears identified as occurring within the site are bottom otter trawl and multi-rig trawl. The number of vessels operating in the area across the assessment period is less than 5, so of reasons of confidentiality the nationalities of these vessels cannot be disclosed.

3.2.3 Demersal Trawls

The aggregated gear method of demersal trawls captures the two trawl gears (bottom otter trawl and multi-rig trawl) that were found to have operated within the Anton Dohrn Seamount SAC between 2015 and 2019. The target species for these gear types are demersal fish. As both these gear types exert similar pressures, the aggregated gear type of ‘demersal trawl’ was used to map activity across the site.

According to VMS intensity averaged over 2015 to 2019 within the site, 2 – 4 hours of demersal trawling activity occurs within the Northern section of the site per year per grid cell (Figure 2.).

Swept-Area Ratio (SAR) information averaged over the same time period shows similar patterns of fishing intensity as the VMS data (Figure 2) with cells being swept less that once per year.

3.2.4 Summary of fishing activity within Anton Dohrn Seamount SAC

The only fishing activity identified as occurring within Anton Dohrn SAC is Demersal trawling which occurs at less than 12 hours per year per grid cell. The activity occurs within the Northern area of the site.

3.3 Fishing activity effects overview

The following sections explore the pressures associated with fishing activity (demersal trawls) within the Anton Dohrn SAC that were identified as potentially having likely significant effects (LSE) on the reef feature. The pressures considered in the following sections are:

• Abrasion/disturbance of the substrate on the seabed;
• Penetration and/or disturbance of the substrate below the surface of the seabed, including abrasion;
• Smothering and siltation rate changes (light);
• Removal of target species; and
• Removal of non-target species.

Given the similarity between ‘abrasion/disturbance of the substrate on the surface of the seabed’ and ‘penetration and/or disturbance of the substrate below the surface of the seabed’, these two pressures are considered together in the text below. All pressures with the potential for LSE are discussed under the aggregated fishing gear types of ‘mobile demersal gears’.

The detailed pressure information for this section is based on the JNCC Advice on Operations for Anton Dohrn SAC, and the JNCC Fisheries Management Options Paper for Anton Dohrn SAC.

3.3.1 Impacts of mobile demersal gears (trawls) on Annex I Reef

As detailed in the JNCC Advice on Operations for Anton Dohrn SAC, abrasion/disturbance of the surface of the substrate and penetration and/or disturbance of the substrate below the surface of the seabed, including abrasion, occur where the gear makes contact with the seafloor. The area affected is determined by the footprint of the gear and the amount of movement across the seabed. The different gear components will make variable contributions to the total physical disturbance of the seabed and its associated biota, and hence the pressure will vary according to factors such as gear type, design/modifications, size and weight, method of operation (including towing speed) and habitat characteristics (e.g. topography) (Lart, 2012; Polet & Depestele, 2010; Suuronen, et al., 2012). Towed bottom fishing gears are used to catch species that live in, on or in association with the seabed and therefore are designed to remain in close contact with the seabed. That interaction with the seabed can lead to disturbance of the upper layers of the seabed, damage, displacement or death of the benthic flora and fauna; short-term attraction of scavengers; and the alteration of habitat structure (e.g. flattening of wave forms, removal of rock, removal of structural organisms) (Kaiser M. J., Collie, Hall, Jenning, & Poiner, 2003; Gubbay & Knapman, 1999; Sewell & Hiscock, Effects of fishing within UK European Marine Sites: Guidance for nature conservation agencies, 2005; Collie, Hall, Kaiser, & Poiner , 2000; Kaiser M. J., Collie, Hall, Jennings, & Poiner, 2002).

As a relative comparison of gear types, otter trawls tend to have less physical impact on the seafloor than beam trawls (and dredges) with the heavy tickler chains of beam trawls able to penetrate up to 8 cm into the seabed, although the doors of an otter trawl do create recognisable scour of the seabed (Hinz, Murray, Malcom, & Kaiser, 2012; Polet & Depestele, 2010; Lart, 2012; Paschen, Richter, & Köpnick, 2000);. The magnitude of the immediate response to fishing disturbance, cumulative effects and recovery times varies significantly according to factors such as the type of fishing gear and fishing intensity, the habitat and sediment type, levels of natural disturbance and among different taxa (Collie, Hall, Kaiser, & Poiner , 2000; Boulcott, Millar , & Fryer, 2014; Kaiser, et al., 2006; Hinz, Prieto, & Kaiser, 2009; Kaiser M. J., Collie, Hall, Jenning, & Poiner, 2003).

Smothering and siltation rate changes (light) may result from physical disturbance of the sediment, along with hydrodynamic action caused by the passage of towed gear, leading to entrainment and suspension of the substrate behind and around the gear components and subsequent siltation (Gubbay & Knapman, 1999; Lart, 2012; Sewell, Harris, Hinz, Votier, & Hiscock, 2007; Kaiser M. J., Collie, Hall, Jennings, & Poiner, 2002; Riemann & Hoffmann, 1991; O'Neill, Summerbell, & Breen, 2008; Dale, Boulcott, & Sherwin, 2011; O'Neil & Summerbell, 2011). The quantity of suspended material, its spatial and temporal persistence and subsequent patterns of deposition will depend on factors associated with the gear (such as type/design, weight, towing speed), sediment (particle size, composition, compactness), the intensity of the activity and the background hydrographic conditions, (Sewell, Harris, Hinz, Votier, & Hiscock, 2007; Kaiser M. J., Collie, Hall, Jennings, & Poiner, 2002; Dale, Boulcott, & Sherwin, 2011; O'Neil & Summerbell, 2011). Sediment remobilisation and deposition can affect the settlement, feeding, and survival of biota through smothering of feeding and respiratory organs. Prolonged exposure of an area to the pressure may result in changes in sediment composition, (Gubbay & Knapman, 1999; Kaiser M. J., Collie, Hall, Jennings, & Poiner, 2002; O'Neil & Summerbell, 2011; Kaiser M. J., Collie, Hall, Jenning, & Poiner, 2003; Sewell, Harris, Hinz, Votier, & Hiscock, 2007).

