About 60 papers and reports dealing with heavy metal contents in different eel species were reviewed in order to document various patterns of uptake, elimination and accumulation of these metals and to underline their detrimental effects (lethality, histo-pathology). Two main toxicological topics were considered: observations on contaminant levels in eels taken from the wild, mainly from contamined waters, and experimental studies under laboratory conditions.

Les caractéristiques biologiques des civelles (Anguillaanguilla) ont été étudiées entre novembre et mars lors dedeux campagnes d'échantillonnage successives (1996–1997 et1997–1998) dans l'estuaire de l'Adour. Une diminution de lalongueur (en moyenne de 73,5 à 67,4 mm) et du poids (en moyenne de 3,5à 2,6 dg) des civelles durant la saison de migration est observéecomme sur les autres estuaires. Différents groupes de civelles peuvent êtreidentifiés au cours de chaque saison étudiée. Les variations ducoefficient d'allométrie statique et de l'indice de similaritéindiquent l'arrivée successive de différents flux dans le bas estuaire. Cesgroupes sont bien différenciés lors de la première campagne alorsqu'ils se chevauchent dans le temps lors de la seconde. La conjonction deforts débits fluviaux et de faibles coefficients de marée induit desconditions de migration défavorables pour les civelles qui pénètrenten estuaire. Après accumulation des bancs de civelles dans la partie basse del'estuaire, quand les conditions hydrologiques redeviennent favorables, les bancsmélangés remontent vers l'amont par « vagues »successives, au rythme des marées.

Bycatch in longline fisheries is considered one of the main threats for the conservationof albatrosses and petrels worldwide. However, the relative impact of fisheries on all theaffected populations or species still remains poorly understood. This paper applied aProductivity and Susceptibility Analysis (PSA) and the concept of “Potential BiologicalRemoval Level” (PBR) to assess the relative impact caused by the Uruguayan pelagiclongline fishery on several populations. This two-step approach allowed us to obtain anobjective view of the relative impact of the Uruguayan pelagic longline fleet on most ofthe populations or species of albatrosses and petrels with high association with thisfishery. Of fifteen species considered, fourteen were finally assessed and a ranking ofrisk derived. The concept of PBR was applied to the nine most at-risk species. The impactof fishing on populations could not be straightforwardly inferred from their bycatchrates. Results indicate that large albatrosses (Diomedea spp.) andThalassarche chlororhynchos are more affected than some of the mainspecies caught by the fishery (i.e. Thalassarche melanophrys andProcellaria aequinoctialis). Diomedea exulans fromSouth Georgia is likely to be the population most affected by the Uruguayan fleet. Thiswork should be seen as a case study of the fisheries operating in the southwesternAtlantic. The Uruguayan fleet within its operation area was responsible for only the 4.3%to 12.5% of the total annual effort deployed by the different fleets during 2004–2008. Thecombined impact of these fleets could be sufficiently high to account for many of theobserved declines in the populations of D. exulans, D. dabbenenaand T. chlororhynchos. However, the seabird bycatch numbers formost of the pelagic longline fleets that operate in the southwest Atlantic remain unknown.Applying mitigation measures to reduce the impact of pelagic longline fleets operating inthis region should be considered a high priority.

A simulator dedicated to the modeling of individual search behaviors of fishing vessels has been built using multi-agents systems methodology. The harvesting activity of a virtual fleet is simulated and applied to a static virtual fish population, distributed in a bi-dimensional spatially explicit environment. The resource population can differ depending on different degrees of aggregation. Each vessel of the fleet is modeled as a singular and autonomous agent of the fishery system. The model focuses on the representation of information transfer among vessels, which results in an orientation of search effort. The informative search behavior is compared to a stochastic search, in order to estimate efficiency gains allowed by information transfers. Results show a strong dependence of the fleet's efficiency towards the level of aggregation of the resource. For higher levels of aggregation the informative behavior results in important gains in efficiency. Conversely, a misleading effect of information appears in the weakest aggregations. The informative behavior leads to the progressive convergence and the gathering of the agents. When the aggregation is strong, this “pack effect” is stable in time and enables the vessels to make quick catches. For the weakest aggregation levels, the “pack effect” is unstable and leads the ships to a perpetual pursuit state, without catches. Thus, the size of existing networks appears as a key parameter of vessel behaviors. This approach, using an individual-based simulator, seems quite appropriate to connect individual behaviors to the dynamics of the fishing efficiency, which are generally studied in an aggregated manner. It allows to quantify the effects of the exchange of information among vessels, which is commonly considered as a qualitative phenomenon. Such an approach should be enlarged to a more global modeling of all of the components of the individual search behaviors of vessels.

