Converging results in different scientific fields (behavioural ecology, fisheriesbiology, acoustic tagging, fisheries acoustics, behavioural modelling) suggest theexistence of “micro-groups” inside fish schools. These would comprise a few (5–10) fishmaintaining contact during a period long enough to allow individuals to recognise eachother. It is hypothesised that they would prefer to share the space with familiar ratherthan anonymous conspecifics. To evaluate whether acoustic methods could be used torecognise “micro-structures” inside fish schools and help test the “micro-group” hypothesiswe analysed acoustic data from anchovy schools off Peru, and gadoids in the North Sea.Data collection used a multibeam sonar (Reson SeaBat 6012). In the Peruvian case study,the sonar was mounted set horizontally on a drifting research vessel and the internalstructure of the schools of anchovies was analysed, although individual fish could not bediscriminated. In the North Sea case study, the sonar was orientated vertically above ademersal trawl to allow observation of individual fish entering the trawl. Geostatisticalanalyses were used to evaluate the existence of small spatial structures in anchovyschools. In these schools, “micro-structures” with a scale as small as 0.5 m were observedacoustically. For the gadoids nearest neighbour distance (NDD) measurements were carriedout, suggesting that the fish aggregated in small groups (2 to 25 individuals, with anaverage of 3.7 fish per group) in the trawl catches. The perspectives and limitations ofthese results are discussed.

Simulation of fisheries systems is a widely used approach that integrates monitoring and assessment tools. We applied the ALADYM (age-length based dynamic model) simulation model to three different studies aimed at investigating correlations between pressure and population metrics, exploring the viability of different mortality levels in long-term scenarios and predicting the effects of combined management measures. Uncertainty was incorporated into the simulations following the Monte Carlo paradigm. Three stocks were used for these exercises: red mullet in the central-southern Tyrrhenian Sea and European hake in both the Bay of Biscay and the Aegean Sea. The analysis of the relationships between total mortality and indicators highlighted significant pairwise negative correlations for red mullet. These signals of decline were supported by the spawning potential ratio indicator (mean exploited to mean unexploited spawning-stock biomass ESSB/USSB), which was low compared to target levels. It only remained within safe bounds (>0.2; probability: 0.90–0.95) at total mortality levels lower than 1.6. The simulation results for European hake in the Bay of Biscay showed that a sustainable exploitation rate might range from 0.87 to 1.04. The benefits of combined management measures were demonstrated for European hake in the Aegean Sea, and with a further dataset on the Eastern cod stock in the Baltic Sea.

We analyzed stable isotopes of carbon and nitrogen to investigate the trophic structureof the subtidal food web around the Mingan Islands, northern Gulf of St. Lawrence, easternCanada. All benthic consumers were enriched in 13C (mean δ13C of–17.1‰) compared to particulate organic matter (POM: –23.3‰). Nitrogen stable isotoperatios ranged from 6‰ to 14‰ and the organisms studied fell into three distinct trophicgroups, primary producers, primary consumers (herbivores), and predators. The sea starCrossaster papposus and the sculpin Myoxocephalusscorpius, known to be top level predators, had slightly higher δ15Nthan other predators. Although the average isotope signature of the sea starSolaster endeca placed it among regular predators, the δ15Nincreased with sea star size and large individuals could be considered as top predators.The relatively small number of organisms located at intermediate trophic levels suggests alow level of omnivory in the Mingan Islands’ system, which contrasts with previouslydescribed benthic systems that exhibit a continuum between herbivores and predators. Lowomnivory, in addition to low diversity, suggests that this ecosystem may be relativelyunstable if exposed to natural and/or anthropogenic disturbances such as exploitation andclimate change.

