Search

DNA barcoding and metabarcoding is increasingly used to effectively and precisely assess and monitor biodiversity in aquatic ecosystems. As these methods rely on data availability and quality of barcode reference libraries, it is important to develop and follow best practices to ensure optimal quality and traceability of the metadata associated with the reference barcodes used for identification. Sufficient metadata, as well as vouchers, corresponding to each reference barcode must be available to ensure reliable barcode library curation and, thereby, provide trustworthy baselines for downstream molecular species identification. This document (1) specifies the data and metadata required to ensure the relevance, the accessibility and traceability of DNA barcodes and (2) specifies the recommendations for DNA harvesting and for the storage of both voucher specimens/samples and barcode data, (undefined)

International audience; Electrofishing in streams of low water conductivity has technical limitations leading to the widespread use of poison fishing. In theory, provided a high enough voltage gradient can be created in water, electrofishing should be possible in all but the lowest of conductivities (

This study aimed to describe the influence of different electrofishing engine configurations on electric field dispersion in water. Several experiments with original results are included. The aims were to (i) assess the equivalent electrode resistances and the output voltage at the anode, (ii) assess the influence of electrode misuse on the dispersal of the electric field in water, (iii) assess the influence of the duty cycle and the frequency on the radius of attraction around the anode, and (iv) set the voltage and the duty cycle based on information from models for backpack and bankside electrofishing engines. A synthesis of equivalent electrode resistances from different studies was created. Using an oxidised anode induced a decrease in the radius of attraction. Frequency had no influence on the radius of attraction, in contrast to the duty cycle. Models including the voltage and the duty cycle were created to enable the configuration of electrofishing engines.

Performing fish survey protocols with different electrofishing equipment and settings can lead to difficulties in comparing the data obtained. In this study, we captured two fish taxa (i.e. the European eel and salmonids: Atlantic salmon and brown trout) in the field using four models of electrofishers that provided different waveforms: direct current (DC), pulsed direct current (PDC) and pulsed exponential current (PEC). This study aimed to assess effects of using different waveforms and frequencies, while considering environmental variables, on i) attraction, represented by occurrence and catch-per-unit-effort (CPUE) of fishes, and ii) spinal damage, based on ultrasound of the spinal column. For all species, DC and PDC yielded equivalent occurrences and CPUEs, regardless of the frequency. In contrast, PEC induced a significant decrease in occurrences and CPUEs of both eels and salmonids. The percentage of injured fishes increased as the frequency or length of the salmonids increased while waveform had no effect. Ultrasound was determined to be a good non-invasive method to detect injuries in fishes.

This work is a contribution to the Selune River dams removal project. This study was supported by a grant from the French Seine-Normandy Water Agency (AESN); Maintaining connectivity in aquatic ecosystems is important to ensure adequate ecological functioning. A large dam removal project in the Selune River (Normandy, France) would reconnect 827 km(2) of catchment area to the sea. Only the downstream section of the Selune is currently available to diadromous fish, which migrate between freshwater and the marine environment. In particular, managers focus on the future potential abundance of Atlantic salmon, Salmo salar, for conservation and fishery purposes. As in stream channel habitat drives carrying capacity of juvenile salmon, salmon abundance is usually inferred from intensive and linear habitat surveys. However, this approach is neither cost-effective for large-scale surveys nor feasible for riverbed sections with low accessibility for measurement with traditional methods, e.g. dam lakes. We used well-defined relationships between gradient, hydrology and channel habitat structure to construct a simple model to estimate potential suitable habitat for juvenile salmon. Using fine-scale habitat data from nearby rivers, we parameterized a linear mixed model to estimate the area of suitable habitat based on simple physical descriptors of river characteristics. We compared our predictions to fine-scale habitat surveys on the upper Selune. Using only slope and width, our model was able to explain 80% of the variance in suitable habitat. Estimates indicated that dam removal on the Selune River would generate a threefold increase in suitable habitat for juveniles. This could increase the mean number of adult salmon returning to the river by 1420.9 (s.e. = 1015.5). More generally, this model provides an alternative and cost-effective tool to help better manage salmon populations in rivers impacted by dams.

Salmonids are characterized by a large diversity of life histories, but their study is often limited by the imperfect observation of the true state of an individual in the wild. Challenged by the need to reduce uncertainty of empirical data, recent development in medical imaging techniques offered new opportunities to assess precocious maturation in Atlantic salmon parr. Traditional phenotypic (external) examination and ultrasound (internal) examination were compared and recommendations on fish handling and ultrasound image interpretation are provided. By allowing to see the unseen, portable ultrasound imaging offers great opportunities for ecological studies in the wild, such as the assessment of individual sexual maturation.

Understanding the geographical scales at which environmental variables affect an individual's body size, and thus their mortality risk, can inform management strategies to help conserve wild populations under climate change. Yet, our current understanding of these relationships is based on studies done at different scales that report inconsistent findings. We predicted that temperature-related variables (e.g. winter temperature) influence body size at a regional scale, that is, affecting individuals in geographically independent catchments similarly, whereas non-temperature-related variables (e.g. conspecific competitor density) exert a local influence, that is, affecting individuals in geographically independent catchments differently. We developed statistical models to test our predictions using body length measures of a large and long-term sample of juvenile Atlantic salmon (Salmo salar) from three rivers in the U.K. and France. We developed mixture models to predict the individual juvenile salmon ages objectively from their body length. We then developed linear mixed models to describe inter-annual changes in mean length of the youngest (age 0) cohort of juvenile salmon from river-specific seasonal variables, and tested whether they exerted their influence at a local or regional scale. All models accounted for spatio-temporal differences in sampling protocols and individual reproductive strategy. We estimated and interpreted coefficients using Bayesian theory. Our findings supported our predictions. Juvenile salmon were longer in years of higher overwinter water temperature and this effect was best parameterised as a single regional coefficient applicable to all three rivers. Similarly, spring mean temperature was best parameterised with a single regional nonlinear coefficient. In contrast, juvenile salmon were shorter in years of high densities of competing conspecifics and their interaction with total mean discharge and these effects were represented by local river-specific coefficients. Summer droughts had a negative effect on juvenile salmon length but was best parameterised as a single regional coefficient, contrary to our expectations. We show that environmental variables affect biological processes at different but predictable geographical scales. Temperature-related variables affect body sizes of exothermic animals at a regional scale, whereas non-temperature variables, such as the density of conspecific competitors and water abstraction, exert their influence at a local scale. These findings highlight the importance of integrating local and regional management plans to mitigate the impacts of climate change on the body size, and ultimately the conservation, of exothermic species.

