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Life-history traits of eels display a high level of phenotypic plasticity in response to large-scale biogeographical drivers, as well as local conditions encountered during the continental phase. Here, we provided a biogeographical snapshot of the variability of life-history traits of eels (Anguilla anguilla), across a large proportion of their natural distribution range. Silver eels (n = 99) were collected across eleven European catchments to investigate how life-history traits vary along geographical and saline habitats, as it was inferred from the Sr:Ca ratio in otoliths. Among 13 life-history traits tested, 3 of them such as total length, body or liver weight were related to geographical coordinates. Overall, eels grow faster in southern Europe and migrate earlier suggesting that the silvering process is related to the local growth conditions more than fish age. The salinity profiles revealed by the otoliths' Sr:Ca ratios indicate that eels with a brackish life-history generally grow faster, reach larger size-at-age, and have a better condition than eels living in freshwater. This observation associated with the lower abundance of the sanguivorous swimbladder nematode, Anguillicola crassus, confirms the importance of brackish areas for sustaining the eel production. A large proportion of the observed variation of life-history traits remained unexplained by the biogeographical trends and salinity condition, which suggests that other drivers act at the catchment scale. [ABSTRACT FROM AUTHOR]

This study quantifies the processes involved in regulating the European eel population of Lough Neagh, a lake in Northern Ireland. The relationship between glass eel input and silver eel output for the 1923–1997 cohorts was best described by a Beverton–Holt stock recruitment model. Glass eel input time series was not complete and was thus derived from the relationship between catches elsewhere in Europe and Lough Neagh, together with the addition of stocked glass eel. Silver eel output was the sum of silver eel escapement, catch and yellow eel catch converted to silver eel equivalents. Natural mortality increased with glass eel density, ranging from 0.017 to 0.142 year−1. The mean carrying capacity increased from ≈3.25 M silver eels (≈26 kg ha−1) for the 1923–1943 cohorts to ≈5.0 M (≈40 kg ha−1) for the 1948–1971 cohorts before regressing back to ≈3.25 M. The total silver eel output was highest during the late 1970s/early 1980s at 35–45 kg ha−1 year−1 and lowest during the early years of the 20th century and is currently at 10–15 kg ha−1 year−1. The findings are discussed in relation to (a) the ecological changes that have occurred within the lough, associated with eutrophication and the introduction of roach (Rutilus rutilus L.), and (b) the decline of the wider European eel stock across its distribution range. The findings from this study have relevance for the wider management of the European eel stock. [ABSTRACT FROM AUTHOR]

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Abstract: European eels (Anguilla anguilla) migrate ~6000km towards their spawning area in the Sargasso Sea. Based on the recent discovery that males swim even more efficiently than females, it was predicted that males also would be able to swim ~6000km within six months. Additionally, eels do not mature naturally in captivity due to strong neural inhibition. Earlier, it was hypothesized that swimming exercise is a natural trigger to induce sexual maturation and may even result in full maturation. In the present study two groups of farmed male silver eels were subjected to either endurance swimming or resting for up to 6months. It was found that male eels were able to swim continuously for a total distance of 6670km within 6months. The body weight decrease in swimming and resting males after 6months was similar (<30g) underlining the extreme low energy cost of swimming. In contrast to our expectation long-term swimming did not induce sexual maturation in farmed silver eels, suggesting that swimming alone is not sufficient as a trigger for sexual maturation. In conclusion, male eels are efficient long distance swimmers and likely able to cover the distance to the Sargasso Sea within the expected time span of 6months. [Copyright &y& Elsevier]

