Wrasse

Live Wrasse Fishery

Background

The Atlantic salmon aquaculture industry is a major sector in finfish aquaculture with, Scotland being one of the top three producers of Atlantic Salmon globally. Scottish farms produced 162,817 tonnes of salmon, equal to a value of £765 million in 2016. However, sea lice infestation is one of the most challenging issues faced by the Atlantic salmon aquaculture industry. Traditional methods of sea lice control involve the use of pesticides; however, these chemical treatments are becoming less effective as sea lice have begun to develop resistance.

The wrasse family (Teleostei: Labridae) is a large and widely distributed group of marine fishes, found in both tropical and temperate seas. Wrasse display a wide variety of life history strategies (combinations of age- and stage-specific patterns and timings of life events such as growth, maturation and reproduction), making them one of the most ecologically and morphologically diverse fish families. Five species of wrasse are common in temperate reef habitats in the northeast Atlantic, including around the British Isles: ballan (Labrus bergylta), corkwing (Symphodus melops) goldsinny (Ctenolabrus rupestris), rock cook (Centrolabrus exoletus), and cuckoo (Labrus mixtus) wrasse. These fish carry out a cleaning behaviour that was first observed in 1973. Subsequent trials conducted in 1983 identified that wrasse could be used to control parasites in salmonid aquaculture. As a result, a commercial fishery targeting live wrasse began in 1988 in Norway, 1989 in Scotland and 1990 in Ireland.

Fishing for live wrasse began in Southwest England (Dorset, Devon and Cornwall) in 2015 because local supply in Scotland could no longer meet demand, and warmer sea temperatures in Southwest England allowed longer fishing seasons. Four species of wrasse are targeted in the fishery in D&S IFCA’s District: goldsinny, corkwing, ballan, and rock cook. Cuckoo wrasse are rarely caught but are not retained.

The live wrasse fishery in the D&S IFCA District comprises up to four vessels per year, each ranging from approximately five to ten metres in length. Over the course of 2017–2020, some vessels have left the fishery and been replaced by new entrants.  The fishery is highly regulated in D&S IFCA's District and is restricted (via voluntary closed areas) to within Plymouth Sound and the surrounding coastal waters. Fishing is mainly conducted between mid-July to October, but some fishing occurs through to December. Some vessels resume fishing early in the year, but there is a closed season (permit restriction) between April and mid-July in the D&S IFCA District. Fishers use wrasse traps (pots) with escape gaps, with multiple pots attached to one ‘string’.

Introduction of Management

Due to the complex nature of this new fishery Devon and Severn IFCA (D&S IFCA) carried out an extensive review of wrasse ecology and fisheries interactions in order to gain more in-depth knowledge and understanding regarding their life history traits and any ecological impacts that may arise from targeting this species.

As the live wrasse fishery in Plymouth Sound occurs within the Plymouth Sound and Estuaries Special Area of Conservation (SAC), D&S IFCA has a duty to ensure the fishery is sustainable and does not negatively impact the designated features or integrity of the SAC. As a result a summary of evidence and reasoning for the introduction of management measures to the live wrasse fishery was prepared for Authority members.

Although wrasse are not designated as a feature of the SAC, D&S IFCA conducted Habitats Regulation Assessments (HRAs) in order to determine the effect of the fishing activities on the conservation objectives of the Plymouth Sound and Estuaries SAC’s qualifying features. 

This assessment, as agreed by Natural England, concluded that the activity would be unlikely to have a significant effect in view of the site’s conservation objectives. However, Natural England agreed that the fishery needed to be closely monitored and any impact on the MPA’s ecosystem as a whole would be determined by the sustainability of the fishery.

Due to a lack of available data, at the time of the emerging wrasse fishery, on the impacts of such a fishery on stock abundance or reef ecology, D&S IFCA proposed new data collection priorities in order to inform fisheries management decisions. Management measures were subsequently implemented in June 2017, through the Potting Permit Byelaw conditions. These included a limit of 120 pots per vessel, minimum and maximum conservation reference sizes for landings, temporal and spatial closures and requirements for fishers to submit landings data from every fishing trip. The management measures introduced by D&S IFCA have been under review ever since.

Data Collection

As part of the management measures, an intensive data collection programme was introduced in 2017. This programme aims to capture temporal and spatial trends in catches and landings per unit effort (CPUE and LPUE) allowing D&S IFCA to closely monitor the fishery. 

CPUE is the number of fish caught per pot, while LPUE is the number of those fish that are within the Conservation Reference Size range and were retained by the fishers. This involved collection of landings data recorded on forms by fishers and returned to D&S IFCA. Data recorded on these forms include the total number of wrasse retained per day and the location of fishing activity.

In addition to the landings data, D&S IFCA’s Environment Officers have carried out observer surveys of the wrasse fishing vessels every year since 2017. Officers record the start and end position of each string of pots, and the number of pots per string. Each wrasse caught is then identified to species level, measured for length, checked for signs of spawning and sexed where possible. Fish within the minimum and maximum conservation reference sizes are retained whilst any that are below the minimum or above the maximum conservation reference sizes are returned in such a way as to minimise predation by seabirds and ensure survival.

