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

1. Introduction

The wild wrasse fishery has developed in Scotland since the late 1980s. Baited wrasse traps/pots are used to fish for five species of wrasse: ballan (Labrus bergylta), corkwing (Syphodus melops), cuckoo (Labrus mixtus), goldsinny (Ctenolabrus rupestris) and rock cook (Centrolabrus exoletus).

In Scotland, the wrasse fishery primarily occurs in shallow inshore waters, typically 10 metre or less in depth. Ballan wrasse is the most common reported and landed species of wrasse by weight, accounting for 71.6% (average annual %) of the landings between 2017 and 2024 in Scotland. Wrasse species are landed live and used as a biological control mechanism to treat sea lice in salmon farms, as an alternative to other potential treatments such as mechanical, thermal and pharmaceutical methods. Fisheries for that purpose also exist in Northern European coastal states such as Norway and Ireland but predominant species landed can vary between countries.

Access to the wrasse fishery in Scotland is restricted. All participating vessels (typically 6 – 12 metres in length) must hold a domestic fishing licence as well as a specific letter of derogation issued by the Scottish Government following an application process, during which proof of an appropriate contract with an aquaculture business must be supplied. The letter of derogation contains specific conditions appropriate to the management of the fishery, including minimum/maximum landing sizes, a seasonal closure aligned to spawning periods and limits on the number of baited traps/pots which may be deployed in a 24-hour period (detailed in section 1.2).

1.1 Background

Voluntary arrangements in respect of catching wrasse species using baited traps/pots in Scottish inshore waters were introduced in 2018 jointly by the Scottish Government and Salmon Scotland due to growing concerns over the long-term sustainability of the fishery and lack of specific management measures.

In March 2020, the Marine Directorate of the Scottish Government set out new proposals for managing the wrasse fishery, including mandatory controls over harvesting, access to the fishery and data reporting. The consultation ‘Wild Wrasse Harvesting: Consultation on Proposed New Mandatory Fishing Measures’ (Scottish Government, 2020a) invited views on whether the Marine Directorate should introduce mandatory measures to control the harvesting of live wrasse for the salmon farming industry.

The consultation concluded in May 2020 and attracted 154 responses from a range of interests including fishers, salmon farm operators, environmental groups, industry representative groups and members of the public (Scottish Government, 2020b). Most of the proposals received strong support and, as a result, the new scheme put in place mandatory measures controlling access to the fishery. All sea fishing licences, which provides a general authority to fish in the UK EEZ, issued by the Scottish Ministers were varied by the addition of a new licence condition which closes the wrasse fishery to all licence holders unless they have been issued with a letter of derogation.

In early 2025, Marine Directorate officials have undergone a period of engagement with wrasse fishers to improve understanding of their operations, including technical features of traps/pots and improving geospatial information and knowledge on the Scottish fishery.

1.2 Management measures in place 2020 – 2024

All fishers wishing to participate in the commercial wrasse fishery must apply, on an annual basis, for a wrasse letter of derogation. If issued, the fisher must abide by the following conditions:

1. The licence holder is permitted to fish within the Scottish zone (as defined by section 126(1) of the Scotland Act 1998, as amended) for the species of wrasse, between 1 May and 30 November.

2. The minimum and maximum landing sizes for wrasse are as follows:

Goldsinny (Ctenolabrus rupest ris) 12cm – 17cm

Rock Cook (Centrolabrus exoletus) 12cm – 17cm

Corkwing (Symphodus melops) 12cm – 17cm

Ballan (Labrus bergylta) 12cm – 24cm

Cuckoo (Labrus mixtus) 12cm – 24cm

3. Only wrasse traps specifically designed to target and catch live wrasse and ensure their welfare may be used to fish for wrasse.

4. The traps used to fish for wrasse must have otter exclusion devices, such as a fixed eye aperture at the entrance to the trap and traps must feature escape hatches.

5. All reasonable precautions must be taken to ensure that traps used to fish for wrasse are lifted in a manner that ensures the best possible welfare of the wrasse and a maximum rate of six metres per minute must not be exceeded when lifting traps.