1. Despite carrying capacity being one of the most important parameters in population management and modelling, we lack substantial evidence for habitat limitations on freshwater species. Here we tested the ideal free distribution (IFD) hypothesis using an indirect behaviour-based method for small closed populations assuming that animals can effectively estimate habitat suitability and distribute themselves accordingly in time and space. 2. We analysed spatiotemporal variations in the density of the European eel Anguilla, a catadromous species with good colonisation abilities in a small coastal catchment in France. The general linear model used enabled us to test simultaneously the effect of temporal, macro- and meso-scale habitat factors on the presence and abundance of eels at 30 sites over an 8-year period. 3. Almost every site sampled had eels, whatever its location on the catchment and its habitat characteristics. Density estimates (overall mean ± SD of 0.40 ± 0.48 m) were at the upper range of other values for European catchments. Moreover, eel densities were mainly influenced by the availability of suitable habitats (rocky substratum and instream cover), which suggests that their distribution reflects an IFD. 4. Despite marked variability in recruitment, the density of the oldest size-class remained stable over the study, suggesting that density-dependent mortality occurred, probably due to intraspecific competition for space and food and to predation. 5. These findings suggest that eel habitats are saturated in the Frémur. Therefore, we suggest that the mean abundance of eels observed could serve as a threshold value for other male-dominated river stocks (provided they have a similar overall percentage of suitable habitats) that are common in small, low gradient streams on the north-Atlantic coast of Europe. [ABSTRACT FROM AUTHOR]

The European eel, Anguilla anguilla, is considered an endangered species that is under pressure for many reasons. Among others, the introduced parasite Anguillicola crassus is thought to play an important role in the decline of eel populations. These nematodes have been shown to negatively affect many fitness-related traits in eels, e.g., growth, osmoregulation, and stress tolerance. Nevertheless, there has been little work on the way in which the host-parasite interaction influences the molecular regulation of these key physiological processes. We experimentally analyzed the effect of this nematode on the expression of genes involved in the physiology of European eels during their continental life. Included are genes that are implicated in the eel's somatic growth (insulin-like growth factor 1 and thyroid hormone receptor b), osmoregulation (Na+/K+-ATPase b1 and aquaporin 3), and hematopoiesis (hemoglobin a-chain). Our results showed the absence of an effect on genes involved in fish growth; the parasite may, however, have an effect on osmoregulation and hematopoiesis. We also noted a differential impact of male and female parasites on the expression of some genes, perhaps owing to the sexual dimorphism in body size of the parasite. [ABSTRACT FROM AUTHOR]

The aim of the study was to determine the effect of two photoperiod regimes under artificial conditions on growth performance and survival in the European eel Anguilla anguilla during the transition from glass eel to elver. The fish were held in 12-h-light:12-h-dark (12L:12D) and in continuous darkness (DD) in fed and fast trials lasting 80 days. Fed fish kept in the dark showed higher somatic growth, and a better feed conversion ratio, higher protein and lipid content, with significant differences between treatments. Dark environment increased the survival rate in comparison with fish exposed to 12L:12D, during which eels showed lower survival rates and greater variations in size. Fasted fish suffered loss of body mass in both photoperiods at the end of the experimental phase, but fish exposed to 12L:12D lost more body mass. These results indicate that the photoperiod is a key factor during the glass eel–elver stage, which may contribute to optimizing the early stages of eel culture. [ABSTRACT FROM AUTHOR]

Abstract: The spatial distribution of the European freshwater eel (Anguilla anguilla) was very different in historic and prehistoric times in comparison to the present. A database of the spatial and temporal distribution of eel remains in archaeological and palaeontological sites is presented and used to assess the spatial distribution of populations from the height of the last glacial maximum. The results show that the eel was absent from northern Europe until about 11000 years ago. The reason was probably a southerly displacement of the Gulf Stream carrying the larval migration from the Sargasso Sea. However, additional factors preventing eel populations in northern Europe may have also been the colder temperatures in the Arctic tundra landscape that existed at the time and the extreme distance to the European Atlantic coast along the Channel River. The archaeological record shows that eels were absent from the Baltic Sea until about 6700calBC, but there is some indication of an earlier presence during the Yoldia Sea stage at the beginning of the Holocene. Only in southern Europe south of the Gironde river basin were eel populations maintained through the last glaciation. The species may have survived the last glaciation in a relatively restricted area in the Mediterranean and the Atlantic coast of western Europe. Published palaeontological and genetic information gives important insights into climatic, geologic, and tectonic events on longer time scales. The oldest subfossil remains from Pleistocene sediments in northern Europe are approaching the age of the estimated genetic divergence of the European and American eel populations, and hence the species identity of the oldest subfossil remains may be ambiguous. [Copyright &y& Elsevier]

