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.

This study was designed to measure responses of four-year-old black-lip pearl oysters(Pinctada margaritifera) to different temperatures and foodconcentrations and to identify the energy requirements of each sex. Oysters were fed amonospecific microalgal diet of Isochrysis affinis galbana(T-iso). Measurements of oxygen consumption and ingestion rates were carried outat 24 °C and 27 °C and at two algal (T-iso) concentrations: 5000 and 30 000 cellml-1. Glycogen content in adductor muscle, absorption efficiency and scopefor growth were also estimated. Females and males responded differently to environmentalfactors, with food level being the most influential parameter. Oxygen consumption andabsorption efficiency were significantly higher in females than in males, but males hadsignificantly higher glycogen content than females. At high food concentration, glycogencontent, ingestion rate, oxygen consumption, and scope for growth were significantlyhigher than at the low food concentration. Only absorption efficiency was significantlyhigher at the low food concentration. Oxygen consumption was significantly higher at 27 °Cthan at 24 °C. These results indicate that females and males have different bioenergeticfunctioning and that energy demands for reproduction are higher in females.

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.

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.

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.

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.

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.

Piracanjuba (Brycon orbignyanus) is a Brazilian migratory fast-growing omnivore, very appreciated as a sport fish, which is threatened to extinction in Southern Brazil due to stock over exploitation and dam building. Therefore, efforts have been made to raise this fish in captivity for reintroduction and aquaculture purposes. In the present study, the effects of different dietary protein and lipid concentrations on piracanjuba fingerlings growth performance, feed utilization, body composition, hepatosomatic index (HSI) and activity of the lipogenic enzymes fatty acid synthetase (FAS), glucose-6-phosphate dehydrogenase (G6PD) and malic enzyme (ME) were investigated using a 2 × 3 factorial experiment. Six casein–gelatin based diets were prepared combining two protein (30% and 32%) and three lipid concentrations (5.5%, 8.8% and 12.1%). Eleven fish, average weight 11.30 ± 0.1 g, were held in each of 18100–l aquaria, supplied with recirculating freshwater. Each diet was randomly assigned to triplicate groups of fish and fed to apparent satiation, twice a day for 100 d. Piracanjuba fingerlings' daily weight gain (0.36–0.40 g), specific growth rate (1.43–1.51%), feed utilization and HSI were not influenced by dietary protein or lipid concentration. However, body composition was directly affected by dietary treatment. An increase in body fat and dry matter was observed as dietary lipid increased, for both dietary protein concentrations tested. The activity of FAS was depressed by increasing dietary fat levels but the G6PD activity did not differ among dietary treatments, although ME activity showed some regulation by dietary protein. These results indicate that an increase from 5.5% to 12.1% in the dietary lipid, at a dietary protein concentration of 30% or 32%, promotes body fat accumulation in piracanjuba fingerlings with no improvement in growth, suggesting that the lipid requirement for this species should be 5% or less, when raised for commercial purposes. However, the additional energy reserve from body fat accumulation could be desirable for piracanjuba fingerlings produced for stock enhancement.

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.

Fisheries research monitoring surveys provide an ensemble of measurements on fish stocks and their environment. Because the interannual variability in such survey-based indicators is high and because diagnostics on fish stocks cannot be based on noise, our concern is to make use of what is continuous in time to obtain a reliable diagnostic. In this paper, we show how min/max autocorrelation factors (MAFs) can be useful for assessing the status of a fish stock. Indeed, MAFs will allow us to (i) summarize the multivariate indicator signals into orthogonal factors that are continuous in time, (ii) select those indicators that carry the major signal in time, and (iii) forecast stock status by modelling the time continuity of the MAFs. These different potential uses of MAFs in an indicator-based approach to assessment were illustrated with North Sea cod, for which a suite of biological and spatial indicators are available over a 21-year survey series.

A comparative study, using biological indicators, was conducted in Mali where two man-made reservoirs (Selengue and Manantali) are particularly suited for investigating the impact of fishing effort on the fish assemblage: these two ecosystems have relatively similar morphological, edaphic and environmental properties but are subjected to radically different levels of fishing exploitation (low at Manantali, high at Selengue). The comparison is based on a three-month survey of commercial fisheries, focusing on fishing activities and catches on the two reservoirs.

The results show that some indicators are useful for evaluating fishing impacts. Among these indicators are: fishing effort which is much higher at Selengue (22 800 fishing trips per month) than at Manantali (3000), catches per unit effort (lower at Selengue than at Manantali following a ratio ranging from 1.5 to 4 according to the gears used), annual yields per ha higher at Selengue (100 kg ha−1) than at Manantali (27 kg ha−1), the average fish lengths in the catches (16.2 cm at Selengue compared to 23.6 cm at Manantali) and the maximum lengths of the targeted species generally smaller at Selengue (10 to 30 cm) than at Manantali (30 to 50 cm). By contrast, a second class of indicators exhibit values that are contrary to expectations: the species richness (52 compared to 36), the species diversity (I sh = 4.02 compared to 3.24) and evenness (0.76 compared to 0.69) were higher at Selengue where 4 species accounted for 50% of the landings compared to only 2 species at Manantali (9 species compared to 7 for 80% of the landings). The trophic structure of the landings is higher (37% primary consumers compared to 49% at Manantali) as well as the mean trophic level (2.74 compared to 2.54 at Manantali).