In order to elucidate the population structure of the deep-sea shrimp (Pandalus borealis) in the NE Atlantic, 32 subsamples and 3865 individuals were analysed for allozymic variation. They were caught at various locations in the Barents Sea, in waters off Svalbard, Jan Mayen and Iceland, and in fjords along the Norwegian coast. Only three enzymes (malate dehydrogenase, phosphoglucomutase and glucosephosphate isomerase) of the 22 initially tested showed a combination of gel images that could be interpreted with confidence and allozymic variation. The locus coding for malate dehydrogenase was by far the most polymorphic. Samples caught within the Barents Sea and in the Svalbard area showed no significant heterogeneity in allele frequencies, supporting earlier suggestions of only one population of P. borealis in the Barents Sea. Genetic differentiation was found, however, between Norwegian fjords and the Barents Sea, and among fjords.

Historically, nation-state level fisheries management has relied primarily on the disciplines of biology, ecology, and to some extent economics – usually in some combination, and with varying degrees of emphasis and success. Recently, as an increasing number of fisheries have begun to experience severe declines there has been increased interest in how social scientists might help to address some of these problems. In managing fisheries, it is humans who must be understood and managed. Furthermore, some managers have begun to question the view of biological conservation as the primary goal of management, sceing economic and social goals as equally important. Social science studies of fisheries indicate that not all members of a given user group operate in the same way, or have the same impact on marine ecosystems. People's behavior is often influenced by family, community, and other sociocultural variables in addition to economic and cological considerations. Using the perspectives and methodologies derived froin disciplines such as anthropology and sociology, fisheries managers should be able to develop policies which integrate and balance economic, social and biological objectives. Management systems which are more compatible with broad user group values should result in higher coinpliance and reduced enforcement costs.An overview of recent social science research pertaining to fisheries management is discussed, andexamples presented on the relevance of social science information in crafting successful managementregimes.

The objective of the study was tu evaluate the capacity of rainbow trout to discriminate diets containing micro-granulated or powdered novel fluoroquinolone in comparison with a positive (containing sulfamerazine sodium) and a negative control (placebo). In a first trial, groups of trout had access to a self-feeder containing the placebo feed for 10 days, and then to one of the four feeds during another period of 10 days. Fish reduced their voluntary feed intake (VFI) by more than 50 % when they had access to the positive control, and by more than 20 % when they had access to feed containing micro-granulated premix. There was no significant decrease in VFI when the fish had access to feed containing powdered premix, but in this latter case, an increase in feed refusals was observed. In a second trial, the capacity of the trout to discriminate between two self-feeders containing different feeds was tested. During a first period of 10 days, all the feed hoppers were loaded with the placebo feed, to determine the feeder preference relative to any dietary-independent factor. In the following period of 10 days, fish had access simultaneously to the two medicated fecds. During a third period of 10 days, a validation of the results was attempted, using the placebo feed or the positive control in one of the feeders. It was shown that trout were able to discriminate between the two medicated feeds and that micro-granulated premix was better accepted than powdered premix. In addition, an increase in feed refusals was observed when the preferred feeder was loaded with feed containing powdered premix. It is concluded that this tested fluoroquinolone could decrease significantly VFI. The powdered premix was more detectable by the fish than the micro-granulated premix and led to some refusals.

