Article
Ecology
Nicola J. Baker, Rosalind M. Wright, Ian G. Cowx, Leona A. Murphy, Jonathan D. Bolland
Summary: The study found that European eels choose to pass through pumping stations, gravity sluices, or retreat upstream during downstream migration. It is recommended to make operational changes to increase the attractiveness of gravity sluices to reduce passage through hazardous pumping stations.
ECOLOGICAL ENGINEERING
(2021)
Article
Fisheries
Eamonn S. Lenihan, T. Kieran McCarthy, Colin Lawton
Summary: Estimation of silver eel production is crucial for managing eel stocks. Generalised additive models were used to model daily catch in rivers Shannon and Erne, explaining 83.7% and 78.8% of deviance in daily catch. Incorporating catch data from a nearby fishing site in the Erne river model improved explanatory power, explaining 91.7% of deviance.
FISHERIES MANAGEMENT AND ECOLOGY
(2021)
Article
Environmental Sciences
Andrew S. Vowles, Paul S. Kemp
Summary: Artificial light at night (ALAN) is a pervasive form of environmental pollution that can negatively impact the critically endangered European eel. This study found that European eels exposed to high levels of ALAN were more likely to reject illuminated routes, less likely to choose illuminated channels when given a choice, and moved downstream more rapidly when selecting the illuminated route. These findings provide a basis for future research and highlight the ecological impacts of ALAN as a significant environmental pollutant.
ENVIRONMENTAL POLLUTION
(2021)
Article
Fisheries
Olvin Alior van Keeken, Ralf van Hal, Hendrik Volken Winter, Tony Wilkes, Arie Benjamin Griffioen
Summary: The study found that most European eels passing through pumping stations in Friesland, the Netherlands, pass the stations within a day, while a few eels may stay for several weeks. Prioritizing pumping stations based on degree of blockage, mortality rates, and importance for migratory fish can maximize the effectiveness of measures and mitigation taken to protect the migrating population.
FISHERIES MANAGEMENT AND ECOLOGY
(2021)
Article
Marine & Freshwater Biology
Jeroen Van Wichelen, Pieterjan Verhelst, David Buysse, Claude Belpaire, Kristof Vlietinck, Johan Coeck
Summary: Tidal barrages pose a major threat to diadromous fish species like the European eel, but adjusted tidal barrage management can enhance glass eel colonization. Research shows that glass eels have different migration strategies after passing through the sluice, with some continuing upstream migration and others choosing to settle in the canal.
ESTUARINE COASTAL AND SHELF SCIENCE
(2021)
Article
Ecology
Akihide Kasai, Aya Yamazaki, Hyojin Ahn, Hiroki Yamanaka, Satoshi Kameyama, Reiji Masuda, Nobuyuki Azuma, Shingo Kimura, Tatsuro Karaki, Yuko Kurokawa, Yoh Yamashita
Summary: The distribution of Japanese eels was investigated using environmental DNA (eDNA) monitoring, revealing high eDNA concentrations in rivers on the Pacific side and lower concentrations on the Sea of Japan side. The study suggests that the distribution of Japanese eels is mainly determined by maritime larval transport, with their survival and growth dependent on food abundance in rivers.
FRONTIERS IN ECOLOGY AND EVOLUTION
(2021)
Article
Fisheries
Seishi Hagihara, Ryoshiro Wakiya, Tatsuhiko Maeda, Shingo Kimura
Summary: This study examined the morphological and gonadal-histological characteristics of eight silver-phase male Indo-Pacific eels (giant mottled eels) collected from three small rivers on subtropical Amami-Oshima Island, Japan. The findings showed that the silver eels had significantly advanced silvering-related and reproductive characteristics compared to yellow eels.
JOURNAL OF FISH BIOLOGY
(2022)
Article
Multidisciplinary Sciences
Takaomi Arai, Naoko Chino
Summary: The recent depletion of catadromous eel populations has raised global concerns, but little is known about the biology and ecology of tropical eels. By studying the otolith microchemistry of silver eels, it was found that there are two migratory types of eels in estuarine and marine habitats, but no typical freshwater resident eels. This suggests that eels inhabiting coastal areas may contribute significantly to reproduction in this region.
Article
Ecology
Mhairi Miller, Jasper de Bie, Suleiman M. Sharkh, Paul S. Kemp
Summary: This study conducted two experiments to quantify the response of downstream migrating adult European eel to electric fields and the effectiveness of electricity to block movements. The results suggest that the effectiveness of electric barriers to block downstream migrating European eel is likely limited at higher water velocities.
ECOLOGICAL ENGINEERING
(2021)
Article
Biodiversity Conservation
Alienor Stahl, Sarah M. Larocque, Jesse Gardner-Costa, Alastair Mathers, Thomas C. Pratt, Scott Schlueter, Jonathan D. Midwood
Summary: American Eel undertake extensive migrations from their rearing grounds to spawn, and translocated eels from eastern Canada were found to successfully migrate out of Lake Ontario. The timing of migration was consistent regardless of year or tagging season, and primarily occurred in late summer or fall. The results also showed a temporal mismatch between translocated eels and naturally recruited eels, which may impact their arrival times at the spawning grounds and recruitment potential.
