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Anguilla anguilla

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA ACTINOPTERYGII ANGUILLIFORMES ANGUILLIDAE

Scientific Name: Anguilla anguilla
Species Authority: (Linnaeus, 1758)
Common Name/s:
English European eel
Taxonomic Notes: Other Anguilla species have occasionally been stocked in Europe, but none have established a self-sustaining population. Pure A. rostrata's (American Eel) have been recorded, but are very rare. DNA analysis is the best tool to distinguish between European Eels and other species, but also the length of glass eels can be used as A. anguilla are almost always more than 6 cm length, while all other species are less than 6 cm (W. Dekker pers. comm. 2007) and A. rostrata have fewer vertebrae than A. anguilla (102-112, usually 106-108, vs. 111-119, usually 114-116). Hybrids are known from Iceland (where eel stocks are small) where pure rostrata and anguilla exist.

Assessment Information [top]

Red List Category & Criteria: Critically Endangered A2bd+4bd ver 3.1
Year Published: 2010
Date Assessed: 2008-01-02
Assessor/s: Freyhof, J. & Kottelat, M.
Reviewer/s: Wickström, H. & Smith, K.
Justification:

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].

History:
2006 Not Evaluated (IUCN 2006)
2006 Not Evaluated

Geographic Range [top]

Range Description:

Anguilla anguilla is found in all European rivers draining to the Mediterranean, North and Baltic seas, in the Atlantic south to Canary Islands and parts of Mediterranean north Africa and Asia. It very rarely enters the White and Barents seas, but is recorded eastward to the Pechora River in northwest Russia. The species occurs in low abundance in the Black Sea where it migrates east to the Kuban drainage (occasional individuals reach the Volga drainage through canals), in northern Scandinavia and eastern Europe, but 'trap-and-transport' stocking is interfering with natural population numbers (W. Dekker pers. comm. 2007). Large parts of the population remain at sea particularly in the north western Atlantic and Mediterranean. It is also widely stocked in most inland waters of Europe. 

The species is thought to breed in the Sargasso Sea in the West Central Atlantic, migrating across the Atlantic from Europe.

Countries:
Native:
Albania; Algeria; Austria; Belarus; Belgium; Bosnia and Herzegovina; Bulgaria; Croatia; Cyprus; Czech Republic; Denmark; Egypt; Estonia; Faroe Islands; Finland; France; Germany; Gibraltar; Greece; Guernsey; Iceland; Ireland; Isle of Man; Italy; Jersey; Latvia; Lebanon; Libya; Lithuania; Luxembourg; Macedonia, the former Yugoslav Republic of; Moldova; Montenegro; Morocco; Netherlands; Norway; Poland; Portugal; Romania; Russian Federation; Serbia (Serbia); Slovakia; Slovenia; Spain; Sweden; Switzerland; Syrian Arab Republic; Tunisia; Turkey; Ukraine; United Kingdom
FAO Marine Fishing Areas:
Native:
Atlantic – eastern central; Atlantic – northeast; Atlantic – northwest; Atlantic – western central; Mediterranean and Black Sea
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Glass eels:
Since the early 1980s, a steady and almost continent wide decline of 90% has been observed in the recruitment of glass (juvenile) eels (Dekker 2003). According to an ICES and FAO report (2006) European Eel recruitment levels reached an historical low in 2001 of 1 to 2% of the pre-1980 level, this has not improved and is an indication that the reproduction is seriously impaired and that the stock is severely depleted. In recent years, no substantial recovery in recruitment has been observed (Dekker 2007). This recent decline in recruitment will translate into a future decline in adult stock, at least for the coming two decades (ICES 2006).

