This World Fish Migration Day, the importance of maintaining healthy and connected rivers and streams for species that occupy both fresh and marine waters is being highlighted across the globe. Together with scientifically-backed fisheries management schemes, habitat maintenance plays a huge role in the conservation and sustainable use of migrating species, such as the European eel.
Spawning in the Sargasso Sea in the middle of the North Western Atlantic Ocean, larval European eels migrate into the estuaries, rivers, and lakes of Europe and North Africa, living most of their lives in fresh water.
The eel has been hit hard by exploitation, climate change, degradation and loss of freshwater habitat, and migration barriers such as dams and hydropower installations prevalent throughout Europe.
Now listed as Critically Endangered, ‘Glass eel’ recruitment (the first time eels enter freshwater) is thought to have declined to about 90% of that 30 to 50 years ago. With all eels being part of a single stock and having extensive movements, the successful rebuilding and the subsequent creation of sustainable eel fisheries cannot rely solely with one - or even a few - nations.
2007 saw the introduction of the EC Regulation for the recovery of the eel stock, requiring member states to produce an Eel Management Plan wherever eels naturally occur. The objective of each plan is to put in place measures that will allow at least 40% of adult eels to escape from inland waters into the sea, relative to estimated escapement that would occur if there were no human influences.
This includes reversing habitat degradation, restricting fishing activity, restocking to bolster populations, and arguably most essentially removing/mitigating barriers to migration. Discussions surrounding the effectiveness of Eel Management Plans will be one of the main topics for the Sustainable Eel Group conference held at the end of May in London.
With some inland waters crossing two nations, cooperation between member states must go beyond multiple nation-based plan. How states deal with these transboundary, and indeed single-nation, water bodies varies. In Ireland, three International River Basin Districts cross the Republic of Ireland and Northern Ireland, each with a different management approach. As most of the Shannon Basin lies in the Republic of Ireland it has been decided that its management will lie solely with the Republic. Management of the Neagh-Bann Basin has been divided based on river flow. Those flowing into Carlingford Lough from the Republic and into Dundalk Bay fall under the Republic’s responsibility, whilst Northern Ireland is charged with managing the rivers flowing into Carlingford Lough from Northern Ireland.
In terms of fisheries, whilst the Republic has banned commercial harvesting, a fishery still exists in Norther Ireland’s ‘section’ of the Neagh-Bann Basin. For the North Western Basin a single transboundary management plan approach will be taken. The different designations of management areas as well as management focus has raised concerns that management is not as harmonized as it could be, potentially reducing the efficacy of a multi-national approach to eel restoration.
The European eel also faces challenges outside E.U. waters. A recently published paper from PhD candidate Elsa Amilhat (Universitié de Perpignan) demonstrated that, contrary to previous suggestions, European eels in the Mediterranean Sea cross the Gibraltar strait, migrating into the Atlantic Ocean and potentially breeding with other European eels. With European eels also inhabiting freshwater bodies in North African States, these non-E.U. Mediterranean nations may also have a significant role to play in pulling the species back from the brink.
International efforts are also required for the protection and maintenance of the eels’ spawning grounds. Located in international waters, the Sargasso Sea, named after the floating sargassum weed in the area, is considered at risk from shipping and fishing activity, as well as climate change and ocean acidification. The Hamilton Declaration on the Conservation of the Sargasso Sea, signed in 2014 by 11 nations, hopes to address these threats.
Unlike EC Regulations, The Declaration is entirely voluntary, though will rely on existing legal international frameworks for implementing strategies such as the phasing out of destructive fishing, the harvesting of the sargassum, and vessel management to prevent harmful discharges into the area.
Alongside habitat restoration and protection, multi-nation efforts are also needed to combat illegal trafficking of eels. In 2009, the European eel was listed under CITES, banning international trade of the eel outside of the EU Despite this, the Sustainable Eel Group estimate some 30 tonnes of eel have been illegally exported out of Europe, primarily to Asia, this season alone – a figure that outstrips the still-legal within-EU trade, and represents over half of the available stock. Given the volume of eels being moved illegally, organised rather than opportunistic criminals are the most likely culprits, though it is believed that most of the illegally traded eel originates from legal fisheries, primarily in France, Spain, and Portugal.
Whilst the onus is on originating nations to improve traceability of eels and crack down on illegal trade, international pressure to reduce demand and clamp down on illegal imports also has a significant role to play.