Several fleets with various fishing strategies operate as a mixed fishery in the Bay of Biscay. Among the main fleets, bottom trawlers target Norway lobster (Nephrops norvegicus) and, together with gillnetters, they also catch hake (Merluccius merluccius). Trawling leads to average-size catches that are below the minimum landing size (MLS); such catches are discarded since they cannot be sold. These discards result in negative impacts on stock renewal, as most of them do not survive. This also results in an economic loss for both bottom trawlers and gillnetters since these discards represent a future loss of rent. This study, based on the 2009 and 2010 selectivity experiments at sea, assesses the short- and long-term bio-economic impacts of four experimental selective devices aimed at reducing N. norvegicus and M. merluccius discards over a 20-year simulation period. Tests were conducted at sea on a research trawler. Using the impact assessment model for fisheries management (IAM model), selectivity scenarios for trawlers in the Bay of Biscay were compared to a theoretical selective scenario of adopting an optimal device that catches only N. norvegicus and M. merluccius above MLS (9 cm and 27 cm total length, respectively). Costs and benefits were analyzed with the objective of finding the best compromise between a reduction in discards of undersized fish and a loss of valuable catches among the experimental devices. Selectivity scenarios show positive impacts on stocks but different economic impacts between fleets. The combination of a square mesh cylinder with a grid and square mesh panels gives the closest results to the theoretical scenario tested in terms of stock recovery and economic benefits. This experimental device leads to low economic losses in the short term and eventually to higher N. norvegicus yields, which would be favourable for fleets that greatly contribute to N. norvegicus fishing efforts.

The diversity of reef ecosystems, the multiplicity of reef resource uses and the breadth of the range of the island socio-cultural contexts concerned make coral reef fisheries (CRF) management in the South Pacific a complex task. The health and state of the targeted resources depend both on ecosystem characteristics (as determined by ecological and biological factors) and on fishing pressure, whose effects are only partly known. Increasing harvests from commercial and recreational fishing increasingly overlap with traditional subsistence activity, creating an important CRF management challenge. This paper presents a new approach to CRF assessment and monitoring by providing a set of multidisciplinary indicators. The fisheries system is assessed from three different viewpoints: ecology of targeted populations, exploitation and the broader socio-economic fishery context. The use of complementary indicators chosen from each of these fields could balance the chronic lack of human and financial resources for the management of these fisheries. We suggest the use of these indicators through an assessment grid or an indicator dashboard specifically adapted to given situations and management objectives determined through a participatory approach. The operational efficiency of this dashboard depends on i) dialogue between users, ii) the objectivity of the proposed monitoring, iii) the visual transcription of divergent/convergent interests amongst stakeholders, and iv) stakeholder involvement in the decision-making process. The use and constraints of such a tool are described with reference to Ouvea atoll (New-Caledonia, South Pacific) for which an analysis of available indicators for assessing fisheries status is presented.

Respiration rates of various geographical strains of Crassostrea gigas were compared to assess the respiratory expenditure as a physiological indicator of catabolism (cost of maintenance). Parental oysters, sampled in France (Marennes-Oléron), Japan (Hiroshima), Taiwan (Tunkang) and Spain (Cadix), were differentiated by both their geographic origin and by mitochondrial DNA markers, allowing the distinction between the two closely related taxa Crassostrea gigas and Crassostrea angulata. After reproduction of these parental oysters, respiration rates of spat of each strain, reared under common controlled conditions, were individually estimated at 20 °C by using a volumetric microrespirometer. Our results demonstrated that physiological variability existed among the Crassostrea gigas strains and is likely to be related to physiological differences between geographical regions and/or genetic adaptations. The French strain showed the highest rates (0.71 μL·h−1), while the Japanese, Taiwanese and the hybrid between Spanish and French strains consumed less, 0.53, 0.43 and 0.40 μL·h−1, respectively. Our results confirmed the discrepancies previously suggested between Crassostrea gigas and Crassostrea angulata. Comprehensive physiological assessments should be carried out over a wide temperature range to confirm our results and to further evaluate growth potential. Appropriate decision making based on these studies will help future shellfish management in shellfish rearing areas such as the overstocked Marennes-Oléron Bay.