An advection diffusion reaction model was used to estimate movement and tag attrition parameters from skipjack tuna tagging data off the Maldives. Two sets of data were available from the experiments carried out during two distinct periods: 1990–1991 and 1993–1995. The results of the analysis were compared with the previous analyses and discussed in relation to management of skipjack fisheries in the Maldives and in the Indian Ocean. The movements were found to be highly variable in space and time, and few consistent patterns were observed between the two data sets. Similarly, significantly different estimates of fishing and natural mortality rates were observed from the two data sets. These differences were found, in part, to be due to the uneven distribution of tag releases in both space and time. Estimates of movement and attrition rates show that emigration from the Maldivian fishery to the rest of the Indian Ocean’s was small. The exploitation rate was found to be substantial, contributing about 30-40% of the total attrition in the fishery area. Such levels of localized exploitation may be maintained by steady immigration from outside of the Maldives, but more extensive tagging is required to be certain. The impact of tuna fisheries elsewhere in the Indian Ocean on the domestic Maldivian fishery cannot be determined until a comprehensive large-scale tagging program, including all the fisheries in the Indian Ocean, is completed.

Foraging activities of goosanders (Anatidae, Mergus merganser) were studied in relation to seaward migration of smolt in the River Halselva in northern Norway, 1987-1989. Birds aggregated in the estuary in June, during mass migration of smolts. When present in the estuary males and femalesspent 28.7 and 35.6% of their time feeding. Only 15% of dives resulted in birds' bringing prey to the surface and about 25% of prey found in goosander stomachs were salmonids. For hatchery-reared smolts released in the estuary, average length taken did not differ from that available; for wild smolts of Arctic char, however, smaller fishes than those available were taken. For 1989, we estimate that goosanders took 1% of the hatchery-reared smolts released in the estuary, and 2% of the wild smolts when smolts passed the estuary during seaward migration. As it is likely that less fit smolts (e.g. sick, injured, small) are most prone to predation, we argue that such a level of predation on migrating smolts from goosanders has only a minor impact on salmonid production. Suggestions to reduce predation are discussed.

Atlantic salmon juveniles were subjected to a precocious (day 104 after first feeding) photoperiodic (P) and thermic (T) control. After rearing the fry at 16 °C, constant (16 hours of light and 8 hours of darkness, 16 °C) (C) and shortened simulated natural S photoperiod and temperature regimes were used in a factorial experimental design until transfer to seawater. The growth obtained with constant (C) regimes was better than with S regimes. In all cases, we observed very early (day 141, mid-June) a clear segregation of the population into two different subpopulations. Among the conditions, all the differences between the upper and lower modes were growth-dependent. We observed different developmental trends of the gill (Na+-K+)-ATPase activity: the S regime gave a very progressive increase of the enzymatic activity, while we had a rapid decrease after a first phase of increase with a constant photoperiod. The absolute levels of the gill (Na+-K+)-ATPase activity were slightly lower than those observed in one year-old smolts. However, they are quite similar to those of upper-mode fish that have a good salinity tolerance. After transfer to seawater, fish subjected to shortened simulated temperature and photoperiod had the lowest mortality and osmotic disturbance (after 48 hours and 3 weeks). Although the freshwater phase generally lasts more than 15–17 months for this species in a natural environment, we concluded that it is possible to obtain a good salinity tolerance after 7–8 months, with shortened simulated natural photoperiod and temperature regimes, in spite of the absence of a real smoltification; these regimes, however, must be applied during the "dynamic" presmolting phase when the growth is intense.

