International Governance of Fisheries Ecosystems: Learning from the Past, Finding Solutions for the Future
Chapter 13: Coming to Grips with the Eel Stock Slip-Sliding Away
Eels are weird animals. Despite decades of scientific research, crucial aspects of their biology remain a mystery. In recent decades, juvenile abundance has declined dramatically: by more than 95% for the European eel Anguilla anguilla and by 80% for the Japanese eel A. japonica. Recruitment of American eel A. rostrata to Lake Ontario, near the species’ northern limit, has virtually ceased. Other eel species, including Australian and New Zealand eels (A. dieffenbachii and A. australis), also show indications of decline. Aside from the implications for biodiversity, loss of eel resources will have considerable impact on the socio-economics of rural areas, where eel fishing still constitutes a cultural tradition. The scientific community working on eels has strongly urged precautionary protective action (Anonymous 2003).
The causes of the downward trends are still unclear. The lack of access to basic life history information about the oceanic phases makes it especially difficult to monitor and identify the cause of their population declines. This is in distinct contrast with other declining fishes such as anadromous salmon, whose localized spawning stocks can be relatively easily surveyed when the adults return to freshwater to spawn, and Atlantic cod Gadus morhua, which spawn in relatively open waters and can be surveyed by standard techniques.
In recent years, the alarming state of eel stocks has been recognized, and restoration plans are now being developed for the European and American eel. This article will review the status of the stock, the development of international recovery plans, and the interplay between scientists, governments and stakeholders. For pragmatic reasons, this article focuses predominantly on the European eel, but many of the results and ideas will also apply to other Anguilla species, especially those in temperate waters.
In this article, I will use the word eel (without qualification) to indicate the European eel, i.e. Anguilla anguilla (L.). Where confusion might arise, I will use European eel, but the latter is not meant to restrict the discussion to the European part of the distribution area.
Following a brief introduction to the eel’s life history, the current status of the stock and fishery will be described.