In fish like in mammals, dopamine (DA) is a major catecholaminergic neurotransmitter that contributes to many functions of the nervous system like sensory perception, tuning of sensori-motor cues, and hypothalamic and pituitary functions. In the eel, DA inhibits gonadal development, and juvenile silver eels remain blocked at a prepubertal stage if their reproductive migration does not occur. From data in other teleosts and vertebrates, it is suggested that DA would be involved also in the last steps of eel reproduction (oocyte maturation, ovulation, and spermiation) as well as in eel reproductive migration (locomotion and olfaction). Investigating dopaminergic systems in the eel may help in understanding the mechanisms of its complex life cycle and provide new data for its conservation and reproduction. In this article we review the biosynthesis and catabolism of catecholamines and discuss available methods to investigate brain dopaminergic systems in vertebrates and their application to the eel. Immunocytochemistry, in situ hybridization, and different tracing methods are used to map dopaminergic neurons and projections in the brain and pituitary and infer their potential functions. Moreover, variations in dopaminergic activity may be approached by means of quantitative methods like quantitative real-time RT-PCR and HPLC. These tools are currently used to study dopaminergic systems in the eel brain, their anatomy, regulation, and potential roles with special emphasis on the regulation of reproduction and reproductive migration. [ABSTRACT FROM AUTHOR]

Stocks of European eel (Anguilla anguilla) have declined continuously and steadily, since 1980. A model, GEMAC, namely Glass Eel Model to Assess Compliance, has been developed with the objective of assessing anthropogenic impacts on glass eels in estuaries and evaluating the effects of management measures, to support initiatives aimed at helping the eel stocks recover. The model is described and applied to two estuaries with contrasting anthropogenic pressures: the Vilaine and the Garonne. It assesses the proportion of settled glass eels relative to a non-impacted situation with current (%S/R) or pristine recruitment (%S/R0). The estimated %S/R (%S/R0) is 5.5% (1.1%) for the Vilaine and 78% (19%) for the Garonne, in accord with the different levels of anthropogenic pressure in these two estuaries. A sensitivity analysis shows that the assessment of %S/R is accurate, and that in a data-poor context, the %S/R is under-assessed, as required by the precautionary approach. Seven management scenarios are explored all aiming to halve the anthropogenic pressure, but in fact leading to different levels of glass eel escapement, from almost zero to a 13-fold increase. This variation emphasizes the need for the estuarine context of eel stock management to be carefully evaluated for effectiveness when implementing management measures. [ABSTRACT FROM PUBLISHER]

One of the mysteries of the animal kingdom is the long- distance migration (5000-6000 km) of the European eel Anguilla anguilla L. from the coasts of Europe to its spawning grounds in the Sargasso Sea. The only evidence for the location of the spawning site of the European eel in the Sargasso Sea is the discovery by Johannes Schmidt at the beginning of the previous century of the smallest eel larvae (leptocephali) near the Sargasso Sea. For years it has been questioned whether the fasting eels have sufficient energy reserves to cover this enormous distance. We have tested Schmidt's theory by placing eels in swim tunnels in the laboratory and allowing them to make a simulated migration of 5500 km. We find that eels swim 4-6 times more efficiently than non-eel-like fish. Our findings are an important advance in this field because they remove a central objection to Schmidt's theory by showing that their energy reserves are, in principle, sufficient for the migration. Conclusive proof of the Sargasso Sea theory is likely to come from satellite tracking technology. [ABSTRACT FROM AUTHOR]

