Transport of European Eel Larvae through the Strait of Gibraltar
Author Information
Author(s): Marko Freese, Lasse Marohn, Luis Ferrer, Jan-Dag Pohlmann, Klaus Wysujack, Tina Blancke, Reinhold Hanel
Primary Institution: Thünen Institute of Fisheries Ecology
Hypothesis
Optimal conditions for the larval transport into the Mediterranean Sea occur when strong eastward surface currents happen at nighttime, coinciding with the ascent of eel larvae into the upper water column.
Conclusion
The study provides evidence that the interaction between eel larvae's vertical migration behavior and tidal conditions in the Strait of Gibraltar facilitates their recruitment into the Mediterranean Sea.
Supporting Evidence
- Zero larvae were caught during daytime hauls, while 31 leptocephali were caught at night.
- The highest catch per unit effort was recorded during a haul with strong eastward currents.
- Current velocities reached almost 200 cm/s in the upper 100 m of the water column during the study.
Takeaway
Eel babies swim from the Atlantic Ocean to the Mediterranean Sea, and they do it best at night when the water is flowing in the right direction.
Methodology
The study involved oceanographic and leptocephalus catch data collected during a 24-hour sampling period using an Isaacs-Kidd Midwater Trawl and acoustic doppler current profiler.
Limitations
The study was limited to a 24-hour observation period and may not represent conditions throughout the year.
Digital Object Identifier (DOI)
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