Yellow/silver eels:
Even though there is no analytical assessment of the state of the [continental] European Eel stock, all available information indicates that the stock is at an historical minimum in most of the distribution area and continues to decline (ICES and FAO 2006). Unfortunately, a total continental stock assessment cannot be made as it is hard to monitor, being scattered over millions of rivers, lakes, estuaries, etc. (Dekker 2000). However, even though catch effort can be variable and under reporting of landings is a serious problem in most European countries, trends in the reported catch data will to some extent reflect true changes in fishing yields. According to FAO global capture statistics (exploited at all stages of their freshwater life), capture peaked in 1968 with 20,278 tonnes, in 1975 this had dropped to 16,110 tonnes, in 1985 it was 12,665 tonnes, 1995 8,706 tonnes and the most recent available figure in 2005 was 5,059 tonnes a decline of 76% since the peak in 1968. This is supported by the possibly only long-term scientific data [from Lake Ijsselmeer in the Netherlands] where there has been a gradual decline since 1960 (Dekker 2004a). However, there is also evidence that in Norway catches seem to be stable over this period (ICES 2002). 

The overall population is continuing to decline as the older eels disappear from the stock and recruitment rate is so low and declining. Noting the longevity of the species, and the extremely depleted state, restoration of the stock is expected to take several generations from 60 to 200 years depending on the protection level (Astrom and Dekker 2007). Temporary increases (over 10-15 years) in abundance following the implementation of protective measures thus do not guarantee ultimate recovery, if not severely protecting the stock (W. Dekker pers. comm.).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: Habitat:
The species is found in all types of benthic habitats from small streams to shores of large rivers and lakes. Naturally it only occurs in water bodies that are connected to the sea; it is stocked elsewhere.

Biology:
The species is catadromous, living in fresh water but migrating to marine waters to breed. While its life in freshwaters are well understood, relatively little is known about its life history at sea. The spawning peaks at the beginning of March continuing until July, and the adults probably die after spawning. There are no concrete data about specific spawning, however, it is assumed that spawning takes place only in an elliptic zone, about 2,000 km wide in the Sargasso Sea, in the West Central Atlantic (about 26°N 60°W). The mechanisms by which leptocephali reach the European coasts are not also well understood. By the time the leptocephali reach the continental slope they are about 70 mm in size and metamorphose into glass-eels which are almost adult in appearance, but have a transparent body, and enter estuaries. These glass-eels are observed in the autumn on Portuguese coasts, and in winter and spring in the North Sea. The generation length of the species varies greatly and ranges from 2 to 50 years, and having a typical mean of 20 years with females being twice the size and age of males (W. Dekker pers. comm. 2007).
Systems: Freshwater; Marine

Threats [top]

Major Threat(s): The causes of the declining recruitment rates are still unclear (Dekker 2007), but there are many hypotheses:

The North Atlantic Oscillation (NAO) may have reduced larval survival and/or growth rate (Castonguay et al. 1994). However, Dekker (2004b) shows that the NAO index correlation is strong for growth rate but weak for glass eel numbers as in 2000 the NAO index returned to normal but recruitment still declined.

Overfishing for glass eels (mainly in France, Spain, Portugal and UK) and downstream migrating eels (silver eels) across Europe (W. Dekker pers. comm.) is also a threat to the species. The demand from Asia and Europe for glass eels is huge and the price is increasing (750 Euro per kilo in 2006 from around 100 Euro in 1990.). According to ICES (2006) Anguilla anguilla fisheries are currently not sustainable, and a recovery plan urgently needs to be developed for the whole stock.

There is also a parasite nematode (Anguillicola crassus), from introduced eels from Japan which is suspected to impact the ability of the European Eels to reach their spawning grounds.

Dams (for hydropower and water management) are also a threat to the species by blocking migration routes and also through causing high mortality rate as the downstream migrating eels are killed by turbines.

Climate change may be having an impact on the suspected breeding grounds (Sargasso Sea).

Increasing numbers of predators, in particular cormorants, across Europe may also have a negative impact on this species.

Conservation Actions [top]

Conservation Actions: The majority of conservation actions historically in place for the European Eel were set up and controlled at local and national level. Their aims are often securing fishing rights, supporting local stock levels and sustainable income for fishing communities and not to increase recruitment.

