THE Salmon & Trout Association (S&TA) National River Fly Survey results demonstrate that there has been a dramatic decline in river fly numbers from the 1950s to 2001.


Peter Hayes, the Survey co-ordinator, explains that, ¡§River flies are the miner¡¦s canary of environmental quality.  They have been declining at a tremendous rate. While there are indications that the Government and its agencies are moving to understand this problem, the willingness to ensure adequate investment to overcome the problems is perhaps still in doubt.  The government and EU concerns about the poor quality of our waterbodies are well placed.  These results place further pressure with Government to comply with new EU water regulations.¡¨


Over 182 river keepers, riparian owners, angling club officials and anglers, together spending 3,822 days on the river bank, from the Scottish Highlands to the Southern chalk streams, participated in this comprehensive overview of river fly life.  


The results from this national fly life survey parallel the decline previously revealed by the Millennium Chalk Stream Fly Survey.  The river fly decline is revealed as a national problem, and not just one of the chalk streams.  Overall, fly numbers have fallen to one third of those observed in the 1950s and 1960s.  This is not surprising given the well-evidenced declines in terrestrial insects extending across the country as a whole, with their damaging impact upon numbers of insect eating birds and other wildlife. 


The survey posed the key question ¡§How good was the fly?¡¨  Respondents replied with ¡§Good Hatches Frequently¡¨ (GHF), ¡§Good Hatches Infrequently¡¨, ¡§Sparse Hatches Frequently¡¨, ¡§Sparse Hatches Infrequently¡¨, ¡§Very Little Fly¡¨ and ¡§Absent¡¨. 


The percentage of GHF reports has fallen nationally from 85% in the 1960s to 33% in the first half of the 1990s to a devastating low of only 13% in 1998 (which increased slightly to 17% in 2000 and 2001, probably because of improved river flows following the drought years of the late 1990s).


The angler is uniquely qualified to observe and report on fly life, as anglers study flies almost as closely as fish.  Fly fishers, as anglers call themselves, create imitation flies in their larval, nymph, and adult form, and cast them out to tempt fish, which rise to the surface of the water to catch river flies.  Without the fly, and the fish that feed on them, there is no fly fishing.


¡§We now know how vital healthy river flows are in encouraging an abundance of fly life,¡¨ Paul Knight, S&TA Director, declares.  ¡§Diffuse pollution including pesticides and silt, excessive water abstraction, inadequately treated sewage, and urban run-off are all having a negative impact on the health of the aquatic environment throughout the nation.¡§


Dr. Cyril Bennett, a river fly expert with the John Spedan Lewis Trust for the Advancement of Natural Sciences, and member of the Riverfly Interest Group says, ¡§the decline may not be one single problem across the whole country.  It may be many local problems in a lot of places.¡¨ 


Paul Knight adds, ¡§We must do everything we can to reverse this parlous situation.  The stark equation is:  no fly life on the river equals no life in the river.  It¡¦s that simple.  The survival of fish, and ultimately, all other water-dependent wildlife, relies on an abundance of river flies heralding a healthy aquatic environment.¡¨ 




Note to Editors:  River Fly Photos available

Carry on includes: 

„h   Why the mixed messages about the state of the country¡¦s rivers?

„h   What the Government needs to do to help our river flies

„h   Example of a local problem that led to fly life decline

„h   Regional breakdown of river fly results

„h   Highlights by species of fly

„h   Who completed the survey and with what aids

„h   Overall conclusions

„h   How to participate in the river fly survey

„h   Upcoming conference on river flies at the Natural History Museum


The Salmon & Trout Association (S&TA) is the senior game angling organization in the United Kingdom.  For over 100 years, the S&TA has had successful input to every major piece of fisheries related legislation. We represent 15,000 individual members and 100,000 club members, and have 52 branches spread across the UK.  Environmental issues are at the core of our work. 




Why the mixed messages about the state of the country¡¦s rivers?


