Inshore waters - regulated commercial use of traps/pots to catch wrasse: fisheries assessment

7. Assessment of the wrasse fishery on mobile species (Minke whale (Balaenoptera acutorostrata) and Basking shark (Cetorhinus maximus)) in NCMPAs

Marine animal entanglement has the potential to cause injury or mortality, so can impact species by reducing their population size and connectivity, and consequently could risk the achievement of the conservation objectives of relevant MPAs.

Within the MPA network, the wrasse fishery has the potential to interact with certain species at risk of entanglement.

7.1 Sites affected

The following MPAs have been identified by NatureScot as sites where minke whale and/or basking shark are a protected feature and where the Scottish wrasse fishery could potentially exert pressures on the features.

Sea of the Hebrides MPA

Southern Trench MPA

7.2 Conservation objectives

High level conservation objectives for the sites are that the protected features:

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

“Favourable condition”, with respect to a mobile species of marine fauna, means that:

a) the species is conserved or, where relevant, recovered to include the continued access by the species to resources provided by the MPA for, but not restricted to, feeding, courtship, spawning or use as nursery grounds;

b) the extent and distribution of any supporting features upon which the species is dependent is conserved or, where relevant, recovered; and

c) the structure and function of any supporting feature, including any associated processes supporting the species within the MPA, is such as to ensure that the protected feature is in a condition which is healthy and not deteriorating.

Site specific conservation objectives are given in the relevant CMA.

7.3 Marine Protected Area assessment

7.3.1 Screening for activities capable of affecting, other than insignificantly, the protected features within the site

Relevant fishing activities are defined as commercial fishing gears (traps) that currently operate or could conceivably operate in the future within this site for the prosecution of wrasse.

Minke whale

Site

Sea of the Hebrides NC MPA

Advice to support management

Reduce or limit pressures The further development and adoption of existing best practice to reduce or limit the risk of entanglement of minke whales in creel ropes and long lines is recommended.

Relevant pressures

Removal of non-target species (including lethal)

Site

Southern Trench NC MPA

Advice to support management

Reduce or limit pressures The further development and adoption of existing best practice to reduce or limit the risk of entanglement of minke whales in creel ropes and long lines is recommended.

Relevant pressures

Removal of non-target species (including lethal)

Basking shark

Site

Sea of the Hebrides NC MPA

Advice to support management

Reduce or limit pressures The further development and adoption of existing best practice to reduce or limit the risk of entanglement of basking sharks in creel ropes and long lines is recommended.

Relevant pressures

Removal of non-target species (including lethal)

Site where fishing activity has occurred and where there is an indication of future demand.

Site

Sea of the Hebrides NC MPA

Advice to support management - Static gear

Reduce or limit

Potential interaction with the wrasse fishery (typically <10m depth)

Minke whale

Basking shark

Removal of non-target species (including lethal)

Capable of affecting feature

Site where no recent recorded wrasse fishing activity has occurred and there is no indication that there will be a future demand. From 2025, no wrasse fishing activity will be authorised in the site below unless following appropriate review of this assessment.

Site

Southern Trench NC MPA

Advice to support management - Static gear

Reduce or limit

Potential interaction with the wrasse fishery (typically <10m depth)

Minke whale

Removal of non-target species (including lethal)

N/A

7.4 Assessment of the impacts of the fishing for wrasse on minke whale and basking shark within Sea of the Hebrides NC MPA

Relevant site & species

Sea of the Hebrides NC MPA

Minke whale & Basking shark

Brief description and Site Condition Monitoring of relevant mobile species

The MPA protects high densities of basking sharks and minke whales, compared to other parts of Scottish territorial waters, particularly during the months of April to October. The basking sharks and minke whales are drawn to the abundant food source in the area.

Basking shark: Favourable (2019)

Minke whale: Favourable (2019)

7.4.1 Mobile species assessment - the species is conserved or, where relevant, recovered to include the continued access by the species to resources provided by the MPA for, but not restricted to, feeding, courtship, spawning or use as nursery grounds

Site specific advice (basking shark):

• Basking shark within the Sea of the Hebrides MPA are not at significant risk from injury or killing.
• Conserve the access to resources provided by the MPA for feeding, courtship like behaviour and breeding.
• Conserve the distribution of basking shark within the site by avoiding significant disturbance

Assessment of risk from identified effect mechanisms:

Higher numbers of shark are present are particularly notable during the months of June to October when they spend most of their time close to the surface feeding and often in aggregations (Speedie, 2009, Doherty et al., 2017). The areas in which these aggregations occur more frequently have been termed basking shark awareness zones. There are tentative estimates of basking shark numbers from smaller areas within the MPA (Booth et al., 2003, Gore, et al., 2016), but there are no population assessments for basking sharks that could be used for assessments in relation to this Conservation Objective at present.