ANIMAL BIOTELEMETRY
(2023)
Article
Ecology
Ciara O'Leary, Sarah Healy, Robert Cruikshanks, Karen Kelly, Patrick Gargan
Summary: This study examined the impact of environmental variables on the abundance of glass eels in transitional waters. The results indicate that water temperature and moon phase are the most important factors.
ENVIRONMENTAL BIOLOGY OF FISHES
(2022)
Article
Agriculture, Dairy & Animal Science
Joanna Nowosad, Dariusz Kucharczyk, Mariusz Szmyt, Joanna Luczynska, Mueller Tamas, Laszlo Horvath
Summary: Cadmium pollution is a possible factor contributing to the critically endangered status of the European eel. Research has shown that female eels have lower levels of cadmium in their muscles compared to their ovaries and eggs, indicating a transfer of cadmium from maternal organisms to offspring. This movement of cadmium from tissues to oocytes may pose a significant problem for the reproduction of European eels.
Article
Fisheries
Yusuke Kumai, Mari Kuroki
Summary: The study found that Anguilla japonica glass eels from southern Japan show strong preferences for fresh water and agricultural water, with water temperature influencing their locomotor activity and preference for fresh water. The attraction to agricultural water suggests a potential impact on their upstream migration and habitat selection.
JOURNAL OF FISH BIOLOGY
(2021)
Article
Environmental Sciences
Olvin Alior van Keeken, Arie Benjamin Griffioen, Nicola Stella Henriette Tien, Hendrik Volken Winter
Summary: Habitat fragmentation and migration barriers have led to the decline of European eel population. A study was conducted to investigate the migration patterns of silver eels in the North Sea Canal basin using acoustic telemetry and mark-recapture methods. It was found that 55% of silver eels passed barriers between polders and canals, and 46% passed the barrier complex at IJmuiden to reach the sea. Silver eel escapement to the North Sea averaged 81,629 individuals per year, with 14.3% mortality at the pumping station in IJmuiden. The study highlighted the importance of addressing barriers and implementing mitigation measures for eel management.
RIVER RESEARCH AND APPLICATIONS
(2023)
Article
Fisheries
Ben Parker, Demetra Andreou, Iain D. Green, Katsiaryna Pabortsava, Rose M. Boardman, Adrian C. Pinder, Rosalind M. Wright, Robert Britton
Summary: The microplastic loads in elvers of the critically endangered European eel sampled in three English rivers were very low and did not vary with body length or between rivers. The particles were mostly black, polyolefins, fibres, and fragments of size 101-200 μm. This suggests that local contamination pressure is low and management efforts should focus on mitigating other stressors affecting the species.
JOURNAL OF FISH BIOLOGY
(2023)
Article
Evolutionary Biology
Sebastian Wacker, Tonje Aronsen, Sten Karlsson, Ola Ugedal, Ola H. Diserud, Eva M. Ulvan, Kjetil Hindar, Tor F. Naesje
Summary: The study found that genetic introgression from escaped farmed salmon negatively impacts the survival rate of wild Atlantic salmon in a river in northern Norway, leading to a decrease in population-level genetic introgression. This suggests that there is natural selection against genetic introgression in the wild, potentially resulting in lower productivity.
EVOLUTIONARY APPLICATIONS
(2021)
Article
Fisheries
R. D. Hedger, O. H. Diserud, B. Finstad, A. J. Jensen, D. K. Hendrichsen, O. Ugedal, T. F. Naesje
Summary: The study reveals that infestation of salmon lice can potentially lead to significant declines in sea trout population, even at low rates of infestation. Compensatory behavioral mechanisms aid in reducing these declines, however, persistent premature return may result in reduced body mass of returning adults. The shape of the stock-recruitment relationship strongly influences how lice-induced mortality impacts the population.
AQUACULTURE ENVIRONMENT INTERACTIONS
(2021)
Article
Environmental Sciences
Marlene Waege Stubberud, Chloe R. Nater, Yngvild Vindenes, L. Asbjorn Vollestad, Oystein Langangen
Summary: For species with individual variation in reproductive success, experience in breeding and the distribution of different breeders is important for population productivity and viability. This study found that the reproductive output of repeat spawners is more important for population growth than that of first-time spawners, and the contribution of first-time spawners to growth is more important through their own survival than through reproduction.
Article
Environmental Sciences
Chloe R. Nater, Marlene W. Stubberud, Oystein Langangen, Atle Rustadbakken, S. Jannicke Moe, Torbjorn Ergon, L. Asbjorn Vollestad, Yngvild Vindenes
Summary: Freshwater species are at risk from climate change due to already being impacted by habitat destruction, pollution, and exploitation. This study explores the consequences of terminating a long-term stocking program for brown trout populations and evaluates alternative management strategies for population viability under climate change.