Reporting on the live wrasse fishery

A report has been produced each year based on the data collected during that year, and the management measures have been appropriately adjusted based on the best evidence available at that time, to ensure the continued sustainability of the fishery. The reports were used as the basis for a review of the relevant HRAs, conducted in August 2020, for the impacts of fish traps on rock (including the fish communities of rocky reef ecosystems), intertidal sediments, subtidal sediments, seagrass and shad.

Natural England’s advice on these HRAs is also available here, and outlines that D&S IFCA has used the best available evidence to carry out these assessments and to determine whether management is required to ensure the protection of site features from direct and indirect impacts of fishing with wrasse pots. It is Natural England’s view that D&S IFCA’s officers have appropriately identified: (1) activities likely to have a significant effect on site conservation objectives; and (2) any management measures required in order to ensure there will be no adverse effect on the integrity of the European Marine Site(s).  Natural England has confirmed that it believes that any foreseeable risk or harm to designated sites has been appropriately assessed and agrees with D&S IFCA’s conclusion of no adverse effect to site integrity. Natural England has also highlighted that D&S IFCA’s ongoing commitment to monitoring this fishery, together with the application of the current thinking on adaptive risk management, provides an appropriate mechanism for re-assessing this risk.  

The latest D&S IFCA report on the live wrasse fishery can be found here, and represents the best available evidence for the wrasse fishery in D&S IFCA’s District. A summary of this report was produced for the February 2021 Byelaw & Permitting Sub-Committee meeting and was revised for use by all stakeholders. It can be found here. The latest report used the data collected from the observer surveys and an updated approach to statistical analysis adapted from Henly et al. (in press), which provided greater understanding of environmental, geographic and fishery-related drivers of CPUE and LPUE of wrasse in the D&S IFCA’s District.

A summary of all changes to the management measures to date can be found here. This report has been produced to document the decision-making process for the changes to the Potting Permit Conditions and merges all relevant information into a single publication. Individual reports documenting changes to permit conditions can be found in the Resource Library (Section F – Byelaw Development & Reports).

Findings from the latest report

In 2020, D&S IFCA’s Environment Officers completed observer surveys on approximately 6.3% of total fishing trips (7 out of 111), despite the difficulties posed by the COVID-19 pandemic.

The main drivers of variation in CPUE and LPUE differed between species. There was evidence of a decline in ballan wrasse CPUE and LPUE during the 2017–2020 period, particularly on the landward side of Plymouth breakwater. This decline over time is likely driven by the relatively high retention rate of ballan wrasse in combination with specific life history and behavioural characteristics that leave the species vulnerable to overfishing. Under the current CRS limits of 15–23 cm, up to 71% of ballan caught in pots were retained during 2017–2020. The latest report emphasised that targeting this size range with high retention rates risks highly sex-selective fishing and removal of mature females from the population, potentially limiting reproductive potential and affecting population growth. D&S IFCA Officers therefore recommended a revised CRS range of 18–26 cm, which would afford greater protection to recently matured females and continue to protect the larger mature males.

There was no evidence of a decline over time in any of the other species, despite an apparent decline in rock cook CPUE and LPUE that was highlighted in the Three Year Comprehensive Review of the Live Wrasse Fishery. The updated analyses presented in the latest report show that rock cook CPUE and LPUE vary significantly between broad-scale fishing areas (significantly lower in the more sheltered areas). The spatial distribution of fishing and survey effort has varied markedly over the 2017–2020 period, and in 2019 and 2020 the majority of the observer surveys were conducted in more sheltered locations. The previous year’s analysis was unable to account for this geographic variation in CPUE and LPUE, which was mistakenly attributed to declines in rock cook between years.

Goldsinny wrasse showed seasonal and geographical variation in CPUE and LPUE that supports previous observations of goldsinny. Finally, there was a significant increase in corkwing wrasse CPUE across the 2017–2020 period. The change in corkwing CRS limits in 2018 has likely benefitted the species as a lower proportion of corkwing are being landed and mature individuals of each sex are likely being protected. There was also evidence of seasonal variation in corkwing CPUE and LPUE which may reflect the species’ spawning season and concurrent activity levels.

Finally, the report highlighted that robust monitoring of the fishery relies on high quality observer surveys, which provide information that cannot be gained from fishers’ returns forms. It was therefore recommended that the requirement for fishers to submit returns forms is removed.

Future of the Wrasse Fishery

The results of the most recent report and recommendations for revised management (as outlined above) were presented to D&S IFCA’s Byelaw & Permitting Sub Committee (B&PSC) in February 2021. The B&PSC took forward the following recommendations:

  • Continue to manage the fishery for 12 months as outlined in the D&S IFCA’s Policy Statement and Potting Permit Conditions for the Live Wrasse Fishery (24th June 2020), except in the case of ballan wrasse, and except with regards to fishers’ returns forms.
  • Change the ballan wrasse CRS range from 15–23 cm to 18–26 cm.
  • Remove the requirement for wrasse fishers to submit returns forms.

The B&PSC did not support a recommendation to lift the prohibition (relax a management measure) on the removal of rock cook from the fishery and reintroduce the previous conservation reference size (an alternative management measure).

The proposed management measures that require a change to the permit conditions (revision of ballan wrasse CRS limits) were subjected to a formal consultation that ended on Wednesday 12th May 2021. A report documenting the findings of the consultation will be prepared and presented to D&S IFCA's Byelaw and Permitting Sub-Committee in June 2021. The report will be published on the website.

Page updated: 13th May 2021.