European eels (Anguilla anguilla L.) were caged for 8 and 48 h in two polluted areas to assess the contamination cleanup process in the Vouga River 2 years after the official closing of a bleached kraft pulp mill effluent (BKPME; experiment 1), and to monitor the effects induced by contaminated offward fishing harbor waters (experiment 2). Plasma cortisol, glucose, and lactate were evaluated as stress responses. In experiment 1, plasma cortisol, glucose, and lactate increased after 8 h of exposure in site 3, which is located farthest from the deactivated sewage outlet. However, A. anguilla seemed to adapt after 48 h of exposure in site 3, because all three parameters returned to control levels. Plasma glucose also significantly increased after 8 h of exposure at sites 1, 2, and 3, returning to control levels after 48 h. Plasma lactate levels increased after 8 h of exposure at site 3 and after 48 h of exposure at site 1. In experiment 2, A. anguilla exposed to contaminated harbor waters increased their plasma lactate after 8 and 48 h of exposure, whereas their cortisol and glucose plasma were elevated only after 48 h of exposure. The results demonstrate that even 2 years after the official closing of the BKPME sewage outlet, the river Vouga water remains contaminated by the sediment associated chemicals. Because the fishing harbor induced in A. anguilla the same type of stress responses, it is also an area of concern. The adopted stress parameters allied to a caging strategy are recommended for future environmental monitoring assessments. [Copyright &y& Elsevier]

Introduction of the blood feeding swimbladder parasite, Anguillicola crassus, into Europe in the 1980s led to its establishment in the European eel, Anguilla anguilla, and more recently the parasite has been identified in the American eel, Anguilla rostrata. Mass mortalities of wild European eels infected with A. crassus suggested that infected eels may be more stressed by extreme changes in environmental conditions than uninfected eels, but the effects of aquacultural stressors are unknown. The present study therefore compared the physiological effects of netting and aerial exposure on European eels infected with A. crassus and uninfected eels. Both A. crassus-infected and uninfected eels showed a significant endocrine response to the 4 h of netting confinement and aerial exposure. Cortisol responses of parasitised and non-parasitised eels were similar with recovery by 4 h despite continued exposure to the stressors. Although there were no significant differences between the plasma glucose concentrations of eels infected with A. crassus and uninfected eels, at any of the blood sampling points in the netting and aerial exposure, differences in the dynamics of glucose mobilisation and utilisation are suggested. Plasma glucose concentrations rose significantly in infected eels, peaking at 135.0±19.8 mg/100 ml after 2 h compared to basal levels of 59.46±11.2 mg/100 ml. This, together with a positive correlation between plasma glucose and total worm load at time 0 h, leads us to hypothesise that glucose mobilisation and utilisation is increased in Anguillicola-infected eels as a result of the metabolic strain of harbouring a blood-feeding parasite, and that aquacultural stressors further elevate glucose turnover. As glucose is an important metabolic fuel in eels, the growth and subsequent yield of farmed eels infected with A. crassus may potentially be compromised. [Copyright &y& Elsevier]

The impact of the parasitic swimbladder nematode, Anguillicola crassus Kuwahara, Niimi & Itagaki, on European eel populations is assessed with reference to published research on its origin and rapid dissemination, life cycle and transmission dynamics, and its pathogenic effect. The parasite was originally endemic to East Asia, but has transferred from its native host, the Japanese eel, Anguilla japonica Temminck & Schlegel, to the European eel, Anguilla anguilla (L.) and American eel, Anguilla rostrata (Le Seur). Anguillicola crassus is a very successful colonizer and is now known to occur in four continents (Asia, Europe, Africa and America). The nematode can severely impair swimbladder function and has caused mortalities in both farmed and wild populations in the presence of other stressors. Anguillicola crassus may impair the capacity of European eels to complete the spawning migration, although direct evidence is not available to support this hypothesis. Areas for future research are recommended. [ABSTRACT FROM AUTHOR]

Panmictic species pose particular problems for conservation because their welfare can be addressed effectively only on a global scale. We recently documented by means of microsatellite analysis that the European eel (Anguilla anguilla) is not panmictic but instead shows genetic isolation by distance. In this study, we extended the analysis to the American eel (A. rostrata) by applying identical analytical procedures and statistical power. Results obtained for the American eel were in sharp contrast with those obtained for the European eel: the null hypothesis of panmixia could not be rejected, and no isolation by distance was detected. This implies that the species must be managed as a single population. Using Bayesian statistics, we also found that the effective population sizes for both species were surprisingly low and that the populations had undergone severe contractions, most probably during the Wisconsinan glaciation. The apparent sensitivity of eels to climatic changes affecting the strength and position of the Gulf Stream 20 000 years ago is particularly worrying, given the effects of the ongoing global warming on the North Atlantic climate. Moreover, additional short-term stresses such as surging glass eel prizes, overfishing and lethal parasitic infections negatively affect eel population size. The fascinating transatlantic migration and life cycle of Atlantic eels is also their Achilles' heel as these negative short- and long-term effects will probably culminate in a fatal synergy if drastic conservation measures are not implemented to protect these international biological resources. [ABSTRACT FROM AUTHOR]

