The bigeye thresher, Alopias supercilious,is commonly caught as bycatch in pelagic longline fisheries targetingswordfish. Little information is yet available on the biology ofthis species, however. As part of an ongoing study, observers sentaboard fishing vessels have been collecting set of information thatincludes samples of vertebrae, with the aim of investigating ageand growth of A. supercilious. A total of 117 specimenswere sampled between September 2008 and October 2009 in the tropicalnortheastern Atlantic, with specimens ranging from 101 to 242 cmfork length (FL) (176 to 407 cm total length). The A. supercilious vertebraewere generally difficult to read, mainly because they were poorlycalcified, which is typical of Lamniformes sharks. Preliminary trialswere carried out to determine the most efficient band enhancementtechnique for this species, in which crystal violet section stainingwas found to be the best methodology. Estimated ages in this sampleranged from 2 to 22 years for females and 1 to 17 years for males.A version of the von Bertalanffy growth model (VBGF) re-parameterisedto estimate L0, and a modified VBGF using a fixed L0 were fittedto the data. The Akaike information criterion (AIC) was used tocompare these models. The VBGF produced the best results, with thefollowing parameters: Linf = 293 cm FL, k = 0.06 y–1 and L0 = 111 cmFL for females Linf = 206 cm FL, k = 0.18 y–1 and L0 = 93 cm FLfor males. The estimated growth coefficients confirm that A. supercilious isa slow-growing species, highlighting its vulnerability to fishingpressure. It is therefore urgent to carry out more biological researchto inform fishery managers more adequately and address conservationissues.

The technique already adopted by the authors for the cryopreservation of rainbow trout blastomeres was applied to carp. Three stages were utilised for cell freezing: the morula stage, the early blastula stage and the late blastula stage. Survival rates were 89 ± 1.6 % for morula cells, 94 ± 0.6 % for early blastula cells and 96 ± 0.4 % for late blastula cells. Early blastula and late blastula cells reaggregated into morula-like bodies within 2 h in culture medium. Results suggest that the freezing technique adopted for rainbow trout may be successfully applied to carp. The morula stage blastomeres were more sensitive to freezing than blastula stage blastomeres, as already found in rainbow trout.

Oil spills can have direct effects on organisms (mortality or morbidity), indirect effects (through alteration of lower trophic levels) or be associated to exposure to trace elements contained in oil (markers). An effect of the “Erika” oil spill was investigated by spatio-temporally comparing mortality, population structures, diets and concentrations of vanadium, nickel and porphyrines in small delphinids, seals and otters from the French Atlantic coasts. These species might differ in their vulnerability to oil. Changes in mortality and its demographic structures were within previously observed ranges. The diet of the common dolphin showed an extended period of high inter-individual variability in the year 2000. Vanadium concentrations in delphinids were chronically high, but did not increase significantly after the oil spill. Porphyrins concentrations in seals and otters were low suggesting a limited exposure to contaminants, but the ratio between proto- and copro-porphyrins in otter spraints from oiled vs. unoiled sites varied significantly. No measurable effect of the “Erika” oil spill was found in dolphins and seals.

A method to assist the reading of calcified structures with digital images is proposed. An a priori growth pattern is introduced in the image processing to take into account both the variability of the ring size and the non-linearity of their growth. The introduction of biological knowledge is performed within a demodulation processing using the reciprocal growth function. The ring number is estimated by spectral analysis. The constraints introduced by the growth model are weak since they are restricted to the definition of L0, in the case of an exponential model, or of L∞ in the case of a Von Bertalanffy model. When applied to larval Dover sole otoliths (Solea solea) results close to the expert's are obtained. In the case of saithe otoliths (Pollachius virens) the mean discrepancy with the expert's, i.e. 1.5 years, can be assigned to the lack of processing of marginal rings and to the inadequacy of the morphogenesis model on which the processing algorithm is based. This approach which is only founded on the dynamic features of the "biological signal", will have to be completed in future work with the introduction of structural information.