In order to demonstrate the involvement of nitric oxide in the defence systems of marine bivalves, we investigated the production of superoxide and nitrite, following in vitro phorbol myristate acetate stimulation of Mytilus galloprovincialis, Crassostrea gigas and Ruditapes decussatus haemocytes. Whereas M. galloprovincialis and C. gigas haemocytes were found to produce superoxide and nitrite, R. decussatus haemocytes were found to be unable to generate either of these mediators. Nitrite is a stable end product of nitric oxide and peroxynitrite as well; it appeared therefore that some marine bivalves, to kill microbial pathogens, use NADPH-oxidase and nitric oxide-synthase pathways. This was confirmed at an experimental level where inhibitors of both enzymatic pathways blocked the production of nitrite. Moreover, this notion was strengthened by the inability of the haemocytes from R. decussatus, which cannot produce superoxide, to release nitrite when stimulated.

Mediterranean demersal fisheries have experienced an ongoing decline in catches over the past 20 years as a result of excessive increases in effort caused both by growth in trawler engine power and by rapid technological advances in fish finding and fishing technology. This has led to an overexploitation of these resources. An increasing share of the catches consists of immature individuals. This study was undertaken to test a sorting grid with a bar spacing of 20 mm as a means of excluding juveniles in the commercial hake (Merluccius merluccius) fishery in the Catalan Sea, western Mediterranean. The grid was placed in the extension section of the gear 5 m in front of a cod-end. Divided cod-end design was used to collect the escapees and target species. The mean selection length (L50) of the ten hauls was 14.2 ± 0.7 cm SE, with a selection range of 7.3 cm ± 0.4 SE. The biomass of hake under L50 that escaped through the grid represented 50.1% ± 6.7 SE of the total hake biomass. These results are promising and indicate that a sorting grid can be used in excluding young hake. This was a first step toward implementation of sorting grids in commercial trawl gears as means of avoiding unwanted catches of small individuals in the hake fisheries in the Mediterranean Sea. Further trials are required to improve the sorting efficiency of the grid.

Fish assemblage structure of 29 Brittany streams is examined. Catchment area, stream gradient, and distance from sources are significantly correlated with species richness. Addition of species with increasing stream size occurs for all streams with no evident longitudinal replacement, suggesting little discontinuity in the stream geomorphology or temperature. Total density of fishes decreases significantly with an increase in stream size but no relation was found between total biomass and catchment area. Headwaters are characterized by short-lived, solitary, and nocturnal feeding species, whereas downstream sites are characterized by long-lived, schooling, diurnal feeding species. Presence of solitary and nocturnal feeding species upstream could be related to predation and/or competition factors. Temporal variation of individual species density varies from an upstream-downstream gradient with the highest variation upstream. Species responsible for this variation were mostly small benthic ones relatively difficult to sample, therefore, the greater temporal variation in upstream areas could be attributed to a deficiency of the sampling methodology.

An experiment was carried out to evaluate the effects of brine shrimp nauplii (Artemia sp.), Cladocera (Moina sp.), Tubifex worms and a trout starter diet on growth performances and survival rate of Mekong catfish larvae (Pangasius bocourti Sauvage, 1880). Larvae accepted all four types of experimental diets, owing to large mouth opening at the first feeding (0.6–1.0 mm at 45° and 90° mouth opening, respectively). Artemia nauplii and Tubifex worms resulted in the same growth performances and survival rates for a 9-d nursing time with specific growth rates of 36–37 %·d−1 and survival rates of 92–93 %. Moina led to a lower growth performance (31 %·d−1) but the survival rate (94 %) was not significantly different to that of larvae fed Artemia nauplii or Tubifex worms. Trout starter feed, dry pellet, proved relatively less suitable for larval rearing of P. bocourti owing to a low survival rate (68 %) and growth performance (21 %·d−1). The study confirmed the feasibility of completely replacing Artemia nauplii by Tubifex worms.

Marine protected areas (MPAs) have been depicted as a useful tool for improving fisherymanagement and protecting biodiversity. For example, by acting as source populations, MPAsmay provide a spillover of adults/propagules, enhancing recruitment to surrounding,non-protected waters. However, such positive effect will depend on how a MPAs designmatches population biology and dispersal abilities of the target species. High levels ofintraspecific genetic diversity without pronounced structure have been found in manymarine organisms over large spatial scales (from hundreds to thousands kilometres) but donot hold for other ecologically and economically important species such as coral reeffishes, seagrasses and kelps. In particular, the limited potential for dispersal of manymacroalgae suggests the occurrence of self-sustaining, “closed” populations that contrastwith the “open” populations of many fishes and invertebrates. Consequently, the highresilience of fish/invertebrate populations cannot be generalized to the whole marinerealm. In the present work, we use genetic tools to explore the role of the MPAParc naturel marin d’Iroise in the management of the emblematic kelpLaminaria digitata. While kelps have received much more scientificattention than any other seaweed group, there is still critical baseline knowledge whichneeds to be addressed for their effective management. Our genetic survey of 12 L.digitata populations along the Brittany coast, four of them located within theboundaries of the Parc naturel marin d’Iroise, allowed us to assess theconservation value of these kelp populations. In particular, classical genetic metrics aswell as more recent clustering approaches were used to identify and characterizeManagement Units. Moreover, assignment tests were employed to determine contemporarymigration events and source/sink populations. Our results show that populations withinthis MPA have high conservation value. However, we also identify other populations ofconservation interest.

