This study was carried out to investigate the effect of feeding diets containing herring or anchvoy oil, on flesh quality parameters of Atlantic salmon (Salmo salar). Two extruded experimental diets with the same basal composition but one coated with herring oil and the other with anchovy oil, were each fed during 24 weeks to salmon with an average initial weight of 1.8 kg. Salmon grew to a final weight of 3.9 kg. Growth, condition factor and biometric parameters were not affected by the dietary treatment. No significant differences were found for intramuscular fat. Monounsaturated fatty acid (MUFA) concentrations were highest in the group fed the diet containing herring oil, in both neutral and polar lipids, while the group fed the diet containing the anchovy oil showed a higher concentration of n-3 fatty acids in both fractions of intramuscular lipids. The n-3/n-6 ratio was higher in the neutral lipid fraction of fish fed the southern hemisphere oil, while no significantly differences were found for the polar lipid fraction. No differences were found on muscle α-tocopherol levels. Muscle homogenates from fish fed the anchovy oil showed the highest thiobarbituric acid reactive substances (TBARS) after 9 days of storage. However no differences were found between groups on the induced oxidation tests. It is concluded that the origin of the fish oil has no effect on growth perfomance, but there is a marked effect on fatty acid composition and susceptibility to lipid oxidation.

Two 12-week feeding experiments were conducted in aquaria with juvenile blue catfish, Ictalurusfurcatus. In experiment 1, juvenile (6 g) blue catfish were fed one of four isonitrogenous (34% protein) and isocaloric (10.0 kJ of digestible energy/g of diet) diets containing 13, 9, 4, and 0% menhaden fish meal. Soybean meal was added in increasing percentages (48, 55, 62, and 69%) to the respective diets. Fish were fed all they would consume in 40 minutes twice daily (08:00 and 16:00). After 12 weeks, fish fed a diet with 13% fish meal had a significantly higher individual body weight than fish fed any of the other diets. There was no significant difference (P > 0.05) in body weights of fish fed the other four diets. No significant differences were found in percentage survival, feed conversion ratio, and protein efficiency ratio among treatments. In experiment 2, blue catfish (9 g) were fed one of five isonitrogenous (35% protein) and isocaloric (10.5 kJ of digestible energy/g of fiet) diets. Diet 1 contained 15% menhaden fish meal and 42% soybean meal. Diets 2-5 contained 0% fish meal and 69% soybean meal with various (0.0, 0.3, 0.6, and 0.9%) percentages of added L-methionine. Fish were fed as in experiment 1. After 12 weeks, individual weight, weight gain, survival, specific growth rate, and feed conversion ratio were not significantly different (P > 0.05) among treatments and averaged 36 g, 302%, 100%, l.6%/day, and 2.4, respectively. Whole-body compositions of fish were not significantly different (P > 0.05) among treatments and averaged 61% and 27% for percentage protein and fat, respectively. These data indicate that soybean meal can totally replace fish meal in a diet for blue catfish without supplemental L-methionine. This may allow producers to feed more economical diets without adverse effects on growth and survival.

The effect of short-time Artemia spp. feeding on growth performance and cumulative survival rate of barbel (Barbus barbus) larvae were studied under controlled aquaria conditions during the 21-day larval period. Three different diets (presenting reduced Artemia feeding) were tested for first exogenous nutrition of larvae (since 13 days post hatch): (1) artificial feed (Asta); (2) Artemia nauplii for 7 days followed by artificial feed; (3) Artemia nauplii for 14 days followed by artificial feed. The longer period of live food statistically improved growth of larvae (W = 174 ± 20 mg and SGR = 14.5 ± 0.5% d−1). The artificial dry food Asta without the addition of Artemia nauplii caused statistically decreased growth (W= 135 ± 22 mg and SGR= 13.1 ± 0.7% d−1). However, the growth of larvae with the short period of Artemia nauplii (W = 153 ± 25 mg and SGR = 13.8 ± 0.7% d−1) did not differ compared to either group. All used feeding diets did not have a significant effect on the cumulative survival rate of larvae ranging from 73 ± 1% to 74 ± 1% at the end of the larval rearing period.