To assess the correlation between four visual morphological types based on body colour and shape (fario trout, FT; shiny fario, SFT; presmolt trout, PST; typical smolt ST) of juvenile brown trout Salmo trutta during downstream spring migration and the biological form at the adult stage (river or sea), mark-recapture experiments were carried out over a period of 23 years. Evidence is provided that the visual SFT type is not a relevant one, while objective colorimetric measurements using a black basin are the best way to determine the morphological type in migrating juveniles.

La truite (Salmo trutta) présente deux formes écologiques « rivière » et « mer » qui cohabitent sur de nombreux fleuves du littoral Manche-Atlantique. Ces deux formes sont considérées comme formant un seul stock en raison de la production d'une forme à partir de l'autre et de leurs possibilités de croisement lorsqu'elles sont en sympatrie sur les zones de reproduction. L'étude réalisée montre l'existence de critères morphologiques fiables permettant une identification de ces deux formes au cours de leur cycle biologique. Chez le juvénile, la distinction est impossible au stade résident, mais est possible au stade migrant à partir du taux d'argenture qui est élevé pour la forme marine (groupe des smolts). Chez l'adulte, la distinction est rendue facile par l'analyse des critères de taille et de couleur mais doit être vérifiée par une étude scalimétrique. L identification de ces deux formes permet alors de mesurer leur niveau d'abondance et d'analyser leur évolution sur le long terme sur un même bassin.

The objective of this study is to assess the effects of the unique 1-year health-wellness program of exercise and health education for obese youth on body mass index (BMI) and blood pressure. The CEMHaVi program included 74 obese children. Participants, 19 girls and 18 boys, and controls, 17 girls and 20 boys, were assigned to treatment. The treatment participants were compared with a group who chose not to participate. Treatment consisted of a unique program of physical activity that emphasized playing games. Activity sessions were offered once per week, 2 h each session, for 12 months. Physical activity was complemented with health education. Controls received only the normal care of a physician in pediatrics. Physical and physiological measures were assessed before and after intervention. Findings of the study showed a significant difference in BMI between treatment and control participants (P

This study presents the validation of a scale-reading method for age estimation of brown trout (Salmo trutta). Age estimated from the scale reading was compared with the true age from recaptured fishes pit-tagged at the 0+ stage. Recapture was performed via electrofishing or trapping during migration up to 6 years later. A sample of 375 fish was analysed, including freshwater (363 fish) with two sub-groups (resident and migratory) and anadromous forms (12 fish). Average percentage of error in the scale reading was low (6.4%) in the whole sample. Error rate dramatically increases with age. There was no error in the sea trout sample. When considering freshwater fish alone, average error rate remained low (6.6%) and was higher in resident fish (older individuals) than in migratory fish (younger individuals). No statistical difference was observed between the true age and the age estimated from scales, thus confirming the reliability of scale reading for age estimation.

Since 1985, the dynamics of the Atlantic salmon (Salmo salar) population in the River Oir, a spawning tributary of the River Sélune (Lower Normandy, France), have been studied from a data set of parr density and the number and the age structure of migrating fish (smolts and adults). Parr densities (1.5–17.4 per 100 m2) and smolt production (0.25–9.2 per 100 m2) varied considerably from year to year. Migrating juveniles were mainly 1 year old. Abundance of parr and smolts was strongly correlated with 0+ densities. Egg-to-smolt survival rates were highly variable year on year (0.044–1.07%). During the juvenile freshwater phase, mortality was highest between the egg and the 0+ stage (97.5–99.9%). The fluctuations in abundance of juvenile salmon appear to be linked to the number and distribution of spawners within the stream during spawning, and also to the amount of silt deposition on the spawning beds. As a result, mortality was highest during the under-gravel phase, and the mean survival rate from egg to smolt was much lower than in rivers less impacted by human activities. Therefore, during the study period, the low production of smolts during some years might lead to a low renewal rate of the salmon population.

From 1993 to 1995, more than 2000 of 0+ brown trout (Salmo trutta L.) were captured in a small brook in October and released after clipping the left pelvic fin. More than 1700 of them were also tagged with a small Passive Integrated Transponder (PIT) tag (11 mm long) implanted in the body cavity. Tagged juveniles were recaptured in May in the brook but also one year later in the river Oir, and continuously in a trap during spring downstream migration in the river Oir.

Qu'elles soient complètes ou partielles, les pêches à l'électricité ont pour objectif d'obtenir un échantillon suffisamment représentatif des populations ou communautés présentes dans les stations prospectées. L'échantillonnage doit être reproductible dans le temps et dans l'espace pour pouvoir évaluer l'état du peuplement vis-à-vis d'un peuplement de référence et permettre une analyse comparative temporelle et spatiale.