While the 2003 Environment Agency annual river quality report, released last week, stated that the rivers of England and Wales have never been cleaner, we also learned at the same time, that a Government risk assessment of these same rivers showed that 95% would fail the European Union (EU) criteria for good ecological status under the Water Framework Directive (WFD).  Now, the Salmon & Trout Association National River Fly Survey reveals a dramatic decline in fly life abundance across the nation.


What the EU WFD criteria and the dramatic decline in fly life mean for the Government is that the monitoring tools currently used to assess river quality do not include the range of measurements required to assess ecological health. For example, fly life abundance is dependent on water quality and quantity.  The current criteria only looks at water quality, and ignores water quantity.


Another example of where the current methods fall short is in the biological monitoring of invertebrates, which, although an integral part of the monitoring process, may not highlight changes.  The invertebrate measurement was never designed to assess for particular species abundance, or dramatic declines in numbers, thus those declines may not be identified. If the number of river flies drops from 999 to 100, it counts as the same number of river flies within the scoring system, thus ecological impacts and declines are not recorded. 


Similarly, the biological sampling does not take place in the summer when pollutants and pesticides can have their greatest impact due, in part, to low water flows.  Also, the limited seasonality of the sampling does not deal with summer fly life changes. What this shortcoming means is that a toxic substance such as sheep dip, which can wipe out the abundance of river flies, but not alter the species present, may not be noted.  It can mean the cause of the decline (i.e. from pollution) is missed completely and goes unrecorded.


Additionally, the new EU WFD standards will require noting the effects of water abstraction on aquatic ecology.  Currently, water abstraction and water quality are not necessarily being jointly assessed, yet fly life depends on river flow and temperature. 


What the Government needs to do to help fly life

The Government needs to ensure adequate measurement of abundance in its biological surveys, set up an agreed test for anglers and others to measure fly life in the summer months, and set firm limits on water abstraction to protect river flows and ensure that invertebrates are not ¡¥dried out¡¦ from lack of water or pollution.


To set abstraction limits, the river flow, quality, and temperature requirements for river flies and the habitats (i.e. plants) they depend on needs to be better understood, and then serve as a strict limit to abstraction. When the Government knows and acts on what is required to sustain abundant fly life populations, it will enable tighter environmental protection.  Flies are small and vulnerable and to keep them alive we have to manage the whole aquatic ecosystem.


Example of weakness in current water quality measuring system: local problem of fly life decline

Dr Cyril Bennett provides an example, ¡§On one stretch of the River Wey, the fly life numbers have been low for 15 years.  We discovered the cause was insecticides entering the sewage treatment system, and being discharged into the river in the summer months.  The insecticides killed most of the freshwater invertebrates for 10-15 miles down the river, dramatically reducing their abundance, or knocking some out completely. But, the pollution incidents were unknown to the authorities and going unrecorded.  Anglers were the ones who initially noticed the problem.  Now in collaboration with the water company and the Environment Agency, we are monitoring the situation.  There are passive monitoring systems in the sewage system to note where insecticides enter the system, to find the source and press charges as necessary.  Anglers continue to monitor the river by measuring the abundance of river flies.¡¨


Regional breakdown of results for the S&TA National River Fly Survey

The Yorkshire region exhibited much less of a decline up until 1999, and a higher than average final level of abundance of 44 for 2000 and 2001 – however, it finished the period in decline when other regions were recovering.

Northumbria region suffered a very fast decline through the ¡¥70s,¡¦80s and early ¡¥90s.  Overall, it has half the average abundance level of other regions at an abundance score of 13, and showed no recovery in 2001 and 2002.

The North West region has not seen good numbers of fly since the 1960s, and reached a low point of abundance at a score of 27 in 1998, recovering, however, to 36 in 2001, slightly above average. 

Scotland showed a distinct improvement in 2000 and 2001 from a very low level — fly abundance fell much later, but very sharply from a score of 75 as late as the 1980s, to 17 in the late 1990s.  Encouragingly, a dramatic recovery to a score of 38 is reported by 2001.