Selection, hybridization, and genome manipulation in the Siluroidei is reviewed. Selection topics include strain evaluation, qualitative traits, quantitative traits, mass selection, family selection, inbreeding, and crossbreeding. Hybridization is discussed with reference to culture traits. Genome manipulation technologies-sex reversal, gynogenesis, androgenesis, polyploidization, and gene transfer-are considered with application to genetic improvement of Siluroidei. Strains of ictalurid catfish Vary significantly for traits such as growth, disease resistance, harvestability, reproduction, body conformation and carcass yield. Growth of domestic strains can be 250% greater than that of wild strains. Strain differences have also beenidentified for clariid, bagrid, and silurid catfishes. Mass selection has increascd growth rate by up to 30%. Heritability estimates predict a response to selection for the traits of disease resistance and tolerance to low oxygen levels. Crossbreeding strains of Ictalurus punctatus have improved growth, disease resistance and reproductive performance. Two generations of inbreeding depressed body weight of I. punctatus as much as 30%, and can reduce viability and reproductive performance. Hybridization of I. punctatus X I. furcatus has resulted in a 20% increase in growth. Traits for tolerance to oxygen deficit, feed conversion, disease resistance, harvestability, and carcass yield were also improved. Interspecific, intergeneric, and interfamilial hybrids have been made with clariid fishes; heterotic growth was indicated. Hybridization has also been used to combine desirable traits of parental species. Sex reversal of I. punctatus using estrogen treatment followed by progeny testing can result in monosex, all-male populations. Gynogenesis and androgenesis are approaches to production of inbred lines of catfish, but thus far have limited application in aquaculture. Polyploidization has been applied in several ictalurid, silurid, and clariid fishes, but predicted improvements in performance have not been realized. Gene transfer has been accomplished in I. punctatus and Clarias gariepinus using microinjection and electroporation; the foreign genes have been expressed and inherited. Transgenic I. punctatus containing salmonid growth hormone genes grew 20–40% faster than controls.

The objective is to study different factors of variations in the body shape of trout (Salmo trutta) belonging to the Mediterranean lineage (indigenous trout) or Atlantic lineage (introduced trout), and their hybrids. Using thin plate-spline (TPS) method by pointing landmarks, it made possible to provide a graphical representation of the characteristic conformation of the individuals. The characteristics of form highlighted let appear – that the male trout have a dorsal part more prominent than that of the female trout and a larger head – the existence of a general curvature of the body related to the size of trout, independently of the sex. In addition, characteristics of form provide satisfactory results to distinguish the Mediterranean lineage from the Atlantic lineage. The recognition of hybrid trout is more random because very near to Mediterranean trout. The existence of a sexual dimorphism could be established in spite of the absence of information on the sex. Comparative with the sexual dimorphisms in spawning period reveals morphological transformations during the reproduction, mainly for the males. Independently of the genotypic and sexual dimorphisms, a general curvature of the body related to the size was detected.

Competent larvae of 4 tropical reef fish species, i.e. two pelagic spawners (Parupeneus barberinus and Acanthurus triostegus) and two benthic spawners (Abudefduf sexfasciatus and Dascyllus aruanus) were collected over two years in Wallis Islands, in order to compare 1) their size and age at settlement, 2) the variability of these parameters and 3) their spatial and temporal variations. The larvae were collected in three sites approximately 10 km apart in September 2002, December 2002, March 2003 and June 2003. The otoliths were examined to obtain early life history information: pelagic larval duration and timing of settlement. Size at settlement varied from 3 mm for A. sexfasciatus, D. aruanus and A. triostegus to 10 mm for P. barberinus. For the benthic spawners, settlement occurred after 17 and 19 days within a narrow age interval (7 to 9 days) and mainly in the middle of the interval. For the pelagic spawners, settlement occurred later (after 35 and 42 days), within a larger age interval (13 days). These estimates are lower than those from other locations in the Pacific but their range is larger. Size at settlement differed significantly between sampling sites only for D. aruanus and between surveys only for A. sexfasciatus. Age at settlement differed significantly between sampling sites only for A. sexfasciatus and between surveys only for D. aruanus. For the pelagic spawners the variability of size and age within site and survey was up to ten times greater than for the benthic spawners. This flexibility would be an advantage for larvae of the pelagic spawners that have to travel greater distances to settle.