Demersal trawls target a range of demersal fish species and also remove species which may themselves be of conservation importance or may form part of the biotope (e.g. Norway lobster - Nephrops norvegicus) or wider community composition associated with protected features/sub-features. As part of targeted fisheries, incidental non target catch may also be retained and landed due to its commercial value (e.g. spiny lobster (Palinurus elephas), lobsters (Homarus gammarus), crabs, scallops (Pecten spp.), etc). These species may be considered part of the wider community composition associated with features or sub-features of protected sites or may themselves be of conservation importance (e.g. crawfish) (Dale, Boulcott, & Sherwin, 2011; Sewell & Hiscock, Effects of fishing within UK European Marine Sites: Guidance for nature conservation agencies, 2005; Joint Nature Conservation Council, Natural England, 2011).

Bycatch (i.e. discarded catch) is associated with almost all fishing activities and is related to factors such as the gear type and its design (i.e. its selectivity), the targeted species and effort. There are significant concerns over the impacts of discards on marine ecosystems, including changes in population abundance and demographics of affected species and altered species assemblages and food web structures (Alverson, Freeberg, Murawski, & Pope, 1994; Kaiser M. J., Collie, Hall, Jenning, & Poiner, 2003). Mixed-species and shrimp/prawn demersal trawl fisheries are associated with the highest rates of discarding and pose the most complex problems to resolve (Alverson, Freeberg, Murawski, & Pope, 1994; Feekings, Bartolino, Madsen, & Catchpole, 2012; Catchpole, Frid, & Gray, 2005). Benthic trawls most frequently result in bycatch of fish, crustaceans and other invertebrates and less frequently turtles and birds (Gubbay & Knapman, 1999; Sewell & Hiscock, Effects of fishing within UK European Marine Sites: Guidance for nature conservation agencies, 2005; ICES, 2013; Pierpoint, 2000; Bergmann & Moore, 2001; Catchpole, Frid, & Gray, 2005; Tulp, Piet, Quirijns, Rijnsdorp, & Lindeboom, 2005).

Whilst it is unlikely that demersal mobile gear can affect the long-term natural distribution of bedrock and stony reef features, there is evidence to indicate that the use of demersal mobile gears can impact the structure and function of the habitat and the long term survival of its associated species which is outlined below.

The animal communities found on bedrock and stony reefs on seamounts 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 & Tittensor, An index to assess the risk to story corals from bottom trawling on seamounts, 2010; Clark, et al., 2010; Løkkeborg, 2005). The use of demersal mobile fishing gears is likely to cause damage or death of fragile, erect species, such as sponges and corals (Freese, Auster, Heifetz, & Wing, 1999; Løkkeborg, 2005). Other species such as hydroids, anemones, bryozoans, tunicates and echinoderms may also be vulnerable (McConnaughey, Mier, & Dew, 2000; Sewell & Hiscock, Effects of fishing within UK European Marine Sites: Guidance for nature conservation agencies, 2005). Where fragile, slow growing species occur, even low levels of fishing have the potential to change the structure and function of the habitats and may result in the loss of some characteristic species. Recovery from such damage is estimated to be measured on a decadal scale, depending on the environmental conditions (Clark, et al., 2010; ICES, 2010).

Demersal mobile gears reduce the long-term natural distribution of cold-water coral (biogenic reef) features, as well as impacting the structure and function of the habitat and the long term survival of its associated species. The passage of 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, Mortensen, & Furevik, 2002).

The passing of a heavy trawl reduces the three-dimensional structure of the coral to rubble, decreasing the complexity of the habitat with impacts on the associated community composition (Koslow, et al., 2001; Fosså, Mortensen, & Furevik, 2002). Indirect impacts on cold water coral reefs from trawling are from increased levels of suspended particles in the water column causing smothering and polyp mortality (Larsson & Purser, 2011). Given the slow growth rate of the reefs, they may take centuries to recover from damage, if at all (ICES, 2010).

Through physical impacts from gear interacting with the seabed, mobile demersal trawl activity has the potential to affect restoring reef to favourable condition, such that the extent and distribution of the qualifying habitat in the site; the structure and function of the qualifying habitat in the site; and the supporting processes on which the qualifying habitat relies are restored. Accordingly, Scottish Ministers conclude that demersal trawls are not compatible with the conservation objectives of the site and may result in an adverse effect on site integrity.

3.4 Part B Conclusion

The assessment of fishing pressures at current activity levels on the Annex I Reef Feature in Anton Dohrn SAC has indicated that an adverse effect on site integrity cannot be ruled out where mobile demersal trawling activities occur. As such Scottish Ministers conclude that management measures to restrict mobile demersal gears would be required within Anton Dohrn Seamount SAC to ensure the integrity of the site. Section 5 contains further details on potential measures.