The research examines the lifecycle of the twaite shad, which each spring begin the migration to their natural spawning ground of the Severn's upper reaches, only to be prevented by man-made structures such as weirs. Over the next four weeks teams will be stationed at Upper Lode near Tewkesbury counting the number of twaite shad who make it over the weir before being halted at the larger Diglis Weir in Worcester.
The information gathered will be vital for Unlocking the Severn which aims to restore the shads' access to 158 miles of the River Severn, the nation's longest river, north of Worcester by providing fish passes at a series of weirs that currently the fish cannot swim over or around.
The £19.7 million project is one of the largest of its kind ever attempted in Europe and includes £10.8 million of funding from the Heritage Lottery Fund (HLF) – using National Lottery players' money – and £6 million from the European Union LIFE programme. Unlocking the Severn is being run by the Canal & River Trust, Severn Rivers Trust, Environment Agency and Natural England.
In order to learn more about the remaining small population of shad, particularly the conditions they need to prosper, the teams together with volunteers will spend time watching and counting twaite shad swimming over Upper Lode weir. A suite of remote monitoring techniques enable monitoring all day, every day. This includes cameras, counter plates triggered when a shad passes upstream, as well as the use of an acoustic beam giving an image similar to the ultrasound of a baby in the womb.
Acoustic tracking tags fixed to over 80 shad will also show how they migrate up the river, what habitats they use, and how barriers delay them. This is all crucial to understanding how to create the best access routes for the fish.
Environment Agency Fisheries Monitoring Specialist, Charles Crundwell said: “Last year our results suggested we had at least 7,000 twaite shad migrate beyond Tewkesbury to reproduce in the lower reaches of the river Severn. This is a tiny fraction of the documented run before the navigation weirs were constructed in the 19th Century but is an encouraging number to re-establish the fish to their historic spawning grounds once the project completes.
“The twaite shad, is now a rare fish, only breeding in four rivers in the UK, but our work on the Unlocking the Severn project will both protect and increase the number of twaite shad returning but also open up the river for all fish species. This will benefit wildlife, communities, tourists and anglers.”
Jason Leach, Canal & River Trust programme director, says: “This project has been in the waiting for centuries. Hundreds of years ago shad were a staple food in the court of Henry III, but they became extinct in the upper reaches of the Severn following the installation of the locks and weirs that powered the Industrial Revolution in the 1700s. We've now reached a crucial stage in our work to bring them back. The scientists and volunteers researching the journey of the shad will give us the insight we need into the potential population so we can help them return to their natural spawning ground.”
Unlocking the Severn has already seen enhancements completed on Powick Weir on the River Teme. Engineering work is underway at Diglis and Bevere weirs, with a further two weirs at Holt and Lincomb to be completed over the next three years.
In addition, Unlocking the Severn has ambitious heritage, education and science programmes that aim to reconnect eight million people with the River. This includes working with community groups, over 6000 school children, and creating opportunities for hundreds of volunteers. The project aims to have the knock-on effect of attracting more visitors to the region and boosting the local tourist economy. Recreational fishing on the River Severn currently contributes £13.5 million per year to the local economy, and it is hoped that the project will boost this by a further £4 millon.
