Millions of critically endangered eels have indeed been exported from Britain to Russia this year, but this is not “bonkers”, as Andrew Kerr of the Sustainable Eel Group claims, as it is a project to conserve the species that was in development before the invasion of Ukraine by Russia (UK export of millions of endangered eels to Russia attacked as ‘bonkers’, 22 October).

Juvenile eels are transported from the Severn estuary to the Vistula and Curonian lagoons, which Russia shares with Poland and Lithuania. Unlike the River Severn, the lagoons are pristine habitats for eels, with unrestricted migratory pathways to the Baltic and thence to their breeding grounds in the Sargasso Sea.

In contrast, the wetland eel habitat of the Severn has been destroyed by modern agriculture, industry, housing estates and pollution. What little remains is inaccessible to the eels because of the human-made barriers to migration, including locks and weirs used by pleasure boats, and flood defences. Therefore, most of the eels that swim into the Severn estuary perish.