Summary A 12-week feeding trial was undertaken to evaluate the effects of partial replacement of marine raw materials in the diet with soybean meal and beef tallow on growth and product quality of European eel (Anguilla anguilla ). Based on growth, feed efficiency and chemical composition, soybean meal was found to be an unsuitable ingredient for eel diets as a substitute for fishmeal (25% on a protein basis), probably because of the low digestibility of its carbohydrate content. However, beef tallow can be used to replace 50% of fish oil without reduction in growth, provided that digestible carbohydrates are present in the diet. No major effects of protein and lipid sources in the diet were found on fillet chemical composition. Sensory analysis revealed no significant differences between fish fed the control and the experimental diets, with the exception of salty taste which was significantly higher in fish fed combined soybean meal and beef tallow compared with fish fed the control diet. [ABSTRACT FROM AUTHOR]

World production and consumption of eels, Anguilla spp., was about 100000–110000 tonnes/year in 1987. About 70–80% of the world production is consumed in Japan. This amount is almost completely produced by eel culture in Japan and Taiwan. The remaining 20–30% of the world production is consumed in Europe. About 15% of the European eel market, i.e. 3000–4000 tonnes/year, is covered by cultured eels. In this review a description is given of the history and present status of eel culture in Japan and Europe. The economical comparison between eel culture in Japan and Europe shows much higher levels of both production costs and sales prices in Japan. Uncertainty about the future price developments and competition within Japan and with Taiwan (and China) keep a constant pressure on Japanese eel farmers to optimize their production process. Although a further optimization of the recirculation systems in north-west Europe is also needed, it will depend on the availability of trained husbandry personnel and on the future development of the eel market in Europe whether eel culture in north-west Europe can in the long term remain competitive with natural catches and with eel culture in the Mediterranean area. [ABSTRACT FROM AUTHOR]

Mistrust between scientists and non-scientist stakeholders is a key challenge in fishery management. The support of management with complex models is difficult, as these models cannot easily communicate their results to end users, resulting in a lack of confidence. As an example, the complex life cycle of the European eel raises problems of coordination and discussion among the multiple actors involved in the species' management. The GEREM model has been proposed as a tool for estimating recruitment, but its complexity, which is essential for addressing the characteristics of the species, makes it difficult to understand and accept by all stakeholders. In the context of the SUDOANG project, we proposed a co-parametrisation of this assessment model to tackle this mistrust. Through the use of various questionnaires, stakeholders were involved in two important choices for the model (zone definition and prior construction). Regular workshops and presentations were organised to explain the model rationales and to gather feedback and expectations. The results show that stakeholders have very similar perceptions of the potential definitions of sub-areas of recruitment in south-western Europe, and these perceptions are consistent with the underlying environmental conditions. On the other hand, the stakeholders have contrasting opinions about the exploitation rates of fisheries in different river basins, and the use of their knowledge currently has little effect on GEREM estimates. More importantly, the overall approach of this study is thought to have reconstructed the trust and confidence among participants. [ABSTRACT FROM AUTHOR]

Discusses the efficacy and safety of azamethiphos, a phosphorus compound, for the treatment of pseudodactylogyrosis in the European eel. Uses of azamethiphos; Active ingredient; Examination of fish gills for prevalence and mean intensity of parasites; Antiparasitic agents.

