Assessing the biodiversity of eels “BIOEELS-TZ”

Tanzania/East Africa

Project duration October 2020 to September 2022 

project summary

The East African eel species are important but vulnerable components of the tropical estuarine and coastal fish fauna in Tanzania. Due to increased anthropogenic impacts to fragile coastal ecosystems, in particular related to uncontrolled economic activities, pollution and urban development, many populations of eel species are in steady decline with regard to abundance, range as well as productivity. Eels have been traditionally fished by coastal communities and are a valuable source of food and income. Furthermore, tropical eels are facing a growing interest for the international live fish trade as seed for aquaculture operations, due to the decline of temperate eel species. In relation to an expected considerable growth of the human population in Tanzania in the near future, there is urgent need to document the current status of coastal and estuarine biodiversity and identify areas of high biodiversity and ecosystem value.

The overarching goal of this project is to assess the biodiversity of migratory eels of Tanzania, reconstruct their dynamics of abundance and catch trends, assess their habitat needs, evaluate cultural and socioeconomic factors affecting utilization and promote sustainability through knowledge transfer and capacity building. The scientific results of certain biological and socio-economic investigations will be a first starting point for a proper monitoring and management of eel species in Tanzania and an important step towards a monitoring of environmentally sensitive habitats.


Assess species composition, distribution, abundance of migratory eels and associated fish communities in selected coastal ecosystems and define ecosystem parameters.

Reconstruct the dynamics of abundance and catch trends of eels.

Evaluate socio-cultural and economic factors affecting the sustainability of eel fisheries and habitat quality. 


Develop concepts and applications for effective knowledge transfer and capacity building for biodiversity conservation and sustainable use.

areas of work

Biodiversity assessment for specific eel habitats and documentation of the biology and ecology of migrating eels in selected riverine and coastal aquatic systems

  • Habitat mapping of two Tanzanian river systems and adjacent coastal areas
  • Assessment of the catch composition of fishing communities in these habitats with a special focus on anguilliform species
  • Analysis of gut content of eels and other fish species to determine feeding behaviour
  • Conduct interviews with fishers to collect information on traditional knowledge and myths on species occurrences and biodiversity utilization  

Reconstruct the dynamics of abundance and catch trends of eels to assess the impacts of fishing on the eel stocks

  • Design and administer questionnaire for obtaining information on historical catch and effort data
  • Field visits to gather data on catch composition and weight, fishing effort, size of boat, gears used, distance fished, fishing locations, and target species
  • Record environmental variables such as salinity, surface temperatures and wind to determine the effect on the catch or landings rate
  • Train enumerator to collect catch data and input

Evaluation of social-cultural and economic factors affecting the sustainability of the eel fishery

  • Study to review information on existing governance frameworks and sustainability in control of fisheries resources
  • Focus group discussion meetings in the selected sites to examine role of Beach Management Units, collaborative fisheries management areas, Local governments, private sector and NGOs/CBOs
  • Design questionnaire and administer to fishers, fishing vessels and gear owners, traders, middlemen, vendors, buying agents and District authorities as well as both men and women to obtain information on potential buyer/markets, fishing production activities, suppliers, product destination and to gain an understanding of gender dimensions and their social implications in eel fishery

Knowledge Transfer, Co-production and Capacity building

  • Training on the use of pop-up satellite transmitters, species identification, genetics analysis and e-CAS mobile application   
  • Engage policy-makers, local government authorities, local communities, private sector to discuss on policy implications of the project findings
  • Conduct community workshop with key stakeholders, public and policy makers to address coastal biodiversity conservation issues as well as the sustainable use of fisheries resources
  • Develop a Policy-brief into relevant policies and legislations


University of Dar es Salaam

Tanzania Fisheries Research Institute (TAFIRI)

Thünen Institute of Fisheries Ecology