Gametogenic cycle, gross biochemical composition, condition indices and soft tissuecaloric value of the brown mussel Perna perna were investigated in thecoastal waters of the Gulf of Aden over ten months, to delineate ecophysiologicalperformance of the bivalve. The timing of reproductive activity and seasonal variations ofphysiological features appear to depend on interaction of environmental (exogenous) andinternal (endogenous) factors. Two major spawning events occurred during seasonal monsoonsi.e. in late summer (SW monsoon, August-September) and early spring (NW monsoon,February-March), although these differed considerably in relative intensity and the extentof the resulting changes in physiology and body weight. The summer breeding, which wascorrelated with low water temperature and abundant food, exerted little effect onbiochemical constituents, indicating protracted and portioned spawning. Reserve stores(lipids, carbohydrates and proteins) accumulated gradually in the cooler inter-monsoonperiod of gametogenic quiescence, to provide energy for periods of natural nutritionalstress when water temperature increased and primary production diminished. The secondspawning in spring was accompanied by a substantial decrease in lipids, carbohydrates andcondition indices of the mussels probably due to the release of nutrient-rich gametes inadaptive response to lower food availability in the environment. High reproductive effortpresumably induced increased mortality of females, which were strongly outnumbered bymales at a ratio of 1.8:1.0. Caloric value of this mussel falls within a range typical formussel species in other subtropical areas, highlighting the importance of Pernaperna as a local food resource and its potential suitability foraquaculture.

Initiatives for the sustainable development of aquaculture have so far focused on theproduction of codes of conduct, of best management practices, of standards etc., most ofwhich have been developed by international organisations, the industrial sector and nongovernmental organisations. They were, to a large extent, produced using a “topdown” process and inspired by models from intensive industrial shrimp and sea fish farming(mainly salmon). However, most of global aquaculture production comes from small- andmedium-sized farms, essentially in Asia which contributes 92% of the total worldaquaculture production volume. The objective of this article is to define the contours ofsystemic typologies that are able to express the sustainability conditions of aquaculturesystems. The proposed approach builds on surveys of aquaculture systems which differ interms of their biogeographical nature (temperate/tropical and north/south countries) ortheir farming techniques and their governance systems. This work is a prerequisite to anyattempt at an individualised and comparative evaluation of specific aquaculture systemsfrom either global or territorial viewpoints. In order to go beyond the cleavage of atypology based on the differentiation between developed and developing countries, threetypologies were produced. These typologies allow for discriminatory variables to beidentified such as for example the marketing methods or the pace of innovation: astructural typology, a functional typology and a systemic typology. Finally, therepresentations of aquaculture activity and of its sustainability that producers have ofthe 4 different types that emerge from the systemic typology were recorded andanalyzed.

Microsatellites are one of the most popular markers in genetic studies but typically theyneed to be isolated and characterized de novo for each species. In thiswork, a genomic library enriched for a trinucleotide motif was constructed to identifypolymorphic microsatellite loci in Aequipecten opercularis, a scallopspecies commercially fished in Europe, and to examine the level of genetic variation andgenetic differentiation in samples from Spain and Northern Ireland. Sequencing of 83clones led to the identification of 30 microsatellite-containing sequences which showedoften other repeated sequences. Five microsatellite loci were successfully amplified andfound polymorphic. The number of alleles and the expected heterozygosity per locus rangedfrom 9 to 86 and 0.341 to 0.927, respectively, all localities showing similar levels ofgenetic variation (allelic richness, 13.164–15.487; expected heterozygosity, 0.527–0.638).Discrepancies in genotype proportions from Hardy-Weinberg equilibrium were observed in 11out of 25 locality-locus combinations, a heterozygote deficiency occurring in all casesprobably due to null alleles. Significant genetic differentiation was detected amongA. opercularis from Northern Ireland, Fuengirola (southern Spain) andthe homogeneous samples from northwest Spain. Isolation by distance was the most likelyhypothesis to explain the differentiation detected.

Fish tests must be developed for both regulatory and conservation reasons, as such testing forms an indispensable component of integrated toxicity testing strategy for the marine environment. To standardise a fish embryo test, the acute toxicity of metals and polycyclic aromatic hydrocarbons (PAHs) to early life stages (ELS) of turbot (Psetta maxima) was studied. Embryos were exposed to dilutions of cooper, cadmium, mercury, fluoranthene, phenanthrene, pyrene and naphthalene in darkness and under visible light. Hatching success, yolk sac alterations, pericardial edema, skeletal deformities and mortality were observed. The effective concentrations (EC50, EC10,) no observed effect concentration (NOEC) and the lowest observed effect concentration (LOEC) were determined at the end of the bioassays. Exposure to metals and PAHs in ecologically relevant concentrations, either in darkness or under artificial light, caused significant lethal and sublethal effects in turbot, such as alterations in yolk sac, pericardial edema and skeletal abnormalities. According to the 96 h EC50, the ranking of acute toxicity for metals was respectively: 47.4 (46.8–59.2) μg L−1 Cu; 51.5 (20.9–91.7) μg L−1 Cd, and 83.2 (62.3–125) μg L−1 Hg. For PAHs, acute toxicities were 5.2 (4.3–6) μg L−1 pyrene, 12.3 (6.4–12.7) μg L−1 fluoranthene, 52.2 (30.4–82.7) μg L−1 phenanthrene, and 142 (55–228) μg L−1 naphthalene. Pyrene was consistently the most toxic PAH. In addition, light exposures were performed and photo-enhanced toxicity was found only for fluoranthene and pyrene. Turbot embryos were found to be more tolerant to metals and PAHs than were hatched larvae. These results suggest that, considering the short duration of the ELS turbot test and its high sensitivity, it is suitable for use as a standard test for marine fish.