Cumulative and continuing human emissions of greenhouse gases to the atmosphere are causing ocean warming. Rising temperature is a major threat to aquatic organisms and may affect physiological responses, such as acid-base balance, often compromising species fitness and survival. It is also expected that warming may influence the availability and toxicological effects of pollutants, including Rare Earth Elements. These are contaminants of environmental emerging concern with great economic interest. This group comprises yttrium, scandium and lanthanides, being Lanthanum (La) one of the most common. The European eel (Anguilla anguilla) is critically endangered and constitutes a delicacy in South East Asia and Europe, being subject to an increasing demand on a global scale. Considering the vulnerability of early life stages to contaminants, we exposed glass eels to 1.5 μg L -1 of La for five days, plus five days of depuration, under a present-day temperature and warming scenarios (△T = +4 °C). The aim of this study was to assess the bioaccumulation, elimination and specific biochemical enzymatic endpoints in glass eels (Anguilla anguilla) tissues, under warming and La. Overall, our results showed that the accumulation and toxicity of La were enhanced with increasing temperature. The accumulation was higher in the viscera, followed by the head, and ultimately the body. Elimination was less effective under warming. Exposure to La did not impact acetylcholinesterase activity. Moreover, lipid peroxidation peaked after five days under the combined exposure of La and warming. The expression of heat shock proteins was majorly suppressed in glass eels exposed to La, at both tested temperatures. This result suggests that, when exposed to La, glass eels were unable to efficiently prevent cellular damage, with a particularly dramatic setup in a near-future scenario. Further studies are needed towards a better understanding of the effects of lanthanum in a changing world., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The European eel is critically endangered. Although the quality of silver eels is essential for their reproduction, little is known about the effects of multiple contaminants on the spawning migration and the European eel management plan does not take this into account. To address this knowledge gap, we sampled 482 silver eels from 12 catchments across Europe and developed methods to assess three aspects of eel quality: muscular lipid content (N = 169 eels), infection with Anguillicola crassus (N = 482), and contamination by persistent organic pollutants (POPs, N = 169) and trace elements (TEs, N = 75). We developed a standardized eel quality risks index (EQR) using these aspects for the subsample of 75 female eels. Among 169 eels, 33% seem to have enough muscular lipids content to reach the Sargasso Sea to reproduce. Among 482 silver eels, 93% were infected by A. crassus at least once during their lifetime. All contaminants were above the limit of quantification, except the 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), Ag and V. The contamination by POPs was heterogeneous between catchments while TEs were relatively homogeneous, suggesting a multi-scale adaptation of management plans. The EQR revealed that eels from Warwickshire were most impacted by brominated flame-retardants and agricultural contaminants, those from Scheldt were most impacted by agricultural and construction activities, PCBs, coal burning, and land use, while Frémur eels were best characterized by lower lipid contents and high parasitic and BTBPE levels. There was a positive correlation between EQR and a human footprint index highlighting the capacity of silver eels for biomonitoring human activities and the potential impact on the suitability of the aquatic environment for eel population health. EQR therefore represents a step forward in the standardization and mapping of eel quality risks, which will help identify priorities and strategies for restocking freshwater ecosystems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2020. Published by Elsevier B.V. All rights reserved.)

European eel( Anguilla anguilla; Teleostei) is a valuable commercial species. However, over the past 25 years, the population of European eel has been declining to such a degree that major concerns have been raised for its long-term conservation. Since little information is available on the life-cycle and genetic structure of European eel, it has been difficult to evaluate the existence of any population substructuring. Molecular genetic methods contribute to a better knowledge of the demography and population structure in marine fish. In addition, management strategies and conservation goals must consider information on genetic substructuring as well as on life history patterns.The aim of the study is to provide more detailed knowledge on the genetic variability, demography and population substructuring of European eel by analysing and comparing natural and farmed individuals. Natural eel samples have been obtained in two geographical sites(Netherlands, France) including temporal samples in a short-scale(within years) and a long-scale(between years). Simultaneously, farmed glass eels have been grown in two separate batches during one year. Batches have been monitored and genetic samples have been obtained during the year.A combination of selection-sensitive(allozymes) and selection-neutral markers(microsatellites) has been used in the study since selection seems to play an important role in the determination of the quality of future eel spawners. Results suggest a positive correlation between growth and genetic variability since individuals attaining a large length and mass present significant higher heterozygosities. [ABSTRACT FROM AUTHOR]

Reports on the decreasing stock of eels in Asia and Europe, based on data presented at a meeting held by the International Council for the Exploration of the Sea. Reason for the difficulty to find the cause of the decrease; Possible causes of the decline in eel stock; Remarks from Willem Dekker of the Netherlands Institute for Fisheries Research on the eels.

