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The European Silver Eel (Anguilla anguilla) oceanic migration

Vedor, Marisa (2013) BIOP24 20122
Degree Projects in Biology
Abstract
Abstract

The population and recruitment of European eels has declined dramatically over the last thirty years. Several anthropogenic threats to the eel population were identified and, in response, the EU established a management plan that imposes restrictions on exploitation. However, the impact of changes in oceanic and environmental factors may also affect the population dynamics of eels and it has been suggested that migration failure may have contributed to the collapse in eel recruitment.

We used data collected from electronic tagging experiments to map the behaviour and thermal experience of female silver eels as they migrated across the Atlantic Ocean. The eels travelled up to 50 km per day and exhibited a consistent vertical... (More)
Abstract

The population and recruitment of European eels has declined dramatically over the last thirty years. Several anthropogenic threats to the eel population were identified and, in response, the EU established a management plan that imposes restrictions on exploitation. However, the impact of changes in oceanic and environmental factors may also affect the population dynamics of eels and it has been suggested that migration failure may have contributed to the collapse in eel recruitment.

We used data collected from electronic tagging experiments to map the behaviour and thermal experience of female silver eels as they migrated across the Atlantic Ocean. The eels travelled up to 50 km per day and exhibited a consistent vertical diel movement pattern, ascending to warmer shallower waters at dusk and descending into deep, colder water at dawn, from ~200–900m and 14–9°C every day. During the day and night the vertical movement was consistently distinct, suggesting foraging for cues, predator avoidance or metabolism regulation. Female silver eels migrate over 6000 km in 10 months up to the Azores. To assess energy use during the migration, I conducted respirometry experiments to determine metabolic rates at different temperatures, and extrapolated these to the recorded observations of thermal experience and swimming speed from the tagging data.

The results of this study provide the first estimates of migration routes and energy expenditure, as well diel vertical migration behaviour analysis of free-ranging eels during their oceanic migration shedding new light on the role of fat reserves during the spawning migration and the impact that trends in fat content may have on spawning success of the European eel. This application of experimental results to the eel migration success will help to establish how management measures and effective conservation plans might need to adapt in the future. (Less)
Abstract
Popular science summary:

The European silver eel oceanic migration

During the past 30 years the population of the European silver eel has been declining dramatically. This is a commercially important species and several action plans have been established but little information about the biology of the European eel is known. During the EELIAD project female silver eels were electronically tagged in several European countries in order to describe their migration routes. This project reveals the mysterious oceanic migration of the European silver eel, as well the diel vertical migration and the energy expenditure of this movement. Therefore, a huge step towards the conservation actions effectiveness can be done with these results.

... (More)
Popular science summary:

The European silver eel oceanic migration

During the past 30 years the population of the European silver eel has been declining dramatically. This is a commercially important species and several action plans have been established but little information about the biology of the European eel is known. During the EELIAD project female silver eels were electronically tagged in several European countries in order to describe their migration routes. This project reveals the mysterious oceanic migration of the European silver eel, as well the diel vertical migration and the energy expenditure of this movement. Therefore, a huge step towards the conservation actions effectiveness can be done with these results.

The population and recruitment of European eels has declined dramatically over the last thirty years. Several anthropogenic threats to the eel population were identified and, in response, the EU established a management plan that imposes restrictions on exploitation. However, the impact of changes in oceanic and environmental factors may also affect the population dynamics of eels and it has been suggested that migration failure may have contributed to the collapse in eel recruitment.

We used data collected from electronic tagging experiments to map the behaviour and thermal experience of female silver eels as they migrated across the Atlantic Ocean. The eels travelled up to 50 km per day and exhibited a consistent vertical diel movement pattern, ascending to warmer shallower waters at dusk and descending into deep, colder water at dawn, from ~200–900m and 14–9°C every day. During the day and night the vertical movement was consistently distinct, suggesting foraging for cues, predator avoidance or metabolism regulation. Female silver eels migrate over 6000 km in 10 months up to the Azores. To assess energy use during the migration, I conducted respirometry experiments to determine metabolic rates at different temperatures, and extrapolated these to the recorded observations of thermal experience and swimming speed from the tagging data. Marisa Vedor 2013-09-09

The results of this study provide the first estimates of migration routes and energy expenditure, as well diel vertical migration behaviour analysis of free-ranging eels during their oceanic migration. The results suggest eels spend much less energy than the expected in previous literature studies and would have to swim for more than 8 months to reach the Sargasso Sea, where is believed to be the spawning grounds. This application of experimental results to the eel migration success will help to establish how management measures and effective conservation plans might need to adapt in the future.

Advisor: Susanne Ǻkesson
Master´s Degree Project 60 credits in Conservation Biology 2012 / 2013
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Vedor, Marisa
supervisor
organization
course
BIOP24 20122
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
4057023
date added to LUP
2013-09-19 15:04:32
date last changed
2013-09-19 15:04:32
@misc{4057023,
  abstract     = {Popular science summary:

The European silver eel oceanic migration

During the past 30 years the population of the European silver eel has been declining dramatically. This is a commercially important species and several action plans have been established but little information about the biology of the European eel is known. During the EELIAD project female silver eels were electronically tagged in several European countries in order to describe their migration routes. This project reveals the mysterious oceanic migration of the European silver eel, as well the diel vertical migration and the energy expenditure of this movement. Therefore, a huge step towards the conservation actions effectiveness can be done with these results. 

The population and recruitment of European eels has declined dramatically over the last thirty years. Several anthropogenic threats to the eel population were identified and, in response, the EU established a management plan that imposes restrictions on exploitation. However, the impact of changes in oceanic and environmental factors may also affect the population dynamics of eels and it has been suggested that migration failure may have contributed to the collapse in eel recruitment. 

We used data collected from electronic tagging experiments to map the behaviour and thermal experience of female silver eels as they migrated across the Atlantic Ocean. The eels travelled up to 50 km per day and exhibited a consistent vertical diel movement pattern, ascending to warmer shallower waters at dusk and descending into deep, colder water at dawn, from ~200–900m and 14–9°C every day. During the day and night the vertical movement was consistently distinct, suggesting foraging for cues, predator avoidance or metabolism regulation. Female silver eels migrate over 6000 km in 10 months up to the Azores. To assess energy use during the migration, I conducted respirometry experiments to determine metabolic rates at different temperatures, and extrapolated these to the recorded observations of thermal experience and swimming speed from the tagging data. Marisa Vedor 2013-09-09 

The results of this study provide the first estimates of migration routes and energy expenditure, as well diel vertical migration behaviour analysis of free-ranging eels during their oceanic migration. The results suggest eels spend much less energy than the expected in previous literature studies and would have to swim for more than 8 months to reach the Sargasso Sea, where is believed to be the spawning grounds. This application of experimental results to the eel migration success will help to establish how management measures and effective conservation plans might need to adapt in the future. 

Advisor: Susanne Ǻkesson 
Master´s Degree Project 60 credits in Conservation Biology 2012 / 2013 
Department of Biology, Lund University},
  author       = {Vedor, Marisa},
  language     = {eng},
  note         = {Student Paper},
  title        = {The European Silver Eel (Anguilla anguilla) oceanic migration},
  year         = {2013},
}