IUCN Red List Assessment
Red List Category
Red List Criteria
The species has undergone a sharp decline in recruitment, yield and stock, which will continue into the future.
The recruitment of glass eels has declined from 1980, and since 2000 is at an historical low at just 1-5% of the pre-1980 levels, showing a 95 to 99% decline. This recent decline in recruitment will translate into a future decline in adult stock, at least for the coming two decades (ICES 2006).
Yield and stock abundance have declined since the 1960s. As the recruitment rate is so low the population is continuing to decline as older eels disappear from the stock. According to the FAO global catch landings (which cannot be directly linked to population due to stocking and harvest effort, though scientific evidence supports this decline) show that in 2005 only 4,855 tonnes were caught, a decline of 76% since a harvest peak in 1968, 37 years earlier (three generations of the species is estimated to be 60 years).
Even though the exact cause of the decline in recruitment is not known the species has many threats. The level of harvest of the species according to the International Council for the Exploration of the Seas (2006) is currently unsustainable. A nematode parasite (Anguillicola crassus) from introduced eels from Japan is suspected to impact the ability of the eels to reach the spawning grounds. Dams (for hydropower) are also a threat to the species by blocking migration routes and by causing high mortality rates as downstream migrating eels are killed by turbines. Pollution, loss of wetlands and climate change are also potential threats to the species.
Although a reliable population decline in mature individuals is not known, it is inferred that there has been a decline of over 80% in the past three generations (60 years) based on the massive decline in recruitment (95% in 24 years) which is supported by the decline in catch landings of 76% between 1968 and 2005 (37 years). This decline is likely to continue. Full and immediate protection is required and ICES have recommended that a recovery plan be developed for the whole stock on an urgent basis.
Action has already been taken at the international level, but the impacts of this will not be detected for many years. In 2007, CITES listed the species in Appendix II (this came into force in March 2009) and will require exporting states to have an export permit which can only be issued if the export will not be detrimental to the survival of the species. Also the European Commission has issued a Regulation requiring all member states to produce eel management plans, amongst other measures. These management plans were required to be in place by July 2009 and have the objective to permit the escapement to the sea of at least 40% of the silver eel biomass [relative to the estimated stock levels in the absence of human influences].
- 2006Not Evaluated(IUCN 2006)