Draft Fisheries Assessment – Faroe-Shetland Sponge Belt NCMPA: Fisheries management measures within Scottish Offshore Marine Protected Areas (MPAs)

1. Introduction

1.1 Scope of the Faroe-Shetland Sponge Belt NCMPA assessment

The geographic scope of this assessment covers the whole of Faroe-Shetland Sponge Belt NCMPA. The purpose of this assessment is to determine whether the current levels of fishing activities occurring within the site would or might hinder the conservation objectives of the Faroe-Shetland Sponge Belt NCMPA, and to identify options for management measures.

In this assessment, Scottish Ministers use the best available evidence to review the site characteristics and current fishing activity (Part A), both taken alone and in combination with other relevant activities (Part C), to determine if the fishing activities are capable of affecting the protected features (ocean quahog aggregations, offshore subtidal sands and gravels and deep-sea sponge aggregations). Any fishing activities capable of affecting the protected features, either alone or in combination with relevant activities, are considered further to assess whether they would or might hinder the achievement of the conservation objectives (Part B).

Where there is the potential for the achievement of the conservation objectives to be hindered, or in the case of this site, potentially require a higher level of protection due to other factors (see section 5), fisheries management measures are identified for the site by the Scottish Ministers. These measures are considered in light of the conservation objectives, biological characteristics, current fishing and other activity levels and existing fisheries restrictions for Faroe-Shetland Sponge Belt NCMPA. A final decision on which measures, if any, are to be adopted, will follow upon a statutory consultation exercise and will take into account all relevant statutory obligations incumbent upon Scottish Ministers.

A methodology document has been prepared to aid understanding of these assessments.

1.2 Site description

The Faroe-Shetland Sponge Belt NCMPA (Figure 1) is located in offshore waters on the Scottish side of the Faroe-Shetland Channel, a large rift basin that separates the Scottish and Faroese continental shelves. The site is designated for deep-sea sponge aggregations, offshore subtidal sands and gravels, ocean quahog aggregations, continental slope, continental slope channels, iceberg plough marks, prograding wedges and slide deposits representative of the West Shetland Margin paleo-depositional system Key Geodiversity Area and sand wave fields and sediment wave fields representative of the West Shetland Margin contourite deposits Key Geodiversity Area.

The Faroe-Shetland Sponge Belt NCMPA covers 5,278 km² and covers an area where five different water masses meet in the Faroe-Shetland Channel, which interact with each other and the continental slope to generate ideal conditions for the boreal 'ostur' type of deep-sea sponge aggregations to settle. Offshore subtidal sands and gravels are also present, supporting a diversity of polychaete worms and a slow-growing bivalve mollusc known as ocean quahog. The site contains an area of continental slope which could be important for maintaining the health and biodiversity of Scotland’s seas.

The higher current speeds created by the intermediate water masses, along with the presence of cobbles and boulders associated with iceberg ploughmarks, generate ideal conditions for the settlement of sponges. Deep-sea sponge aggregations are an OSPAR Threatened and/or Declining habitat and have been recorded in the channel between 400 m and 600 m depth. The type of deep-sea sponge aggregation which occurs within the Faroe-Shetland Sponge Belt NCMPA is boreal 'ostur'. Boreal 'ostur' sponge aggregations typically have a high abundance of species of giant sponge (Demospongia), which local fishermen refer to as "Osterbunds" or "cheese-bottoms" due to their appearance. The sponges themselves often support a range of other species, for example by providing shelter for fish species and perches for filter feeders such as brittlestars. Within the UK, the boreal 'ostur' sponge aggregations only occur within the biogeographic region which includes the Faroe-Shetland Channel.

The shallowest parts of the Faroe-Shetland Sponge Belt NCMPA are 400 m below sea-level, however depths within the site reach 800 m below sea-level in the Faroe-Shetland Channel. There are two distinct sedimentary communities within the site representative of offshore subtidal sands and gravels; one is found between 300 m and 600 m and is characterised by a greater proportion of cobbles and boulders; and a second below 600 m, characterised by finer sands and muddy sands. The two communities are dominated by contrasting families of polychaete worm. The sedimentary habitats in the NCMPA also support ocean quahog (Arctica islandica). This species of bivalve mollusc is usually buried in sand and muddy sand and can regularly live for over 100 years. Ocean quahog is an OSPAR Threatened and/or Declining species.

The NCMPA also includes an area of continental slope. It is thought that the Faroe-Shetland Channel continental slope is important for maintaining the health and biodiversity of Scotland’s seas. The interaction between the various water masses and the channel slope create conditions that supply organic material to sponges and other benthic fauna, as well as aggregating prey. The wider Faroe-Shetland Channel may be an important pathway for migrating fin and sperm whales.

