The amphidromous life cycle and morphological characteristics of Sicydiinae species allowthem to colonise tropical freshwater habitats from the river mouth to the upper reaches ofthe river basin. Otolith microchemistry of 62 Sicydium punctatum from thePérou River, Guadeloupe (French West Indies) was investigated with a femtosecond laserablation-inductively coupled plasma mass spectrometer (fs-LA-ICP-MS) in order toreconstruct individual life history and follow the possible movements of Sicydiumpunctatum after the recruitment. Sr:Ca fingerprint confirmed the amphidromouscycle of this species. Variations of Ba:Ca in some individuals indicated changes inenvironmental conditions after the recruitment in the river. Even if results did not allowconcluding to the specific origin of these variations, the hydrological regime and thebiofilm composition may have a non negligible influence on the Ba availability. Resultssupported the use of multi-elemental signatures in otoliths and highlight the need for alarge geographical and temporal sampling of Ba and Sr in freshwater systems for a betterunderstanding of amphidromous fish species.

Among benthic organisms, bivalves are often used as bioindicators of environmental pollution because of their high bioaccumulation capacities for heavy metals leading to metallothioneins (MT) induction. MT are small cytosolic metal-binding proteins involved in metal homeostasis and detoxification in living organisms. These proteins can also be induced by a wide range of factors, such as hormones, physical stress, parasitism. MT quantification in relation to parasitism is rarely reported in literature, while parasites are omnipresent and have deleterious impacts on bivalves. Moreover, only a few number of MT genes have been characterized in molluscs. This study describes the partial sequence of the MT gene (Cemt1) in the edible cockle Cerastoderma edule. The cockle's MT cDNA was sequenced and showed over 80% homology to several other bivalve MT sequences. This sequence was then used to determine MT specific primers which can be used in quantitative real time PCR. MT protein and gene expression levels were quantified for individuals selected under different conditions: free from or infected by the digenean trematode Himasthla elongata, and under cadmium exposure at 15 µg Cd L−1. Results evidenced that MT concentrations were significantly increased by both treatments; parasite infection and Cd exposure. Moreover, congruent results between MT protein and gene expression levels were obtained.

Vibrio harveyi is the main pathogen of the European abaloneHaliotis tuberculata, and recently caused important mortalities at theproduction sites of this marine gastropod in France. In the present work, the monthlyantibacterial activity of two red seaweed species from the French Atlantic coast, thenative Palmaria palmata and the introduced Grateloupiaturuturu, were investigated against the abalone pathogen Vibrio harveyistrain ORM4. Water-soluble extracts were screened using the microplate method.Grateloupia turuturu showed an antibacterial activity with a maximalgrowth inhibition in spring of around 16%. In contrast, Palmaria palmatawas inactive, as further growth of the bacteria was observed. Preliminaryone-dimensional proton nuclear magnetic-resonance (1H NMR) profiles identified thedifferences between the two water-soluble extracts.

A study of microhabitat use by fourteen abundant fish species was undertaken in the lower Ntem River Basin in Cameroon (Africa). Seventy-one microhabitats including pools, raceways and riffles were studied twice during the 1994 and 1995 dry season. Results obtained by Canonical Correspondence Analysis (CCA) showed a good niche separation along the ordination axes I (λ1 = 0.37) and II (λ2 = 0.20). Microhabitat selection by these species reflects response to several physical factors including width, depth, current velocity and substrate type. However, a substantial part of the variation in species segregation was explained by both instream (% leaves, woods and roots, and aquatic plants) and bankside (% mean canopy closure)cover. A striking pattern encountered during this study was the frequent size-related variation in habitat use displayed by many species. For example, smaller individuals of Brycinus longipinnis, Barbus camptacanthus, Distichodus notospilus, and D. hypostomatus, occurred more often in faster flowing waters than did their larger conspecifics. The association displayed by CCA was high (0.957 and 0.938, respectively for the first and second axis), and Monte Carlo test (99 permutations) revealed that these associations were significantly different from random (p = 0.01). The implications of these results for habitat management are discussed.