Article
Fisheries
Kim Tallaksen Halvorsen, Torkel Larsen, Howard Browman, Caroline Durif, Nicolai Aasen, Leif Asbjorn Vollestad, Alessandro Cresci, Tonje Knutsen Sordalen, Reidun M. Bjelland, Anne Berit Skiftesvik
Summary: The movement patterns of three wrasse species in a small marine protected area on the west coast of Norway were analyzed over 21 months. The distance between capture and recapture locations varied between 10 and 187 meters, with no relation to body size or sex. This suggests that strategically located marine protected areas can be effective in protecting wrasses from selective fishing mortality based on size and sex.
JOURNAL OF FISH BIOLOGY
(2021)
Article
Multidisciplinary Sciences
Charlotte Evangelista, Julia Dupeu, Joakim Sandkjenn, Beatriz Diaz Pauli, Anders Herland, Jacques Meriguet, Leif Asbjorn Vollestad, Eric Edeline
Summary: The study examines the impact of size-selective mortality on fish and prey communities using a pond mesocosm experiment. It found that large-breeder medaka produced more offspring at high density, had a greater impact on benthic prey, and displayed better control over benthic grazers.
ROYAL SOCIETY OPEN SCIENCE
(2021)
Article
Fisheries
V. Fernandez-Gonzalez, E. M. Ulvan, P. Sanchez-Jerez, O. H. Diserud, K. Toledo-Guedes, N. Casado-Coy, P. Klebert, I. Uglem
Summary: This study aims to evaluate and determine a standardized method to measure sea lice abundance in the salmon farming industry, providing a sampling and analysis strategy for quantifying sea lice larvae. Quantifying sea lice larvae can lead to more accurate predictions of their dispersal and the risk of infestation in salmon farms.
Article
Fisheries
Arne J. Jensen, Ola H. Diserud, Bengt Finstad, Peder Fiske, Eva B. Thorstad
Summary: The timing of seaward migration is crucial for the growth and survival of anadromous fish species. Early migrating individuals show higher growth and survival rates, while first-time migrants have increased survival with body length and number of smolts migrating simultaneously.
JOURNAL OF FISH BIOLOGY
(2022)
Book Review
Ecology
Leif Asbjorn Vollestad
TRENDS IN ECOLOGY & EVOLUTION
(2022)
Article
Fisheries
Mehis Rohtla, Francoise Daverat, Michael T. Arts, Howard I. Browman, Camilla Parzanini, Berit Skiftesvik, Eva B. Thorstad, Terje van der Meeren, Leif Asbjorn Vollestad, Caroline M. F. Durif
Summary: Many anguillid eel species display facultative catadromy, and northern European shallow marine habitats may serve as important yellow eel growth habitats and may be critical to the population's survival.
CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES
(2023)
Article
Limnology
Svenja Christiansen, Oystein Langangen, Josefin Titelman, Leif Asbjorn Vollestad, Stein Kaartvedt
Summary: This study provides detailed analysis of the three-dimensional swimming behavior of mesopelagic fishes using submerged stationary echosounders. The study shows that M. muelleri mainly drift with currents at night, but undergo vertical migration during dusk and dawn, accompanied by changes in horizontal direction.
LIMNOLOGY AND OCEANOGRAPHY
(2022)
Article
Ecology
Annette Taugbol, Monica Hongro Solbakken, Kjetill S. Jakobsen, Leif Asbjorn Vollestad
Summary: This study conducted an experiment on threespine stickleback and found that saltwater and freshwater populations show different gene expression differences in response to abrupt salinity changes. This indicates that osmoregulation relies not only on genomic expressional plasticity, but also other important factors.
ECOLOGY AND EVOLUTION
(2022)
Article
Fisheries
Jan Grimsrud Davidsen, Andrine Emilie Halvorsen, Sindre Havarstein Eldoy, Eva Bonsak Thorstad, Leif Asbjorn Vollestad
Summary: Brown trout and Arctic charr migrated from fresh water to the sea mainly in May and June, with large individual variation in migration timing. Large brown trout migrated earlier than small ones, while no such pattern was found for Arctic charr. Brown trout stayed longer at sea than Arctic charr, and the two species showed differences in their choice of marine areas and feeding strategies. Stable isotope analysis revealed that brown trout fed on marine fish and shrimps, while Arctic charr had a diet with a larger proportion of freshwater invertebrates.
JOURNAL OF FISH BIOLOGY
(2023)
Article
Environmental Sciences
Jan Henning L'Abee-Lund, Havard Lo, Leif Asbjorn Vollestad
Summary: Research indicates that brown trout exhibit a crepuscular activity pattern, while Arctic char show a more complex diel activity pattern. The activity variation in both species is reflected in their stomach contents, with individuals sampled at night having the highest stomach-content mass. Diet overlap between brown trout and Arctic char is high in early spring and decreases afterwards.
BOREAL ENVIRONMENT RESEARCH
(2022)
Article
Geography, Physical
Jan Henning L'Abee-Lund, Leif Asbjorn Vollestad, John Edward Brittain, Anund Sigurd Kvambekk, Tord Solvang
Summary: Long-term observations of ice phenology in Norwegian lakes reveal significant impacts of factors such as elevation, latitude, and longitude. In recent years, there have been accelerating trends in earlier ice break-up, later freeze-up, and lengthening ice-free periods in lakes. Understanding the relationship between climate change and ice phenology is crucial for predicting future consequences.