This Objective seeks to conserve basking shark by minimising the risk to the animals from injury or killing. For the purposes of MPA assessments basking shark are only protected when they are within the site. Any activities that take place within or outside the MPA that could potentially kill or injure minke whale in the MPA should be considered in assessments. The interpretation of ‘significant’ risk from killing or injury will depend on factors including the scale of the impact, the duration of the activity and measures that are put in place to minimise the risk. An important consideration is whether any killing or injury would result in reduced densities within the site, from which recovery to above average densities cannot be expected. Basking sharks are classed as Endangered in the North East Atlantic region. The MPA is one of very few areas in this region which attract consistent and significant aggregations of individuals. Significant levels of killing or injury within the MPA therefore could affect basking shark numbers at a wider scale due to importance of the MPA for feeding, aggregating and potentially breeding.

The wild wrasse fishery in Scotland is not an open fishery, the Marine Directorate controls access to it. Each year, vessel owners apply to take part in the fishery which is open from May – December. Successful applications are authorised to participate in the fishery as an additional dispensation (which takes the form of a derogation certificate issued to the vessel owner) granted under domestic fishing licences. All derogation certificates issued are subject to strict Terms and Conditions, including a restriction on the number of wrasse traps/pots that each vessel is authorised to use (250 traps/pots). Engagement with wrasse fishers suggests there may be five vessels active to some degree in the MPA during the open season.

Given the nature of the wild wrasse fishery, the quality and physical appearance of live fish is of vital importance. Fishers typically set/haul their fishing gear on a daily basis, in shallow inshore waters less than 10 metres in depth within the MPA, reducing the potential interaction basking shark and adopting best practice measures regarding minimising soak time of fishing gear.

Activity authorised under the wild wrasse fishery is compatible with NatureScot’s advice that static gear fisheries should be reduced or limited in the MPA, with a recommendation that best practice is adopted to reduce or limit the risk of entanglement of basking sharks in the ropes of the fishing gear.

Site specific advice (minke whale):

• Minke whale in the Sea of the Hebrides MPA are not at significant risk from injury or killing.
• Conserve the access to resources (e.g. for feeding) provided by the MPA for various stages of the minke whale life cycle.
• Conserve the distribution of minke whale within the site by avoiding significant disturbance.

Assessment of risk from identified effect mechanisms:

Sightings of minke whale within the MPA are highest during the late summer months, however, there is evidence that minke whale are present throughout the year, albeit in lower numbers (Anderwald and Evans 2007, Paxton et al., 2014). This Objective seeks to conserve minke whale by minimising the risk to the animals from injury or killing. For the purposes of the MPA assessments minke whale are only protected when they are within the site.

Any activities that take place within or outside the MPA that could kill or injure minke whale in the MPA should be considered in assessments. The interpretation of ‘significant’ will depend on factors including the scale of the impact, the duration of the activity and measures that are put in place to minimise the risk. An important consideration is whether any killing or injury would result in reduced densities within the site, from which recovery to above average densities cannot be expected.

The wild wrasse fishery in Scotland is not an open fishery, the Marine Directorate controls access to it. Each year, vessel owners apply to take part in the fishery which is open from May – December. Successful applications are authorised to participate in the fishery as an additional dispensation (which takes the form of a derogation certificate issued to the vessel owner) granted under domestic fishing licences. All derogation certificates issued are subject to strict Terms and Conditions, including a restriction on the number of wrasse traps/pots that each vessel is authorised to use (250 traps/pots). Engagement with wrasse fishers suggests there may be five vessels active to some degree in the MPA during the open season.

Given the nature of the wild wrasse fishery, the quality and physical appearance of live fish is of vital importance. Fishers typically set/haul their fishing gear on a daily basis, in shallow inshore waters less than 10 metres in depth within the MPA, reducing the potential interaction with minke whales and adopting best practice measures regarding minimising soak time of fishing gear.

Activity authorised under the wild wrasse fishery is compatible with NatureScot’s advice that static gear fisheries should be reduced or limited in the MPA, with a recommendation that best practice is adopted to reduce or limit the risk of entanglement of minke whale in the ropes of the fishing gear.

7.4.2 Mobile species assessment the structure and function of any supporting feature, including any associated processes supporting the species within the MPA, is such as to ensure that the protected feature is in a condition which is healthy and not deteriorating.

Site specific advice (basking shark):

• Conserve the extent and distribution of any supporting feature upon which basking shark are dependent.
• Conserve the structure and function of supporting features, including processes to ensure basking shark are healthy and not deteriorating

Assessment of risk from identified effect mechanisms:

Resources in the context of basking shark are zooplankton prey and the fronts that influence the presence and concentration of zooplankton. The areas where zooplankton are concentrated are particularly important as they offer efficient feeding grounds for basking sharks.

NatureScot advise that there are two main ways in which access to resources could be restricted and basking shark distribution affected: 1) large scale physical barriers or 2) significant disturbance which alters their distribution within the site or disrupts important behaviours.

Only large-scale physical barriers or obstructions within basking shark awareness zones (as shown in Figure 3 of the Conservation and Management Advice) are likely to prevent or restrict access to resources to an extent that may result in significant impacts on feeding, courtship-like behaviour and potentially breeding. Disturbance is also of particular relevance within basking shark awareness zones.

