The migration behaviour of European silver eels (Anguilla anguilla) released in open ocean conditions

2015 ◽  
Vol 66 (2) ◽  
pp. 145 ◽  
Author(s):  
K. Wysujack ◽  
H. Westerberg ◽  
K. Aarestrup ◽  
J. Trautner ◽  
T. Kurwie ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Anguilla Anguilla ◽  
Large Female ◽  
Sargasso Sea ◽  
Migration Routes ◽  
Long Distance ◽  
European Continent ◽  
Vertical Movements ◽  
Migration Behaviour ◽  
Silver Eels

Despite some recent progress, there are still large gaps of knowledge about migration routes and behaviour of European eels, Anguilla anguilla, during their long-distance oceanic migration. To achieve a better understanding of the migration behaviour, 28 large female silver eels were equipped with pop-up satellite transmitters and released at three different locations in the north-eastern Atlantic Ocean and in the Sargasso Sea. The study covers tracking periods between 7 and 92 days. The distance between release point and estimated pop-up position ranged from 40 to 1000km, the mean minimum migration speeds from 1.5 to 17.0km day–1. The eels consistently conducted distinct diel vertical movements (DVM) with daily amplitudes of more than 300m and maximum diving depths of more than 1000m. Eels released in the Sargasso Sea used greater depths and a broader temperature range than individuals released in the Atlantic Ocean closer to the European continent. At least two eels were clearly preyed upon. The transmitters ascended in a considerable range of directions from the release points. Hence, the results of the study did not allow clear conclusions about the detailed location of the spawning site and on the routes of the eels to the spawning grounds.

Disrupted downstream migration behaviour of European silver eels (Anguilla anguilla, L.) in an obstructed river

2016 ◽  
Vol 99 (10) ◽  
pp. 779-791 ◽  
Author(s):  
Marc L. Besson ◽  
Thomas Trancart ◽  
Anthony Acou ◽  
Fabien Charrier ◽  
Virgile Mazel ◽  
...  
Keyword(s):  
Anguilla Anguilla ◽  
Downstream Migration ◽  
Migration Behaviour ◽  
Silver Eels

Migration behaviour of silver eels (Anguilla anguilla) in a large estuary of Western Europe inferred from acoustic telemetry

2014 ◽  
Vol 137 ◽  
pp. 23-31 ◽  
Author(s):  
Elise Bultel ◽  
Emilien Lasne ◽  
Anthony Acou ◽  
Julien Guillaudeau ◽  
Christine Bertier ◽  
...  
Keyword(s):  
Acoustic Telemetry ◽  
Western Europe ◽  
Anguilla Anguilla ◽  
Migration Behaviour ◽  
Silver Eels

How does the European eel (Anguilla anguilla) retain its population structure during its larval migration across the North Atlantic Ocean?

2006 ◽  
Vol 63 (1) ◽  
pp. 90-106 ◽  
Author(s):  
A James Kettle ◽  
Keith Haines
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Anguilla Anguilla ◽  
European Eel ◽  
Sargasso Sea ◽  
Larval Migration ◽  
The North ◽  
The North Atlantic ◽  
And Migration

A Lagrangian model is presented of the current-carried migration of the leptocephali (larvae) of the European eel (Anguilla anguilla) across the North Atlantic Ocean from the spawning area in the Sargasso Sea to the adult range in Europe and North Africa. The success of larvae in crossing the Atlantic Ocean and reaching particular latitude bins on the eastern side depended strongly on starting location in the Sargasso Sea and migration depth. In the model domain, silver eel spawners can develop strategies for spawning location and migration depth to preferentially target particular regions in the adult range. This observation may help to explain the presence of gradients in molecular markers in eel samples collected across Europe. Spawning in the period of late winter – spring maximizes the average food availability along the 2-year larval trajectory. The fastest transatlantic larval migration in the model is about 2 years, and the route to Europe takes most of the larvae past the east coast of North America in the first year. These model results are consistent with the hypothesis that the European and American eel (Anguilla rostrata) could separate themselves on different sides of the Atlantic Ocean on the basis of the different durations of their larval stages.