6. It is prohibited to deploy traps used for fishing wrasse when the water into which they would otherwise be deployed is at a temperature exceeding 17°C.

7. A vessel may deploy a maximum of 250 wrasse within any 24-hour period.

8. Fishers targeting any species of wrasse will be required to accept observers if requested subject to operational practicalities.

9. Vessels must operate active spatial monitoring equipment when required by Marine Scotland.

10. The licence holder must hold a valid, current, contract to supply wrasse to a person who carries on a business of fish farming and who is authorised as an aquaculture production business under The Aquatic Animal Health (Scotland) Regulations 2009) and, where requested by Marine Scotland to do so, supply a copy of such contract in order to evidence the same.

11. In addition to the statutory requirements to provide accurate landings details on Form FISH1, Log Books and landings declarations, the licence holder must submit in writing to the licence holder’s local Marine Scotland Fishery Office on a weekly basis, one week in arrears by no later than 2359 hours each Monday, the following information^[1]

a) an accurate record of the total number of wrasse, by species and per ICES rectangle, landed for each trip made in each given week; and

b) an accurate record of the total number of under and over-sized wrasse, by species, returned to the sea for the first 20 traps deployed in each given week.

12. If required by Scottish Ministers, the licence holder shall install vessel tracking or remote electronic monitoring equipment in the vessel to which their licence relates and participate in interviews and data gathering exercises where the activity has been approved by the Scottish Ministers.

13. All fishers targeting wrasse will be required to accept observers if requested subject to operational practicalities.

14. The Letter of Derogation granted must be retained aboard the vessel at all times to be made available for inspection on request by a British Sea Fishery Officer.

These management measures are based on the best available evidence and kept under review by the Scottish Government. The controls are administered and varied by licence condition which ensures that if they need to be amended based on emerging evidence, this can be done so swiftly.

1.3 Wrasse ecology, habitat association and implications for management

Wrasse species are closely associated with inshore rocky reefs and macroalgal habitats. These environments provide essential ecological functions, including refuge from predators, foraging grounds, and nesting sites. Algal cover, especially kelp and other canopy-forming species, plays a critical role in supporting the structural complexity that wrasses rely on throughout their life cycles.

A key ecological trait of many wrasse species is their strong site fidelity, particularly during the spawning season (Villegas-Ríos et al., 2013). Male ballan wrasse, for example, have been observed defending the same territory (often a single rock or a small cluster of rocks) for multiple years (Mucientes et al., 2019). These territories are important for individual survival but also for maintaining the spatial structure of populations. In both ballan and corkwing wrasse, male nest-guarding behaviour enhances egg survival and recruitment success, making territorial stability a vital component of population resilience.

Reproductive strategies differ between wrasse species, with important implications for management. Ballan wrasse are protogynous hermaphrodites: all individuals are born female, and some transition to male as they grow, typically in response to local sex ratios. This makes larger males particularly important for population dynamics and suggests that size-selective fishing could disproportionately affect reproductive output. In contrast, corkwing wrasse are gonochoristic, maintaining fixed sexes throughout life, and exhibit alternative reproductive tactics, including sneaker males that mimic females to gain access to nests.

Spawning in wrasse typically occurs during the spring and summer months, with peak activity varying by region. In Scotland, authorised vessels may only participate in the wrasse fishery from 1 May to 30 November in order to protect spawning individuals. Evidence from UK waters shows that the highest Gonadosomatic Index (GSI) for ballan wrasse, the dominant species in the Scottish fishery, occurs between January and April, with peak values of 5–9% recorded in March and April (White & Ellis, 2025). In contrast, GSI values recorded during the open season (May to November) between 2022 and 2024 were consistently ≤1%, indicating reproductive quiescence during this period (Pritchard, 2025a).

