B2. Sustainable fisheries

a. Percentage of marine fish (quota) stocks of UK interest harvested sustainably

b. Percentage of marine fish (quota) stocks of UK interest with biomass at levels that maintain full reproductive capacity

Type: Pressure (a) and state (b) Indicator

This indicator was updated in 2023.

Introduction

Sustainable fisheries help to ensure our marine ecosystems remain diverse and resilient, providing a long-term and viable fishing industry.

Changes were made to the indicator in the 2021 publication to bring it in line with the Multi-Annual Plans (MAPs) for fisheries. The indicator is therefore not directly comparable with previous versions of the indicator pre-2021. This indicator has been developed to meet the needs of the UK Marine Strategy and uses quota-fish assessments for UK commercial fisheries to assess Good Environment Status for the UK Marine Strategy. Data have been updated to 2020 for both fishing pressure and spawning stock biomass.

Key results

The revised indicator includes a category for stocks that are fished in acceptable mortality range (in F_MSY range). Estimates show that the percentage of UK quota-fish stocks (including Norway lobster, Nephrops norvegicus) fished at or below F_MSY, and/or within acceptable mortality range levels, has increased from 11% in 1990 to 56% in 2020. In 2020, 21% of UK quota-fish stocks were assessed to be fished at levels of fishing pressure above both F_MSY and the upper F_MSY range where this estimate is available.

To maintain the reproductive capacity of stocks, each stock’s spawning biomass (SSB) should be at or above the level capable of producing maximum sustainable yield (MSY B_trigger). The revised indicator introduced a zone ‘below MSY B_trigger but above B_lim’ to indicate conditions where a stock is at low risk of reproductive impairment relative to those stocks at high risk. The percentage of stocks subject to quota management and achieving SSB at or above MSY B_trigger increased from 28% in 1990 to 58% in 2020. However, 16% of stocks remain with SSB below MSY Bt_rigger, with a further 3.5% with SSB below MSY B_trigger but above B_lim.

Overall, a positive trend towards a greater proportion of stocks fished sustainably is evident in both the long term and short term. There is also a positive trend for fish within safe biological limits in the long term, however no change in the short term. For stocks fished sustainably, the percentage of stocks with an ‘unknown status’ is decreasing and is 23% in 2020. Whereas the percentage of stocks fished within safe biological limits with an ‘unknown status’ is increasing, and in 2020 is 23%.

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Indicator description

The indicator uses quota-fish assessments developed to assess good environment status (GES) for the UK Marine Strategy. It comprises of two measures: the percentage of fish stocks in seas around the UK that are harvested sustainably; and those at full reproductive capacity.  It is based on a group of 20 species in 57 stocks for which there are estimates available for fishing mortality and/or spawning stock biomass (SSB), together with MSY reference points for fishing mortality (including F_MSY ranges) and SSB (including a management reference point MSY B_trigger and a lower limit, B_lim) that allow the sustainability of the stocks to be evaluated.

The indicator stocks include a range of local and widely distributed species of major importance to the UK fishing industry.

The measures are assessed as follows:

1. An evaluation of the temporal trends in the exploitation level of stocks of UK interest with respect to the fishing mortality target F_MSY and F_MSY ranges where available. The aim is to increase the proportion of stocks fished at or below F_MSY and reduce to zero the number of stocks of unknown status relative to F_MSY.
2. An evaluation of the temporal trends in the spawning stock biomass (SSB) of stocks of UK interest with respect to safe biological limits. The aim is to increase the proportion of stocks with SSB at or above MSY B_trigger and reduce to zero the number of stocks that have unknown status relative to MSY reference points.

The updated indicator methodology for fishing mortality accommodates complications that arise due to multi-species interactions in mixed-fisheries that characterise demersal fisheries in UK waters. The methodology allows a more flexible approach to the fishing mortality target when spawning stock biomasses are above MSY B_trigger, but a stricter approach under conditions where the biomass is below MSY B_trigger, especially where this falls below B_lim. The MAP approach allows for fishing within F ranges around MSY (F_MSY ranges) as advised by ICES (International Council for the Exploration of the Sea). However, fishing within the upper F_MSY range (i.e. above the F_MSY point estimate) is only acceptable if the stock size is above MSY B_trigger (or in the case of Nephrops: Abundance_buffer). When the biomass falls below MSY B_trigger, the MAP states that “all appropriate remedial measures shall be adopted to ensure rapid return of the stock or functional unit concerned to levels above those capable of producing maximum sustainable yield” (EC, 2018), thus the acceptable target for F_MSY is reduced linearly by multiplication of F_MSY by the ratio of SSB/MSY B_trigger. If the biomass were to further decrease below B_lim, then the MAP states that “further remedial measures shall be taken to ensure rapid return of the stock or functional unit concerned to levels above the level capable of producing maximum sustainable yield”.

Although stocks that are fished in the ‘in F_MSY range’ (Figure B2a) are not fished at the target level (≤ F_MSY) such stocks can be considered acceptably fished in the short term if SSB levels are high. For the reproductive capacity measure (SSB) the revised indicator introduces a zone ‘below MSY B_trigger but above B_lim’ (Figure B2b) to indicate conditions where a stock is at low risk of reproductive impairment relative to those stocks at high risk, i.e. SSB < B_lim. In this way, a distinction can now be made between stocks that require the greatest degree of management action.