scholarly journals Just go with the flow? Route selection and mortality during downstream migration of silver eels in relation to river discharge

2007 ◽  
Vol 64 (7) ◽  
pp. 1437-1443 ◽  
Author(s):  
Henrice M. Jansen ◽  
Hendrik V. Winter ◽  
Maarten C. M. Bruijs ◽  
Harry J. G. Polman
Keyword(s):  
River Discharge ◽  
Radio Telemetry ◽  
Anguilla Anguilla ◽  
Downstream Migration ◽  
European Eel ◽  
Route Selection ◽  
Migration Routes ◽  
Silver Eel ◽  
Silver Eels ◽  
The Impact

Abstract Jansen, H. M., Winter, H. V., Bruijs, M. C. M., and Polman, H. J. G. 2007. Just go with the flow? Route selection and mortality during downstream migration of silver eels in relation to river discharge. – ICES Journal of Marine Science, 64: 1437–1443. The European eel (Anguilla anguilla) has been in steep decline for several decades. Fisheries and hydropower-induced mortality presumably play an important role during the downstream migration of silver eels, and downstream-migrating silver eels must make various navigation and route-selection decisions to reach the sea. We examined the influence of river discharge on route selection of silver eels. To quantify the impact of hydropower and fisheries on silver eel mortality, radio-telemetry experiments were performed in the River Meuse in 2002 and 2004, surgically implanting 300 silver eels with Nedap-transponders. Route selection and passage behaviour near detection stations was assessed. Silver eels were distributed over the alternative migration routes in the river in proportion to the discharge until the silver eels reached the entrance to the turbines. The eels altered their behaviour when approaching the turbines of hydropower plants and showed stationary and recurrent behaviour. We discuss the consequences of this on route selection and mortality rates caused by hydropower facilities and fisheries.

European eel Anguilla anguilla compromise speed for safety in the early marine spawning migration

2018 ◽  
Vol 75 (6) ◽  
pp. 1984-1991 ◽  
Author(s):  
Robert J Lennox ◽  
Finn Økland ◽  
Hiromichi Mitamura ◽  
Steven J Cooke ◽  
Eva B Thorstad
Keyword(s):  
Anguilla Anguilla ◽  
Spawning Migration ◽  
European Eel ◽  
Population Declines ◽  
Long Distance ◽  
Directed Movement ◽  
Freshwater Habitat ◽  
Silver Eels ◽  
Marine Migration ◽  
Long Distance Movement

Abstract There are substantial benefits to potential fitness conferred to animals that undertake migrations. However, animals must make compromises to maximize survival and compensate for the risks associated with long-distance movement. European eel (Anguilla anguilla), a migratory catadromous fish, has undergone population declines owing to changes in marine and freshwater habitat and interactions with human infrastructure, instigating research to investigate the mechanisms controlling their migration. Yellow-phase European eels from the local River Opo and silver-phase European eels transplanted from River Imsa, Norway, were implanted with acoustic transmitters and released within a network of receiver stations in the Hardangerfjord, Norway. Silver-phase eels exhibited more movement within the array than yellow-phase eels, signifying the onset of migration. Silver-phase eels moved through the fjord nocturnally, arriving at gates predominantly at night. Eels had slower rates of migration than expected based on models predicting continuous movement, suggesting that movement ceased during daylight hours. Reduced net rates of travel supported the hypothesis that eels compromise speed for safety during the early marine migration by avoiding predators and not actively migrating during daylight. The silver eels were capable of directed movement towards the ocean and were not recorded by receivers in bays or dead ends. European eels must successfully transit this coastal zone, where their residence is prolonged because of the relatively slow speeds. These results suggest that the early marine phase of the European eel spawning migration be a focal period for European eel conservation efforts.