The Rideau Canal in Canada was constructed in the 1800s to enable strategic military andcommercial transport in eastern Ontario between Lake Ontario and the Ottawa River. Today,the Rideau Canal is managed by Parks Canada and remains an engineered ecosystem,particularly in the urban Ottawa reach (7 km long) where it is largely channelized and ispartially drained during the winter to protect canal infrastructure (i.e., locks) andprovide recreational opportunities (i.e., skating). Interestingly, the Ottawa reach of theRideau Canal supports one of the few wild urban muskellunge (Esoxmasquinongy) fisheries in North America supported by natural reproduction.However, little is known about the spatial ecology, residency patterns or survival of thisapex freshwater predator in urban environments or canal systems. Radio-telemetry was usedto study adult (N = 10; total size range of 64 to 122 cm) muskellunge inthe Ottawa reach of the Rideau Canal over a multiple year period. The seasonal movementsand home range of muskellunge were greatest during spring corresponding with the periodwhen water levels in the canal were raised and muskellunge were presumably seeking outsuitable spawning habitats following ice-off. During the summer fish ranged throughout theentire 7 km urban reach of the canal and by early fall muskellunge moved to the deeperparts of the reach and became largely restricted to an embayment known as Dow’s Lake priorto the lowering of the canal where they stayed for the entire winter. The same pattern ofseasonal movements persisted across several years. None of the tagged muskellunge werestranded from the fall canal drainage. One fish emigrated from the urban reach of thecanal during the study period, moving upstream through a lock to an exurban reach. Inaddition, a single tagged fish died from a winterkill event. Environmental influences suchas seasonality and water depth (associated with canal operations) are believed to be theprimary mechanisms contributing to habitat selection and movement patterns of muskellungein this reach of the Rideau Canal. Data on the spatial ecology of muskellunge in the urbanreaches of the Rideau Canal will inform management of this unique population of fish toensure that the historic and ecological values are balanced to preserve this iconicCanadian natural heritage site and its biota.

The present paper suggests a method for estimating the fishing power of vessels and for analysing fleet dynamics. The approach is based on quantification of stocks catchability (q), derived from fishing mortality coefficients (F) as calculated by virtual population analysis. Catchabilities for each harvested stock are thus estimated relatively to the fishing effort (fn) of each vessel, according to the equation: q = (F/fn). A linear model is then fitted to these catchabilities. The model allows the identification and quantification of trends in average mortality rates per fishing hour for each stock. Under some assumptions, trends are interpreted as variations in the overall fishing power of each fleet. The approach is applied to three industrial and semi-industrial fleets of Brittany (Lorient, Concarneau and Douarnenez) and to the main gadoid stocks they exploit off the west coast of Scotland (ICES area VIa), and in the Celtic Sea (ICES area VIIf,g,h) for Concarneau. Results show large variations in fishing power. Particularly, a marked increase trend in the fishing power exerted on saithe (Pollachius virens) is highlighted for the three fleets, over the period 1983-1989. These variations can be explained by the redirection of fishing strategies, which may occur on a large scale. Thus, we show how the collapse of saithe stock at first led the three fleets to intensify the harvesting of saithe, and from 1989 on, to adopt different strategies. The possible causes of the observed dynamics are discussed, as well as their consequences for fisheries management. In particular, the relevance of direct control of fishing effort as a regulatory tool is questioned.

The commercially important fish which contribute substantially to the total inland fish production in South Asia areAurichthys aor, A. seenghala, Mystus cavasius, M. gulio, Rita rita, Wallago attu, Ompok bimaculatus, Heteropneustes fossilis, Clarias batrachus, Silonia silondia and Pangasius pangasius. These are widely distributed in all the South Asian countries; Pakistan, India, Bangladesh, Sri Lanka and Myanmar except Bhutan and the Maldives. In comparison to carp culture, catfish culture has just begun in the region. Techniques of seed production have been standardized in C. batrachus, H. fossilis and W. attu which can be spawned even repeatedly at short intervals of 30-40 days. Such methods are, however, in an experimental stage for other species. C. batrachus is the most popular and its traditional culture in rice fields is well known. It is now being incorporated in carp ponds and semi-intensive and intensive monoculture systems have also been developed. The species fetches a very high price in India and Bangladesh and has a great export potential. C. macrocephalus and C. gariepinus have been introduced in Bangladesh with considerable success but their impact on the indigenous species needs to be studied.A vast grow-out potential exists all over the region for small catfish in carp nurseries as a second crop. Extensive culture of large catfish in derelict ponds could be an intermediate step in their improvement through control of all trash fish. With increased seed availability, semi-intensive and intensive mono-culture systems, being tried experimentally, could be developed in the view of an industrial production of catfishes as new export items from the region, if conditions for proper water quality management, aeration and partial replenishment, and availability of adequate pelleted feed could be met.