Skates and rays constitute important resources for several fishing fleets of mainland Portugal with total annual landings around 1500 tons. Regardless of their commercial interest, landed specimens are not differentiated at species level. To get a preliminary insight into the species diversity of landings, a pilot sampling program on skates and rays composition was executed in the two ports of mainland Portugal with the highest landings of this group– Matosinhos and Peniche. Sampling was carried out once a month in each port between January and April 2001. Based on the information obtained, a new sampling plan was established for the artisanal fishery (gillnet fleet), at each landing port. This sampling program was conducted until the end of 2001. A total of eight species were identified. Raja brachyura and Raja clavata were the most common species found in the landings of each port, while Raja miraletus was only occasionally recorded. Rajidae landings in mainland Portugal are mainly by-catch of the artisanal segment of the commercial fishing fleet.

The meagre Argyrosomus regius is a large Sciaenid fish known to reproduce in the eastern Atlantic and Mediterranean Sea in just five distinct and restricted geographic areas: along the Mauritanian coast and at estuary openings (Gironde, Tagus, Guadalquivir and Nile). The biological traits of A. regius (high dispersal capabilities, high fecundity, long larval phase, overlapping generations, reproduction until 40 years of age) are, in principle, favourable to high gene flow, which should lead to genetic homogeneity over large geographic scales. Nevertheless, the high geographic distances between the few reproductive areas leads one ask whether there is genetic differentiation in this species. In the present study, the genetic differentiation of the wild A. regius was investigated across most of its natural range from the Atlantic Ocean (France, Portugal, Spain, Mauritania) to the Mediterranean Sea (Egypt, Turkey), using 11 microsatellite markers previously identified in another Sciaenid, the red drum Sciaenops ocellatus. At least two very distinct groups could be identified, separated by the Gibraltar Strait. Genetic divergences (FST values) were intermediate between the Atlantic samples (0.012–0.041), high between Egypt and the Atlantic (0.06–0.107) or Aegean Sea (0.081) and extremely high between the Aegean Sea and the Atlantic (0.098–0.168). A. regius exhibited a very high level of genetic differentiation rarely reported in marine fishes. These results also demonstrate the existence of a sixth independent spawning area in the Menderes delta (Turkey). Factors potentially involved in this very high genetic fragmentation are discussed, including physical barriers, glaciation pulses and biological traits.

Paddlefish are endemic to most rivers and tributaries of the Mississippi basin and are found in 22 states of the United States. In 1989, US Fish and Wildlife Service (USFWS) listed paddlefish as a category 2 species because data were lacking on its population status. In 1992, USFWS added paddlefish to the list of Appendix II of the Convention on International trade in Endangered Species of Wild Fauna and Flora (CITES) primarily due to concerns about illegal poaching in the international caviar trade. Therefore, paddlefish aquaculture will provide alternative fish sources for the marketplace in the era of strict federal and state regulations on wild populations. Aquaculture of paddlefish is in a research and developmental phase. Most broodstock are obtained from wild sources, though some mature fish have been developed in captivity. Artificial propagation techniques are resulting in > 80 % egg fertility. Larval paddlefish are initially raised in organically fertilized, zooplankton-rich (i.e. Daphnia sp.) ponds, and then trained on extruded trout/salmon diets until the juvenile fish are > 30 cm in total length. Tank culture is also an alternative for raising juvenile fish. Juvenile paddlefish, a filter feeder that requires zooplankton as its primary food, are being grown in reservoirs and in polyculture with channel catfish (Ictalurus punctatus) in Kentucky, Indiana, Missouri and Alabama. Production yields are 200–400 kg·ha–1 in polyculture and in reservoirs ranching resulted in 55–175 kg·ha–1. Reservoir ranching is ideal for caviar production; whereas, paddlefish (1.5 to 4.0 kg) cultured with catfish is for meat production. A system to produce all-female progeny through artificial propagation with sex-inverted, gynogenetic broodstock and attempting to develop optimal cryopreservation techniques for the milt of these unique broodstock is currently being tested. Value-added products such as hot and cold smoked paddlefish are the major effort being developed for the marketplace. Consumer acceptability of value-added products from paddlefish has been better than channel catfish.

