B7: Health of freshwaters assessed through fish populations

Interim Interim

Short description

This indicator tracks changes in populations of native freshwater fish in England. Fish are a good indicator of healthy freshwater environments, responding to changes in water quality (including temperature) and quantity, as well as the quality of river habitats, necessary to sustain healthy juvenile populations and enable migration throughout the rivers to complete their life cycles. Fish also provide an important recreational and economic benefit from freshwaters.

This indicator is not available for reporting in 2021 in a finalised form. An updated interim indicator is presented here that expands on previous reporting to show (a) the proportion of principal salmon rivers at risk in England and, additionally, (b) the classification of fish species within English rivers. B7a shows annually published national salmon stock data. For this assessment, each river’s salmon stocks are placed into one of 4 categories: at risk; probably at risk; probably not at risk; and not at risk. The results act as a proxy for whether a particular river is at risk or not. In addition, a second measure of freshwater health has been included for the first time in 2021. Fish classification data for B7b reflect the status of fish species within rivers assessed in England. The results act as a proxy for whether the status of a particular river is: high; good; moderate; poor or bad. Further work will examine the coverage of the indicator.

Trend description

a) Salmon stock status

The percentage of principal salmon rivers at risk in England has risen by 10 percentage points, from 48% in 2004 to 58% in 2019; the percentage of rivers in the ‘probably at risk’ category has increased by 15 percentage points, from 21% to 36% over the same time period. The percentage of rivers in the ‘not at risk’ category has fallen by 24 percentage points to zero between 2004 and 2019, and while the percentage of rivers that are probably not at risk has fluctuated in the intervening years, it is the same in 2019 as it was in 2004.

b) Classification of fish

The data show a slight but consistent increase in the numbers of rivers classed as high and good ecological status for fish between 2009 and 2015 and a corresponding small decrease in numbers of rivers in the poor and bad categories. Indications are that there was no change in the proportions of rivers in the 5 different categories between 2016 and 2019.


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This table provides metadata for the interim or final indicator presented above.

Indicator name

Health of freshwaters assessed through fish populations

Indicator reference


Outcome Indicator Framework theme


Headline indicator status

Not applicable

Relevant goal(s) in the 25 Year Environment Plan
  • Clean and plentiful water
  • Thriving plants and wildlife
Relevant target(s) in the 25 Year Environment Plan
  • Restoring 75% of our one million hectares of terrestrial and freshwater protected sites to favourable condition, securing their wildlife value for the long term
  • Taking action to recover threatened, iconic or economically important species of animals, plants and fungi, and where possible to prevent human induced extinction or loss of known threatened species in England and the Overseas Territories
Position in the natural capital framework
  • Condition of assets - freshwater
  • Condition of assets - species and ecological communities
Related reporting commitments
  • Aligns with assessment of fish populations in rivers as undertaken and reported through our obligations to the Water Environment (Water Framework Directive) (England and Wales) Regulations 2017
  • Assessment of salmon stocks is reported separately to the International Council for the Exploration of the Seas and the North Atlantic Salmon Conservation Organisation
  • Relevant to Convention on Biological Diversity Aichi Target 6
Geographic scope

England; data for river basin district are also available.

Status of indicator development


Date last updated

11 June 2021