Even if a good understanding of the two fisheries can explain the unexpected trends of the second class of indicators which increase with fishing effort, it clearly appears from this study that only the first class of indicators is robust and can be used for comparative studies across ecosystems.

Goldfish embryos of pre-morula, somite formation, optic vesicle, heart formation and pigment formation stages were tested for cryoprotectant toxicity, using DMSO and glycerol at 10, 12 and 15% concentration. Those that showed 50% or more survival were employed for cold shock test, from 24 to 4 °C at the rate of –1 °C/min. Only embryos at the heart formation stage protected with 12% DMSO showed 60% survival and 35% hatching. A group of embryos of that stage went through a freezing and thawing test to temperatures of –15, –25 and –35 °C. They showed 30, 5 and 2% survival and 12, 3 and 1% hatching respectively.

La palourde japonaise présente un grand polymorphisme de coloration de la coquille. Bien que ce polymorphisme soit connu depuis longtemps, son hérédité n'a jamais été analysée. Cette étude a pour but, hormis la connaissance fondamentale du déterminisme génétique des caractères de la coloration, de permettre de produire des individus homozygotes pour la coloration. Ceux-ci pourront être utilisés comme marqueurs génétiques dans des expériences au laboratoire. La coloration est définie par trois caractères, l'asymétrie, l'ornementation et la couleur de fond. Les palourdes à coloration asymétrique sont totalement ou partiellement dépigmentées, à l'exception d'une bande postérieure sur la valve gauche. Les palourdes à coloration symétrique sont pigmentées sur les deux valves. Quatre séries de croisements ont permis l'analyse de différents caractères, Asymétrie et Symétrie, et des ornementations Vague [V] et Zébré [Z]. Les résultats suggèrent que la coloration est contrôlée par au moins deux gènes. Le caractère d'asymétrie est contrôlé par un gène à deux allèles, asymétrie (A) dominante et symétrie (S) récessive. Quelquesindividus asymétriques homozygotes ont été identifiés. Un phénotype Bigarré (Bi), est apparu dans les ségrégations du croisement V × V et des croisements Z × Z. Les résultats suggèrent que Vague et Zébré sont dominants sur Bigarré. Cependant, il existe d'autres ornementations (phénotype 1) et le gène codant pour l'ornementation serait ainsi multiallélique. Le déterminisme de la couleur n'est pas défini. Par contre, les observations montrent que la coloration n'est pas liée au sexe. Dans la majorité des croisements, les proportions observées pour l'asymétrie s'éloignent des rapports attendus selon les lois de Mendel. Cette différence est due à un déficit systématique en individus homozygotes symétriques qui n'a pu être expliqué.

Multibeam omnidirectional sonars are tools currently used by fishers, but also allow the monitoring of pelagic fish schools surrounding a platform. Multibeam processing methods now offer improved capacities for raw data storage. The Simrad SP90 sonar was used for the detection of fish schools associated with drifting fish aggregating devices (FADs), and digital systems developed for the acquisition and processing of volume backscattering echoes and position data. Data sampling methods were defined based on two modes: one for periods searching for FADs and associated schools, and one for school monitoring in drifting mode. Validation of the detection of several FAD-associated schooling species was made by simultaneous visual observations or/and cross-checking with echosounder recordings. The characteristics of schooling behaviour in the targeted fish species are fundamental for the correct interpretation of acoustic data. Sonar detection threshold is the result of a compromise between fish number, size, species and the nearest neighbour distance (NND) of individuals per dynamic structure (school or shoal). Tuna schooling dynamics mean that NND can sometimes be too large to allow the presence of these fish to be detected, despite their number. Sonar data should be analysed and interpreted in a holistic manner, in combination with behaviour pattern and dynamics of all species around the drifting FADs. An autonomous sonar buoy prototype equipped with 360° scanning sonar coupled to video cameras will increase our understanding of tuna behaviour around drifting or anchored objects. A similar methodology can be applied to different kinds of platforms, either anchored or in permanent positions. This would improve the monitoring of fish schools around artificial reefs, open sea aquaculture farms, and across estuaries, channels or straits; applications which are undoubtedly essential for progressive fisheries management.

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.