NatureScot consider that ‘significant disturbance’ may result in the following effects:

• contributes to long-term decline in the use of the site by basking sharks.
• changes to the distribution of basking sharks within the site, with particular emphasis on the basking shark awareness zones, on a continuing or sustained basis.
• changes to basking shark behaviour such that it reduces the ability of the species to feed efficiently, breed or survive.

There is very limited, if any, authorised wild wrasse fishing within the identified basking shark awareness zone. Vessels participating in the fishery are typically local inshore vessels, hugging the coastline with their fishing activity and not transiting significantly within the MPA. Therefore, the wild wrasse fishery will not create a large-scale physical barrier or obstruction, or cause significant disturbance.

Activity authorised under the wild wrasse fishery is unlikely to significantly alter water flow, currents, topography or nutrient availability and therefore unlikely to affect the species composition, abundance or concentration and distribution of zooplankton available to basking sharks

Site specific advice (minke whale):

• Conserve the extent and distribution of any supporting feature upon which minke whale is dependent.
• Conserve the structure and function of supporting features, including processes to ensure minke whale are healthy and not deteriorating.

Assessment of risk from identified effect mechanisms:

Resources in this context are their prey and particular areas of the MPA or habitats that may be used during feeding and for supporting various stages of their lifecycle.

NatureScot advise that there are two main ways in which minke whale’s access to resources could be restricted and disturbance affected: 1) large scale physical barriers or 2) significant disturbance which alters their distribution within the site or disrupts important behaviours.

Only large-scale physical barriers or obstructions within or outside the MPA may prevent or restrict access to resources to an extent that may result in significant impacts on stages of their life cycle, including feeding.

NatureScot consider that ‘significant disturbance’ should be interpreted to mean disturbance that affects the distribution of minke whale within the site such that recovery cannot be expected. Effects of activities which last beyond the average generation time of minke whale are more likely to constitute significant disturbance. ‘Significant disturbance’ may result in the following effects:

• contributes to long term decline in the use of the site by minke whale.
• changes to the distribution of minke whale within the site on a continuing or sustained basis.
• changes to the behaviour such that it reduces ability of the species to feed efficiently, breed or survive.

Vessels participating in the fishery are typically local inshore vessels, hugging the coastline with their fishing activity and not transiting significantly within the MPA.

Activity authorised under the wild wrasse fishery is unlikely to significantly alter the hydrography of the area or alter the composition of the substrate and therefore unlikely to affect species composition, abundance or concentration of prey species available to minke whale.

7.5 Assessment of cumulative and in combination effects of the wrasse fishery with other activities

The wrasse fishery under consideration operates in shallow, nearshore, rocky reef and kelp habitats. Due to the specific habitat requirements there is limited spatial and operational overlap with demersal towed gear fisheries such as trawling or dredging, which are generally confined to deeper, softer sediment habitats. As such, the potential for in-combination effects with demersal towed gear is considered negligible.

However, there is a greater likelihood of interaction with other static gear fisheries, particularly creel fisheries targeting crab and lobster, which may also operate in similar shallow, rocky environments. Currently, comprehensive spatial data on the distribution and intensity of these creel fisheries is limited, but as the main concern with the wrasse fishery is primarily to do with the impact of removing the target species, rather than abrasion to the seabed, the potential for significant in-combination effects with other static gear fisheries is considered low.

There are no active licences or applications for plans or projects within Sea of the Hebrides MPA which would, in combination with the wrasse fishery, hinder the achievement of the conservation objectives.

7.6 Taking account of management measures

The above appraisal suggests that the wild wrasse fishery could have an interaction with the minke whale and basking shark feature. However, due to existing management measures in place and the nature of fishing operations, it is unlikely that there is a significant risk of the wrasse fishery hindering the achievement of the conservation objectives.

Key management measures that help minimise potential impacts include:

• Restricted access to the fishery.
• Effort controls, with limits on the number of wrasse traps/pots that each authorised vessel may deploy.
• Shallow water operation, as wrasse traps are predominantly deployed in depths of 10 metres or less, which is generally outside the preferred foraging or transit depths of minke whales and basking sharks.
• Frequent hauling of gear, typically on a daily basis, which reduces the likelihood of entanglement or prolonged gear presence in the water column.

These operational characteristics, combined with regulatory controls, significantly reduce the potential for entanglement or disturbance to these marine mammals.

7.7 Conclusion

Given the existing management measures and the shallow inshore nature of the fishery, it can be concluded that the activity authorised under the wild wrasse is not capable of affecting, other than insignificantly, the basking shark or minke whale feature at the relevant sites.

7.8 Monitoring and Review

Scottish Ministers will review this assessment as required. A review of this assessment may be in response to updated conservation advice; updated advice on the extent, distribution or condition of the feature; new information on the sensitivity of the feature to pressures arising from activities within the site; or information on changes in fishing activity within the site.