scholarly journals Empirical observations of the spawning migration of European eels: The long and dangerous road to the Sargasso Sea

2016 ◽  
Vol 2 (10) ◽  
pp. e1501694 ◽  
Author(s):  
David Righton ◽  
Håkan Westerberg ◽  
Eric Feunteun ◽  
Finn Økland ◽  
Patrick Gargan ◽  
...  
Keyword(s):  
Anguilla Anguilla ◽  
Spawning Migration ◽  
European Eel ◽  
Data Sets ◽  
Sargasso Sea ◽  
Migration Routes ◽  
Diel Vertical Migrations ◽  
Using Data ◽  
Migratory Strategy ◽  
Electronic Tagging

The spawning migration of the European eel (Anguilla anguillaL.) to the Sargasso Sea is one of the greatest animal migrations. However, the duration and route of the migration remain uncertain. Using fishery data from 20 rivers across Europe, we show that most eels begin their oceanic migration between August and December. We used electronic tagging techniques to map the oceanic migration from eels released from four regions in Europe. Of 707 eels tagged, we received 206 data sets. Many migrations ended soon after release because of predation events, but we were able to reconstruct in detail the migration routes of >80 eels. The route extended from western mainland Europe to the Azores region, more than 5000 km toward the Sargasso Sea. All eels exhibited diel vertical migrations, moving from deeper water during the day into shallower water at night. The range of migration speeds was 3 to 47 km day−1. Using data from larval surveys in the Sargasso Sea, we show that spawning likely begins in December and peaks in February. Synthesizing these results, we show that the timing of autumn escapement and the rate of migration are inconsistent with the century-long held assumption that eels spawn as a single reproductive cohort in the springtime following their escapement. Instead, we suggest that European eels adopt a mixed migratory strategy, with some individuals able to achieve a rapid migration, whereas others arrive only in time for the following spawning season. Our results have consequences for eel management.

scholarly journals Silver eel migration behaviour in the Baltic

2007 ◽  
Vol 64 (7) ◽  
pp. 1457-1462 ◽  
Author(s):  
Håkan Westerberg ◽  
Ingvar Lagenfelt ◽  
Henrik Svedäng
Keyword(s):  
Baltic Sea ◽  
Data Storage ◽  
Anguilla Anguilla ◽  
Light Level ◽  
Thermocline Depth ◽  
Silver Eel ◽  
Migration Behaviour ◽  
Swimming Depth ◽  
Silver Eels ◽  
The Baltic

Abstract Westerberg, H., Lagenfelt, I., and Svedäng, H. 2007. Silver eel migration behaviour in the Baltic. – ICES Journal of Marine Science, 64: 1457–1462 Female silver eels (Anguilla anguilla L.) were tagged with data storage tags and released in the Baltic Sea at the same time at a single site on the east coast of Sweden. Data on temperature, light, and depth were obtained from six eels, continuous records for 71 d at sea. The swimming behaviour was similar for all fish, almost stereotyped: swimming activity was between dusk and dawn, starting at a light level corresponding to civic twilight and ending in the morning at generally the same light level. During daylight, the eels rested on the seabed at depths of 2–36 m. Swimming depth was typically close to the surface: up to 95% of swimming time was spent within 0.5 m of the surface. Short dives at irregular intervals (some 1–2 h−1) were made down to the thermocline depth, or occasionally, to the seabed. The duration of such dives were typically 5–10 min. Although only a few days at liberty, the eels had migrated a considerable distance between recapture and release sites, indicating a mean rate of travel of ∼16 km d−1. The recapture positions suggested unidirectional movements towards the southwestern Baltic Sea, i.e. close to the straits leading to the ocean, supporting a belief that the recorded movements were related to eel spawning migratory behaviour.

scholarly journals Geomagnetic imprinting predicts spatio-temporal variation in homing migration of pink and sockeye salmon

