Project Overview
What? European eel (Anguilla anguilla)
Why? European eels are one of the most endangered species in the UK
How? Working with partners to evaluate population trends and identify ways to aid migration
Where? Gannel Estuary, Cornwall, UK
When? Since 2022
Our mission: Wild Planet Trust is committed to supporting the migration routes of European eels
A 95% population decline
European eels were once widespread, but they are now one of the most endangered species in the UK. They are listed as Critically Endangered on the International Union for Conservation of Nature (IUCN) Red List of threatened species, due to a 95% population decline in the last 40 years.
The main threats to European eels are overfishing, along with habitat loss and degradation. Unfortunately, the construction of dams and other man-made structures create barriers to the eels’ migration upstream.
A mysterious lifecycle
European eels are one of the most elusive species, with a lifecycle that continues to mystify scientists.
Eels live in freshwater, but converge in huge numbers in the Sargasso Sea – in the Atlantic Ocean – to spawn. The exact location of their spawning site is still unknown.
Fertile eggs float on oceanic currents, and then hatch into larva (leptocephali), which look a bit like transparent leaves. The larvae travel to European waters using currents on a journey that takes up to two years.
Once they reach the coast, eels change into a glass eel stage, where they are still small and transparent, but look more like eels. As they use the tides to carry themselves upstream into freshwater, the eels begin to pigment and become elvers. Their sex is only determined once they reach fresh water, though nobody knows quite how that happens.
Eels will then live in freshwater for between five and 20 years, before heading back to the sea. They change colour, their eyes grow up to 10 times their original size, and they also gain muscle mass, thicker skin and wider fins, to help them make the arduous journey back to the Sargasso Sea to spawn.
Working in partnership
Our team at Newquay Zoo has been collaborating with Newquay Marine Group, Cormac and the Environment Agency to try to evaluate the European eel population using the Gannel estuary and river catchment as part of their migration patterns, including the stream that runs through Newquay Zoo itself.
Early indications show that there are peak times for eel migrations, but that numbers are still lower than expected, considering that eels were once found in their hundreds in Newquay’s boating lake.
Newquay Marine Group has now successfully installed a mussel rope eel pass, which aids glass eels to move upstream.
In addition, we are in the planning stages of a collaborative project, working with Newquay Marine Group and University Centre Newquay, to monitor eel populations and barriers to migration through video recording methods and eel catches.
