Short-term growth, movement and response of European eel Anguilla anguilla to re-meandering of a small English chalk stream DOI Creative Commons
James D. Champkin, Tea Bašić, Phillip J. Haubrock

et al.

Knowledge and Management of Aquatic Ecosystems, Journal Year: 2024, Volume and Issue: 425, P. 23 - 23

Published: Jan. 1, 2024

In recent decades, the population of European eel Anguilla anguilla has strongly declined and stock is outside safe biological limits. Freshwater habitat degradation been cited as a key causal factor in decline, but there are limited studies assessing responses this species to river restoration efforts. This study utilized mark-and-recapture data from annual electrofishing surveys conducted between 2009 2014 describe density size structure (length, weight) River Glaven − chalk stream eastern England. Short-term effects on were assessed via Before-After-Control-Impact experimental design. Of recaptured individuals, 73% sedentary rest mobile. Despite re-meandering work increasing heterogeneity reach relative control reach, no change or was detected across treatments time. While length weight increased downstream over period, declined. can be attributed various local stressors such barriers migration, well broader range-scale causes including climatic oceanic factors. Although further research ideally necessary ensure adequate sample sizes, provide long-term monitoring restoration, emphasizes need for whole-catchment efforts conservation that combine river–floodplain with greatly improved fish passage.

Language: Английский

Responses of fish to nationwide improvements in the water quality of a densely populated and heavily modified country over four decades DOI Creative Commons
A. D. Nunn, Rachel F. Ainsworth, Yueming Qu

et al.

Water Research, Journal Year: 2025, Volume and Issue: 274, P. 123163 - 123163

Published: Jan. 18, 2025

Globally, fish have been severely affected by the widespread, chronic degradation of fresh waters, with a substantial proportion species declining in abundance or range recent decades. This has especially case densely populated countries an industrial heritage and intensive agriculture, where majority river catchments deteriorations water quality changes land use. study used spatially temporally extensive dataset, encompassing 16,124 surveys at 1180 sites representing wide typologies pressures, to examine populations England's rivers over four decades (1980s-2010s). The analyses revealed gradual, nationwide increases mean richness diversity across pressure gradients. In cases, were most pronounced 1980s, since when any further comparatively minor, but there no trends full time series. There also temporal, assemblage structure, driven largely variations densities brown trout Salmo trutta roach Rutilus rutilus, consistent sensitive, pollution-intolerant response improvements wastewater treatment and, consequently, quality. Although last are encouraging, subtle contrasting require investigation, causal relationships between structure putative drivers should be modelled national scale. is first long-term, freshwater England, significantly advances our understanding ecological health heavily modified countries.

Language: Английский

Citations

0
Assessing Trends and Challenges: Insights From 30 Years of Monitoring and Management of Threatened Southern Atlantic Salmon Populations DOI
Ana García‐Vega, Juan Francisco Fuentes‐Pérez, Francisco Javier Bravo‐Córdoba

et al.

Aquatic Conservation Marine and Freshwater Ecosystems, Journal Year: 2025, Volume and Issue: 35(1)

Published: Jan. 1, 2025

ABSTRACT The Atlantic salmon ( Salmo salar ) has suffered significant population declines worldwide, prompting urgent conservation efforts, especially in its southern distribution area. This study is aimed at characterising the dynamics of Bidasoa River (Spain), by focusing on fluctuations and long‐term trends returns, characteristics effects angling stocking activities. For this, monitoring data spanning three decades (1993–2023) from a station anglers' captures were used together with activities provided Fish Management Section Navarre Government. Results reveal cyclical patterns driven distinctive wavelengths linked to life cycle, climatic variations local habitat connectivity improvements. was primarily dominated one‐sea‐winter males returning during autumn–winter season. Over period, reduction body size observed, likely reflecting challenging marine conditions. Angling pressure notably skewed towards multi‐sea‐winter females, which could influence natural recruitment dynamics. Despite low mean return rate stocked (0.13%), they contributed one‐third annual underscoring their potential role supporting persistence albeit expense reducing spawning, amid broader ecological challenges. provides valuable insights into complex interplay anthropogenic factors affecting populations European rivers. These are crucial for developing implementing effective strategies preserving salmon, species cultural importance.

Language: Английский

Citations

0
Lessons learned from applying eDNA surveying to diadromous fish detection across the north-east Atlantic region DOI Creative Commons
Mukesh P. Bhendarkar, Cristina Claver,

Iñaki Mendibil

et al.

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 5, 2025

Abstract Regular monitoring of diadromous fishes is critical to inform their management and conservation. Yet, the in-situ data collection these species challenging due complex life cycle low abundance. Focusing on sea lamprey ( Petromyzon marinus , Petromyzontidae) European shads Alosa alosa A. fallax Clupeidae), emblematic in Northeast Atlantic region, this study leverages use water environmental DNA (eDNA) samples monitor distribution range. For that aim, we developed quantitative PCR (qPCR) digital (dPCR) assays applied them detect shad a network 44 river basins across Spain, France, Ireland, UK. We found qPCR efficiently detected presence/absence shads, while higher sensitivity dPCR was essential for detecting lower abundant partly sessile behaving amount collected. Moreover, showed significantly eDNA copies per litre compared probably larvae spending several years burrowed within soft sediments, reducing shedding into column. The integration historical datasets with snapshot wide-ranging enhances our understanding rivers. Importantly, lessons learned international collaboration are towards prevailing framework conservation migratory fishes, highlighting need well-designed sampling strategies coupled species-specific bust long-term efforts species.