The availability of various dietary carbohydrate sources for juvenile giant freshwater prawn, Macrobrachium rosenbergii, was evaluated according to weight gain and body composition. Different carbohydrate sources, α-potato starch, soluble starch, dextrin, sucrose, glucose and glycogen were separately included in a purified diet. After 60 days the greatest weight gain was achieved in the groups fed potato starch or soluble starch. The group receiving glucose as the carbohydrate source had low weight gain. Food conversion efficiency and the protein efficiency ratio were higher in the group receiving soluble starch as the dietary carbohydrate source. Muscle lipid consisted mainly of phospholipids and partial glycerides; midgut gland lipids were composed of triglycerides and phospholipids. A change in dietary carbohydrates had a minor influence on muscle lipid levels but caused variations in lipid class composition of the midgut gland. Comparatively high levels of free fatty acids and phospholipids were found in the midgut gland of groups fed soluble starch and potato starch, respectively. No major differences in fatty acid compositions were apparent. Soluble starch and potato starch were efliciently utilized by the prawn as dietary carbohydrate sources.

Juveniles of the mussel Mytilus chilensis were exposed to a dietcontaining paralytic shellfish poisoning (PSP) toxins produced by the dinoflagellateAlexandrium catenella (strain ACC02). The feeding behaviour and thedynamics of intoxication and detoxification were evaluated over an intoxication period ofnine days, followed by a detoxification period of eight days. A significant reduction inthe feeding activity was measured during the first days of exposure to the PSP toxins(days 0 and 2), followed by a period of recovery observed on days 5 and 9, when theclearance rate of the contaminated mussels significantly increased. During thedetoxification period, the contaminated bivalves showed a total recovery of clearancerate, and no significant differences were observed between contaminated and controlgroups. The intoxication dynamic was characterised by a rapid and sustained increase inthe amount of PSP toxins accumulated in the tissues of the bivalves. Due to this increase,the level of PSP toxins critical for human consumption was reached on the first day, andat the end of the intoxication period, the mussels had accumulated 1601μg STX eq. 100 g-1 tissue. During the detoxification period, adecrease of PSP toxins was observed, down to 319 μg STX eq. 100g-1 tissue. The lower clearance rates observed over the first days ofexposure would produce a decrease in the energy intake and could affect the rate of growthof juveniles. Despite this initial effect, the rapid intoxication capacity of M.chilensis corroborates that this species is a good indicator for the earlydetection of harmful algal blooms.

Hoplosterum littorale (Hancock, 1828) shows a marked circadian rhythm of food demand. Feeding activity is mainly nocturnal, with two peaks, and is synchronized with the diel light cycle. We tested the effect of infradian (period >28 h) light/dark cycles on this rhythm in fish with demand-feeders: fish subjected to a 13.5 L/22.5 D light/dark cycle for 8 days and a 25.5 L/10.5 D cycle for a further 8 days showed a strictly nocturnal feeding activity, a response that only passively reflected the cyclic alternation of light and dark.

