EU eel management
Published: 15/11/2005The European eel population has declined drastically, with glass eel recruitment now lower than ever. Climate change might be contributing, but pollution, diseases, parasites and loss of habitat have also had a negative impact, and the mortality rate in all of the eel life stages remains high. A joint EU management plan was agreed in 2007. Implementation has taken an important step forward with national management plans for eel that were submitted to the European Commission at the end of 2008.
Contents:
- The biology of European eel
- Negative impacts
- Eel fisheries
- Management
1. The biology of European eel
Little is known about the biology of the European Eel, Anguilla anguilla. It's thought that the eels spawn somewhere in the Sargasso Sea, south of Bermuda, where small eel larvae called Leptocephalus larvae have been found. The eel passes through four developmental stages during its life cycle. During the first of these, the 'larval stage', the Leptocephalus larvae drift with the Gulf Stream from the Sargasso Sea to the coasts of Europe - a journey which takes them 2-3 years. On reaching coastal waters, the larvae transform into the 'glass eel' stage. Swimming up the rivers, they develop a yellow/brown pigment and the now 'yellow eels' remain in the European rivers or coastal waters for between five and 25 years. They mature and grow and finally develop into 'silver eels' - the last stage of their life cycle. At this point, their backs darken and their bellies become silvery, providing camouflage on their long journey back to the spawning grounds. The head and the eyes grow and the breast fin takes on a sharper, angular shape.
Decades of decline
Although many aspects of European eel biology remain a mystery, one thing is clear: the European eel population has reached a critically low level. According to landing statistics from the Food and Agriculture Organisation (FAO), the population has declined dramatically since the early 1970's. This is corroborated by data on recruitment and landings from the International Council for the Exploration of the Sea (ICES), which show a drastic decline from the end of the 1960s until today. Eel numbers stabilised briefly during the 1990s, according to both recruitment data and catch records, before declining to an all-time low of about 1 % of the 1960's population in 2001. The population has stayed around that level ever since. Based on these trends, eel biologists mean that the population will not be able to recover unless immediate action is taken. In 2005, the European eel was put on the red-list, i.e. a list of threatened and endangered species, by the Swedish Species Information Centre and classified as critically endangered. On the IUCN Red List of Threatened Species it is classified as “Critically Endangered”.
Recruitment of new eels
As we do not know exactly where the eels spawn, the number of glass eels that reach the estuaries of Europe and northwest Africa from the Sargasso Sea is what is defined as recruitment. It has been very low for several decades and has continued to decline all over. Glass eel catch figures are often used as another measure of recruitment, and these have been declining as well. For example, catches of glass eels in France declined from 1,345 tons in 1970 to 520 tons in 1989, with similar trends in most other countries. Glass eel numbers hit their lowest point in 2001. However, recruitment remains quite high in some coastal areas, and glass eels from these areas are exported or used in restocking programmes in places where recruitment is low.
Migration
In eel biology, the phase when silver eels are swimming from the estuaries where they mature and grow to the Sargasso Sea to reproduce is called migration. If eels do not live to maturity and reach the Sargasso Sea to reproduce, the amount of eel larvae and glass eels will continue to decrease. Therefore, the continuous decrease in the number of migrating eels is also a problem. It probably has multiple causes as well, including impacts of hydro-power plants, pollution, habitat loss and fishing pressure, affecting both yellow eels and silver eels.
Mortality
Considering the low recruitment and population numbers, the mortality rate of the eel population is too high, according to recruitment and landing statistics in Europe. According to the Commission (COM(2005)472), in ten years time, the eel stock will no longer be an exploitable resource unless action is taken to improve survival and reproduction rates. Along with the eel, associated jobs and markets would disappear.
Likely causes of the high mortality include environmental factors such as climate change and changes in currents, as well as anthropogenic factors such as over-harvesting at all eel life stages, habitat loss, crushing in hydro-electric power turbines, pollutants and parasites. Measures need to be taken at all life stages if the stock shall have a chance to recover, and since eel are long-lived and slow to reproduce it will take time before any improvements can be noticed or we even know if the measures are successful.
Contents:
- The biology of European eel
- Negative impacts
- Eel fisheries
- Management
2. Negative impacts
The following impacts are affecting the European eel stock at all life stages, and measures addressing all of them are urgently needed to enable the stock to recover.
Environmental factors
The lack of knowledge about eel biology, particularly about spawning area and aspects of larval biology, makes it difficult to identify changes in the environment that might be critical to eel survival. Possible factors include changes in access to food as well as changes in the direction of sea currents that transport the Leptocephalus larvae to the European coasts.