However, in 2007 two major multi-lateral bodies recognized the state of the European Eel and have acted upon it.

The European Council (EC) Regulation No 1100/2007 establishing measures for the recovery of the stock of European Eel was published in September 2007. The Regulation required, by 1 July 2009, all member states that contain natural habitats of the European Eel to establish eel management plans at a river basin scale. The objective of these plans was 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], through various measures including reducing commercial and recreational fisheries, restocking, measures to improve habitats and make rivers passable, transportation of silver eels to the sea and monitor eel status in each basin. The Regulation also requires that by 31 July 2013, 60% of eels less than 12 cm in length caught annually should be reserved for restocking [and not aquaculture], also that over a 5 year period starting from 1 July 2009 catches or fishing effort of eels in coastal and sea waters [i.e. beyond river basin plan] should be reduced by at least 50% [of average between 2004-2006], and that a control and monitoring system be set up by each member state.

The European Eel was listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) in June 2007. The listing came into effect on 13 March 2009, after which time all Parties to the Convention will be required to issue permits for all exports of the species. An export permit may be issued only if the specimen was legally obtained and if the export will not be detrimental to the survival of the species. In the European Union, which includes 24 eel range States, CITES is implemented through Council Regulation 338/97 and Commission Regulation 865/2006 which require both import and export permits to be issued for species listed in Annex B of the Regulation (Annex B contains most CITES Appendix II species). In the case of specimens introduced from the sea, a certificate has to be issued by the Management Authority of the State into which the specimens are being brought, for species listed in Appendix I or II.

Bibliography [top]

Åström M. and Dekker W. 2007. When will the eel recover? A full life-cycle model. ICES Journal of Marine Science 64: 1-8.

Boëtius, J. and Harding, E.F. 1985. A re-examination of Johannes Schmidt's Atlantic eel investigations. Dana 4: 129-162.

Castonguay, M., Hodson, P., Moriarty, C., Drinkwater, K. and Jessop, J. 1994. Is there a role of ocean environment in American and European eel decline? Fisheries Oceanography 3(3): 197-203.

Dekker, W. 2000. The fractal geometry of the European eel stock. ICES Journal of Marine Science 57: 109-121.

Dekker, W. 2003. Did lack of spawners cause the collapse of the European Eel, Anguilla anguilla? Fisheries Management and Ecology 10: 365-376.

Dekker, W. 2004. Slipping through our hands - population dynamics of the European eel. Doctoral Thesis. University of Amsterdam.

Dekker, W. 2004. What caused the decline of Lake Ijsselmeer eel stock since 1960? ICES Journal of Marine Science 61: 394-404.

Dekker, W. 2007. Coming to grips with the eel stock slip-sliding away. In: M. G. Schechter, W. W. Taylor, & N. J. Leonard, (ed.), International governance of fisheries ecosystems: learning from the past, finding solutions for the future.. Bethesda, MD.

ICES. 2002. Report of the ICES/EIFAC working group on eels. International Council for the Exploration of the Seas.

ICES and FAO. 2006. Report of the 2006 session of the Joint EIFAC/ICES Working Group on Eels. International Council for the Exploration of the Seas & European Inland Fisheries Advisory Commission Food and Agriculture Organization of the United Nations.

IUCN. 2010. IUCN Red List of Threatened Species (ver. 2010.4). Available at: http://www.iucnredlist.org. (Accessed: 27 October 2010).

Schmidt, J. 1925. The breeding places of the eel. Smithsonian Report 1924: 279-316, 7 pls.

Tesch, F.-W. 1999. Der Aal. Parey, Berlin.

Wirth, T. and Bernatchez, L. 2001. Genetic evidence against panmixia in the European eel. Nature 409: 1037-1040.

Citation: Freyhof, J. & Kottelat, M. 2010. Anguilla anguilla. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 23 April 2014.
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