Welsh respondents reported a sharp decline through the 1980s and 1990s to a level of abundance over the millennium period that equals the average of other regions.  There was an improvement to a score of 37 in 2000, which unfortunately fell back to 27 in 2001 (this may have been due to sheep dip problems).

Seven Trent region has been recovering slowly from a score of 32 in the mid-1990s reached after a comparatively late, but very steep decline from 59 in the early part of the last decade — and was by 2001 at a score of 41, somewhat above average and improving.

Southern region suffered a dramatic decline in the early and mid-1990s from an abundance score of 79 in the 1980s to a score of around 27 in 1998, but was steady at that level over the millennium.

(Reporting numbers in other regions were too few to make commentary possible).


Highlights by species of fly

Small upwings generally, as in the chalk stream survey, have been suffering slightly more than average, crossing the millennium with a score of 27 compared with that shown above for fly in general of 31.


Within the small upwings category, Blue Winged Olive were still falling nationally in 2000 and 2001, and had reached an abundance score of 25.  The Iron Blue was showing a very slight improvement in these recent years, from a score of 13 to a score of 16.  The March Brown is now at very low levels.  It was common in the Sixties, but has declined to the low teens of abundance in the 1990s and subsisted in 2001 at a score of 13 having hit a low point of 11.  The Olive Upright had an early decline that brought it down to an abundance score of 35 by the 1980s, from which it has slowly subsided to 22 in 2001.


Mayfly (Ephemera, Danica, etc) has exhibited no real decline at all on a national basis, and has a higher average abundance score than small upwings generally, steady at between 32 and 34 since the 1980s.  It’s long lived nymph relies on silt and probably does well as a result of the agrarian change we have seen over the period in question which results in greater winter runoff.

Sedges have had less of a decline than small upwings, and also enjoy somewhat higher abundance levels across the country at around 35 to 37 in recent years.

Stoneflies suffered an earlier decline than most river flies, starting in the 1970s and completed their decline by the 1980s.  Abundance scores have been steady at about 25 to 27 since then.


Who completed the survey and with what aids

About half our respondents were able to rely on written records in completing the questionnaire.  As in the chalk stream survey, those with written records are in close agreement with those without, over the final two to three years of the period reported — but before that, they record rather better hatches than those without written records, with a steeper decline following.  In the case of respondents without written records, to a degree rose tinted nostalgia tells them of a sharper decline over past decades than probably actually occurred, if as seems sensible the reports of those with written records are to be accorded greater credibility. The encouraging conclusion from this is that when the survey moves next year to incremental single-season, current-year reporting, memory reporters are likely to be as good as those writing down the fly that they see.


The average number of days fished by our 182 respondents was 21 days, with 3822 days in total for 2001. More than average those on the riverbank were more likely to report good hatches, which seems sensible, as their more frequent visits would be more likely to coincide with good hatches coming off the water.  Over half the questionnaire respondents were river keepers, riparian owners, or club officials.


Overall conclusions

The river fly decline is revealed as a national problem and not just one of the chalk streams.  This is not surprising given the well-evidenced declines in terrestrial insects extending across the country as a whole, with their damaging impact upon numbers of insect eating birds and other wildlife.  There is no doubt that a combination of climate change and both diffuse and specific pollution is largely to blame, aggravated in the case of river flies by extremes of flow.  The Government and its agencies are recognising the seriousness of these problems and beginning to take appropriate actions, however, the willingness to ensure adequate investment to overcome the problems is perhaps still in doubt.  Meanwhile, we have a lot to learn as river managers about how to help our fly back to higher abundance levels.


How to participate?

Anglers wishing to partake in the S&TA Fly Life Survey can access the form on the S&TA web site at, or call S&TA HQ on 020 7283 5838.


Upcoming conference on river flies at the Natural History Museum

Thursday 25 November provides an opportunity to bring together those with an interest in river flies to work together towards solutions.  For futher information and registration forms please contact Bridget Peacock via email:,

tel: 0207 942 5932