INDAGA

Context

The European eel (Anguilla anguilla) is in a critical situation both globally and in the Basque Autonomous Community. After more than a decade of implementing the Eel Management Plan, there is still no evidence of recovery: recruitment remains at very low levels and, in the Basque Country, silver eel biomass stands at around 10% of pristine biomass, well below the 40% escapement target established for the recovery of the species.

This situation persists despite improvements in water quality, habitat restoration and river connectivity, highlighting the need for a more accurate assessment of the effectiveness of the measures implemented.

With the post-evaluation of the Eel Management Plan scheduled for June 2027, INDAGA will strengthen the available scientific and technical evidence by updating information on electrofishing surveys, migration barriers and the characteristics of the river network, while developing new diagnostic and assessment tools.

AZTI brings to the project its extensive experience in the study of the European eel and its active participation in the ICES Working Group on Eels (WGEEL).

Objectives

INDAGA aims to generate the scientific and technical basis required to review and update the Eel Management Plan in the Basque Autonomous Community, assessing the effectiveness of the measures implemented and identifying the factors that may be limiting the recovery of the species.

To achieve this, the project will:

• Integrate and harmonise all available eel electrofishing data from 1982 to 2026 into a single database.
• Characterise the current distribution of the species across the river network of the Basque Autonomous Community, incorporating information on barriers to migration.
• Develop a spatially explicit model to estimate eel abundance at river-section level.
• Assess the degree of implementation and effectiveness of the management measures applied between 2008 and 2023.
• Design SMART indicators to objectively measure the effectiveness of the measures implemented.
• Propose adjustments to existing measures or new management measures to support the post-evaluation of the Plan in 2027.

Expected impact

INDAGA will provide the Basque Government with a quantitative, spatially explicit and reproducible tool for monitoring and assessing European eel populations in the Basque Autonomous Community, supported by a harmonised and updated historical database.

The spatial model and SMART indicator system will support progress towards evidence-based adaptive management, enabling management measures to be periodically reviewed in light of observed results.

The project will also help target resources for European eel recovery more effectively and provide a robust technical basis for the post-evaluation and update of the Eel Management Plan scheduled for June 2027.

Funding