Five geodiversity features are included in the NCMPA which are representative of the West Shetland Margin palaeo-depositional system and the West Shetland Margin contourite deposits Key Geodiversity Areas. The sand and sediment wave fields in the West Shetland Margin contourite deposits were formed during interglacial periods and are unique to UK waters. Geodiversity features in the West Shetland Margin palaeo-depositional system were created in the last glacial period. During the last ice age, icebergs scoured the seabed leaving iceberg ploughmarks that remain on the sea floor. These iceberg ploughmark fields are associated with cobbles and boulders, which are ideal settlement points for deep-sea sponge aggregations.

JNCC’s view on the overall condition of deep-sea sponge aggregations, offshore subtidal sands and gravels, ocean quahog aggregations, continental slope channels and sand wave fields and sediment wave fields is that the features are in unfavourable condition. Continental slope is considered to be in favourable condition.

The conservation objective for the Faroe-Shetland Sponge Belt Nature Conservation Marine Protected Area (NCMPA) is that the protected features:

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

With respect to deep-sea sponge aggregations and offshore subtidal sands and gravels, this means that:

• extent is stable or increasing; and
• structures and functions, quality, and the composition of characteristic biological communities (which includes a reference to the diversity and abundance of marine fauna forming part of or inhabiting each habitat) are such as to ensure they remain in a condition which are healthy and not deteriorating.

Any temporary deterioration in condition is to be disregarded if the habitats aresufficiently healthy and resilient to enable their recovery from such deterioration. Any alteration to the features brought about entirely by natural processes are to be disregarded.

With respect to the ocean quahog (Arctica islandica) aggregations, this means that the quality and quantity of its habitat and the composition of its population are such that they ensure that the population is maintained in numbers which enable it to thrive.

Any temporary reduction of numbers is to be disregarded if the population of ocean quahog is thriving and sufficiently resilient to enable its recovery from such reduction. Any alteration to that feature brought about entirely by natural processes is to be disregarded.

With respect to the continental slope channels, Iceberg plough marks, prograding wedges, slide deposits, sand wave fields and sediment wave fields representative of the West Shetland Margin Paleo-Depositional System and West Shetland Margin Contourite Deposits Key Geodiversity Areas, this means that:

• their extent, component elements and integrity are maintained;
• their structure and functioning are unimpaired; and
• their surfaces remain sufficiently unobscured for the purposes of determining whether the points noted above are satisfied.

Any obscuring of the features entirely by natural processes is to be disregarded. Any alteration to the features brought about entirely by natural processes is to be disregarded.

With respect to the area of the Faroe-Shetland Channel Continental slope protected as a large-scale feature, this means that:

• its extent, distribution and structure is maintained;
• its function is maintained so as to ensure that it continues to support its characteristic biological communities (which includes a reference to the diversity of any species associated with the large-scale feature) and their use of the site for, but not restricted to, feeding, courtship, spawning, or use as nursery grounds; and
• the processes supporting it are maintained.

Any alteration brought about entirely by natural processes is to be disregarded.

Further information regarding the designation and conservation objectives for the protected features of Faroe-Shetland Sponge Belt NCMPA is available on the JNCC Faroe-Shetland Sponge Belt NCMPA webpage.

1.3 Activities assessed

The assessments consider the impacts of fisheries activities at each NCMPA in terms of the conservation objectives stated for the protected sites. This was deemed appropriate, in order to assist in identifying potential management measures.

In this context, the implications of the fishing activity in view of the conservation objectives for the NCMPA are being assessed through the fisheries screening stage (Part A), the fisheries assessment (Part B), and the in combination (cumulative effect) assessment (Part C).

Fisheries assessments use the best available evidence to fully consider potential impacts of commercial fishing activity, and in-combination (cumulative) effects with other activities, against the conservation objectives for the site. If the assessment concludes that use of certain fishing gear types would or might hinder the achievement of the conservation objectives of the site, management measures will be considered.

Commercial sea fishing activity has the potential to vary in nature and intensity over time. This assessment considers fishing activity based on activity levels and type between 2015-2019. This date range was considered to provide the best available data on current fishing activity levels for the assessment. Using a five-year date range provides an average view of fishing activity within the site; latter years (2020 – 2021) were not considered representative of regular fishing activity due to the Covid pandemic. The selected date range (2015 – 2019) was used consistently across all assessments within the consultation package. Changes in fishing activity after this time period may be considered in future reviews of this assessment (see Section 6).