Anguilla anguilla (Linnaeus 1758), European eel (Anguillidae)

Author: Ronald Fricke, Germany

1. Description of the habitat/autecology of the species

The European eel, Anguilla anguilla, has an unusual life history. It is a species that migrates catadromously and spawns in the tropical Western Atlantic in the Sargasso Sea. European eel larvae follow the Gulf Stream and arrive in Europe as transparent glass eels. The migration towards Europe takes from 7-8 months to 3 years. Arriving the western seaboard of Europe and North Africa the glass eel gradually gets pigmented and changes into the juvenile yellow eel stage.  Some eels stay in coastal areas while others migrates into the Baltic Sea and into streams and rivers. European eels are also regularly collected upon arrival and introduced into many streams and rivers. Upon becoming sexually mature the eel transform and as a silver eel starts migrating back to the Sargasso Sea where it dies after spawning. European eel is relatively long-lived; the generation time is 12 years in the North Sea drainages and continental Europe, but 13-18 in freshwater and 10-13 in the Baltic Sea (Dekker, 2003; ICES, 2006; Wickström, 2006). Maximum total length 50 cm (male), 133 cm (female); maximum total weight 4-6 kg (Dekker et al 1998); maximum individual age 85 years, usually 15-20 years.

2. Distribution (past and present)

This species was originally distributed throughout the Baltic Sea in the HELCOM area including adjacent freshwater rivers, streams, and lakes. The European eel is considered to be one joint panmictic population (Dannewitz et al., 2005) but there are considerable geographical differences in recruitment patterns, population dynamics (i.e. growth rates, sex ratios, rates of survival, and productivity of the habitat) and consequently in fisheries (Dekker, 2003, 2004; ICES, 2006).

3. Importance (sub-regional, Baltic Sea-wide, global)

European eel is of local importance in the HELCOM area. It is a keystone species since it used to be dominant in interstitial habitats, and several bird species use eel as a food source.

4. Status of threat/decline

European glass eels arriving in Europe have declined severely (see below), and European eel is considered as threatened throughout its range. If the massive decline continues (and there is no indication of an improvement of the situation), European eel is expected to be extinct within 2 generations. Therefore, it is considered critically endangered (CR) in Germany and Sweden. European eel is facing an extremely high risk of extinction in the wild according to IUCN criteria, and is therefore classified as critically endangered (CR) also in the HELCOM area, and is a HELCOM high priority species (HELCOM, 2007).

It should be noted that understanding the severe situation of the European eel, the European Inland Fisheries Advisory Commission (EIFAC) and the Food and Agriculture Organisation of the United Nations (FAO), as well as ICES, have recently called for urgent action to protect this highly threatened species. The EU council of ministers agreed on an Eel management plan that was implemented in 2007. The goal is that 40% of the Silver eel will return to spawn in the Sargasso Seat and every Member State must establish a management plan and take action to fulfill the goal. Furthermore, European eel is suggested to be listed under CITES Appendix II in COP 14 June 2007.

5. Threat/decline factors

Though European eel is still relatively abundant in many areas (due to introduction and a still significant recruitment – there is a time lag of more than 10 years between arriving glass eels and spawning adults), it is affected by severe threats. All life stages of European eel, including newly arriving glass eels, growing yellow eel and maturing migrating silver eel, are commercially heavily exploited, though catches in many areas have considerably decreased. Another severe problem is that most eels never reach the ocean on their spawning migration, as they have to pass turbines and are often injured or killed. European eels are also affected by eutrophication and pollution and chemical contamination can affect spawning success although an effect on the stock level has not been demonstrated (ICES 2006). In recent years, eels have been massively affected by the Anguillicola parasite; this may reflect general health problems.

For European eel, a massive decline of glass larvae supply coming into European waters was observed during the last 25 years. It has been estimated that only 1-5 % of the former numbers of recruits arrive in Europe today (Dekker, 2004; ICES, 2006; Wickström, 2006). There are no signs of improved recruitment since the worst year of 2001. That means that the stock will continue to decrease for at least one generation. The severity of the situation of European eel is often not realized by fishermen, fishery managers and even scientists (Wickström, 2006). The main problem is the long time lag between recruitment (glass eel) and maturity (silver eels).

In Sweden, a decline of 90 % in European eel recruitment has been observed during the past 60 years (3 generations) or often even in a shorter time. Those recruitment series are derived from the amounts of ascending young eels in a series of Swedish rivers (Wickström, 2006).

6. Options for improvement

There is an immediate need to reduce the fishing pressure on all life stages of eel, including the fishing of European glass eel (outside the HELCOM area). In rivers and streams adjacent to HELCOM area, fish passes should be constructed that gives safe passage for migrating eels and prevents mortality of eels in turbines. The heavy metal content and chemical pollution of freshwater habitats must be reduced. Member states of HELCOM should participate in European eel conservation programmes of international institutions. Anguilla anguilla should be added to Annex V of the EU Habitats Directive.

The EU council of ministers have agreed on an Eel management plan that was implemented in 2007. The recovery plan gives a framework for the protection and sustainable use of eel stocks in EU maritime waters, in coastal lagoons and estuarines and in river drainage basins. EU Members States are to identify and define the individual river basins that constitute natural habitats for the European eel and prepare a long term eel management plan for each eel river basin. The objective is to permit the escapement of at least 40 % of the biomass of silver eel into the sea (relative to the biomass without anthropogenic mortalities). All fishery operated by EU Member States in maritime waters that catches eel must reduce catches at least 50 % relative to the average catch from 2004-2006. Furthermore each Member State should establish authorisation lists of vessels, fishermen and sales and marketing bodies.

7. Additional notes

European eel is considered to be highly sensitive due to the threats explained above. Under HELCOM priority assessment, European eel classifies as an amber species. The application of the decline criterion (amber species with a significant or severe decline) leads under OSPAR/HELCOM criteria to a high priority classification.

8. References

 

Dannewitz, J., Maes, G.E., Johansson, L., Wickström, H., Volchaert, F.A.M., and Järvi, T. (2005). Panmixia in the European eel: a matter of time? Proc. Royal Society of London, 272: 1129-1137.

Dekker W. 2003. On the distribution of European eel (Anguilla anguilla) and its fisheries. Canadian Journal of Fisheries and Aquatic Sciences, 60(7): 787-799.

Dekker W. 2004. Slipping through our hands. Population dynamics of the European eel. Amsterdam (Universiteit van Amsterdam), Akademisch Proefschrift, 188 pp. Available in: http://www.diadfish.org/doc/these%202004/Dekker-Thesis-eel.pdf

Dekker, W.; van Os B.; van Willigen, J. A. (1998). Minimal and maximal size of eel. Bulletin Français de la Pêche et de Pisciculture, Conseil Supérieur de la Pêche, Paris (France) 349: 195-197.

HELCOM 2007. HELCOM Red list of threatened and declining species of lampreys and fish of the Baltic Sea. Baltic Sea Environmental Proceedings, No. 109, 40 pp.

ICES (2006). Report of the 2006 session of the joint EIFAC/ICES Working Group on Eels,

ICES CM 2006/ACFM:16. EIFAC Occasional Paper No. 38: 352pp.

Wickström, H. 2006. Ålen. In Kustfiske och fiskevård : en bok om ekologisk fiskevård på kusten. Lindgren B. & Carlstarnd H. (Eds). Sportfiskarna. Göteborg.

www.rktl.fi/english/fish/fish_atlas/eel/