The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) is a multilateral treaty aimed at protecting endangered species subject to international trade. At the 20th Conference of the Parties (CoP20) of CITES, which will take place in Samarkand, Uzbekistan, starting this November 24th, delegates will discuss raising the level of protection for migratory eels of the genus Anguilla, which includes the European eel (Anguilla anguilla). However, an article by Miguel Clavero, a researcher at the Doñana Biological Station-CSIC, which has been accepted for publication in the journal Aquatic Conservation: Marine and Freshwater Ecosystems, contends that the proposed increase in protection is insufficient to reverse the path toward extinction for several eel species.

CITES establishes limitations on the international trade of species based on their degree of threat and the role that trade plays in it, classifying them into different Appendices. Appendix I must include "all species threatened with extinction which are or may be affected by trade," while Appendix II encompasses species which, although not necessarily threatened with extinction now, may become so unless trade in such species is strictly regulated. This latter Appendix also allows for the inclusion of species that are not threatened themselves, but which may be confused with species listed in Appendix I or II when commercially traded. International commercial trade in Appendix I species is essentially prohibited (only authorized "in exceptional circumstances"), whereas trade in Appendix II species can occur internationally provided that a formal assessment (a Non-Detriment Finding or NDF) certifies that the trade "will not be detrimental to the survival of that species.

The European eel, critically endangered

Eels of the genus Anguilla are a group of 17 species of elongated, snake-like fish that are all very similar to one another. Beyond their physical resemblance, they share the unique trait of being sea-spawning fish that live in freshwater: they breed in the ocean, and their young then migrate to rivers and wetlands to mature. The adults eventually return to the sea to reproduce and die. Each eel species spawns in a specific area, though this precise location is known in very few cases. For instance, European eels (Anguilla anguilla) are born in a still-unknown location within the area we call the Sargasso Sea, the origin and final destination of two epic, thousands-of-kilometers-long migrations—the longest among all eel species.

Most, if not all, eel species are currently in a poor state of conservation, experiencing population declines in which commercial exploitation plays a fundamental, though not singular, role. The most intensely exploited species —the European eel (A. anguilla), Japanese eel (A. japonica), and American eel (A. rostrata)— are especially threatened. The most extreme case is that of the European eel, which has been classified as Critically Endangered (the highest threat category) since 2008. The situation is not much better for the Japanese and American species, as both are classified as Endangered. The New Zealand longfin eel (A. dieffenbachii) is in the same category, while other Indian Ocean species (such as A. luzonensis and A. borneensis) are listed as vulnerable.

Currently, only the European eel is afforded CITES protection, where it is listed in Appendix II. At the upcoming Conference of the Parties, a proposal from the European Union and Honduras to include all species of the genus Anguilla in that same Appendix will be debated. "Although this change would represent an improvement over the currently inadequate protection offered by CITES, the proposed modification is clearly insufficient", explains Miguel Clavero. The researcher maintains that the most threatened species within the genus should be listed in Appendix I. "At least four species of the genus undoubtedly meet the criteria for this listing", he asserts.

Pressure from the industry and lack of strict measures

A few months ago, the European Commission explored the possibility of proposing the inclusion of the European eel in Appendix I, but ultimately submitted the currently debated proposal due to pressure from the economic sector that exploits the eel. "The eel lobby's main argument for opposing the European eel's entry into Appendix I is that it would make its commercial exploitation impossible," recounts Clavero. He concludes: "The fact is that the cessation of this exploitation, even if temporary, must be a priority objective for eel conservation; it is incomprehensible that this is being presented as a problem."

The newly published article proposes that the strict protection of the most threatened eel species should be complemented by including the remaining species in Appendix II. This should be done either due to their own unfavorable conservation status or the high possibility of confusing them with more threatened eels when commercially traded. All eel species serve as substitutes for one another in the market, both in their natural state and in processed forms. 'That flexibility in exploiting different species justifies the proposal to include the entire genus in the Appendices,' maintains Clavero, "but for the most threatened species —those for which non-detrimental exploitation is impossible— Appendix II is insufficient".

A commercial moratorium, the last chance for eels

The protection of eels is a complex undertaking, compounded by various factors. On the one hand, as migratory species, they utilize a large number of habitats and require all of them to be in an acceptable ecological state.

On the other hand, the threats facing the different eel species are diverse, including not only overfishing but also habitat loss due to the barrier effect of dams, the appearance of parasites and other invasive species, pollution and/or the disappearance of aquatic systems and climate change. To further complicate the scenario, most eel species have large distribution areas spanning multiple countries, each with its own legal frameworks and conservation priorities.

"The essential international coordination required for effective eel protection has few options of materializing, and CITES is the best of them", proposes Clavero. According to the researcher, intervening in the legal international eel trade by ceasing the exploitation of the most threatened species would hinder illegal trade and send a clear message to societies that still consume eel today, thus encouraging protection measures at the state or regional level. "To prevent the extinction of the European eel, and likely other species of the genus, a moratorium on its commercial exploitation is essential. We hope that in the near future, CITES will serve that purpose", the researcher concludes.

Reference

Clavero, M. (2025) CITES Appendix II is not enough for Anguilla eels: threatened species should be in Appendix I. Aquatic Conservation: Marine and Freshwater Ecosystems. https://doi.org/10.1002/aqc.70271