The African catfish, Clarias gariepinus, is a highly appreciated species for aquaculture, because of its favourable food conversion, its resistance to discases, its relatively low requirements for water quality, the possibility for high stocking density and the excellent meat quality. For those reasons even in the Netherlands, there is a modest, but Europe's largest and still expanding, African catfish farming activity. Although this species grows and matures in captivity, there is no spontaneous reproduction. We coulddemonstrate that the failure to reproduce resides in the brain-pituiary-gonad axis. Hormones required for oogenesis and spermatogenesis are being produced in sufficient quantities. However, final oocyte maturation, ovulation, spermiation and spawning behaviour do not occur, due to the lack of a gonadotropin surge. In nature, the prespawning gonadotropin surge is induced by environmental factors such as the waterlevel in the spawning area. Under farming conditions the environmental cues are hard to identifyand/or to mimic. In combination with unavoidable stress this causes a blockade of the release ofgonadotropin releasing hormone (GnRH). Consequently, gonadotropin surge release fails to occur, which is enforced by an effective hypothalamic dopaminergic inhibition. The gonadrotropin surge induces the conversion of 17 αOH-progesterone into 17 αhydroxy-20 β-dihydroprogesterone, the final maturation inducing substance. Based on these data, several protocols for artificial propagation could be developed. They include either a treatment with a GnRH analogue in combination with a dopamine receptor antagonist, a treatment with homologous gonadotropin or HCG, or a treatment with 17 αOH-progesterone. Since a number of years we have used the African catfish as a model for fundamental research onfish reproductive endocrinology. Till now one gonadotropic hormone (GTH) could be demonstrated. Itsamino acid composition and sequence was analysed and appeared to be homologous with known forms ofthe maturational GTH (GTH-II). Specific radioimmuno assays for the complete hormone and its α- and β-subunit respectively, have been developed. cDNAS encoding the subunits have been cloned. They are applied now for Northern blotting and in situ hybridization. GnRHs were fully characterised (a specific catfish-GnRH and chicken-GnRH-II). Specific antibodiesagainst these peptides were raised and the cDNAS encoding the hormone precursor molecules werecloned and used for respectively immunocytochemical localisation and radioimmunoassays, and in situ hybridisation. The importance of the two GnRH forms for gonadotropin release was studied. Chicken-GnRH-II appears to be 10 to 100 times more potent than catfish GnRH, probably due to its higher receptor affinity. Catfish GnRH, however, is present in the brain and pituitary about 100 times more than chicken GnRH-II. Steroid hormone synthesis by ovaries, testis and seminal vescicles was analysed. The sex sieroids that play a role in the negative feedback control of gonadotopin release were identified (11-keto-testosterone and testosterone) and their interaction with hypothalamic dopamine metabolism was demonstrated as one of the possible mechanisms of action. Several steroid conjugates from the seminal vesicles were shown to have pheromonal activities, involved in reproductive behaviour. They induce under certain physiological conditions attraction between conspecifics and synchronization of ovulation.

An analysis of 273 samples taken at the filter screens of an estuarine power plant cooling water intake showed that herring and sprat were boldly associated with each other and formed mixed species schools. Herring-dominated schools were typically larger, more frequent and contained larger-sized individuals than schools dominated by sprat. The mean body length of both herring and sprat was biased as a function of their relative importance in the school suggesting that the fish schools were assorted by size. However, switching to a fish school dominated by the other species increased the individual body length variation relative to the group average. Diets of both species overlapped boldly but the feeding rate of sprat was significantly lower than that of herring. Our results suggest that during estuarine residency young sprat suffer the consequences of the school trap, possibly to profit from reduced predation risks in herring schools.

Atlantic herring (Clupea harengus)in the offshore regions of the Gulf of Maine migrate each fall fromtheir feeding grounds to the northern portion of Georges Bank tospawn.The Northeast Fisheries Science Center’s (NEFSC) herringacoustic survey has taken advantage of this behavior by conductingsystematic surveys of the pre-spawning fish each year since 1999.Multi-frequency acoustic and midwater trawl data were collectedalong transects oriented perpendicular to bathymetric contours.Acoustic backscatter was analyzed to describe the aggregative patterns(e.g., size, location in the water column, and spatial and temporaldistribution) of Atlantic herring during these surveys and regressiontrees were used to examine the aggregation characteristics. Thepositional variables of distance to spawning grounds and verticallocation in the water column were the primary characteristics fordescribing pre-spawning aggregations. Secondary to these were thetemporal variables of diel and survey timing, and the morphological characteristicof aggregation area. Lower numbers of aggregations were observedclose to the herring spawning grounds but with higher acoustic energythan larger numbers of aggregations observed further from the spawninggrounds but smaller in size and lower in acoustic energy. Most aggregationswere in the lower portion of the water column, but those that werein the upper portion of the water column had higher acoustic energy.Consistently throughout the decade, 90% or more of herring aggregationswere located within 40 nautical miles of their spawning grounds.The regression tree method provided valuable insight to the dataseries where it highlighted spatial and temporal patterns and wasan effective way to quantitatively summarize relationships.

This study describes the in vitro antiviral activity of two species of oyster hemolymph (Crassostrea rhizophorae and C. gigas) collected on Southern Brazilian coastline. Either the acellular and cellular fractions were tested against herpes simplex type-1 (HSV-1), human adenovirus respiratory strain (AdV-5) and simian rotavirus (RV-SA11) by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The evaluation of viral inhibition was performed using four different strategies: simultaneous, pre-infection and post-infection treatments and virucidal assays. The cellular fraction from Crassostrea rhizophorae showed the most prominent inhibition of HSV-1 and AdV-5 replication, particularly in post-infection treatment assay. No inhibition of rotavirus replication was observed. Both oyster hemolymph fractions showed virucidal activity against all tested virus in non-cytotoxic concentrations.