Manila clam (Tapes philippinarum) culture and sediment interactions were tested by comparing two rearing areas, including an oceanic (‘Le-Ferret’) and a more estuarine (‘Les-Jacquets’) sites in the bay of Arcachon (France). The growth of a calibrated clam population (10-mm spat) was monitored in these two areas with a concomitant sediment-water interface survey over a 1.5-year period. Two sites per area, including control and rearing plots, were sampled on a monthly basis. The potential clam farming impacts by bioturbation and interactions were examined at three sediment depths: 0−1, 1−2 and 2−10 cm. Moreover, the main hydrobiological parameters were measured on a weekly basis to establish a relationship between these parameters and sediment-water interface characteristics. The existence of a gradient between the three depths was revealed for most of the parameters examined, with the exception of silt and organic carbon levels, and this regardless of the area examined. Clam growth showed a rate improvement in the oceanic area, which is characterized by a lower silt content. The clam effect was minimal and the activity identified at the ‘Ferret’ site was in fact due to the presence of a net which acted as a particle trap. No significant relationship was established between water column parameters and those of the sediment-water interface at the two geographical sites examined. These results demonstrate that clam rearing had only a limited effect on the environmental sediment parameters (i.e. water percentage, and phaeopigments and silt levels) from a spatio-temporal point of view. Therefore, a return to environmental conditions existing before the implementation of clam farming is likely to occur upon cessation of this activity.

We investigated the impact of the “Erika” oil spill in the Bay of Biscay (France) on seabird populations. Relative abundance and spatial distribution at sea between 1980-1999 and 2000-2002 periods were compared. This study took place in a standardized monitoring at sea carried out with Coast Guard vessels following the line transect method. This work rests on 107 551 standardized counts of one minute before “Erika” and 23 449 after the oil spill. There was not a simple correlation between the number of individuals found oiled and the numerical variation of the populations at sea during the two years following the accident. The guillemot Uria aalge, the most frequently collected species in the north of the Bay of Biscay, showed no decrease in at sea abundance during the two years following the pollution. Conversely, some species found in small numbers on the coast (e.g. divers Gavia sp., razorbill Alca torda, common scoter Melanitta nigra) decreased significantly at sea (20 to 80%). Overall, marine bird populations declined significantly in the northern sector of the Bay of Biscay (48°32' to 46°58' north) and increased in the southern sector (45°13' to 43°15' north), whereas decreases and increases occurred in the central sector (46°57' to 45°14' north). Changes in the spatial distribution of the species after the “Erika” oil spill occurred through disappearance or retraction (Bay of Vilaine, Houat-Hoedic archipelago), or through displacement and reinforcement (Gouf of Capbreton). Overall, this suggests a redistribution of the populations within the Bay of Biscay, depending on the level of injuries to the ecosystems caused by the pollution.

Larvae of the coral reef damselfish Acanthochromis polyacanthus (Bleeker) were fed either unenriched Artemia nauplii or nauplii which had been enriched by pre-feeding with microcapsules containing either squid oil (SQO) or cod liver oil (CLO). Enriched nauplii contained elevated levels of the n-3 highly unsaturated fatty acids (HUFA) eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) which made up 5.22 ± 0.34 and 2.62 ± 0.28 %, respectively, of total fatty acids in nauplii enriched with CLO, and 10.48 ± 0.36 and 3.43 ± 0.33 %, respectively, in nauplii enriched with SQO. In contrast, unenriched nauplii contained EPA (5.03 ± 1.04 %) but did not contain DHA. Survival differed significantly between treatments over the 18-d study; larvae receiving CLO enriched nauplii showed 100 % survival and those receiving SQO enriched nauplii showed 93.3 ± 6.6 % survival. In contrast, only 46 ± 6.7 % of larvae receiving unenriched nauplii survived to the end of the 18-d study. Wet weight, dry weight and proximate biochemical composition did not differ significantly between treatments at the end of the study. Mean standard length of larvae fed CLO enriched nauplii was significantly smaller than that of larvae fed SQO enriched nauplii; however, neither differed significantly from larvae fed unenriched nauplii. The fatty acid composition of A. polyacanthus larvae was significantly influenced by the fatty acid composition of the diet. The results indicate that A. polyacanthus larvae are unable to synthesise DHA from available dietary precursors and, as such, dietary DHA is required to maximise survival. Development of appropriate culture techniques for the larvae of coral reef fishes will allow controlled laboratory studies with these species and may eventually reduce pressure on wild populations exploited for the aquarium trade.