Survival of Silurus glanis ovulated oocytes (ova) measured by the capacity of normal development i.e. percentage of normal and abnormal hatched larvae after in vivo and in vitro storage and exposure to sperm activating or immobilizing solutions and urine was studied. In the case of ovulated oocytes left in the ovaries, total hatching and abnormal hatched larvae (in % of hatching) were respectively 74 and 8.2% immediately after ovulation, 77 and 8.6% after 2 h, 54 and 18% after 4 h, and 38 and 50% after 6 h of storage. Four and 6 h stay of ovulated oocytes in ovaries resulted in a significant increase of abnormal hatched larvae (p < 0.01). For the ova stored in vitro, the capacity to undertake a full embryonic development after fertilization was not significantly changed either after 8.5 h at 19 °C or 3.5 h at 25 °C; there was no ova survival at all after 3.5 h storage at 8 °C, 12 h at 19 °C and 8.5 h at 25 °C. There was a significant increase of abnormal larvae after 3.5 h at 25 °C (74%, p < 0.001) and after 8.5 h at 19 °C (37%, p < 0.05). Exposure of non inseminated ova to water buffered to pH 7.0 (5 mM Tris-HCl) to sperm activating solution (17 or 41 mM NaCl, 5 mM Tris-HCl, pH 8.0) or to immobilizing solution (200 mM NaCl, 30 mM Tris-HCl, pH 7.0) resulted in a regular and rapid decrease of their capacity of development; this was 10% of normal hatched larvae within 4 min in water, and within 6-8 min in the NaCl solutions. A similar situation was observed after exposure to urine with a loss of embryonic development of 30% within 3 min. These results indicate that all steps of the whole procedure of gamete collection and artificial insemination should be carried out rapidly as soon as possible after ovulation.

A biotelemetry experiment was designed to determine whether the selection of a residence area by adult barbel Barbus barbus (Cyprinidae) was dependent on the availability of physical habitat features, on the presence of fish shoals and/or on the presence of specific partners. The experiment took place in 3.0 km stretch of the River Ourthe (Belgium), where the latter features had been characterised by habitat and electric fishing surveys (1 190 fish ≥ 15  cm, at 265 locations). Six barbel (34.8–49.5 cm) belonging to a single shoal of 34 fish were tagged with 40 MHz radio transmitters, transplanted in pairs at different distances (−1 km, −30 m, +1 km) from the capture site and tracked from 3 September to 7 October 1990.

Fish showed variable mobility patterns and home range sizes (200–2 400 m). They selected 17 residence areas of which the cumulative frequency of occupation ranged from 0.1 to 79.5 day × fish. The comparison between the residence areas selected, habitat suitability and the location of fish shoals in the study area indicate that the presence of a shoal of at least 10 resident fish within a suitable habitat (normalised suitability index ≥ 1.0) is necessary but not sufficient to guarantee its long term selection and occupation. Homing movements of transplanted fish were directed towards the activity area rather than to the residence area itself. The fish that did not home, selected residence areas in a part of the river with a higher availability of potential feeding areas. These elements are discussed within the context of habitat utilisation and foraging strategies by a gregarious species. It is suggested that resident fish of the same species may ease the exploitation of a non familiar environment by a naive fish, and that this may positively trade off the benefit provided by home site fidelity, depending on the availability of food resources.