The effects of the rearing environment on growth performance and survival rate of juveniles were tested under intensive controlled conditions in aquaria and troughs for 84 days following the larval period (from 34 to 118 dph). The environment of the troughs caused significantly decreased growth (W = 2079 ± 433 mg and SGR = 3.1 ± 0.05% d−1) of juveniles compared to ones reared in aquaria (W = 3236 ± 264 mg and SGR = 3.6 ± 0.1% d−1) at the end of the juvenile rearing period. Nevertheless, rearing environment did not have a significant influence on the cumulative survival rate of barbels (S C = 90 ± 4% and 81 ± 3% in aquaria and troughs, respectively).

The Cyprinidae is the largest freshwater fish family in Vietnam, with over 220 recognised species, many of which play an important role in aquaculture or are harvested from the wild. Despite numerous studies on the taxonomy of this family based on traditional morphological data, the relationships between major cyprinid groups is poorly understood and the taxonomic validity of a number of these groups is under debate. While an increasing number of molecular studies on cyprinid relationships have been conducted many have used restricted sampling and none have incorporated Vietnamese species. In this study, mitochondrial 16S rRNA, D-loop and cytochrome b gene sequences from 25 species of cyprinids collected from Vietnam were obtained and combined with sequences of cyprinids available in GenBank, in order to investigate the taxonomic validity of subfamilies within Cyprinidae and their phylogenetic relationships. The molecular data supported traditional division of the Cyprinidae into two major lineages: Cyprinines and Leuciscines. The placement of the Danioninae as the sister lineage to this grouping was not supported. Many of the subfamily boundaries were questioned and doubt was raised on some of the generic level classifications. The validity of species designation in Cyprinus, Tor and Cyclocheilichthys was also questioned. This study will need to be extended with greater taxon and gene sampling to further consolidate our understanding of cyprinid relationships and classification.

Marine populations are distributed heterogeneously in space and time because of the diversity of habitats and the requirements of species life cycles. Human exploitation of these resources also varies as a function of space, time and the type of fishing activities performed. These three factors determine fishing strategy at different levels of integration. The purpose of this study was to describe and analyse, with respect to different time scales, the relations between the modalities of resource exploitation and the biological or demographic characteristics of the species involved. These investigations relate to the more general task of acquiring the basic knowledge needed for spatialised management of fishing effort. A fleet of trawlers from La Rochelle, operating in the Bay of Biscay, was studied over a 15-year period (1979–1993), which led to the development of a reference resource exploitation scheme for these vessels. The degree of stability of this scheme over time was determined from landing profiles of the 18 most important species fished (94% of landings). An annual cycle for the species composition of landings was determined by multiple factor analysis. Two factors account for more than 55% of the inertia of the data. The first, of biological origin, is closely related to the breeding activity of species and associated migrations between the coast and the open sea. The second is spatial in nature, corresponding to the distribution and availability of resources according to a bathymetric gradient. This organisational scheme persisted over the first 13 years, but showed signs of change toward the end of the study period. Analysis of multi-year trends indicated four periods marked by sustained levels of landings per unit of effort for some species (decreasing for sole and wedge sole, or increasing for Norway lobster, striped red mullet, rays and the smallspotted catshark). These changes are attributable to restrictions on resource access imposed on the fleet (regulations and/or competition among the fishing gears for occupation of space), variations in the abundance of traditionally fished populations (hake, anglerfish) and changes in the professional behaviour of fishermen.

