The European eel has long been a popular food fish, but is now threatened with extinction. That is why the populations of the glass-like, transparent young eels are strictly monitored. In the meantime, the number of glass eels on the European coasts has fallen so sharply that the International Council for the Exploration of the Sea (ICES) recommends a complete stop to eel fishing for the first time.
The European eel (Anguilla anguilla) undertakes an impressive journey in the course of its life: from its place of birth in the Sargasso Sea in the Atlantic, the fish larvae migrate more than 5000 kilometers with the Gulf Stream to the European coasts. Meanwhile developed into small transparent glass eels, the animals reach the estuaries of the rivers. Many of them continue their journey there further upstream into the fresh water. Years later they return to the sea and the Sargasso Sea as so-called silver eels to spawn and die.
Eel populations have decreased dramatically
But this migration, combined with fishing for the young eels in particular, has brought the fish to the brink of extinction. Migration barriers such as hydropower plants and dams make it more difficult for eels to reach their habitats and spawning grounds. As a result, the European eel is now listed as critically endangered by the International Union for Conservation of Nature (IUCN). This classification is based on regular controls of the glass eel stocks at over 50 locations along the European coasts. They show that their number has steadily declined, especially since the beginning of the 1980s. In 2011 the eel stocks reached an all-time low and have stagnated at this level ever since.
For conservationists and fisheries scientists, there is an alarm signal: “If the number of young fish remains at a low level over a longer period of time, this is a sign of an insufficient number of parent animals or of unfavorable environmental conditions,” explains Reinhold Hanel, head of the Thünen Institute for Fishery Ecology Bremerhaven. If the glass eels shrink, this suggests that too few fully grown eels have started the migration back into the Sargasso Sea and survived. However, if they are absent, the population is unlikely to recover.
Stop recommended – also for repositioning
In response to the decline in eels, the International Council for the Exploration of the Sea (ICES) recommended some time ago that eel fishing and other potentially harmful impacts on the river and marine environment be reduced as much as possible. Now the Council has tightened this again: In its catch recommendations for 2022, it is for the first time clearly in favor of a complete stop to eel fishing in all habitats. This recommendation is based on the persistently very low incidence of young eel fish. In 2020, their population in the North Sea area was only 0.9 percent compared to the values in the 1960s and 70s. In the rest of Europe the proportion is 7.1.
“This development does not allow any other conclusion and the recommendation is only logical, even if it is overdue,” comments Hanel. He also rates as positive that the ICES recommendation expressly includes the removal of glass eels as a basis for eel aquaculture and their transfer to lakes and rivers. This implementation, which is practiced in many places, is intended to replenish the local stocks in lakes and rivers. Unlike salmon, which can be artificially incubated, this does not add any animals to the total population. In addition, some of these eels die when they are transported from the coast to inland waters and the risk of introducing diseases and parasites increases, as Handel explains. It is therefore doubtful that this is a measure for the protection of grandfathering.
However, it remains to be seen whether and how the current ICES recommendation will be implemented. This is because marine waters are indeed the responsibility of the EU within the framework of the common fisheries policy, but inland fisheries are a matter for the federal states. It is therefore still unclear whether we can agree on a comprehensive protection of this threatened species.
Source: Johann Heinrich von Thünen Institute, Federal Research Institute for Rural Areas, Forests and Fisheries; ICES publication, doi: 10.17895 / ices.advice.7752