The River Thames is one of the most important migration routes and wildlife corridors in the UK. It is home to more than 125 species of fish, many of them migrating in and out of the river as part of their life cycle. One of the most iconic migratory fish species, the European eel, grows and matures in European rivers such as the River Thames and its tributaries, before making its epic transatlantic journey back to the Sargasso Sea where it spawns.
However, eels and other fish often face a big problem. Man-made structures in our rivers can add significant difficulties to their movement. Barriers such as locks, weirs and sluices can either physically block their paths or divert water in such a way that crossing the barrier is exhausting or even impossible.
The Thames Estuary Partnership (TEP) is working together with other organisations to find a solution to this issue. The Greater Thames Estuary Fish Migration Roadmap project focuses on a ‘whole system’ approach to identify the locations of barriers, passes and river habitats, so that for the first time we can visualise every step of a fish’s migration from sea to river and back again.
As its name suggests, the Roadmap takes its inspiration from road networks. By considering rivers as migratory routes (identified as 'Highways', 'A-roads' and 'B-roads'), the Roadmap visualises barrier locations and river network connectivity in entire catchments. This helps to give a good idea of where fish species are most likely to encounter barriers and which river sections need to be opened up. The Roadmap also provides a blueprint for community-led river restoration action. Its name also takes on a second meaning: the project is a roadmap of strategic steps, linking into other initiatives such as land development and flood management plans.
The first three phases of the project largely focused on collating data. However, Wanda Bodnar, TEP’s Project Officer in charge of the Roadmap, quickly discovered that the barrier datasets available were scattered and sometimes conflicting. Bringing all these data together and putting it into a user-friendly online format was not a straightforward task but the Roadmap is now available and will continue to be built upon. You can find it here.
Going forward, TEP hopes that the Roadmap can be used by community groups such as Catchment Partnerships in habitat enhancement and river restoration works; by Local Authorities in land planning and flood management schemes. The project also plans to encompass more rivers, as well as incorporating fish survey data, to understand the distribution of species. There are also exciting plans to use the Roadmap as an education tool to communicate the issues and opportunities surrounding habitat fragmentation and fish migration to members of the public. Together these measures should make the journeys undertaken by eels and other migratory fish just that bit easier!
For more information and relevant resources, check out the Fish Migration Roadmap project page. The presentation summarising the project to date is also available via the project page.