IUCN, International Union for Conservation of Nature, is the world’s oldest and largest global environmental organization. Over 185 countries work together inside IUCN, IUCN helps the world find pragmatic solutions to our most pressing environmental and developmental challenges.
Although determining changes in the international stock in eels is difficult due to limited data and the poor understanding of the relationship between recruitment, freshwater populations, and escapement. Not only is there a huge time lag between the recruitment of glass eels to fresh and brackish water and the subsequent escapement of silver eels, but given that A. anguilla are panmictic, escapement from one area does not translate directly into returning larval recruitment at the same locality. Indeed for all intents and purposes it is assumed that practically nothing is known about the dynamics of the oceanic phase of A. anguilla (ICES WGEEL 2013). It has been proposed that due to the relatively short time-span between spawning and recruitment that the latter is a good indicator of the past spawning stock that produced the juvenile cohort; this will depend, to an extent, on the significance of oceanic factors on larval transport. Assessment of these datasets using the IUCN Red List Categories and Criteria took into account to list the European Eel as critically endangered. Given the relative lack of understanding of the threats IUCN has attempted to quantify this by using the IUCN ‘Threat Classification Scheme’, however, this is by no means definitive. Again a precautionary approach is adopted through lack of data on populations.