Fish schools are aggregative structures encountered in all types of aquatic environments but have as yet been little studied in freshwaters except at small spatial scales. This study represents the three dimensional description of juvenile fish schools (Perca fluviatilis and Rutilus rutilus) in a lake environment using high resolution multibeam sonar system operating at a frequency of 455 kHz, composed of 60 beams of 1.5° allowing a 90° observation plane. The in situ diurnal schooling behaviour of young-of-the-year fish of both species is confirmed. The morphological, energetic and spatial variables of these schools are described and related to one another. The structures described are of the same order of magnitude as those described in the marine environment. The school shape is elliptical, they are shallow and they display a temporal and spatial stability over the course of a day but a highly variable morphology. The number of vacuoles, a descriptor of the internal morphology of the schools, was found to be significantly (p < 0.01) correlated with the volume of the school, and showed two distinct relationships, with proportions similar to the percentage occurrence of both species sampled by a pelagic trawl. The relation may be efficient for fish species discrimination by 3-D acoustics methods in this lake with two main aggregative fish species.

The combined effects of feeding time (morning and evening) and dietary fat concentration on feed intake, growth, body composition and lipid tissue distribution were examined in rainbow trout fed on demand. To that purpose, diets with low (LE, 6% lipid) or high energy concentrations (HE, 24% lipid) were used in four treatments that combined provision of the same (HE–HE or LE–LE) or different (HE–LE, LE–HE) diets at morning and evening meals. Digestible energy intakes of the LE–HE (229 kJ kg–1 d–1) and HE–HE (269 kJ kg–1 d–1) groups were significantly different. There was no significant difference in the amount of energy intake between the two meals of the day in any of the treatments. The main effect of dietary treatment was on lipid intake; fish in the HE–HE, HE–LE and LE–HE treatments ingested approximately 3, 2.2 and 1.8 times more lipid than those on the LE–LE treatment. Growth, weight gain and protein gain were not affected by dietary treatment, but lipid gain reflected lipid intake; fish in the HE–HE, HE–LE and LE–HE treatments gained approximately 2.6, 2.1 and 1.7 more lipid than did fish on the LE–LE treatment. Body composition was significantly affected by dietary treatment; whole body lipid content reflected lipid gain, and visceral lipid concentration was affected in a similar way to whole-body lipid. On the other hand, muscle lipid concentrations were similar in fish submitted to the HE–LE, LE–HE, and LE–LE treatments (< 4%), and were lower than in fish on the HE–HE treatment (ca. 5.5%). Consequently muscle lipid concentration was not directly related to lipid intake, because lipid intakes of fish on HE–LE and LE–HE treatments was higher than in those on the LE–LE treatment, while muscle lipid concentration was lower. Thus feeding fish with different diets in the morning and evening might have potential as a tool for manipulating lipid distributions and concentrations without major adverse effects on growth.

The feeding behaviour of small tuna on the mesopelagic fish Vinciguerria nimbaria was studied in an equatorial area of the Atlantic Ocean (10–20° W, 0–5° N). Acoustic data (from a scientific cruise) and tuna stomach content data (from the tuna purse-seine fishery) were combined. V. nimbaria formed loose schools that occurred in clusters during daytime, and large aggregations during the night. The characteristics of the schools and clusters were analysed. The average length, size and packing density of the day-school were estimated at 48.5 m, 24400 individuals, and 5.8 fish m–3, respectively. The average length of clusters was close to 10 km. The packing density of night-school was estimated at 1.6 fish m–3. The preying of tuna on V. nimbaria was modelled as a stochastic process based on two Poisson processes. Daily rations of tuna were estimated at 3.5% and 7% of the body weight. Taking into account the swimming performance of the prey and the predator, we showed that tuna were able to feed on day-schools in a very short time, whereas feeding during the night by filtering was not competitive. Furthermore, a cluster is able to feed a single tuna school during 2 months, proving the sustainability of the biomass of small tuna in the area by V. nimbaria.