Recirculation aquaculture system (RAS) is the type of land-based aquaculture productionthat interferes the least with the environment, particularly due to low effluent volumeand overall water requirement. Water reuse, sometimes limited by the accumulation of wasteproducts excreted by fish, can be improved by incorporating another biotechnical componentin the form of high rate algal pond (RAS+HRAP), thus adding to the economy and selfsustainability of the system. Our goal was to evaluate whether rearing fish for 1 year ina RAS or RAS+HRAP led to differences in fish production and health, by assessing: (1) fishgrowth; (2) impact on the morphological structure of sea bass target tissues (liver,kidney, and spleen); (3) susceptibility to monogenean parasites; (4) resistance topathogen challenge with Listonella anguillarum; and (5) total bloodprotein. Over the one-year experimental period, sea bass showed no statistical differencesin any parameter evaluated, suggesting that there was a satisfactory purification rate inthe RAS+HRAP system.

The Rideau Canal in Canada was constructed in the 1800s to enable strategic military andcommercial transport in eastern Ontario between Lake Ontario and the Ottawa River. Today,the Rideau Canal is managed by Parks Canada and remains an engineered ecosystem,particularly in the urban Ottawa reach (7 km long) where it is largely channelized and ispartially drained during the winter to protect canal infrastructure (i.e., locks) andprovide recreational opportunities (i.e., skating). Interestingly, the Ottawa reach of theRideau Canal supports one of the few wild urban muskellunge (Esoxmasquinongy) fisheries in North America supported by natural reproduction.However, little is known about the spatial ecology, residency patterns or survival of thisapex freshwater predator in urban environments or canal systems. Radio-telemetry was usedto study adult (N = 10; total size range of 64 to 122 cm) muskellunge inthe Ottawa reach of the Rideau Canal over a multiple year period. The seasonal movementsand home range of muskellunge were greatest during spring corresponding with the periodwhen water levels in the canal were raised and muskellunge were presumably seeking outsuitable spawning habitats following ice-off. During the summer fish ranged throughout theentire 7 km urban reach of the canal and by early fall muskellunge moved to the deeperparts of the reach and became largely restricted to an embayment known as Dow’s Lake priorto the lowering of the canal where they stayed for the entire winter. The same pattern ofseasonal movements persisted across several years. None of the tagged muskellunge werestranded from the fall canal drainage. One fish emigrated from the urban reach of thecanal during the study period, moving upstream through a lock to an exurban reach. Inaddition, a single tagged fish died from a winterkill event. Environmental influences suchas seasonality and water depth (associated with canal operations) are believed to be theprimary mechanisms contributing to habitat selection and movement patterns of muskellungein this reach of the Rideau Canal. Data on the spatial ecology of muskellunge in the urbanreaches of the Rideau Canal will inform management of this unique population of fish toensure that the historic and ecological values are balanced to preserve this iconicCanadian natural heritage site and its biota.

The redclaw crayfish (Cherax quadricarinatus) is a freshwater crayfishspecies endemic to northern Australia and Papua New Guinea that is the focus of a growingculture industry in number of regions around the world. Here we isolated and characterized15 microsatellite loci from Cherax quadricarinatus and tested variabilityof the loci in 66 unrelated cultured individuals. Thirteen of 15 microsatellite loci werepolymorphic. Number of alleles per locus ranged from two to seven while observed andexpected heterozygosities ranged from 0.172 to 0.985 and from 0.373 to 0.778,respectively. Eleven loci conformed to Hardy–Weinberg equilibrium in the sampledpopulation. These microsatellite loci developed here provide an important resource forstudying genetic diversity and population structure in redclaw crayfish and potentially inother related species.