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September 27, 2022

Sandra Ranaivomanana, PhD student, on her fisheries data collection in Ranobe Bay

The quantification of fisheries landings and fish biodiversity are among the ARMSRestore project objectives. The achievement of these objectives is attributed to the “Fisheries” team which is focused on the study of the small-scale reef fishery in Ranobe Bay, Southwest Madagascar.

The reef fishery of Ranobe Bay is the largest fished area in southwestern Madagascar (163 km²) with around 5,000 fishers recorded. In this region, small-scale fisheries are an important source of food and income for coastal populations. However, the sustainability of this activity is threatened by the degradation of coral reefs and  population increases that result in a decrease in fish catch. In addition, there is the lack of appropriate management of the resources due to the lack of complete and reliable data on the state of the fishery. Thus, the major interest of this study is to provide complete and accurate baseline data to assess the effectiveness of artificial reefs in the enhancement of fisheries production, on the one hand, and to evaluate the overall exploitation level of this fishery based on fisheries indicators, on the other hand.

From October 2021 to December 2022, a fishery survey is being conducted in 12 fishing villages along Ranobe Bay. Data collection involves collaboration with 103 fishers per month using five main fishing gear types such as handlines, gillnets, spearguns, beach seines and mosquito net trawls. Data related to the fishing activity such as the fishing gear used per trip, the weight of the catches, the fishing grounds frequented, the effort deployed, and the income from the catches are collected within the participatory survey over 30 days. These fishers are also provided with GPS trackers in order to have precise information on the distribution of their fishing activity and catches. A landing survey is carried out once a month to determine the diversity of the fish caught at the family level as well as their size structure. To this survey is added biological sampling on sexual maturation of reef fishes. To date, over 500 fishing landings have been monitored. After implementation of artificial reefs in 2023, a survey every 3 months will be done in the area via experimental fishing. 

These data are, on the one hand, crucial and relevant information for the reinforcement of resource management. On the other hand, they will serve as a basis to ensure the sustainability of the fishing activity while taking into account the local socio-economic context. Moreover, the project also has an original approach in evaluating the impact of artificial reefs on fisheries production, which is still poorly investigated and known in Madagascar.