Daily growth increments measured in the otolith of Thunnus atlanticus were used to estimate the age and growth of individuals, which were sampled from an artisanal fishery operating around fish aggregating devices (FADs) moored off Martinique Island. In this study, 76 otoliths were analysed for fish ranging from 20 to 68 cm fork lengths (FL). The fish were caught using trolling lines at depths ranging from 0 to 10 m. Counts were made, under a light microscope, on the external part of the transverse section of the sagittae, from the primordium to the ventral edge. The mean coefficient of variation of the age reading was 2.4%. To validate readings, the number of increments for 11 individuals was counted using both optic and scanning electron microscopes. The calculated relationship between readings of both methods was found to be linear, with a slope of 1.03 and R2 = 0.99. Frequency of growth increment formation could not be validated. Growth rates derived from otolith readings were, however, compared to those obtained using a modal progression analysis, which was performed on the length-frequency distributions of the landings over a period of two months. The corroboration between the growth rates was good. One increment was assumed to represent one day. The parameters of the von Bertalanffy growth curve for both sexes were L∞ = 71.4 cm FL, k = 0.002 day−1 and t0 = −80 days. According to our results, there is no evidence that Martinican moored FADs act as ecological traps for blackfin tuna. Instead, young blackfin tuna probably leave the vicinity of Martinican moored FADs to undergo a trophic migration at 7 to 8 month-old, and then come back about 8 months later to breed in the Lesser Antilles area.

The factors affecting spatial distribution of the ormer (Haliotis tuberculata L.) in the vicinity of Saint-Malo (northern Brittany, France) are analyzed using a multivariate approach. A correspondence analysis is applied to a contingency table based on 200 samples. Ormers are always absent from smooth rocky substrata, exposed to a strong current or deeper than 8 m below low chart datum. Abundance and biomass of H. tuberculata are distributed along a gradient correlated with an increasing complexity of habitat and a reduction of current. Otherwise, no correlation has been found between characteristics of ormer distribution and surge, depth or large and turf algae.

La production aquacole de Siluroidei en Europe concerne le silure glane (Silurus glanis), indigène, et des espèces introduites assez récemment, comme le silure africain (Clarias gariepinus ) ou les poissons-chats américains tels que Ictalurus punctatus, I. nebulosus et I. melas. Quelques tentatives de production expérimentales d'Heterobranchus logifilis et H. bidorsalis sont aussi en cours. Les différentes espèces de Siluroidei sont produites dans des systèmes d'élevage variés, en monoculture dans les circuits en eau chaude, fermés ou non, en polyculture d'étang ou en systèmes intensifs en cages ou en bassins. Les Clariidés sont le plus souvent produits dans des circuits fermés thermorégulés du fait de leurs exigences vis-à-vis de la température, mais quelquefois en étang, lors de la saison chaude. Les Ictaluridés sont élevés en étang en conditions intensives ou semi-intensives. le silure glane est produit soit en polyculture d'étang comme carnassier d'accompagnement, soit en eau chaude (effluents thermiques ou sources géothermiques), les circuits fermés thermorégulés étant de plus en plus abandonnés. En France particulièrement. des systèmes de production intensive en bassins sans renouvellement d'eau ou avec lagunage des effluents tendent à se développer; les coûts de production y sont relativement bas et les rejets dans l'environnement quasi-inexistants.La production de Siluroidei en Europe, peu importante actuellement, ne concerne que peu de pays, notamment, l'Allemagne, la France, l'Italie, la Belgique, la Hongrie, la République Tchèque et les Pays-Bas. les chiffres font apparaître des évolutions de la production de Siluroidei très variables suivant les espèces et les pays (évaluation de la quantité totale produite en 1993 : environ 4 195 tonnes, dont 2 080 tonnes de I. melas, 1 210 tonnes de C. gariepinus, 602 tonnes de S. glanis, 302 tonnes de I. punctatus).En Europe orientale, la consommation de Siluroidei est en régression, du fait du renchérissement du coût de production et de la baisse du niveau de vie mais aussi de la difficulté d'exporter vers l'Union européenne.En Europe de l'Ouest, la transformation du poisson sous forme de filet (près de 90 % de la production de (C. gariepinus) permet d'améliorer la commercialisation des Silures en conquérant des marchés dont il reste toutefois à préciser l'importance. Les caractéristiques de la chair des Siluroidei (chair blanche sans arêtes intramusculaires, bon rendement, qualités organoleptiques) augurent favorablement d'un développement de la production en Europe dans les années à venir.