Time-area closures have become a frequently used tool to control fishing effort and protect feeding and spawning areas. However, because time-area closure strata are mainly based on biological and ecological considerations, and do not accounts for fishermen’s behavior-at-sea, this type of regulation tool may not entirely achieve its objectives. With the aim of comparing the impact of two different time-area regulations: (1) a moratorium on Fish Aggregating Devices (FAD) sets (1997–2005) and (2) a no-take area for surface fleets (2005–2010) on the dynamics of the European (EU) tuna purse seine fleet operating in the eastern tropical Atlantic, several fishery indicators were evaluated through a Before-After, Control-Impact (BACI) approach. The results showed that prior to any regulation, the fleet used to be concentrated within the Gulf of Guinea area. During the first years of the moratorium on FAD (from November to January within a large region in the eastern Atlantic) there was a movement towards outside the protected area, increasing the total sets on FAD (restricted fishing activity). In general, this moratorium fulfilled its objectives; however, it was not respected during the last years of this regulation. The no-take time-area closure restricted all tuna catches for the surface fisheries but only in November and within a small area (i.e., the Picolo zone). As a result, there was an increase in activities on free schools outside the no-take area. Our findings suggest the use of some simple fishery indicators to understand fleet dynamics as a complement of ecological information before implementing new time area closures. Furthermore, since tunas are highly mobile species, anticipating the possible re-allocation of effort of purse seiners to adjacent areas in response to the spatial regulation is required to design different candidate time-area closures and to evaluate their effectiveness to protect juvenile tunas.

The in vivo distribution and fate of 14C-cholesterol injected in prepuberal female prawns, Penaeus japonicus Bate, intact (E+) or deprived of their eyestalks (E−), were investigated. Animals were injected at the beginning of the experiment. Three days later, half of them (24 specimens) supported bilateral eyestalks ablation within a 48 hours period. Four days after the ablation, the ovaries of eyestalkless animals were relatively more developed than those of intact animals as seen by the increase in ovarian weight. The total content 14C-cholesterol and/or its metabolic products (total dpm) in whole animals was not significantly different between the two lots of animals and remained nearly constant throughout the experiment.

Distribution of radioactivity (dpm/mg wet weight of tissue) in carcass, muscle, gut, hepatopancreas,eyes and eyestalks and ovaries from E+ and E− after 192 hours of 14C-cholesterol injection indicate that ovaries presented the highest concentration of label (6 to 40 times higher than other organs) while these differences were not statistically significant between E+ and E−. The study of incorporation of 14C-cholesterol in those organs from E+ and E− independent of their volume, expressed as percentage organ radioactivity/whole animal radioactivity, at different time points, indicate that major accumulation was achieved by the carcass and muscle although radioactivity in the muscle progressively increased in inverse correlation with the decrease observed in the carcass. Hepatopanereas, eyes and eyestalks, gut and ovaries showed small incorporation that was kept constant with time in eyes and guts and significantly decreased in ovaries and hepatopancreas. At 192 hours after 14C-cholesterol injection there was an apparent increase in 14C label retention in ovaries from E− compared to E+ that was not statistically significant.

Results indicate that the ovary is presumably the major site of cholesterol metabolism followed bythe hepatopancreas. Muscle seemingly is the major site for storage of large amounts of cholesteroland/or its metabolites while eyes and gut have negligeable retention. Furthermore, in our experimental conditions, the requirement for cholesterol in different tissues does not vary significantly with eyestalk ablation suggesting that the phenomenon could be independent of ovarian maturation and moulting.

The ultrastructure of spermatozoon and sperm production were observed in wolffish (Anarhichas lupus), a species with internal fertilization, from a broodstock. The mature spermatozoon has an elongated head, eccentric flagellum, and comparatively well developed middle piece. Based on the observations of sperm cells with the optical microscope, the mean lengths of spermatozoon head and flagellum were 3.3 and 21.2 μm respectively. A high variability of sperm cell size was observed due to the presence of spermatids and degenerated spermatozoa in the ejaculate. In most males, sperm production was registered throughout the whole year with a peak in December and January. Sperm production decreased to the end of the breeding season. The difference in volumes of ejaculate and sperm concentrations between males kept at two light cycles (18D: 6L and 6D: 18L) was not significant. Features of wolffish sperm are compared with data reported in the literature on other internally and externally fertilizing fish.

