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Assessment of two minimally invasive methodologies for sex identification in the European eel, Anguilla anguillaNARA Subscribed
Sex is an important driver of variation in behaviour, ecology and physiology. Sex identification in the Critically Endangered European eel ( Anguilla anguilla ) currently requires fish sacrifice, or the use of morphological differences such as body length, which can be inaccurate in certain habitats and at intermediate body lengths. Non‐lethal tools for accurate sex identification in this species are therefore required. Here,...
Improving eel pass efficiency: The role of crest shape and water flow in facilitating upstream juvenile eel migrationNARA Subscribed
River connectivity is crucial for the European eel ( Anguilla anguilla ) to complete its complex life cycle, which is vital for upstream recruitment to the declining population of this critically endangered catadromous fish. Eel passes, or ladders, are frequently installed on riverine structures, such as dams and weirs, to mitigate barrier effects and restore connectivity for upstream migrating eel. Efforts to optimise the eff...
Rapid Ocean Warming Drives Sexually Divergent Habitat Use in a Threatened Predatory Marine EctothermNARA Subscribed
Climate change poses one of the greatest threats to marine ecosystems worldwide, altering physical, chemical, and biological processes at unprecedented rates. Severe impacts on marine species and habitats have been extensively documented, with shifts in phenology, spatial distribution, and migratory behaviour increasingly pervasive. However, there is a lack of species‐specific data examining responses and adaptation to rapid w...
The Seaward Migration of European Eel at a Continental Scale: A Europe‐Wide Biotelemetry Meta‐AnalysisNARA Subscribed
The European eel ( Anguilla anguilla L.) has a catadromous life cycle, with a single panmictic population that colonises continental Europe and northern Africa yet migrates 5000 to 9000 km to spawn in the Atlantic Ocean. It is unknown how this continental migration is organised so individual eels arrive in time for spawning with conspecifics. This meta‐analysis combined tracking data from 18 water bodies in freshwater and tran...
Acoustic telemetry (AT) has become ubiquitous in aquatic monitoring and fish biology, conservation, and management. Since the early use of active ultrasonic tracking that required researchers to follow at a distance their species of interest, the field has diversified considerably, with exciting advances in both hydrophone and transmitter technology. Once a highly specialized methodology, however, AT is fast becoming a general...
Sea trout, the anadromous ecotype of the species Salmo trutta , are subject to multiple threats, including exploitation and aquaculture impacts in the marine environment, habitat fragmentation and pollution in freshwaters, loss of genetic resilience due to interbreeding with hatchery strains and environmental change. Small streams contribute relatively little biomass to European sea trout stocks but are thought to be important...
Environmental influences on the phenology of immigrating juvenile eels over weirs at the tidal limit of regulated riversNARA Subscribed
Recruitment of the catadromous and critically endangered European eel Anguilla anguilla in Europe has declined substantially since the 1980s, with considerable knowledge gaps remaining in many aspects of their life cycle. The aim was to assess eel migration phenology in three regulated rivers in England between 2009 and 2019 through analyses of eel numbers using passes at their tidal limits, with calculation of the annual timi...
The European eel ( Anguilla anguilla L.) is a critically endangered catadromous fish. Their inshore and in-river arrival as glass eel and elvers is an important stage of their life cycle, marking the transition from marine to freshwater habitats. Considerable knowledge gaps remain on the temporal and spatial patterns of this transition period to freshwater residency. Stable isotope (SI) analysis (δ 13 C, δ 15 N) was used to as...
Optimising the design of passage facilities to restore fluvial connectivity for juvenile European eel (Anguilla anguilla) is a key priority within conservation efforts for the species, across the majority of its freshwater range. Employing an experimental setup that simulated gravity-fed upstream eel passes, this study demonstrated that novel V-profile passes, which incorporate two lateral slopes (15°), performed better than l...
Effects of preservation by ethanol on δ 13 C and δ 15 N of three tissues of the critically endangered European eel Anguilla anguillaNARA Subscribed
The temporal effects of ethanol preservation on the δ 13 C and δ 15 N values of tissues excised from European eel Anguilla anguilla were assessed. Preservation significantly enriched 13 C values of fin and mucus but not dorsal muscle. The 13 C enrichment occurred in the initial 15 days of preservation and was independent of initial eel mass. Tissue preservation effects on δ 15 N values were negligible. These tissue‐specific is...
Anthropogenic activities since the European colonization of the North American Great Plains have drastically altered landscape composition and configuration, subsequently affecting native biodiversity. These contemporary human‐modified landscapes may affect mammal species' distributions, diel activity patterns, habitat use, and interspecific interactions, though a better understanding of these effects on mammals occurring in r...
Anguillid eels are near globally distributed catadromous fishes with marine spawning areas and inshore and inland growth areas in both lotic (rivers, estuaries) and lentic (lakes, ponds, lagoons) water bodies. As predators, anguillid eels play an important ecological role in both marine and freshwater systems, and several species are harvested commercially for food. However, some of the more widely distributed species have und...
Ecological studies on the critically endangered European eel Anguilla anguilla often incorporate stable isotope analysis that typically uses dorsal muscle sampled from euthanised eels. To minimise the lethal sampling of imperilled populations, fin tissue and/or epidermal mucus can provide non‐lethal alternatives to muscle. The results here indicate that δ 13 C and δ 15 N values of both eel fin and mucus are not significantly d...
Anguillid eels are found globally in fresh, transitional and saline waters and have played an important role in human life for centuries. The population status of several species is now of significant concern. The threats to populations include direct exploitation at different life stages, blockages to migratory routes by dams and other structures, changes in river basin management that impact habitat carrying capacity and sui...
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