Sustainable fisheries: fish stocks harvested within safe limits
Last updated: 2024
Latest data available: 2020
Introduction
This indicator has two parts, the first shows the percentage of marine fish (quota) stocks of UK interest harvested sustainably, in acceptable mortality range (in FMSY range). The second shows the percentage of marine fish (quota) stocks of UK interest with biomass at levels which maintain full reproductive capacity.
Sustainable fisheries help to ensure our marine ecosystems remain diverse and resilient, providing a long-term and viable fishing industry.
The UK biodiversity indicator for sustainable fisheries derives from the UK Marine Strategy Good Environmental Status assessment for commercially exploited fish and shellfish D3 categorising the sustainability of stocks against maximum sustainable yield (MSY) thresholds and uses quota-fish stock assessments data.
The data for this indicator can be downloaded from here: JNCC’s Resource Hub.
Type of indicator
Pressure (a) and state (b) indicator
Type of official statistics
Official statistic
Assessment of change
Assessment of change in the percentage of stocks harvested sustainably and at full reproductive capacity in the UK
| Measure | Assessment | Time period | Result |
|---|---|---|---|
| Percentage of fish stocks harvested sustainably | Long term | 1990 to 2020 | Improving |
| Percentage of fish stocks harvested sustainably | Short term | 2015 to 2020 | Improving |
| Biomass of stocks at full reproductive capacity | Long term | 1990 to 2020 | Improving |
| Biomass of stocks at full reproductive capacity | Short term | 2015 to 2020 | Little or no overall change |
Note on indicator assessment
The long-term and short-term assessments have been made by the Centre for Environment, Fisheries and Aquaculture Science (Cefas) by assessing change in the fitted LOESS smoothed trend for each measure. The assessments are made by applying a 3% rule of thumb to each measure 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. See Assessing Indicators.
Key results
Estimates show that the percentage of UK quota-fish stocks (including Norway lobster) harvested sustainably (fished at or below FMSY) has increased from 9% in 1990 to 49% in 2020. In 2020, 21% of UK quota-fish stocks were harvested unsustainably (Figure 1).
Safe biological limits are where the biomass of fish stocks is at a level capable of producing Maximum Sustainable Yields (that threshold is referred to as MSY Btrigger). The proportion of UK quota fish stocks fished within safe biological limits in 2020 was 58%, an increase from 28% in 1990 (Figure 2). However, 3.5% have a high risk of reproductive impairment in the long term, and 16% have a stock spawning biomass below that required to maintain sustainable yields.
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 was 23% in 2020.
Figure 1: Percentage of marine fish (quota) stocks of UK interest harvested sustainably, 1990 to 2020.
Source: Centre for Environment, Fisheries and Aquaculture Science, see: 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
Figure 2: Percentage of marine fish (quota) stocks of UK interest with biomass at levels which maintain full reproductive capacity, 1990 to 2020.
Source: Centre for Environment, Fisheries and Aquaculture Science, see: 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
Further detail
The percentage of fish stocks harvested sustainably relates to the percentage of stocks relative to the level capable of producing Maximum Sustainable Yield (FMSY). Increasing the proportion of stocks fished at or below the fishing mortality target FMSY increases the sustainability of the fishery.
The percentage of marine fish (quota) stocks of UK interest with biomass at levels which maintain full reproductive capacity refers to trends in the spawning stock biomass of stocks of UK interest with respect to safe biological limits. Safe biological limits are where the biomass is above the level capable of producing Maximum Sustainable Yield (MSY Btrigger). Increasing the proportion of stocks with spawning stock biomass (SSB) at or above MSY Btrigger increases the sustainability of the fishery.
For information on the methods used in this indicator, please see the Technical Annex.
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
The Fisheries Act 2020 provides the legal framework for the management of UK fisheries. The UK Joint Fisheries Statement (JFS), sets the direction of UK fisheries management, including our ambition to deliver world class sustainable fisheries management, whilst protecting and enhancing the marine environment. It sets out the policies to achieve or contribute to achieving the eight fisheries objectives in the Act.