Two experiments were developed in France to assess whether growth and processing traits differ for males and females in the European catfish, Silurus glanis. In the first experiment, fish were raised from 5 to 200 g in a pond for 7 months. A significant sex effect is demonstrated in males for live weight at the end of the experiment (males 147.5 ± 5.4 g vs females 132.9 ± 4.9 g) and head index (males 20.6 ± 0.1 % vs females 21.2 ± 0.1 %, P < 0.05). In the second experiment, fish were raised from 885 ± 196 g to 2 266 ± 418 g in a recirculated system at 20.7 ± 1.4 °C for 120 days. A differential growth between the sexes is also registered. Males are heavier and longer (+ 357 g or + 17.0 % and + 6.2 % in length at day 120) and present a higher gutted weight and yield (+ 367 g or + 18.7 %; 95.0 ± 0.9 % vs 93.8 ± 1.8 %) and fillet weight (+ 233 g or + 20.9 %) than females after slaughter.

Haemocytes of Mytilus edulis, allowed to attach to the plastic surface of a tissue culture plate in the presence of haemolymph, were observed by time-lapse video recording. When bacteria were added at concentrations of 10 or 50 bacteria per haemocyte, certain bacterial strains caused rounding of the cells within 2–3 h. Haemolymph was necessary for the rounding to occur; if bacteria were added in sterile seawater there was no significant difference in the number of rounded cells between control and bacteria-treated cultures for up to 4 h. The haemolymph factor required for this activity was active at 1/64 dilution in seawater, was sensitive to trypsin treatment, and activity was halved on heating at 56 or 100 °C for 30 min. For the most toxic bacteria tested, Vibrio alginolyticus NCMB 1339 and Vibrio anguillarum A7, haemocyte cell rounding appeared to be induced by a very small number of bacterial cells. Bacteria-free culture supernatant of V. anguillarum 2981 induced rounding of haemocytes in a dose-dependent manner, with 50 % of cells being rounded at a dilution of approximately 1/500 of the culture supernatant. In a survey of 226 bacterial isolates, those isolated from incidents of disease in a bivalve hatchery were significantly more toxic towards haemocytes than bacteria isolated from hatcheries without disease or from turbot hatcheries.

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.

This study aims to test the influence of size grading on self-feeding behaviour, socialstructure (measured by the percentage of triggering acts per individual), growthperformances, and blood physiological variables of individually passive integratedtransponder (PIT)-tagged sea bass juveniles, using a computerized on-demand feeding systemcoupled with a PIT tag monitoring device. Three consecutive periods of 27 days each werecompared: a first period (P1) before grading (6 tanks of 100 fish; 40.2 ±  8.9 g) followed by a second period (P2) after grading. The protocolapplied aimed to create two groups of fish of similar mean weight but with either a low ora high coefficient of variation of weight(CVw) corresponding to an imposeddifference in social disruption (Tlow:CVw ~ 10%, 3 tanks of 60 fish each withsocial disruption;Thigh:CVw ~20%,3 tanks of 60 fish each, without social disruption). Tlow andThigh groups were studied over P2, and anadditional 27-day period under identical conditions (P3). The gradingprotocol used and/or time modified the social structure when comparing P1and P2. Thereafter, during P2 and P3,no difference could be observed in growth performances, feed demand, or physiologicalvariables between Tlow andThighgroups. Feeding rhythms and social structures weresimilar in both groups. In conclusion, such grading practice only transiently modifiesfeed demand behaviour and social structure built around the self-feeder, without furtherimprovement in individual growth performances in sea bass.