2014 ◽  
Vol 11 (99) ◽  
pp. 20140542 ◽  
Author(s):  
Nathan F. Putman ◽  
Erica S. Jenkins ◽  
Catherine G. J. Michielsens ◽  
David L. G. Noakes
Keyword(s):  
Magnetic Field ◽  
Temporal Variation ◽  
Ocean Circulation ◽  
Sockeye Salmon ◽  
Movement Patterns ◽  
Oncorhynchus Gorbuscha ◽  
Migration Routes ◽  
Long Distance ◽  
Spatio Temporal ◽  
Olfactory Imprinting

Animals navigate using a variety of sensory cues, but how each is weighted during different phases of movement (e.g. dispersal, foraging, homing) is controversial. Here, we examine the geomagnetic and olfactory imprinting hypotheses of natal homing with datasets that recorded variation in the migratory routes of sockeye ( Oncorhynchus nerka ) and pink ( Oncorhynchus gorbuscha ) salmon returning from the Pacific Ocean to the Fraser River, British Columbia. Drift of the magnetic field (i.e. geomagnetic imprinting) uniquely accounted for 23.2% and 44.0% of the variation in migration routes for sockeye and pink salmon, respectively. Ocean circulation (i.e. olfactory imprinting) predicted 6.1% and 0.1% of the variation in sockeye and pink migration routes, respectively. Sea surface temperature (a variable influencing salmon distribution but not navigation, directly) accounted for 13.0% of the variation in sockeye migration but was unrelated to pink migration. These findings suggest that geomagnetic navigation plays an important role in long-distance homing in salmon and that consideration of navigation mechanisms can aid in the management of migratory fishes by better predicting movement patterns. Finally, given the diversity of animals that use the Earth's magnetic field for navigation, geomagnetic drift may provide a unifying explanation for spatio-temporal variation in the movement patterns of many species.

scholarly journals Genome-wide footprints in the carob tree (Ceratonia siliqua) unveil a new domestication pattern of fruit trees in the Mediterranean

2021 ◽  
Author(s):  
Alex Baumel ◽  
Gonzalo Nieto Feliner ◽  
Frederic Medail ◽  
Stefano La Malfa ◽  
Mario Diguardo ◽  
...  
Keyword(s):  
Eastern Mediterranean ◽  
Ex Situ ◽  
Plant Domestication ◽  
Mediterranean Forests ◽  
Migration Routes ◽  
Long Distance ◽  
Genome Wide ◽  
Western Morocco ◽  
Carob Tree ◽  
The Mediterranean

Intense research efforts on phylogeography over the last two decades uncovered major biogeographical trends and renewed our understandings of plant domestication in the Mediterranean. We aim to investigate the evolutionary history and the origin of domestication of the carob tree that has been cultivated for millennia for food and fodder. We used >1000 microsatellite genotypes to identify carob evolutionary units (CEUs) based on genetic diversity structure and geography. We investigated genome-wide diversity and evolutionary patterns of the CEUs with 3557 SNPs generated by restriction-site associated DNA sequencing (RADseq). The 56 populations sampled across the Mediterranean basin, classified as natural, semi-natural or cultivated, were examined. Although, RADseq data are consistent with previous studies identifying a strong West-to-East genetic structure and considerable admixture in some geographic parts, we reconstructed a new phylogeographic scenario with two migration routes occurring from a single refugium likely located in South-Western Morocco. Our results do not favour the regionally bound or single origin of domestication. Indeed, our findings support a cultivation model of locally selected wild genotypes, albeit punctuated by long-distance westward dispersals of domesticated varieties by humans, concomitant with major cultural waves by Romans and Arabs in the regions of dispersal. Ex-situ efforts to preserve carob genetic resources should prioritize accessions from both western and eastern populations, with emphasis on the most differentiated CEUs situated in South-Western Morocco, South Spain and Eastern Mediterranean. Our study underscores the relevance of natural and seminatural habitats of Mediterranean forests and their refugia in the conservation efforts of tree crops.

Sign in / Sign up

Export Citation Format

Share Document