The assessments of change are made by applying a 3% rule of thumb to each measure (state and pressure) separately. The arithmetic mean of the first three years of the data series is compared with the last point to determine the assessment for the long-term trend, and an arithmetic mean of the year five years back in the time series and the year either side calculated to compare with the last point to assess the short-term trend.

Stocks that meet both the pressure and state thresholds (F_MSY,  F_MSY ranges and MSY B_trigger) are harvested sustainably and in the long term will deliver the largest possible catches under the prevailing environmental conditions. While pressure is directly manageable through implementation of management measures, the change in state is not wholly manageable. State changes are dependent on environmental conditions and predator-prey interactions and although conditions for recovery of stocks may be in place (i.e. through reductions in pressure), recovery time may still be extensive (many years).

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Relevance

Fish are an integral component of marine biodiversity. They are an important element of the food chain for seabirds, seals and cetaceans and are a source of food and employment for people. Sustainable fisheries will help to ensure marine ecosystems remain diverse and resilient and provide a long-term and viable fishing industry.

In 2004, the Royal Commission on Environmental Pollution advised significant and urgent action to avoid collapse of fisheries or harm to the marine environment. The assessments indicate an increase in the last five years in the percentage of fish stocks being harvested sustainably. However, substantial further improvements in stock status would be needed to ensure that all UK fish stocks are fished sustainably and attain biomass levels that maintain full reproductive capacity.

The Marine and Coastal Access Act was introduced in 2009 to ensure clean, healthy, safe, productive and biologically diverse oceans and seas. As a result, better systems for delivering sustainable development of marine and coastal environment are being put in place.

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Background

This UK indicator is based on a consistent set of 57 stocks since 1990. A ‘stock’ refers to a population of a species occurring in a defined sea area; a particular species may occur in multiple stocks in waters around the UK. The stocks represent a wide range of different stocks and fisheries including demersal roundfish (e.g. cod, haddock, saithe), flatfish (sole, plaice), pelagic fish (blue whiting and mackerel) and shellfish (Nephrops). Table B2i shows the species included. Many of these stocks are extremely valuable or have a high conservation profile. The indicator is intended to provide a relative trend over time. The indicator includes stocks with ‘unknown’ status if data are not adequate to allow estimation of historical biomass and fishing mortality, or for which ICES does not provide MSY reference points.

ICES classifies a stock’s status by comparing the quantity of mature fish (the spawning stock biomass) and the rate at which the stock is exploited (fishing mortality), in relation to agreed reference levels and/or ranges. The stock trends and reference levels are obtained from fishery and survey data from each zone. The UK indicator shows the percentage of the 57 stocks of UK interest that are at full reproductive capacity and harvested sustainably in each year.

Each year ICES updates the assessment of each stock with another year of commercial fishery (catch data) and scientific survey (abundance) data, or may revise an assessment to include new time-series of data or adopt an improved method of analysis. This can result in substantial changes to the trends in spawning stock biomass and rate of exploitation, causing changes to the historical values in the UK indicator series. On the basis of new evidence, ICES may also provide advice in relation to reference points for stocks for which the assessments were previously considered unreliable, or stop providing such advice for stocks for which the assessments or reference points are no longer considered reliable.

All stock data are derived from ICES advice and stock assessment working group reports.

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Goals and Targets

The UK and England Biodiversity Indicators are currently being assessed alongside the Environment Improvement Plan Targets, and the new Kunming-Montreal Global Biodiversity Framework Targets, when this work has been completed the references to Biodiversity 2020 and the Aichi Global Biodiversity Framework Targets will be updated.

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Web links for further information

• Marine online assessment tool  (PDF, 517kb)
• Sustainable Fisheries Management
• Fisheries Statistics
• Turning the Tide: Addressing the Impact of Fisheries on the Marine Environment. (2004) London, the Stationary Office. (PDF 8.2mb)
• Regulation (EU) 2019/472 of the European Parliament and of the Council
• Regulation (EU) 2018/973 of the European Parliament and of the Council

Full details of this indicator and its supporting data are available here:
https://moat.cefas.co.uk/pressures-from-human-activities/commercial-fish-and-shellfish/fishing-pressure/

https://moat.cefas.co.uk/pressures-from-human-activities/commercial-fish-and-shellfish/reproductive-capacity/

Lynam, C., Allison, C., Ribeiro, J., Campon-Linares, V., Garnacho E. (2022) International (ICES) and national UK fish stocks and shellfish data from 2020 assessment year. https://doi.org/10.14466/CefasDataHub.130

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Downloads

Download the Datasheet and Technical background document from JNCC's Resource Hub.

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Last updated: November 2023

Latest data available:

Percentage of marine fish (quota) stocks of UK interest harvested sustainably – 2020;

Percentage of marine fish (quota) stocks of UK interest with biomass at levels that maintain full reproductive capacity – 2020.

 

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