The present paper analyzes data collected between 2001 and 2002 on 81 reef fish species targeted by fishers at 5 sites in the Kingdom of Tonga (South Pacific). We first ranked the sites with respect to fishing pressure using two independent methods: (i) Tongan demography and reef surfaces available for fishing, and (ii) the differential effects of fishing on the whole set of 81 species grouped by their life history traits (LHT). We then focused on Parrotfish (Scaridae), which are heavily targeted in coral reef fisheries. We used the identified gradient of fishing pressure to study the effect of fishing on the community structure and test the hypothesis of “shifting dominance” amongst the 20 Scarid species present in the surveys. In addition to the classical effect of decreasing fish size in a family strongly targeted by fishers, the shifting dominance phenomenon includes a decrease in the abundance of the large-bodied and highly targeted species, favouring their replacement by smaller-bodied species from the same family, which are less impacted by fishing. In a context of interspecific competition amongst Scarids, the stress of fishing appears as a factor favouring the replacement of species with large maximum size, and LHT promoting low resilience, by smaller species with the opposite attributes. The discussion focuses on the various processes that can explain the shifting dominance phenomenon. The total density of resilient species, which increased along the gradient of increasing fishing pressure, can be used as an indicator of the over-exploitation of fish communities for reef fisheries management.

Argentina is one of the countries with the largest overall landings of skates and rays(24 000 t/year). As a consequence of high levels of exploitation and deficient managementtools, many of these species are threatened with extinction. In the bottom trawl fisheryof San Matías Gulf, northern Patagonia, skates and rays are caught as bycatch and all havehistorically been recorded in the fishery logbook under the category “rays”. Therefore,species composition and their characteristics were unknown. The aim of this study was tocharacterize the commercial exploitation of batoid species in this fishery. Our resultsindicate that commercial landings include nine species of skate, six of which are common.Among these, Atlantoraja platana, Sympterygia bonapartiiand Dipturus chilensis were considered the main species of thisfishery. Their combined relative abundance and weight made up about 90% of the batoidcatch throughout the year. Sexual segregation was detected in four species in whichindividuals of one sex dominated commercial landings. The commercial fraction was composedof individuals with a wide range of sizes. Immature individuals could represent 90% of theindividuals landed for some species. At present, lack of data prevents us from quantifyingthe impact that this fishery is having on these species, but our findings highlight theimportance of conducting research surveys to assess the abundance and geographic extent ofthese populations. The information presented here provided the basis for the proposal of anew logbook format incorporating species-level identification. The new logbook wasimplemented on 1 January 2010.

We analysed the patterns of variation that characterize 33 catch time series of large pelagic fishes exploited by the Japanese and Taiwanese longline fisheries in the Indian Ocean from 1968 to 2003. We selected four species, the yellowfin (Thunnus albacares), the bigeye (T. obesus), the albacore (T. alalunga), and the swordfish (Xiphias gladius) and aggregated data into five biogeographic provinces of Longhurst (2001). We carried out wavelet analyses, an efficient method to study non-stationary time series, in order to get the time-scale patterns of each signals. We then compared and grouped the different wavelet spectra using a multivariate analysis to identify the factors (species, province or fleet) that may influence their clustering. We also investigated the associations between catch time series and a large-scale climatic index, the Dipole Mode Index (DMI), using cross wavelet analyses. Our results evidenced that the geographical province is more important than the species level when analyzing the 33 catch time series in the tropical Indian Ocean. The DMI further impacted the variability of tuna and swordfish catch time series at several periodic bands and at different temporal locations, and we demonstrated that the geographic locations modulated its impact. We discussed the consistency of time series fluctuations that reflect embedded information and complex interactions between biological processes, fishing strategies and environmental variability at different scales.

Yield-per-recruit models are often used to provide management guidance for the efficient use of a fish cohort and to estimate the biological reference points, such as F0.1 or FMAX. Although model parameters are usually age-specific, these parameters are thought to be more likely related to length than age. In this study, age- and length-structured models are compared in calculating yield per recruit, F0.1, and FMAX at which the yield per recruit is maximized. Using a Monte Carlo simulation approach, I also compare differences in effects of uncertainties of the model parameters on yield-per-recruit analysis and estimation of F0.1, and FMAX using age- and length-structured models. This study shows that differences are small in estimating yield per recruit, F0.1, and FMAX using two types of models when there are no error variances in the model parameters. However, such differences increase with the uncertainties of the model parameters. The yield-per recruit, F0.1, and FMAX estimated using the age-structured model tend to have smaller values and variations compared with those estimated using the length-structured model. This study indicates that although the length-structured model can better incorporate the information observed from fisheries, age-structured yield-per-recruit model can provide estimates of yield per recruit, F0.1, and FMAX, more precisely and more conservatively, and thus is preferred from the conservation viewpoint in fisheries management.

