(Press-News.org) Contact information: Jan Steffen
presse@geomar.de
Helmholtz Centre for Ocean Research Kiel (GEOMAR)
The fate of the eels
GEOMAR scientists prove oceanographic influences on eel recruitment
Smoked, fried or boiled - the European eel (Anguilla anguilla) has always been a popular fish in Europe. Even though people have consumed it for millennia, the origin of the eel has long been shrouded in mystery. While the fish spend most of their lives in fresh and coastal waters, spawning and the birth of the larvae take place in the Sargasso Sea in the central Atlantic Ocean, about 4500 km away from the European coastlines. "Because the observation of eels in the Sargasso Sea is scarcely possible, some details of the life cycle are still unknown" says biologist Miguel Baltazar-Soares, from GEOMAR Helmholtz Centre for Ocean Research Kiel.
In a multidisciplinary study recently published in the international journal "Current Biology", biologists, geneticists and theoretical oceanographers at GEOMAR, together with colleagues from Hamburg, London, Belfast and Antofagasta (Chile), discovered a relationship between ocean currents and the variation in eel recruitment.
The study is based on a latest generation ocean model developed in Kiel. Originally it was used to simulate the effects of melting Greenland glaciers on the North Atlantic. "It has a resolution approximately ten times larger than the conventional ocean and climate models," explains Prof. Dr. Arne Biastoch, a theoretical oceanographer at GEOMAR. "The new model allows us to understand even small-scale changes in the ocean, so we came up with the idea of using it for a simulation of eel migrations," adds Miguel Baltazar-Soares, lead author of the new study.
The model simulation was run for 45 years, and in each of these years, the researchers seeded the Sargasso Sea with 8 million tiny drifting particles. "They represent the eel larvae which, for the first few years of their life, mainly drift with the currents," says biologist Dr. Christophe Eizaguirre from GEOMAR, who initiated the study. External factors, like wind and weather conditions, were the same in the model as the conditions observed in each year from 1960 to 2005. "We were able to track how the larvae migrated to Europe. Only those who reached the European shelf seas within two years were considered viable. This also corresponds to eel life cycle," explains Dr. Eizaguirre.
In fact, the eel recruitment in the model fluctuated significantly, mimicking the patterns reported across Europe. "In the early 1980s, for example, only a fraction of the larvae managed their way to Europe," reports Professor Biastoch. The researchers found that small-scale, wind-driven ocean currents strongly determine the eel population fluctuation. Depending on the presence of regional currents in the Sargasso Sea, the larvae's path to Europe was either extended and led to low recruitment or shortened leading to high recruitment in Europe. "We had not seen these flow changes in any of the older ocean models. But they seem to play a crucial role in the migration of the eel larvae," explains Professor Biastoch.
Combining those discoveries with genetic analyses, the scientists found evidence that, contrary to what is typically thought, eels do not return to random locations in the Sargasso Sea to reproduce but rather return to where their mother spawned in particular locations within the Sargasso Sea. "This is a new finding - so far, it was assumed that the mating in the Atlantic takes place completely independent of the area of origin and future scientific expeditions will have to verify this result in situ " says Baltazar-Soares.
The ultimate fate of eels making the long migration from the Sargasso Sea to the continental waters of Europe is still very difficult to predict, even using state of the art techniques. Indeed, from the 1960s to the 1980s, the results of the computer simulation matched up well with the observed occurrence of young eels reaching the European coasts. After that, however, the status of eel populations seems to be disconnected from the climatic influences in the Atlantic. "Since then fishing pressure, habitat destruction in European rivers and diseases appear to play an increased role" said Baltazar-Soares. Today, the European eel is on the list of endangered species and biologists, managers, fishers and politicians across the continent are working together to conserve eels and the valuable fisheries they support.
Although the current study does not solve all the lifestyle mysteries of the eel, "it clearly shows that not only biological, but also climatic, oceanographic and genetic conditions must be taken into account for a meaningful management of fish stocks," says Dr. Eizaguirre who has recently relocated from Kiel to Queen Mary, University of London. And for co-author Arne Biastoch the study illustrates the potential that lies in the interdisciplinary cooperation between biologists and oceanographers: "The ocean models are becoming more and more accurate. This offers a great opportunity for reassessing the threats to marine organisms and understanding their fundamental biology."
### END
The fate of the eels
GEOMAR scientists prove oceanographic influences on eel recruitment
2013-12-27
ELSE PRESS RELEASES FROM THIS DATE:
Are concussions related to Alzheimer's disease?
2013-12-27
Are concussions related to Alzheimer's disease?
MINNEAPOLIS – A new study suggests that a history of concussion involving at least a momentary loss of consciousness may be related to the buildup of Alzheimer's-associated plaques in the brain. The research ...
