Aquaculture for all

DNA Analysis Reveals All Eels From Same Stock

Breeding & genetics

DENMARK - Genetic analysis determines decades of doubt: All European eels from Iceland to Denmark to Morocco belong to the same stock, which mate crisscrossing when they meet to spawn in the Sargasso Sea.

Overfishing and environmental degradation in one European country therefore has implications for the number of this enigmatic and critically endangered fish throughout Europe.

When the European eel has swum thousands of miles from its coasts to the Sargasso Sea on the far side of the Atlantic, all eels from north to south mate. An eel from Iceland, is just as likely to mate with an eel from Norway, Denmark, France, Morocco or with another eel from Iceland.

The research from the Technical University of Denmark (DTU) Aqua reveals the most comprehensive genetic analysis of the eel, which has just been published in the scientific journal Molecular Ecology.

Biologists Thomas Damm Als, DTU Aqua, Technical University of Denmark, and Michael M. Hansen, Department of Biology, University of Aarhus have spearheaded a focus group, that during a number of expeditions, has gathered unique samples of eel larvae in the Sargasso Sea.

The result states that all European eels belong to one and the same stock. It is scientifically sensational and highly unusual that individuals of the same species that live so far apart geographically, such as in Iceland and Morocco, are not genetically different and adapted to local conditions of temperature and environmental conditions. For comparison, trout and salmon are typically genetically distinct from streams to rivers, although there are only a few kilometers from the rivers.

The researchers behind the study are now examining how eels are genetically adapted to living in conditions ranging from arctic to nearly subtropical temperatures.

Eels are critically endangered The new understanding of the eel population structure can be used directly in the management of the critically endangered eels. Migration of elvers (small eels arriving at the coast after 1-2 years of travel) are currently only two percent of what it was in 1980. And the eel is on the list of endangered species in the international organization, the IUCN (International Union for Conservation of Nature). Described here eels as "critically endangered", which is the step just before "extinct in the wild." The results of this study emphasizes that the only way to save the eel through a targeted international cooperation to ensure eel good living conditions.
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