Diel variations in schooling patterns and spatial dynamics during spawning were studied in Norwegian spring-spawning herring (Clupea harengus) off south-western Norway by acoustic surveying, diel cycle experiments and school tracking by sonar, and bottom gillnet sampling. Herring formed horizontally extensive, loosely packed demersal layers shortly after darkness. At night, the fish disappeared in the acoustic dead zone, but lifted off the bottom early in the following mornings. At daytime the herring reorganised into dense pelagic schools. The evening descent to the spawning habitat was considered as part of a precautionary strategy towards visual predators, as the bottom is a high-risk zone for archetypal pelagic fish like herring. Large numbers of gadoids, which are potential herring predators, were present in the area. Herring not ready to spawn dominated the bottom samples in 4 out of 5 days, suggesting that pre-spawning herring followed the descent of ripe herring. The herring spawning layers shifted in a south-easterly direction from day to day in diel spawning waves.

To understand the ecology of the exotic silver European eel Anguilla anguilla introduced into Japanese waters, the migratory behavior of 106 specimens captured in the coastal waters of Japan between April 1997 and March 2002 was analyzed. Their migratory behavior was apparently correlated with various environmental factors, particularly photoperiod, water temperature, lunar phase, and passage of atmospheric depressions, and was similar to the behavior of the species in European waters. These findings suggest that transplanted European eels retain their ability to respond to environmental cues for seaward migration in similar temperate habitats. The timing of the migration of silver European eels coincided with that of the native Japanese eels A. japonica, suggesting that the silver European eel was synchronized physiologically with the native eel by the same environmental factors.

Spatial distribution and species diversity of Cephalopoda caught in ARSA bottom trawlsurveys were studied out during two different seasons (autumn and spring) in the Gulf ofCadiz (Spain) from 2000 to 2007. Species composition of cephalopod assemblages wasanalysed, using both clustering analyses and non-metric multidimensional scaling analysis(nMDS). Spatial distribution of the assemblages identified and abundance of the mainspecies were mapped with Surfer 8.0 software, using kriging as the geostatistical griddingmethod. A total of 35 cephalopod species belonging to 6 families were found at depthsbetween 20 and 700 m. In each season, Sepiolidae was the most abundant family in terms ofnumber of species, followed by Octopodidae. The species richness increased up to 100–120 mdepth, where it reached the maximum value. From 120 m, the species richness decreasedprogressively with depth. In spring, the species with the highest occurrence wasEledone moschata (34%) and in autumn it was Alloteuthis media(70%). In both seasons, the most abundant species in terms of weight wasOctopus vulgaris, while Alloteuthis media showed thehighest yields in terms of numbers. Most species showed wide bathymetric ranges,especially in autumn. Three different assemblages were found in both seasons during thetime period analysed (although 2003 and 2006 were not included in the cluster analysis):shelf assemblage (20–160 m), deep shelf/upper slope assemblage (100–350 m) and middleslope assemblage (320–700 m). The specific composition of these three assemblages wassimilar between spring and autumn and an overlap could be observed between them, mainly inthe two continental shelf groups: shelf and deep shelf/upper slope assemblages.Alloteuthis media and Alloteuthis subulata were themost abundant species in the shelf assemblage as well as in the deep shelf/upper slopeassemblage. In the middle slope assemblage, Illex coindetii was the mostabundant species. The assemblages and their spatial distributions could be largely relatedto a combination of physical and biological factors and their interactions.