Using An Ecosystem Approach To Understand The Link Between Artisanal Capture Fishing And Malaria On Mageta Island In Western Kenya

Abstract

In this study an ecosystem approach was employed to understand the association between artisanal capture fishing (ACF) and the problem of malaria on Mageta Island in western Kenya. In this work and in the local context, the term Mageta Island is generally used to include the adjacent Magare Island. The central goal was to establish whether actions of artisanal fishers, in their unrelenting quest for existence, surpass ecosystems‟ sustainability thresholds with potential negative repercussions on human health. This was achieved through a cross-sectional survey seeking to demonstrate the effect of ACF on creation of Anopheles larval habitats and its effect on Anopheles larval density. Mosquito larvae were sampled using a standard WHO dipper. The association between Anopheles presence/density and ACF activities was inferred. A total of 87 mosquito larval habitats were identified. Stagnant water bodies created through ACF activities or otherwise are hereafter respectively referred to as „fishing‟ and „non-fishing‟ habitats. More fishing (77.8%) than non-fishing habitats (38.3%) contained Anopheles larvae. There was a significant negative association between ACF and the probability of finding Anopheles larvae in habitats. The mean number of Anopheles larvae in fishing boats, rock pools, ditches, lagoons and swamps was 40.08±10.16, 30.81±10.54, 5.71±3.11, 1.14± 0.9 and 1.09± 0.7, respectively. No Anopheles larvae were recovered from fishing ponds, fish bait mines and trenches. Although the total numbers of Anopheles larvae collected from both habitat types were about equal, the mean density in „fishing habitats‟ (N=27; 35.7±1.15) was twice that in „non-fishing habitats‟ (N=60; 17.4±0.539) (P = 0.001). The mean number of Anopheles mosquitoes in habitats with muddy, rocky and wooden bottom surfaces were 2.22 ± 0.29, 27.39 ± 0.87 and 40.08 ± 1.29, respectively. All pairwise comparisons of larval density revealed significant differences between habitats whose bottom surfaces were muddy, rocky or wooden (p = 0.001 in all cases). A map developed using computer algorithms showed that malaria hazard was strongly correlated to the spatial distribution of ACF activities on Mageta Island. These results demonstrate that ACF is a key driver of malaria endemicity on Mageta Island. Larval source management strategies in the global south should be cognizant of the heterogeneity in Anopheles breeding habitats created by livelihood activities.