There is some evidence that climate change is affecting eel recruitment. The drastic decline in recruitment of European eels in the 1970s coincided with an almost identical decline in recruitment of the American eel Anguilla rostrata. Furthermore, the decline in recruitment of both species coincided with the North Atlantic Oscillation (NAO) in the 1980s. NAO is defined as the difference in pressure between Iceland (low pressure) and the Azores (high pressure). A strong NAO during winter gives rise to a warmer climate in north and central Europe, changes in wind velocity and sea surface temperature, with stronger winds and higher sea surface temperatures. All these factors might have a negative effect on eel larvae.
Habitat loss
Turbines of hydro-power plants present a barrier for glass eels heading upstream to good habitats, and massacre yellow and silver eels heading downstream to the coast. In addition, dam constructions, weirs and drained watercourses are blocking migration routes and cutting off paths to good habitats. Discharges of pollutants and other substances from households, industry and traffic have all contributed to deteriorating water quality in what used to be excellent habitats for eels.
Pollution
Eels are very fatty fish and are prone to accumulate pollutants from food and water during their long growth period in European estuaries. These include PCBs and DDTs which, while harmless as long as they are contained in the fat tissue, become highly toxic, even in small concentrations, once released. The accumulated toxins might also have an affect on the eel's fertility or cause deformities in their offspring, making them less viable as they burn off fat reserves during the long migration to their spawning grounds in the Sargasso Sea. Pollutants might also stress the eels, making them more susceptible to diseases and parasites, which in turn reduce their chances of reaching the Sargasso Sea.
Parasites
Anguillicola crassus is a nematode that infects the swim bladder of the yellow and silver eels. Originating from East Asia, the nematode probably reached Europe with ballast water in the 1980s. The nematode larvae are eaten by copepods and small fish species, which are an important food source for eels. Once the nematode larva reaches the intestine, it passes through the intestine wall and into the belly, where it attaches to the inside wall of the swim bladder and develops into an adult nematode. The nematodes infect and damage the swim bladder, affecting the eel's swimming ability and reducing its chance of reaching the Sargasso Sea.
Contents:
3. Eel fisheries
The European eel is the only eel species targeted in Europe, with an estimated annual catch (of eels at all stages of their life cycle) of less than 5,000 tons in 2005. (The corresponding figure for 1997 was approximately 30,000 tons). The eel stock is now in a critical state and well below so called "safe biological limits", making the fishery unsustainable at current catch levels. Still, the fishery continues to employ a large number of people in the EU. The number of European eel fishermen has sunk considerably from some 25,000 just a few years ago. Only in France, where the glass eel fishery is very important financially, there are about 1,100 vessels fishing in the river mouths and another 450 fishermen in the rivers. In this area, the glass eel fishery constitutes 75 per cent of the fishermen's turnover every year.
There are both small-scale and larger-scale glass eel fisheries. Today's high prices for glass eels, occasionally fuelled by rising demand in East Asia, have led to an increase in fishing pressure. To fish for glass eel, no boat or specific gear is needed. This means anyone can give it a try, and fishing activities are difficult to control. Silver eels and yellow eels are exposed to small-scale fisheries and to recreational fisheries, and the fishery pressure is not enormous, but because of today's low recruitment and other threatening factors, even a low fishing pressure is likely to be too much.
The fishing pressure at the glass eel stage is higher than at the yellow and silver eel stages. To enable the European eel stock to recover, one of the most important things to address is the export of glass eels to East Asia, ensuring that a greater proportion remains in Europe. In the EU Regulation that was adopted by the Council in June 2007, it is stipulated that, from January 2009, 35 per cent of the glass eel/elver catches that are smaller than 12 cm will have to be used for re-stocking within Europe. That percentage will increase every year until it finally reaches 60 per cent in 2013 at the latest.
Glass eel (elvers) fishing
Glass eels, captured and cultivated in parts of Europe where they are still abundant, and later sold to countries where recruitment is low, have become a valuable commodity. They are re-stocked in good habitats in order to maintain a small eel fishery and a migrating stock. Glass eels are caught from October until May, mostly using lift-nets and sieves but also with small trawlers. The total European glass eel catch have fallen drastically since the 1970s, according to the Food and Agriculture Organization (FAO).
Varying quantities of the glass eel catches are exported to East Asia. The amount of glass eel purchased by Asian buyers varies significantly from one year to the next. It also varies by country: the Japanese, for example, strongly prefer Japanese eel (Anguilla japonica) and will only buy European eel if there is a shortage, while the situation is different in China and Korea. In the 1990s, most of the European catches were exported to East Asia for aquaculture, 80 per cent of the Asian farmed eel stemming from European glass eels in 1997. Only 50-60 tons of glass eels annually are currently exported to Asia.
In some areas, limitations on the glass eel fishery in the form of season closures and/or restrictions in gear type, mesh size, minimum landing size and licenses are very common. Despite these restrictions, it remains difficult to control glass-eel fisheries since only a sieve is needed to catch some, and the high prices create a strong incentive.