The bigeye cigarfish (Cubiceps pauciradiatus) is a small pelagic nomeid of the tropical world ocean, often recovered in the stomach contents of top predators such as tunas, billfishes and marine mammals. In the Indian Ocean, a few studies have investigated the biology and the ecology of this species that is one of the most abundant fish of the intermediate trophic levels. In this paper, we investigated the spatial distribution of C. pauciradiatus in the Indian Ocean using pelagic trawl catches carried out between 20°N and 45°S, and the importance of bigeye cigarfish in the diet of 9 piscivorous fishes sampled by different fishing gears in the western part of the Indian Ocean. The highest densities were observed along the eastern coast of Africa and in the Arabian Sea (87 000 individuals per square nautical mile) during the South-West Monsoon and in the eastern part of the Seychelles archipelago (62 200 ind. square nmi) during the North-East Monsoon. Small sized bigeye cigarfish (20–80 mm SL) was a regular and abundant prey (20 to 200 ind. per stomach) for schooling predators exploited by purse seine fishery such as large yellowfin and bigeye tunas chasing prey near the sea surface. Large sized bigeye cigarfish (61–150 mm SL) occurred in small numbers (3 to 20 ind. per stomach) in the stomach contents of swordfish and of large yellowfin and bigeye tunas caught by longline sets at great depths. Large concentrations of bigeye cigarfish occurred in zones of high productivity, and that species constituted seasonally a strong link in the transfer of energy from low to high trophic levels in this part of the Indian Ocean.

Using examples, we discuss some aspects of surplus production models. Although the precision of some parameter estimators may appear to be good, the strong asymmetry of confidence intervals and the large impact of the choice of a given formula on those estimators go against this feeling. Models are often formulated with inference to the biological background, but giving a biological meaning to (the estimates of) the parameters may be very dangerous. Fishing effort standardization does not lead necessarily to useful results for management. The fleet dynamics, per se, may not allow equilibrium States. In the context, of general frameworks, where the evaluation of the resource is not the unique objective, surplus production models may be however very flexible tools for fishery analysis, with low parameter requirements.

The potential of carp pituitary powder (CPP) at one dose, or the luteinizing hormone-releasing hormone (LH-RH) analogue, des–Gly10,(D–Ala6)–LH-RH–ethylamide, at three different doses to stimulate spermiation in paddlefish (Polyodon spathula) was tested. Single injections of the LH-RH analogue at 0.2, 0.1, or 0.05 mg·kg–1 increased the number of spermatozoa per kilogram of body weight (kg–1 b.w.) by 4.7, 3.4, and 3.4 times respectively compared to control, but the number of spermatozoa per kilogram of body weight decreased with CPP (4 mg·kg–1) by 1.7 times compared to the control. The LH-RH analogue prolonged active spermiation, with numbers of spermatozoa ranging from 7.69 to 1.19 × 109 kg–1 b.w. up to 96 h after treatment. Analysis of variance showed significant influence of experimental groups on volume of sperm per male and per kilogram of body weight, and the total number of spermatozoa per kilogram of body weight, but insignificant influence on the total number of spermatozoa per male. The percentage of motile spermatozoa was not different between experimental groups for sperm collection at different times after injection. A very high positive correlation (r = 0.93) was obtained between sperm concentration and sperm transmittance measured with a spectrophotometer. This relationship was described with the following linear regression: sperm concentration (× 109 mL–1) = 1.3244 X–0.9969, where X is the percentage of sperm transmittance.

