Riverfly Census

We are seeking funding to enable us to extend and expand our National Riverfly Census across England and Wales for a further three years

Why is it necessary?

83% of English rivers fail the test of "good ecological status" as defined by European environmental legislation. Consequently it should come as no surprise that invertebrate populations are suffering and in some cases very significantly. Even to the point where concern is expressed that some species on certain rivers face the prospect of extinction if action is not taken.

Invertebrates are food not only for fish but also certain species of birds and mammals.

Understanding how and why the riverfly numbers are declining is the first step in the process of safeguarding the aquatic environment.

Environment Agency historic data has been based upon family level and fails to address the question of abundance. S&TC UK Riverfly Census focuses on individual species and also abundance; so important as each species has specific tolerances to aquatic stresses.

What the unique census provides

  • A benchmark of current populations by species richness and abundance.
  • A biometric measure of ecological stress at the sample sites
  • A process which is much more sensitive to ecological problems than existing EA sampling procedures.
  • And, thus, crucially, evidence base with which to challenge the EA - by recourse to the law if necessary - to tackle the problems, which are causing the rivers to fail.
  • This riverfly database will be an enduring legacy for further scientific research.


What S&TC UK has achieved to date

Spring 2015 saw the launch of the S&TC UK Riverfly Census. This involved taking invertebrate samples from five sites from each of the selected 12 rivers. The rivers being deliberately chosen based upon geographic and geological diversification. The Spring survey was repeated in the Autumn on the same sites and rivers.

Each sample is analysed scientifically on behalf of S&TC UK by Aquascience. By focusing at species level it provides much higher resolution data than family-level analysis and consequently highlights ecosystem distress and loss of species richness.

Although the analysis is not yet complete the initial findings show that Riverflies are under the cosh in chalk streams in particular and that there is a worrying lack of gammarus across most of the sampled rivers.

Gammarus matter because we believe they are an important source of winter-feeding particularly on Chalk Rivers.

It has also shown up some stark contrasts which are deeply worrying e.g. not only is invertebrate abundance in general declining but the "best" R Itchen site had a total invertebrate count in the Spring 2015 of 400 against a count of over 4000 on the Derbyshire Wye.

What still needs to be done

Once the Autumn samples have been analysed the data, together with the results from the Spring survey, will be the subject of a full report planned for Spring 2016.

2016 & 2017 will see a continuation of the project across the 12 rivers and ideally the number of rivers increased to 24.

Use the data to influence and press (legally if necessary) the Environment Agency to take action to protect and enhance riverfly populations across all rivers.

We desperately need further funding to continue and expand this important campaign. Please support this vital work and donate now

Other information

State of Nature 2016: Disappearing riverflies…

River invertebrates could hold the key to abysmal state of rivers in Wales

Riverfly App version II

Riverfly Census 2015 Report

Riverfly Census 2016 Report

Biometric sampling explained

Biometric sampling chart

Rivers Surveyed to Date


The importance of data

Riverfly Census Update: Our mid term report

Riverfly Census Report: Latest news form the Upper Itchen

Riverfly Census update

S&TC UK 2015 Riverfly Census