The Western Indian Ocean (WIO) Anguillid eels (Anguilla spp.) are long-distance catadromous migratory fishes that use both marine and freshwater ecosystems to complete their life cycles. As these eels use different environments, they are particularly vulnerable to threats derived from both marine and freshwater ecosystems and can act as ecological indicators of the ecological integrity of riverine, estuarine and oceanic environments. Anguillid eels are proposed to have the highest economic value per weight of any fish and represent an important part of the biodiversity of tropical, sub-tropical and temperate regions of the world’s oceans. Very little is known to the contribution of eels to subsistence fisheries and the contribution of these migratory fishes to the livelihoods of vulnerable African human communities. As threats to eels multiply the wellbeing of this unique resource is rapidly increasing and knowledge of their vulnerable migratory ecology and exploitation in the WIO region is urgently needed. The objectives of this study include; (1) a synthesis and review of existing knowledge regarding the biology, ecology, use and threats of eels in the WIO, (2) characterise the recruitment and escapement ecology in selected estuaries throughout the WIO, (3) evaluate the contribution of eels to local fisheries and livelihood and finally (4) undertake a regional scale ecological risk assessment of multiple stressors affecting populations that includes recommendations for sustainable management and conservation.


Client and or collaborating stakeholders: University of Mpumalanga (UMP); University of Kwazulu-Natal (UKZN); Egerton University, Kenya; Kenya Marine & Fisheries Research Institute; Eduardo Mondlane University, Mozambique; North-West University, South Africa; Western Indian Ocean Marine Science Association (WIOMSA).


Interesting and important outcomes or prospects: The outputs, outcomes and impact of the outcomes are diverse and will contribute to the sustainable management of resources within the WIO and impact the lives of millions of vulnerable African human communities.

Some of the outcomes include:

  • Improved understanding of the socio-ecological value of Anguillid eels and their wellbeing.
  • Data to contribute to our understanding of the recruitment of WIO eels into estuaries, and
  • Information for stakeholders to manage water resources and fisheries, particularly river connectivity and migratory species.


Key publications :


Hanzen, C., Weyl, O., Lucas, M., Brink, K., Downs, C.T., & O’Brien, G. (2019). Distribution, ecology and status of anguillid eels in East Africa and the Western Indian Ocean.  In P. Coulson and A. Don (Eds.), EELS – biology, monitoring, management, culture and exploitation,  pp. 33-58. Proceedings of the International Eels Sciences Symposium, 2017, 5M Publishing, Sheffield.


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