Benjamin Tsirilaza, DIDEM PhD student, presented his work at the PAFFA conference in Brazzaville, Congo, September 18-22, 2023.

#Madagascar , #Betsiboka , #traditional fisheries , #PAFFA Conference

Title: « The length of fish in traditional fisheries in the Betsiboka delta, north-west Madagascar».

  1. Tsirilaza Benjamin. PhD Student, DIDEM Project - Madagascar. Doctoral School in Biodiversity and Tropical Environment, University of Toliara, Madagascar. Aquatic and Coastal Systems Department, National Center for Environmental Research, Antananarivo, Madagascar. Contact :
  2. Rasoloariniaina Jean Robertin. Antsirabe-Vakinankaratra Higher Education Institute, Madagascar.
  3. Andriamirado Rabarison Guy Arthur. DIDEM Project - Madagascar. Aquatic and Coastal Systems Department, National Center for Environmental Research, Antananarivo, Madagascar.



Betsiboka is the second largest river in Madagascar. It flows into the Mozambique Channel at Mahajanga and forms a delta under the influence of the tide. The deltaic environment is a productive but vulnerable ecosystem, as it serves as a spawning and nursery ground for fish. Studying the size structure of landed fish enables us to describe fish communities and fishing practices in the delta. As part of the DIDEM project - Dialogue between Science and Decision-Makers for Integrated Management of Coastal and Marine Environments - the aspect of studying small-scale fishing in the Betsiboka delta conducted daily measurements of landed fish in the four main fishing villages between February and October 2021. The obtained data were processed using the SPSS software. The Fishbase database was used as a reference for the maturity size of fish species. In the Betsiboka delta, the size of fish caught through traditional fishing methods ranges from 1.5 cm to 160 cm, with an average of 21.7 cm and a median value of 19 cm. Among the measured fish, 37.35% reach the adult stage, while the remaining 62.65% are juveniles. Adult captured fish are mainly represented by 13 families, and juveniles by 9 families. The results demonstrate appropriate fishing practices for exploiting fish communities in the Betsiboka delta, while the capture of juveniles raises concerns for the future of resources and the ecosystem.

Keywords: Betsiboka Delta, traditional fishing, size, adult, juvenile