Eeliad

"Considering these points, I perceived that if the problem were to be solved in anything like a satisfactory manner it would be necessary to ascertain, not only where the youngest larvae were to be found, but also where they were not."

Johannes Schmidt, 1922.

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What has the eeliad project achieved?

The eeliad project was a four year EU-funded project (2008 to 2012) with the objective to improve the understanding of the marine ecology and biology of European eels. Field studies were undertaken to map and characterise the ocean migratory behaviour of eel.


Products and outcomes

Over 500 electronic tags were attached or implanted to eels to record data as they migrated west to the putative spawning area. More than 150 datasets have been retrieved that have mapped the migration more than 3000km and for periods of more than 6 months, and have yielded a database of behavioural data that is unequalled on any anguilllid species elsewhere in the world. Characteristic daily patterns of behaviour have been recorded that appear to be related to antipredator behaviour, thermal regulation and navigation. Predation was a significant cause of mortality of migrating silver eels, and occurred in both coastal and oceanic environments.

Spawning ecology and effects on population structure were tested using genetic, otolith microchemistry, and modelling methods. Critically, the analyses were undertaken on eel larvae collected in the Sargasso Sea as well as on glass eels collected from the coastline of Europe and north Africa. The results reaffirmed that eels are a rare but classical example of a panmictic species. On this basis, modelling of larval drift from the Sargasso Sea showed that climatic and oceanographic changes over the last 50 years do not appear to be responsible for the sharp decline in eel recruitment observed over the last 30 years, but was unable to resolve ongoing uncertainty regarding the duration of the larval migration.

The influence of estuarine factors affecting glass eel runs was investigated using a hydroclimatic modelling approach. The model was validated using tidal and light data, and subsequently used to assess glass eel fisheries scenarios.

A large-scale sampling programme was undertaken to collect comprehensive data on the health and quality of eels, resulting in the creation of a new EU silver eel quality database. Assessment of the data show that there are regional differences in parasite load, contaminant levels, fat content and breeding potential of silver eels that are related to catchment characteristics and biogeography. At the catchment level, regional differences occur in stock status, spawner escapement and anthropogenic mortality. Modelling of catchment characteristics and these parameters provided new tools that have the potential for operationalisation within national eel management plans.

Please visit the news webpage for a list of project findings and outcomes. 


Communication and Outreach

Considerable efforts were undertaken to integrate with stakeholders and disseminate information about the need for improved management of eel stocks, the purpose of the project and the results that have emerged from it.

At present, 19 papers resulting from the project have been published, with a predicted total of more than 50 within six years of project commencement. More than 50 presentations were given at national or international scientific conferences, and more than 20 workshops or discussion forums have been attended to contribute to discussions on eel biology and management.

The work in the eeliad project has been communicated to ICES. The project has featured on national and international television, in national and international press, and online. The work conducted within the project can genuinely be said to have reached an international audience numbering in the millions.

In total, the activities conducted within the eeliad project have resulted in significant advancement of knowledge, the development of advice and tools that will contribute to sustainable eel management, and global dissemination of project results that enhance the reputation of European-funded science.

line drawing of an eel