Two scientific articles shedding light on critical issues
VERSION FRANCAISE – ci-desssous
Our researchers, together with partners, have recently published two scientific articles shedding light on critical issues related to marine biodiversity and small-scale fisheries in Madagascar:
Pollution risks for whale sharks by Diamant S., Mahevitra A., et al. 2025. A study on sardines (Sardinella gibbosa), a key prey species of the whale shark (Rhincodon typus), revealed concerning levels of chemical contaminants, including mercury above acceptable thresholds. These findings highlight both the bioaccumulation risks for whale sharks and potential health risks for local communities consuming these fish.
Fishers’ spatial knowledge in small-scale fisheries Randriatsara et al; (2025). Another study showcases the richness of local ecological knowledge among Malagasy fishers. By combining GPS tracking of fishing trips with the recording of vernacular place names, nearly 400 fishing sites were identified and mapped. This innovative approach emphasizes the importance of integrating fishers’ knowledge into sustainable and participatory fisheries management.
Nos chercheurs, en collaboration avec leurs partenaires, viennent de publier deux articles scientifiques qui apportent des éclairages essentiels sur la biodiversité marine et les pêcheries à Madagascar :
Pollution et risque pour le requin-baleine par Diamant S., Mahevitra A., et al. 2025. Une étude menée sur la sardine (Sardinella gibbosa), proie clé du requin-baleine (Rhincodon typus), révèle la présence de contaminants chimiques préoccupants, dont le mercure, au-delà des seuils tolérables. Ces résultats soulignent les menaces de bioaccumulation pour les requins-baleines et les risques sanitaires pour les communautés humaines consommatrices.
Connaissances spatiales des pêcheurs artisanaux par Randriatsara et al; (2025). Une autre étude met en valeur le savoir écologique local des pêcheurs malgaches. Grâce au suivi GPS des trajets de pêche et à l’analyse des toponymes vernaculaires, près de 400 sites de pêche ont été identifiés et cartographiés. Cette approche innovante démontre l’importance d’intégrer les savoirs locaux dans la gestion durable et participative des pêcheries.
Abstract
Fishers’ spatial knowledge in small-scale fisheries Randriatsara et al; (2025). Fishers’ spatial knowledge encompasses a diverse array of social, ecological, technical, experiential, and learning knowledge derived from local environmental and sociocultural contexts. In this study, we used a transdisciplinary framework to shed light on place names of fishing grounds in the context of small-scale fisheries through a case study in Madagascar. First, we jointly monitored fishing boat trajectories based on GPS tracking and recorded the vernacular names of fishing sites in a coral reef fishery from May 2018 to April 2019. This data was processed through spatial analysis to assess the dimensions of each named fishing site. A focus group discussion was conducted with fishers to determine the literal meanings of the toponyms (place names) in the local language. A total of 570 fishers (totaling 15,904 fishing trips) using five gear types were surveyed in eight communities. We identified 397 fishing sites over about 250 km2, 304 of which (76.6%) were mapped. Overall, 371 toponyms (93.4%) were interpreted and categorized based on geographical features (n = 222), biodiversity (n = 86), and maritime uses (n = 63). The dimensions of the fishing sites varied significantly from 0.01 to 11.7 km2, following spatially-explicit fishing distribution patterns and the level of precision of the delimitation method. Most fishing locations (63.3% of the total fishing grounds) were associated with multiple place names, particularly in heavily-targeted areas, indicating that individual fishers typically have their own names for their fishing sites. This study demonstrates that recording boat movements and vernacular toponyms simultaneously throughout an extensive monitoring survey in a coral reef fishery, effectively captured the rich and varied individual fishers’ conceptualizations of the coastal and nearshore marine environment. Our findings suggest that named fishing sites may be used as local spatial reference units with known precision and accuracy, which is relevant for addressing spatial data limitations in small-scale fisheries and incorporating fishers’ knowledge in collaborative fisheries science.
Abstract
Pollution risks for whale sharks by Diamant S., Mahevitra A., et al. 2025. The rapid increase of human activities is threatening the ocean biodiversity, with marine vertebrates, particularly elasmobranchs, facing higher extinction risks. Among them, the whale shark (Rhincodon typus), an endangered migratory filter-feeding species, is threated by multiple anthropogenic pressures, including marine pollution. This study focuses on determining the presence and levels of legacy contaminants (PCBs, DDT) and trace elements (TEs) in baitfish, a primary prey species of whale sharks in Madagascar, and assessing the potential risks to whale sharks and humans through the consumption of contaminated baitfish (Sardinella gibbosa). Results indicate that while levels of DDT were below environmental safety thresholds, Hg levels in baitfish exceeded the acceptable limit, posing significant bioaccumulation risks to higher trophic level organisms, including whale sharks. Furthermore, comparisons with established maximum allowable limits for foodstuffs consumption revealed that Sardinella gibbosa may pose both non-carcinogenic and carcinogenic health risks to humans, particularly for pollutants like PCB, Cd, Ni, and Hg. This research highlights the importance of considering baitfish consumption as a significant pathway for pollutant uptake in whale sharks, suggesting that their exposure may be far higher than previously estimated through zooplankton alone. These findings underscore the critical need for continued monitoring of chemical pollution in coastal ecosystems, which are vital hotspot for global marine biodiversity, particularly in regions like Madagascar, where pollution from industrial, agricultural, and mining activities exacerbates the risk to both marine biodiversity and human health.