Surgery beats chemotherapy for tongue cancer, U-M study finds
2013-12-27
Surgery beats chemotherapy for tongue cancer, U-M study finds
ANN ARBOR, Mich. — Patients with tongue cancer who started their treatment with a course of chemotherapy fared significantly worse than patients who received surgery first, according ...
Researchers point to digital gains in human recognition
2013-12-27
Researchers point to digital gains in human recognition
Human beings are highly efficient at recognising familiar faces, even from very poor quality images.
New research led by a psychologist at the University of York is using advances in the level of detail ...
Environmental fiscal reform would improve the environment and reduce the informal economy
2013-12-27
Environmental fiscal reform would improve the environment and reduce the informal economy
Researchers at the UPV/EHU-University of the Basque Country and the BC3 (Basque Centre for Climate Change) are proposing measures to improve the environment and the efficiency of ...
New drug candidates show promise for cure for Chagas disease
2013-12-27
New drug candidates show promise for cure for Chagas disease
A team of researchers from Canada has developed a class of compounds which may help eradicate a neglected tropical disease that is currently hard to kill in its chronic form. The research was published ...
What does compassion sound like?
2013-12-27
What does compassion sound like?
"Good to see you. I'm sorry. It sounds like you've had a tough, tough, week." Spoken by a doctor to a cancer patient, that statement is an example of compassionate behavior observed by a University of Rochester ...
Rock And Rho: Proteins that help cancer cells groove
2013-12-27
Rock And Rho: Proteins that help cancer cells groove
Cells' adaptations to low oxygen conditions inside tumors promote breast cancer's spread
Biologists at The Johns Hopkins University have discovered that low oxygen conditions, which often persist inside tumors, ...
UTSW study identifies potential therapeutic target for incurable, rare type of soft-tissue cancer
2013-12-27
UTSW study identifies potential therapeutic target for incurable, rare type of soft-tissue cancer
DALLAS – Dec. 26, 2013 – A deadly, rare type of soft-tissue cancer may be completely eradicated simply by inhibiting a key protein involved ...
Toys, books, cribs harbor bacteria for long periods, study finds
2013-12-27
Toys, books, cribs harbor bacteria for long periods, study finds
Streptococcus biofilms persisted on objects and surfaces in a daycare center, in some cases after a cleaning
BUFFALO, N. Y. – Numerous scientific studies have concluded that two common bacteria that ...
Antioxidant drug knocks down multiple sclerosis-like disease in mice
2013-12-27
Antioxidant drug knocks down multiple sclerosis-like disease in mice
PORTLAND, Ore. — Researchers at Oregon Health & Science University have discovered that an antioxidant designed more than a dozen years ago to fight damage within human cells significantly ...
LAST 30 PRESS RELEASES:
Program takes aim at drinking, unsafe sex, and sexual assault on college campuses
Inability to pay for healthcare reaches record high in U.S.
Science ‘storytelling’ urgently needed amid climate and biodiversity crisis
KAIST Develops Retinal Therapy to Restore Lost Vision
Adipocyte-hepatocyte signaling mechanism uncovered in endoplasmic reticulum stress response
Mammals were adapting from life in the trees to living on the ground before dinosaur-killing asteroid
Low LDL cholesterol levels linked to reduced risk of dementia
Thickening of the eye’s retina associated with greater risk and severity of postoperative delirium in older patients
Almost one in ten people surveyed report having been harmed by the NHS in the last three years
Enhancing light control with complex frequency excitations
New research finds novel drug target for acute myeloid leukemia, bringing hope for cancer patients
New insight into factors associated with a common disease among dogs and humans
Illuminating single atoms for sustainable propylene production
New study finds Rocky Mountain snow contamination
Study examines lactation in critically ill patients
UVA Engineering Dean Jennifer West earns AIMBE’s 2025 Pierre Galletti Award
Doubling down on metasurfaces
New Cedars-Sinai study shows how specialized diet can improve gut disorders
Making moves and hitting the breaks: Owl journeys surprise researchers in western Montana
PKU Scientists simulate the origin and evolution of the North Atlantic Oscillation
ICRAFT breakthrough: Unlocking A20’s dual role in cancer immunotherapy
How VR technology is changing the game for Alzheimer’s disease
A borrowed bacterial gene allowed some marine diatoms to live on a seaweed diet
Balance between two competing nerve proteins deters symptoms of autism in mice
Use of antifungals in agriculture may increase resistance in an infectious yeast
Awareness grows of cancer risk from alcohol consumption, survey finds
The experts that can outsmart optical illusions
Pregnancy may reduce long COVID risk
Scientists uncover novel immune mechanism in wheat tandem kinase
Three University of Virginia Engineering faculty elected as AAAS Fellows
[Press-News.org] The fate of the eelsGEOMAR scientists prove oceanographic influences on eel recruitment