Successful commercial production of most cultured fish species has been facilitated by the intensification of larval rearing techniques. Siluroidei species are no exception and early attempts at larval rearing in ponds were soon superseded by intensive hatchery production, at least for those species that are farmed on a commercial scale. The review focuses on alternative life history strategies and how these may provide clues to the early nutrition and feeding of siluroid fishes, as well as on the development and efficacy of practical feeds and feed application. The paper highlights several commonalities in terms of the nutritional and feeding requirements of the larvae of the various species cultured on a commercial and subsistence basis. The requirement for live feed for some species appears to be of short duration and all species can be successfully weaned onto dry feed at a relatively early stage. This is considered to be one of thereasons why the intensification of larval rearing of Siluroidei fishes has, in general, been highly successful. The review also comments on the live food/dry food debate and clearly reveals that our knowledge of Siluroidei larval nutrition and feeding is sorely lacking for many species, in comparison to other groups of fish. This emphasises the need for a concerted fundamental research effort.

The presence of piscivorous fish has a significant effect on the structure of fish assemblages. Exotic, piscivorous largemouth bass (Micropterus salmoides) have been introduced to a number of Japanese farm ponds that were originally characterized by a high level of biodiversity. We evaluated the effects of exotic bass on the structure of the fish assemblage following their introduction into the farm ponds. We collected fish and measured environmental conditions in 14 ponds of northeastern Japan. The species richness of pond-dwelling fish assemblages was negatively correlated with the relative abundance of exotic bass. In addition, the relative abundance of lentic cyprinid species (e.g., Rhodeus ocellatus ocellatus, Pseudorasbora parva and Carassius sp.) was negatively correlated with the relative abundance of exotic bass. The abundance of these species was also influenced by environmental factors, including transparency and/or coverage of aquatic vegetation, likely related to their influence on the predatory efficiency of exotic bass. Our results suggest that the structure of fish assemblages in farm ponds with exotic piscivorous fish was influenced by both biotic (i.e., predation) and abiotic factors and that some environmental factors mediate the effects of exotic bass on fish species richness and composition.

The diel vertical migration of fish and larvae of the phantom midge Chaoborus flavicans was studied using a combined 38 and 200 kHz echo sounder. Multi-mesh gill net was used to sample fish, and a Schindler-Patalas trap to sample Chaoborus. Oxygen and temperature profiles were also recorded. At 38 kHz, only fish were detected, without considerable interference from Chaoborus echoes. At 200 kHz, both fish and Chaoborus were detected and echoes from Chaoborus almost completely masked all fish echoes at night. During the day, Chaoborus remained hidden in an oxygen-poor refuge near the bottom. Tracks of fish diving into the Chaoborus refuge were observed on several occasions. At the onset of dusk, Chaoborus started to rise and by the time it was dark they were occupying the whole water column. Fish were found in patches in midwater during the day. In the dark, the fish were dispersed throughout the water column. Results suggest that a dual-frequency approach can be used to discriminate between fish and Chaoborus and to provide a rapid method for their selective monitoring.