Seasonal changes in feeding habits and diet of the cockle Cerastoderma glaucum (Mollusca, Bivalvia) were analysed using carbon (δ 13C) and nitrogen (δ 15N) stable isotopes. I aimed to investigate the role of benthic and pelagic sources in the diet of this dominant infaunal bivalve on a western Mediterranean sandy bottomed pond. Adult C. glaucum and all potential organic sources (particulate and sedimentary organic matter, seagrass, macroalgae, heterotrophic detritus) were collected and analysed for δ 13C and δ 15N. In total 5 dominant organic sources were found, ranging between –21.0 and –8.0 ‰ for δ 13C and from 3.0 to about 7.0% for δ 15N. C. glaucum assimilated fraction ranged between –14.0/–15.0% and 6.0/9.0% respectively, for carbon and nitrogen, while its estimated fractionation seasonally varied between 1 and 1.5 for carbon and was about 3 for nitrogen. C. glaucum reflected the isotopic composition of its food while maintaining, throughout the year, a fairly constant isotopic composition in its assimilated fraction, despite the high variability in isotopic composition of available sources.

Les relations trophiques entre une population d'huîtres cultivées et la nourriture potentielle sont modélisées en tenant compte des caractéristiques du milieu estuarien. Un modèle en boîtes permet de coupler le transport du matériel particulaire et son assimilation par la population d'huîtres. Les échanges entre boîtes dépendent de leur volume, de l'excursion de marée et des débits résiduels calculés à partir des résultats d'un modèle numérique courantologique. La consommation, l'assimilation et la respiration sont les termes d'une équation de bilan énergétique permettant de simuler la croissance des huîtres. Le modèle met en évidence un gradient de croissance selon un axe sud-nord et l'interaction stock-performance de croissance. L'ensemble des résultats permet de montrer les limites du modèle et de justifier l'étude ultérieure de la remise en suspension au niveau du sédiment et du couplage entre la consommation et la production primaire.

Fin spine ageing is the most common technique used to estimate age and growth parameters of large pelagic billfishes from the families Istiophoridae and Xiphiidae. The most suitable methods for processing and interpreting these calcified structures for age estimation have not been clearly defined. Methodological differences between unvalidated ageing studies are of particular concern for highly migratory species because multiple researchers in different regions of the world may conduct age estimates on the same species or stock. This review provides a critical overview of the methods used in previous fin spine ageing studies on billfishes and provides recommendations towards the development of a standardized protocol for estimating the age of striped marlin, Kajikia audax and white marlin, Kajikia albida. Three on-going fin spine ageing studies from Australia, Hawaii, and Florida are used to illustrate some of the considerations and difficulties encountered when developing an ageing protocol for highly migratory fish species. Particular areas of concern that may influence age and growth estimates included differences in fin spine selection, sectioning methods, criteria for identifying and measuring annuli, distinguishing false annuli, validation procedures, identification of the first annulus, and methods used to replace annuli lost due to vascularization of the fin spine core.

Jusqu'aux dernières décennies on considérait que la limite de répartition entre sardines et sardinelles se situait aux environs du cap Blanc. Au nord de ce cap, les remontées d'eaux ont lieu toute l'année, la production primaire est forte, mais non la biomasse zooplanctonique, du fait de la rapidité de l'advection. Au sud, les résurgences sont saisonnières, la circulation au-dessus du plateau comprend deux veines opposées. La production secondaire suit rapidement les poussées de phytoplancton, notamment grâce à la superposition de courants opposés entre lesquels des migrations de zooplanctonpermettent un couplage des productions primaires et secondaires. Sardines et sardinelles se nourrissent de particules en suspension, mais les sardines peuvent s'accommoder d'un régime presqu'entièrernent végétal, à la différence des sardinelles. Ceci leur confère un avantage sur les sardinelles dans les régions d'upwellings violents. Durant les années 70's, la pêcherie de sardines s'est déplacée vers le sud, or ces mêmes années, les alizés se sont renforcés sur leur bordure méridionale, conduisant à un renforcement des upwellings le long des côtes mauritanienne et sénégalaise. Ceci a entraîné une modification du biotope, favorable aux sardines. D'autre part les courants, modifiés par diminution de leur composante nord et augmentation de celle portant au sud, pourraient être responsables d'un nouveau mode de dispersion des larves, entraînant davantage de sardines au sud et moins de sardinelles vers le nord.

