When people think about the world’s most threatened animals, it’s unlikely that Anguillid (freshwater) eels spring to mind. In Europe, freshwater eels are one of our least appreciated but most critically endangered species, having declined by around 95% since the 1980s. Unlike most people, as a freshwater ecologist, I spend a lot of time thinking about animals like the freshwater eel because globally, all freshwater species are facing considerable threats. In fact, freshwater species are declining at double the rate of terrestrial or marine biodiversity and for me, freshwater eels are a bit of a poster-fish for all freshwater biodiversity.
Anguillid eels have life cycles more complex and mysterious than any other species I can think of. They are catadromous; spending most of their lives in freshwaters but returning to the ocean to spawn (a return journey of around ten thousand kilometres). Eels can live for many years, especially females – the oldest known European eel was over 100 years old. Despite being long-lived they only spawn once in their lives. The marine phase of an eel’s life remains much of a mystery – we do not know what eels do during their time in the oceans or exactly where they spawn. An exciting new project is radio-tracking eels to attempt to answer the mysteries that have eluded scientists since the time of Aristotle.
There are multiple threats facing European eels, and to different extents, all other species of freshwater eel around the world. Threats include: climate change, human infrastructure and development, disease, water pollution, habitat loss, over-exploitation and mortality caused by pumps and hydropower dams. Furthermore, as the illegal trade in European, American and Japanese eel is stopped, eels in other parts of the world where protections are less, may be at increased risk.
A critical step in the conservation of eels is ensuring people care about them and with this in mind, during a recent trip to Ambon, Indonesia, I visited Larike village, home to a population of Marbled eels, Anguilla marmorata, to find out why they are important to the local community. I met with Hafes Lauspa who is the King (or Raja) of Larike village. Hafes has taken the unusual step of protecting the eels in his village, meaning that no one can fish for them or harm them in anyway. Hafes hopes that by protecting the eels, the eels will attract tourism to the village and generate income.