Irish researchers from Inland Fisheries Ireland have contributed to EU-funded research that has helped solve the little known oceanic migration and behaviour of the European eel. An international team led by the Centre for Environment, Fisheries and Aquaculture Science (Cefas), tracked more than 700 eels on their annual migration from Europe to the Sargasso Sea. Over 200 tags were recovered, allowing scientists to map more than 5,000 kilometres of the migration route.

IFI Eel migration routes to the Sargasso Sea copy

Eel migration routes to the Sargasso Sea

Between 2006-2012, eels released by scientists from Sweden, France, Germany and Ireland (Shannon, Corrib, Erne and Burrishoole catchments) were mapped from Europe to the Azores region – approximately half the distance to where by spawn in the Sargasso Sea. Forty-four eels fixed with pop-up satellite tags were successfully tracked from Ireland; one tag registered a journey of 6,982 kilometres and 273 days at sea.

Dr Cathal Gallager, Head of Research and Development, IFI, says the life cycle and mitgration of the eel continues to puzzle scientists given they are born and spawn in remote areas of the ocean.

“While previously it was understood that eels travelled to the Sargasso Sea to spawn, we did not understand the duration and the dangers our eels are exposed to during this migration. We now know more also about their behaviour patterns as all eels exhibited diel vertical migrations (swimming through deeper water during the day and moving closer to the surface at night). This understanding of eel biology will help manage and conserve their population across Europe and beyond more effectively.”

‘Empirical observations of the spawning migration of European eels:The long and dangerous road to the Sargasso Sea’ – Science Advances