La diversité spécifique est généralement considérée comme un facteur-clé de la résilience des écosystèmes en réponse à la pression anthropique et notamment à la pression de pêche. Dans cet esprit, on analyse ici l’impact de la pêche sur la diversité spécifique, à partir du cas des ressources démersales côtières de Guinée. Celles-ci ont la particularité d’avoir subi récemment un très rapide et important accroissement de la pression de pêche. En une quinzaine d’années, on est ainsi passé d’une situation dans laquelle les ressources démersales étaient considérées comme étant « à l’état vierge », à une surexploitation globale. Cette évolution mérite d’être considérée comme un « modèle accéléré » de l’histoire d’une exploitation. L’analyse se fonde sur les données de 18 campagnes scientifiques de chalutage démersal effectuées dans la zone côtière guinéenne entre 1985 et 1992. Le niveau de diversité spécifique, par campagne ou par trait de chalut, est quantifié par des indices synthétiques : la richesse spécifique, la diversité de Shannon et l’équitabilité. Les indices par trait de chalut sont analysés par les méthodes de modélisation en analyse de variance, afin de dégager une évolution temporelle des indicateurs. Les diagrammes rang/fréquence de chaque campagne sont également établis. On montre que les indices de diversité et d’équitabilité restent sensiblement constants, alors que l’abondance et la richesse spécifique diminuent significativement au cours de la période. Les espèces les moins abondantes et particulièrement des espèces de la communauté à Sparidés, tendent ainsi à disparaître des prélèvements. Enfin, l’année 1989 présente des indices de diversité faibles, liés à des conditions environnementales favorables pour certaines espèces entraînant un recrutement exceptionnel de celles-ci. La pertinence des indices utilisés est discutée.

The underwater sound of R/V "Johan Hjort" as a function of aspect angle has been mapped by cruising along parallel transects at various distances from the recording unit. At frequencies over 125 Hz there was a minimum in front of the vessel, and lobes of higher intensity on both sides. About 20% of the herring schools recorded during a survey in the North Sea seemed to react to the survey vessel. The distance at which the schools reacted varied from about 25 m and up to about 1000 m in front of the vessel. Within a sector of 20° on each side of the path of the vessel, the fraction of schools reacting increased to about 50%. Most of the schools that reacted seem to be herded in front of the vessel. This reaction pattern may indicate either that the schools reacted to the higher sound intensity to the side of the vessel or that the pattern occurred because of a "pursuit effect". Despite the apparent herding, more than 40% of the schools in front of the vessel were not recorded by the echo sounder. It is therefore argued that horizontal avoidance close to the vessel may have caused an underestimation of the biomass of herring of about 20%.

A deterministic, forecasting, equilibrium study has been conducted of the multispecies and multi-métier fisheries of the Celtic Sea, ICES divisions VIIf and g. Calculations have been made of the optimal fleet sizes and mesh sizes required to maximize objectives of joint relative sustainable yields, gross revenue and net revenue. The species modelled are the resident populations of cod (Gadus morhua), whiting (Merlangius merlangus), sole (Solea solea), plaice (Pleuronectes platessa) and Norway lobster (Nephrops norvegicus), with additional consideration given to catches of hake (Merluccius merluccius), monkfish (Lophius sp.) and megrim (Lepidorhombus whiffiagonis). The fleet métiers modelled are the beam trawls, Nephrops otter trawls and non-Nephrops otter trawls. If mesh sizes can be calculated independently foreach métier, then the yields and the gross revenue are maximized by increased effort and mesh sizes, especially in the non-Nephrops fleet. If a common mesh size is required for all fleets, then the yields and the gross revenue are maximized when (i) this mesh size is of 114 mm, (ii) the fishing effort in beam and Nephrops fleets is significantly increased, (iii) the non-Nephrops fleet is almost eliminated. Maximization of net revenue requires a mesh size similar to the current mesh of 80 mm, but with significant reductions of fishing effort in all fleets. Average profitability is increased by 50 millions EUROs per year for the Celtic Sea fishery. The model provides a basic structure for examining the management with a more realistic dynamic and stochastic description of the Celtic Sea fisheries.