Parameters of hemocyte populations have been considered as relevant indicators of bivalve health and are currently used in immunotoxicological studies. Hemocytes in hemolymph can be collected by puncturing either the pericardial cavity or the adductor muscle sinus with a syringe. Flow cytometry is a methodological approach that is increasingly being used in laboratories for the study of hemocyte parameters in aquatic invertebrates. However, various protocols for hemocyte processing in laboratories equipped with different types of cytometers have been published. In this context, two flow cytometers (EPICS XL4®, Beckman Coulter and FacsCalibur®, Becton Dickinson) and two sites of hemocyte collection (pericardial cavity and adductor muscle sinus) were compared for the analysis of hemocyte parameters in the Pacific oyster, Crassostrea gigas. Hemolymph cells were analyzed in terms of their number and organelle contents. Cell mortality, phagocytosis, non specific esterase, extension of the lysosomal compartment and production of reactive oxygen species were quantified. The results showed that the phagocytic index was higher for hemocytes obtained in the muscle sinus hemolymph. The results are discussed with respect to the potential use of flow cytometry as a tool for hemocyte studies in bivalves.

Growing pressures from development activities, on aquatic environments in South American countries, have created an urgent need for tools to measure the quality of aquatic systems. The index of biotic integrity, based on fish assemblages, elaborated in North America, constitutes a basis for the development of these tools. However, its direct application is problematic in regions having a rich and diverse ichthyofauna and where the knowledge of fish species ecology is incomplete. The response of taxonomic or trophic groups is often unknown and the selection of fish assemblage metrics cannot be based on previous knowledge, as in intensely studied regions. This work proposes a method, similar to the approach recently pursued in Europe, based on comparing the variability of fish assemblages in reference situations with their variability influenced by human-induced perturbations. The method was developed from 53 samples of 27 reaches in 7 hydrographic basins of French Guiana. For each of 28 fish assemblage descriptors, stepwise multiple linear regressions with 28 habitat variables were carried out. The residuals of the models obtained were used as candidate metrics independent of natural environmental factors. Nine metrics showing significant differences between reference and disturbed samples were selected to constitute the index. The index was validated by analysing a temporal data series obtained from a reach disturbed by dam construction.

The uptake and release of material by oysters (Crassostrea gigas) and mussels (Mytilus edulis) in Marennes-Oléron Bay (SW France) were measured in situ using benthic ecosystem tunnels (BEST). There was a large variation in seston concentrations, owing to high sedimentation/erosion dynamics. Organic matter was diluted by resuspended sediment, but had a low C/N ratio, i.e. a high quality, owing to resuspension of microphytobenthos. In many cases a significant decrease of chlorophyll concentrations was observed in tunnels with oysters and mussels. Average clearance rates per tidal cycle ranged from 4 to 7, and from 0.9 to 2.7 1.g−1AFDW.h−1 throughout the season, for oysters and mussels respectively. Calculation of the filtration pressure (the fraction of the primary production filtered per day), indicated that bivalves in the bay were able to filter much more than the daily pelagic primary production. It seemed obvious that the bivalve stocks depended not only on phytoplankton but also on microphytobenthos. Significant regeneration of nitrogen could be demonstrated from musselbeds on the sediment, at higher rates than direct excretion of ammonium. No significant release of nutrients was observed for the oysters or mussels, when they were put on tables, as practised by the oyster farmers. lt seemed likely that biodeposits were flushed away from the tunnels in this case, and mineralization occurred elsewhere. It was concluded that the carrying capacity of the bay for herbivores is extensively exploited by the shellfish. Mineralization of bivalve biodeposits represent a large potential for nitrogen regeneration.

In recent decades, marine reserves have been established either to protect ecosystem structure and biological diversity or to serve as management tools to counter the overexploitation of fish stocks. The Cape Roux marine protected area (MPA), in the Mediterranean Sea, was established in December 2003 for the management of artisanal fisheries and enhancement target fish stocks.

Monitoring of littoral fish assemblages (0–30 m depth) in this zone began one year after the MPA was set up. The survey was conducted at 6 stations, located inside and outside the MPA, using three methods: underwater visual census (UVC) on transects, UVC using a new fish assemblage survey technique (FAST), and experimental net fishing performed by a fisherman. The FAST indices were derived from visual censuses, performed along a random pathway, scoring species on a presence/absence basis and size on a 2-class basis. Indices were calculated seasonally, by applying “weights” according to species and size. This study presents results obtained between October 2005 and June 2007. In the protected area, the experimental fishing yielded significantly higher abundance and species richness, and the FAST method highlighted a decrease in seasonal fluctuations. These two complementary methods (UVC and experimental fishing) revealed the early changes in fish assemblages in response to protection. The FAST method employed here seems to be relevant for the study of artisanal fishery target fishes, as a low-cost and sensitive UVC method.