Fisheries Management Plans (FMPs), key delivery tool of the JFS, are being developed to deliver long-term sustainability of our fish stocks and fishing industry. They will ensure that UK fish stocks are fished sustainably and attain biomass levels that maintain full reproductive capacity.
International/domestic reporting
The UK Biodiversity Indicators have been reviewed in response to the latest goals and targets agreed under the Kunming-Montreal Global Biodiversity Framework (GBF) of the Convention on Biological Diversity (CBD). The indicators are being adapted, with some new indicators being developed, to better align them with the monitoring framework for the GBF. The suite of biodiversity indicators is therefore expected to change ready for UK national reports to CBD in 2026 and 2029.
The intention is for this indicator to be modified to better align it with the requirements of the GBF monitoring framework, specifically to align with headline indicator 5.1 Proportion of fish stocks within biologically sustainable levels, relevant to Target 5.
This indicator feeds into the Outcome Indicator Framework, a set of indicators describing environmental change related to the ten goals within the 25 year Environment Plan. As part of the Outcome Indicator Framework, this data contributes towards the evidence base used to prepare the annual progress report for the Environmental Improvement Plan. This indicator contributes to OIF indicator C10: Productive seas: fish and shellfish stocks fished sustainably.
Web links for further information
- Commercially exploited fish and shellfish assessments for the UK Marine Strategy
- Sustainable Fisheries and Management on Centre for Environment, Fisheries and Aquaculture Science
- Fisheries Statistics on International Council for the Exploration of the Sea
- Joint Fisheries Statement on Gov.UK
- Fisheries Management Plans on Gov.UK
Supporting data for this indicator are available at:
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.
Acknowledgements
Thank you to the many people who have contributed by providing data and to the many colleagues who have helped produce this indicator. In particular, thanks go to colleagues at Cefas.
Technical Annex
Methodology
The indicator is derived from the good environment status (GES) assessment for the UK Marine Strategy for Descriptor 3 commercially-exploited fish and shellfish that shows the percentage of fish stocks in seas that are harvested sustainably; and those at full reproductive capacity. This UK biodiversity indicator for sustainable fisheries considers quota fish stocks from 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 (FMSY) and SSB (MSY Btrigger) that allow the sustainability of the stocks to be evaluated.
This indicator includes a range of local and widely distributed species of major importance to the UK fishing industry.
The measures are assessed as follows:
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An evaluation of the temporal trends in the exploitation level of stocks of UK interest with respect to the fishing mortality target FMSY. The aim is to increase the proportion of stocks fished at or below FMSY and reduce to zero the number of stocks of unknown status relative to FMSY.
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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 Btrigger and reduce to zero the number of stocks that have unknown status relative to MSY reference points.
The UK biodiversity indicator for sustainable fisheries was updated in 2021 to show percentages of stocks where the fishery is managed by Multiannual Plans (MAPs) in situations of mixed fisheries using precautionary reference levels (Fupper and Blim). Those reference levels are not valid to categorise stocks as sustainably fished or within safe biological limits in the long term. The plan for future reporting is to show only one category for stocks that are unsustainable fished or outside safe biological limits.
The assessments of change are made by applying a 3% rule of thumb to each measure separately. The arithmetic mean of the first 3 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 5 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 MSY thresholds (FMSY, and MSY Btrigger) 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 (that is, through reductions in pressure), recovery time may still be extensive (many years).
Background
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 fisheries including demersal roundfish (for example, cod, haddock, saithe), flatfish (sole, plaice), pelagic fish (blue whiting and mackerel) and shellfish (Nephrops). Table 1 shows the name of species and stocks included in the assessment. 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.
The International Council for the Exploration of the Sea (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 MSY reference points. The stock trends are obtained from fishery and survey data from each zone. The UK biodiversity indicator for sustainable fisheries shows the percentage of the 57 stocks of UK interest were classified 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. Please see the accompanying dataset for a list of the fish species and fish stock included in this indicator.
Development plan
Since our previous publication we have adapted the language and visualisations used in this indicator. We are keen to hear from our users about these changes, as well as our published development plan, please email us.
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