Sex ratios in farmed European sea bass are highly biased towards males (75 to 95%), which is problematic for aquaculture. In this mini-review, we re-analyse fisheries literature data about sex ratios in wild sea bass from 13 population samples, representing altogether 4889 individuals covering the major part of the distribution range of the species. We find that as a whole, the sex ratio of wild populations is biased towards females (59.4% females, p < 0.001), but that the sex ratio of the younger fish (<30 cm total length) is balanced (52.0% females, p = 0.15), while the sex ratio of the older fish is heavily biased towards females (69.5% females, p < 0.01). Possible causes of these differences (differential longevity, biased sampling) are discussed. When age-group sex ratios are available (three population samples out of 13), significant variation between age groups appears, part of which is most likely of environmental origin. This study shows that the excess of males in culture is not a characteristic of the species, but rather a consequence of the environments used in culture, interacting with a complex system where both environmental and genetic influences govern sex determination in sea bass.

This paper concerns eggs of captive fish and gonads of wild fish, from the Brittany coast obtained in the 7-18 °C thermal range. The diameters of eggs, 1.07-1.32 mm are compared to those observed in other areas, especially along the Mediterranean coast. The duration of embryogenesis as a function of temperature and the efficiency of different incubators are discussed. The quality of eggs in relation with larval survival is discussed through the biochemical composition of the eggs collected in captivity compared to that of wild fish gonads. The absolute values of lipids, proteins, fatty acids, lipid classes, phosphatides and minerals measured, also the positive relations obtained between egg dry weight, diameters, mortality during incubation are presented as criteria of egg quality.

Killer whale (Orcinus orca) encounters from commercial pelagic trawlers as well as other types of vessels have been documented in several regions of the northeast Atlantic; however, very little published information is available regarding such encounters in mackerel (Scomber scombrus) and herring (Clupea harengus) fisheries, in the waters between northern Scotland and Norway. Mackerel and herring are the two main fish species targeted by the Scottish pelagic fleet, primarily during October to March and June to September, respectively. Encounters with killer whales were recorded during January and February 2006 by observers on a pelagic trawler fishing for mackerel in this area. These recent data, along with historical records collected since 2000, demonstrate the existence of frequent encounters between commercial pelagic trawlers and killer whales. We describe the foraging behaviour displayed by the whales during fishing operations. Killer whales approached the vessels during retrieval of the net, and remained there until this was completed. They were sometimes sighted during steaming and towing, although there was no observed contact with the boat or net at these times. There is no evidence that the presence of killer whales reduced the amount of fish caught by the trawlers or that killer whales ever become entangled in the nets. We suggest that, during the mackerel fishing season, the whales may obtain a significant proportion of their daily energy requirements from this source.

Through a review of the scientific literature and a more in-depth qualitative meta-analysis of 16 case studies distributed worldwide, this article aims to study impacts of MPAs on marine living resources, ecosystems and related fisheries and to highlight their criteria of efficiency as management tools for a sustainable exploitation. MPAs are efficient for conservation purposes and resource restoration, especially inside their borders. MPAs can also be part of fisheries management systems, but there is a lack of knowledge about their wider scale impacts on fish stocks, ecosystem and fisheries. Adjacent fisheries can increase their catches near closed areas, but such effects are delayed until after MPA establishment and are often limited over distance. Even though local specificities in ecosystems and fishing resources lead to high variability in MPA effects, four major criteria modulate the efficiency of MPAs for fisheries management: (1) the size of the closed area; (2) the level of protection of essential habitats for exploited resources; (3) MPA integration as part of wider integrated fisheries management plans; and (4) efficient monitoring and regulation systems, including participative decision making, to ensure that restrictive measures are respected.