Language: Английский

Citations

0
Revealing hidden sources of uncertainty in biodiversity trend assessments DOI Creative Commons
Martin Wilkes, Morwenna Mckenzie, Andrew Johnson

et al.

Ecography, Journal Year: 2025, Volume and Issue: unknown

Published: March 6, 2025

Idiosyncratic decisions during the biodiversity trend assessment process may limit reproducibility, whilst ‘hidden' uncertainty due to collection bias, taxonomic incompleteness, and variable resolution reliability of reported trends. We model alternative made taxon‐level abundance distribution trends using an 18‐year time series covering freshwater fish, invertebrates, primary producers in England. Through three case studies, we test for bias quantify stemming from data preparation specification decisions, assess risk conflating individual species when aggregating higher ranks, evaluate potential incompleteness. Choice optimizer algorithm filtering obtain more complete explained 52.5% variation estimates, obscuring signal taxon‐specific The use penalized iteratively reweighted least squares, a simplified approach optimization, was most important source uncertainty. Application increasingly harsh filters exacerbated modelled dataset. Aggregation ranks significant uncertainty, leading conflation among protected invasive species. also found substantial positive estimation across six fish populations which were not consistently recorded all operational areas. complement analyses observational with silico experiments monitoring processes simulated enable comparison estimates known underlying trends, confirming that incompleteness have negative impacts on accuracy estimates. Identifying managing is crucial informing effective conservation policy practice. highlight several serious sources affecting present tools improve transparency process.

Language: Английский

Citations

0
Genetic data confirm the presence of juvenile Alosa alosa in the estuary of the River Tamar DOI Creative Commons
R. Andrew King, A. Robert Hillman,

J. Boyle

et al.

Aquaculture Fish and Fisheries, Journal Year: 2024, Volume and Issue: 4(2)

Published: March 8, 2024

Abstract Within the UK, allis shad ( Alosa alosa ) are classified as Critically Endangered and known to breed in only a single river, Tamar. Despite evidence of spawning within lower freshwater reaches river at tidal limit estuary, juvenile have never been found. Genetic analysis, based on mitochondrial DNA haplotype nuclear Polymerase Chain Reaction ‐ Restriction Fragment Length Polymorphism (PCR‐RFLP) data, confirmed that found Tamar estuary autumn 2022 were A. .

Language: Английский

Citations

0
The genome sequence of the gudgeon, Gobio gobio (Linnaeus, 1758) DOI Creative Commons
A. D. Nunn, Paolo Moccetti, Bernd Hänfling

et al.

Wellcome Open Research, Journal Year: 2024, Volume and Issue: 9, P. 409 - 409

Published: July 26, 2024

We present a genome assembly from an individual female Gobio gobio (the gudgeon; Chordata; Actinopteri; Cypriniformes; Gobionidae). The sequence spans 1,460.70 megabases. Most of the is scaffolded into 25 chromosomal pseudomolecules. mitochondrial has also been assembled and 16.61 kilobases in length.

Language: Английский

Citations

0
The genome sequence of the Eurasian minnow, Phoxinus phoxinus (Linnaeus, 1758) DOI Creative Commons
A. D. Nunn, Paolo Moccetti, Bernd Hänfling

et al.

Wellcome Open Research, Journal Year: 2024, Volume and Issue: 9, P. 504 - 504

Published: Sept. 3, 2024

We present a genome assembly from an individual female

Language: Английский

Citations

0
Two decades of body length measurements of larval and juvenile fish populations in English rivers DOI Creative Commons
Rachel F. Ainsworth,

Lauren H. Vickers,

Jonathan D. Bolland

et al.

Scientific Data, Journal Year: 2024, Volume and Issue: 11(1)

Published: Nov. 22, 2024

Abstract Long-term datasets provide context and understanding of complex ecological processes, including temporal variations in species diversity ecosystem dynamics. This dataset is comprised body length measurements (mm) more than 380,000 larval or juvenile fish 30 from five English river catchments collected almost monthly over two decades. Such information can be used to determine growth rates, future recruitment success, population structure compliance with monitoring protocols conservation objectives. The provides a baseline for analysing the impacts anthropogenic disturbances such as climate change, pollution habitat degradation, and, given that many populations are size structured positive relationship between various biological attributes swimming ability, survival fecundity, it will invaluable investigating natural human- induced disturbances.

Language: Английский

Citations

0
Short-term growth, movement and response of European eel Anguilla anguilla to re-meandering of a small English chalk stream DOI Creative Commons
James D. Champkin, Tea Bašić, Phillip J. Haubrock

et al.

Knowledge and Management of Aquatic Ecosystems, Journal Year: 2024, Volume and Issue: 425, P. 23 - 23

Published: Jan. 1, 2024

In recent decades, the population of European eel Anguilla anguilla has strongly declined and stock is outside safe biological limits. Freshwater habitat degradation been cited as a key causal factor in decline, but there are limited studies assessing responses this species to river restoration efforts. This study utilized mark-and-recapture data from annual electrofishing surveys conducted between 2009 2014 describe density size structure (length, weight) River Glaven − chalk stream eastern England. Short-term effects on were assessed via Before-After-Control-Impact experimental design. Of recaptured individuals, 73% sedentary rest mobile. Despite re-meandering work increasing heterogeneity reach relative control reach, no change or was detected across treatments time. While length weight increased downstream over period, declined. can be attributed various local stressors such barriers migration, well broader range-scale causes including climatic oceanic factors. Although further research ideally necessary ensure adequate sample sizes, provide long-term monitoring restoration, emphasizes need for whole-catchment efforts conservation that combine river–floodplain with greatly improved fish passage.

Language: Английский

Citations

0