1.4 Developments for the 2025 season

• We have identified areas where our data gathering can be focussed and improved, including a reworked scientific data return sheet that all fishers will be required to submit on a weekly basis (we will keep this form under review).
• For relevant sites (identified below) proposals to reduce the impact of the wrasse fishery in these include zoning to avoid protected features and account for the site fidelity and home range of wrasse. Ballan wrasse display extreme site fidelity, sometimes to a single rock or a small group of rocks, especially during the spawning season (Mucientes et al. 2019). This strong site fidelity suggests that even small marine reserves could be effective for protecting ballan wrasse (Mucientes et al. 2019). For this reason, zoning 170m around protected features (assessed as reported home range by Villegas-Ríos, 2013) will provide protection for wrasse that rely on/service the protected features within the relevant sites.
• In relation to the minimum landing size for ballan wrasse, the Scottish Government has been undertaking modelling work to determine potential sizes of maturation to inform minimum landing sizes, given the absence of empirical gonad histological observations. We anticipate that work continuing through summer 2025. Whilst that work is being undertaken, inshore science advisors have recommended it would be a sensible approach to increase the minimum landing size at this time, with the understanding that there is a requirement for further work. Until the modelling work is completed, the MLS for ballan wrasse in Scotland will be increased from 12cm to 14cm. Further details are provided in Section 9.
• Since the introduction of mandatory controls in 2021, a consistent seasonal trend has been observed in the Scottish wrasse fishery. Landings typically peak in August, with lower levels of fishing activity in late May and early November. Given that March and April are critical months for wrasse reproduction, and that fishing activity generally begins in late May, it is unlikely that males are being removed from the population during their nest-guarding phase. Furthermore, sampling of landings between 2022 and 2024 indicates that the current maximum landing size of 240 mm is effective in excluding males: 100% of sampled ballan wrasse below this size were female. To further reduce any residual risk, the fishery will open later in May in future seasons, aligning more closely with actual landing patterns and ensuring additional protection for nesting males.
• For the 2025 wild wrasse fishery, we will seek to improve the geospatial data for the fishery (i.e. the granularity of data we hold about where wrasse fishing is taking place) by using appropriate and proportionate onboard technology. The Scottish Government has already signalled that we will increase the use of tracking devices (i-VMS) on under 12 metre Scottish vessels in 2025/2026, a procurement exercise for the project is ongoing at the time of writing but the intention is that the vessels participating in the 2025 wild wrasse fishery will be early adopters of such technology.

1.5 Fisheries Assessment

This document comprises Habitats Regulations Appraisals (for Special Areas of Conservation (SACs)) and Marine Protected Area assessments (for Nature Conservation Marine Protected Areas (NCMPAs)) for the regulated commercial use of traps/pots to catch wrasse within relevant sites in Scottish inshore waters (together referred to as a ‘Fisheries Assessment’).

Scotland’s Special Areas of Conservation (SACs) and Special Protection Areas (SPAs) are areas which have been designated (or classified) as such under the Conservation (Natural Habitats, &c.) Regulations 1994 (as amended) for inshore waters and the Conservation of Offshore Marine Habitats and Species Regulations 2017 (as amended) for offshore waters, hereafter referred to as the Habitats Regulations. Nature Conservation MPAs are areas designated as such under the Marine (Scotland) Act 2010.

Regulation 48 and regulation 28 of the inshore and offshore Habitats Regulations respectively, provide for the Habitats Regulations Appraisal (HRA) process. In terms of this process, there is a requirement for an appropriate assessment to be undertaken for any plan or project proposed which is not directly connected with or necessary to the management of a SAC that is likely to have a significant effect on that site, either individually or in combination with other plans or projects. In the context of this Fisheries Assessment, the commercial fishing for wrasse with traps/pots within SACs are considered to be the plan or project.

No equivalent requirement is in place for NCMPAs. However Scottish Ministers have taken the decision to assess the impact of relevant commercial fishing activities within NCMPAs to determine whether those activities pose a significant risk of hindering the achievement of the conservation objectives for the NCMPA in question.

The primary focus of the assessment is understanding the risks to SACs and NCMPAs arising from the regulated commercial use of traps/pots to catch wrasse in Scottish inshore waters within those sites, in view of their conservation objectives.

The Scottish Government sought advice from NatureScot to inform this Assessment, that advice has been published.