The Gambia Estuary is one of the last estuaries in West Africa not to have been affected by strong environmental changes and adverse human disturbances. In order to describe the spatio-temporal change in fish biomass in this estuary, and the seasonal changes in fish size classes, five research surveys have been conducted at characteristic periods in the river's water regime and meteorological seasons. The fish assemblages were sampled by two vertical echosounding protocols: mobile surveys (zigzag transects) in the estuary and moored stations. The two sampling methods produced a similar image of the fish assemblages in terms of the distribution of total biomass and target strength distributions. Large fish aggregations were detected in the most marine area at the end of the wet season, and fish biomass increased through the dry season in the upstream zone. Fish were smaller at the beginning of the wet season and they were always larger in downstream areas.

Though Crassostrea oysters have been distributed and cultured worldwide, their taxonomy is still difficult and often inaccurately determined because of the high level of phenotypic plasticity of the shell morphology. With the help of mitochondrial DNA, two novel species of Crassostrea oysters (C. hongkongensis and C. zhanjiangensis) were recently recognized, which suggests that the species diversity of Indo-Pacific oysters could be underestimated. Utilizing a combination of shell characteristics, a molecular marker (mitochondrial cox1 gene) and phylogenetic analysis, we identified a mangrove-distributed novel Crassostrea oyster species, C. dianbaiensis. The shell morphology of the new species is phenoplastic, as seen in other congeneric oysters. The left valve of this oyster is usually deeply cupped, and the right valve is usually slightly concave. The body size is classified as medium and is approximately 5–10 cm in height (estimated from 20 individuals). One distinctive feature of C. dianbaiensis is that the adductor muscle scars vary in color from dark purple to white in the right valve, but always appear white in the left valve. Based on the cox1 phylogenetic tree, C. dianbaiensis is inferred to be a new member of the Southeast Asia tropical oysters and is believed to be the northernmost distributed species among the tropical oysters. This study provided basal information for future studies, which are necessary to better understand the faunal characteristics, population and roles of this oyster in nearshore ecosystems.

The taxonomic status of the cupped oysters Crassostrea angulata and C. gigas has received considerable attention in the last decades. Based on larval shell morphology, experimental hybridization, allozymes and nuclear DNA studies several authors have considered these two taxa as being synonymous. However, mitochondrial data showed clear genetic differences between the two taxa. In addition, microsatellite-based studies and cytogenetic studies have also provided evidence that supports their differentiation. Considerable differences have also been observed at the phenotypic level in terms of growth rate and ecophysiological parameters. In the present study, C. angulata from Sado estuary (Portugal) and C. gigas from Seudre estuary (France) were collected and factorial crosses were performed. Juveniles of the different progenies were reared in Ria Formosa (Portugal) under common conditions to determine if they exhibited differences in shell shape and in pigmentation of the adductor muscle scar. Significant morphometric differences between C. angulata and C. gigas progenies were indicated by univariate and multivariate analyses. Univariate analysis of size-adjusted shell measurements revealed significant differences between the two taxa for shell depth, muscle scar height, and length of ligamental area. Both reciprocal hybrids showed intermediate morphometric characters between parental lines. In addition, significant differences were also observed between C. angulata and C. gigas progenies in terms of pigmentation of adductor muscle scar. C. angulata and both reciprocal hybrid progenies showed highly pigmented adductor muscle scars whereas in C. gigas progeny the pigmentation was lighter. The differences in shell shape and muscle scar pigmentation observed in the present study support the distinction of the two taxa.

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.

Cryopreservation is a valuable tool for genetic improvement programs. Several bivalvemollusc species have already been the subject of such programs and the Tahitian blackpearl oyster industry is now planning the development of selective breeding for desirabletraits in Pinctada margaritifera. The ability to cryopreserve spermatozoawould, therefore, offer significant benefits to the cultured black pearl industry.Spermatozoa were cryopreserved with cryoprotectant agent (CPA) 0.7 M trehalose in 0.8 MMe2SO and a two-step freezing process was used: straws were first maintainedin nitrogen vapour for 10 minutes, then directly plunged into liquid nitrogen and storedfor one week before use. The viability of thawed sperm was 23% lower than that of freshsperm. When using thawed sperm, therefore, a higher sperm/egg ratio of 100 000:1 wasrequired to reach 80% oocyte fertilization, compared with 100:1 for fresh sperm.Nevertheless, this first demonstration of cryopreserved sperm fertility in black pearloyster confirms the hatchery applicability of the cryopreservation technique defined here.Monitoring for larval viability during the first 23 days of life revealed no significantdifferences between the progeny produced with cryopreserved sperm and that produced usingfresh sperm.