Fish skin contains a variety of humoral defence lysins which have an integral role in fish immunity because of the ability of these proteins to destroy invading substances (Alexander & Ingram 1992). These lysins generally comprise bacteriolysins, proteolysins and haemolysins. The lysins seem to be either individually or cooperatively stimulated to respond to pathogenic infection and environmental stress, such as ionic, osmotic, thermal and pollution stress (Shephard 1994; Rice, Kergosien & Adams 1996; Bly, Quiniou & Clem 1997). There have only been a few reports on these lysins (Al-Hassan, Thomson, Ali & Criddle 1987; Aranishi, Mano, Nakane & Hirose 1998). The present paper describes thermal effects on defence lysis, such as proteolysis, bacteriolysis and haemolysis, in the skin of the European eel, Anguilla anguilla L. [ABSTRACT FROM AUTHOR]

The stocks of the European eel Anguilla anguilla are in decline and there is an increasing awareness that poor health status due to contaminants and/or diseases might be a key element in this decline and might be a hindrance to recovery. Many countries have started compiling data on the health status of eels in their water bodies. Objectives for these monitoring actions are diverse and there is a large amount of information collected by EU member countries. However, this information is widely scattered over Europe in agencies, institutes or universities. As there is a growing need to collect and report on data on the health status of the eel on international level, the Joint EIFAC/ICES Working Group on Eels initiated in September 2007 the set up of an European Eel Quality Database to collect recent data of contaminants and diseases over the distribution area of the eel. This paper describes the aim, the set up and future development of the database in order to give it greater publicity and to call on scientists or managers to submit data on eel health status. The database represents now the first comprehensive pan-European compilation of eel health data, including data from over 10,000 eels from approximately 1,200 sites over 14 countries. Preliminary work has indicated a number of shortcomings and future developments will be needed. Guaranteeing further development of the database, harmonisation of methods, quality assurance, and setting up harmonised eel monitoring strategies over Europe will be a great challenge and will need pan-European cooperative work.

Possible causes of declines in recruitment of European, American and Japanese eels to continental waters are reviewed. Negative correlations between the Den Oever glass eel recruitment index (DOI) and the North Atlantic Oscillation Index since 1938 are discussed, together with older anecdotal evidence. Correlations are established between the DOI and sea surface temperature anomalies at 100-250 m between 1952 and 1995 in the Sargasso Sea/Sub-Tropical Gyre (STG) spawning area. It is hypothesised that, associated with global warming trends, STG warming inhibits spring thermocline mixing and nutrient circulation, with negative impacts on productivity and hence food for leptocephalus larvae. Concurrent gyre spin-up also affects major currents and slowing of oceanic migration has probably enhanced starvation and predation losses. Local factors, such as unfavourable wind-driven currents, can also affect recruitment of glass eels on continental shelves. In contrast, evidence is discussed that indicates fishing mortality and continental climate change appear to have had lesser impacts. Similar starvation-advection explanations for declines in Japanese eel recruitment are proposed. Predictions for the future are made and multidisciplinary and integrated monitoring and research are recommended for managing eel stocks and fisheries.

Fish are the major dietary source of very-long-chain n-3 polyunsaturated fatty acids. We investigated whether cultured fish contain fewer n-3 fatty acids than do wild fish. Fifty-eight trout, 51 eel, and 5 salmon were collected from fishermen and hatcheries throughout Europe, pooled into 23 lots (8 of wild and 15 of cultured fish), and analyzed. The ratio of n-3 to n-6 polyunsaturates was significantly lower in cultured than in wild fish (2 vs 7 in trout, 2 vs 5 in eel, and 6 vs 11 in salmon). Hunted fish are a better source of n-3 polyunsaturates than are cultured fish.

The administration of desoxycorticosterone acetate (DOCA) induces morphological changes in the kidney of mice and eels. Such changes mainly concern the cells of the distal tubules and collecting tubules. These changes are consistent with the hypothesis that the hormone would exert a different action in Mammals and in Teleosts.