Yellow eel fishing
The yellow eel fishery runs from May until October, but most eels are caught in June and July. The gears normally used to catch yellow eels are fyke nets, baited long lines, fixed traps and baited pots. The yellow and silver eel fisheries are regulated by gear control and minimum mesh sizes, restricted effort in terms of closed areas or fishing seasons, as well as minimum landing size. Yellow eels are now generally used for consumption, as are silver eels.
Silver eel fishing
The silver eel fishery is ongoing from late spring until late fall (May-November), but the bulk of the catches are taken between late August and October when most of the migrating silver eels start their journey back to sea under the cover of the darkness in the fall. They have then reached their maximum weight, have a high fat content and are in peak condition.
The gears for professional silver eel fishing are quite large and very expensive compared to recreational fishing gear. Silver eels are trapped and netted in small-scale fisheries on their way out of the rivers and along the coasts. Once caught, they are either processed into various traditional delicacies, such as smoked eel, eel soup or so called "luad eel", or sold whole for other types of consumption. According to the ICES, the official statistics on silver eel landings constitute only about half of the true catches. Based on the official records, there was a profit peak in the 1960s which had dropped to one third by 2000.
Contents:
4. Management
There are still so many things we don't know about the eel and this knowledge is essential for developing effective management measures and stock enhancement programmes. Monitoring at local, regional, national and international levels is essential for sustainable eel management. According to Ostrom (1990), migratory marine resources are particularly challenging in terms of management. Because regulations of eel fisheries vary greatly from one region to another, it is very important that monitoring programmes are tailored to particular waters, also taking account of the specific habitat type and life stage of the eels found in those waters.
Cultivation
All cultivation (or farming) of eel is based on the capture of glass eels, as nobody has been able to successfully breed eels in captivity yet. In northern Europe, eels are cultivated at a constant temperature of 25ºC in modern indoor aquaculture systems; while in southern Europe, extensive aquaculture in artificial ponds is more common.
Eels are cultivated for re-stocking, live exports and human consumption. A sizeable part of the eels cultivated in northern Europe, where recruitment has declined more substantially than in the south, is used for re-stocking. The aquaculture plants in Sweden are also used to quarantine foreign glass eels destined for re-stocking, whereas plants in the Netherlands and Denmark are mainly used for production. The eel aquaculture industry has grown from about 500-800 tons of eel produced per year during the 1980s to an estimated 9,000 tons in 2007.
Re-stocking
Re-stocking has been used for over fifty years around the Baltic Sea, primarily to maintain the eel fisheries rather than re-build the stock. In recent years, re-stocking was increasingly seen as a way to help the eel stock recover, but in 2008 the International Council for the Exploration of the Sea (ICES) said it is “highly unlikely” that the 40 per cent recovery target set in the EU Regulation can be met primarily through re-stocking. “Stocking should not be considered a remedy/solution for overfishing, or for ameliorating or mitigating any other anthropogenic activities adversely affecting the stock”, ICES concluded.
Re-stocking involves risks associated with moving fish from one place to another, including the spread of diseases, loss of genetic diversity and changes in (or even loss of) migration behaviour. There is a lack of knowledge about eel migration and how the eels find their way back to the spawning area. If eels are re-stocked, there is a risk that they will be disoriented and unable to find their way out to sea and on to the Sargasso Sea. If this is the case, re-stocked eels would not be contributing to the recovery of the eel population. Given these risks and without evidence that re-stocking really does improve eel recruitment, this practice could actually make things worse instead, as more eels are moved around rather than migrating naturally.
Management
For several years, ICES had repeatedly recommended that the European Union urgently develop an international eel recovery plan and that, until such a plan can be implemented, all anthropogenic impacts should be reduced to as close to zero as possible. Conservation efforts like restoring and maintaining good habitats, restoring migration paths, as well as improving water quality and strengthening fisheries regulations in suitable ways were seen as urgently needed if the eel population is to have any chance of avoiding extinction and making a recovery.
Seen in that context, it was a big step forward when the Council adopted the new Regulation in June of 2007. The agreed plan consists of several different components. The main target of the eel recovery plan is to enable 40 per cent escapement of silver eel, so that they can return to the Sargasso Sea to reproduce. All Member States were requested to develop a national management plan, showing how to accomplish this, and hand it in by the end of 2008. The plans will then have to be approved by the European Commission and the Scientific, Technical and Economic Committee on Fisheries (STECF), which is foreseen to happen before July 1, 2009, and then implemented within six months.
Trade
In autumn 2006 Sweden drew up a proposal to the Convention on Trade in Endangered Species (CITES), recommending that the European eel would be included in its appendix II, and on 19 December it was announced that the proposal had been adopted by EU and has been discussed during the CITES negotiations on 3–15 June 2007. The meeting adopted the proposal on 15 June, meaning that export restrictions came into force and European eel could no longer be exported without a special permit.