Cupped oysters (Ostreidae, genus Crassostrea) occupy nearshore marine and estuarine habitats worldwide, providing many ecosystem goods and services as well as being a commercially important group of bivalves. In this study, the species identification of an “adulterant” oyster with small body size, which is often misidentified as a “young individual” of other sympatric species, including C. sikamea and C. hongkongensis, was determined for the first time, based on molecular markers (partial mitochondrial cox1 and rrnL genes), phylogenetic analysis, and morphometric approaches. This novel species, C. zhanjiangensis, commonly known as the “cat ear oyster” in Guandu (a famous estuarine oyster farming region of Zhanjiang, Guangdong Province, China), appears to potentially influence the efficiency of C. hongkongensis spat collection due to niche competition on spat collection devices. Phylogenetic analyses confirm its status as the most basal taxon of the Indo-Pacific Crassostrea. A comparative study of the shell characteristics of C. zhanjiangensis, and other Crassostrea species revealed several distinctive morphological traits, including a generally smaller body size, a deeply cupped left valve, and a right valve that is convex in adults but flat in young individuals. Other distinctive features of the new species include life cycle traits that are unique compared with the sympatric C. hongkongensis and C. sikamea species, such as a higher growth rate in the fast growth phase after settlement, followed by a significantly slower growth rate and mass mortality during subsequent life stages. This study provides the basic information necessary for further ecological and population genetic studies on this new species.

Les deux espèces de sardinelles (Surdinella aurita et Sardinella maderensis) sont présentes dans les trois régions d'upwelling de l'Ouest africain (zones sénégalo-mauritanienne, ivoiro-ghanéenne et congoangolaise). La compétition entre ces deux espèces, présentant une grande similitude de forme, à l'activité et aux régimes alimentaires très proches et occupant les mêmes zones géographiques sembleeffective. Cependant les stratégies d'occupation et d'exploitation du milieu, de croissance et de reproduction sont, pour ces deux espèces, intimement liées à la dynamique des upwellings mais elles divergent en de nombreux points. Une complémentarité spatio-temporelle semble donc exister entre la dynamique de ces deux espèces dont les stratégies démographiques diffèrent. Sardinella aurita présente une plasticité et une adaptabilité remarquable aux fluctuations du milieu dont elle tire parti.En cela, elle semble être plus sensible aux variations climatiques que Sardinella maderensis, espèce tolérant de fortes perturbations de I'environnement. Sardinella aurita possède une stratégie adaptative plus souple liée à une grande plasticité démographique. Cela lui permet une meilleure utilisation d'unaccroissement d'enrichissement temporaire du milieu, mais en retour la population subit le contrecoup de façon plus drastique lorsque les conditions deviennent défavorables.

Même si la compétition entre deux espèces de poissons pélagiques peut souvent paraître effective en écologie marine, rares sont les exemples où elle peut être mise en évidence au niveau de l'abondance respective des stocks. Les mécanismes de la compétition pour des espèces spécialisées comme lespélagiques doivent être précisés au niveau de certains paramètres du cycle vital de l'espèce. L'analyse comparée des stratégies démographiques permet de mieux comprendre la nature différente de la dynamique des stocks, notamment l'organisation du partage de ressources communes. La nécessité de gérer les stocks en considérant la stratégie de vie des espèces qui les composent est soulignée.

Large uncertainties in catch data (officially-reported landings and discards) are undermining the ability of scientific organisations to provide valid management advice based on the conventional approach of analytical stock assessments. There is thus an urgent need to consider alternative tools that do not depend on long series of precise age-structured catch data. This paper presents four fishery-independent assessment models developed under the EU project FISBOAT (Fishery Independent Survey Based Operational Assessment Tools). It also reports on rudimentary tests based on simulated data, using the same data sets and protocol as an evaluation study conducted by the US National Research Council in 1997. The survey-based assessment models at hand are able to reliably capture the major signal in biomass and recruitment, although they smooth out transient changes. However, they cannot provide absolute abundance estimates, only relative values on an arbitrary scale. The survey-based approaches could provide more rapid updates of the state of stocks than catch-based methods.