River restoration project flying high as anglers prepare to reintroduce lost invertebrates

A female blue-winged olive. Copyright Stuart Crofts.

A female blue-winged olive. Copyright Stuart Crofts. - Credit: Archant

Two anglers dedicated to the restoration of the River Lark in west Suffolk have together brought nine million insect eggs to the site.

8m to 9m blue-winged olive eggs collected by Dr Cyril Bennett for release on the River Lark in order

8m to 9m blue-winged olive eggs collected by Dr Cyril Bennett for release on the River Lark in order to trigger the birth of a new generation of the species. Copyright Ian Hawkins. - Credit: Archant

Ian Hawkins, honorary fishery officer for Bury St Edmunds Trout club, and Glenn Smithson have transported a chalkstream species called blue-winged olives, or Serratella Ignita, to Suffolk as part of a decade-long project to restore the once-prized river to its former glory.

According to Salmon & Trout Conservation UK, the loss of blue winged olives and other important aquatic invertebrate species due to pollution problems are an increasing problem on many rivers and chalkstreams.

The invertebrates play a crucial role in the food chain for fish and other wildlife.

After years of concerted effort by the Bury St Edmunds Trout Club and the Lark Angling Preservation Society (LAPS), the River Lark “is turning the corner from decline to recovery”, according to Salmon & Trout Conservation UK, which is carrying out a national riverfly census.

Ian Hawkins, honorary fishery officer for Bury St Edmunds Trout Club.

Ian Hawkins, honorary fishery officer for Bury St Edmunds Trout Club. - Credit: Archant

The blue-winged olive was one of the species lost during a pollution event in 2011 which saw the leakage of 5,000 gallons of oil into the river, the national group said.

Ian and Glenn, who picked up the eggs when they attended a riverfly invertebrate course in Hampshire, are among a group of volunteers who have been striving over the last decade to transform a straight, dredged channel, which was converted into a canal in the 19th Century, into a sinuous, lively river bustling with wildlife.

Most Read

The river now boasts a wild and self-sustaining population of brown trout, as well as benefiting other wildlife including damselflies, ground nesting birds, kingfishers, owls and water voles.

The results of the restoration project are being recorded in the riverfly census, which monitors the rise and fall of rivers across the UK by measuring the loss or increase of river invertebrates, whose presence is seen as crucial in identifying the health of a river.

A view of the River Lark. Copyright Ian Hawkins.

A view of the River Lark. Copyright Ian Hawkins. - Credit: Archant

Paul Knight, chief executive of Salmon & Trout Conservation UK, said: “This is a wonderful example of what can be achieved by ‘citizen science’. Ian Hawkins, Glen Smithson and many others have devoted huge amounts of time and effort into restoring the River Lark, including attending our special river invertebrate identification course, making them qualified to add important scientific data to our Riverfly Census.

“Our 2015 census results, reported earlier this year, have highlighted that many of our iconic rivers are suffering from serious pollution problems because of human pressure from a variety of sources.

“However, the River Lark project sheds a beacon of light and demonstrates that individual groups can really make a difference. The volunteers on the Lark should be congratulated for their relentless determination to succeed against all odds.”

Ian said: “Blue-winged olives are an important part of the aquatic food chain and we wanted to put them back. Following the creation of good habitats, we received a special licence through Natural England for this re-introduction and will be following IUCN guidelines for Translocation of a Species.

“We were delighted that Dr Cyril Bennet and Salisbury and District Angling Club on their section of the River Avon and Mr Peter Nash and the Chisenbury Syndicate collected 9 million eggs for us. These will be kept in special conditions until March when they will be released into the river and will hopefully trigger the birth of a new generation of blue-winged olives on the River Lark in July/August next year. This will really be the icing on the cake.”

Ian paid tribute to part of the early work on the project carried out by the late Dr Nigel Holmes.

“In 2013 the late Dr Nigel Holmes carried out a fantastic “dig & dump” project with the gravel bed, altering the geomorphology of the river so that it would be self-maintaining and would begin to “heal itself” with new pool and riffle sequences, gravel berms to narrow it and speed up flow and clean away the silt accumulated over many years through over widening and dredging, not to mention the canalisation of the 18th and 19th centuries,” he said.

“We are currently trying to raise funding to introduce several hundred tonnes of gravels to complete the last works on our club section.”

The volunteers have ensured the sympathetic planting of the river, using a wide range of native water marginal species sought for their added colour and nectar provision to attract insects, and especially for the damsels and dragonfly for which the area has been designated a Site of Special Scientific Interest (SSSI), he said.

“It is only now that this work is showing an amazing improvement in the river and silt is being cleared to allow the gravel bed to be visible for the first time probably in hundreds of years.”