Comparing fish bycatch of shrimp trawlers with catches made by artisanal fishers in Malindi-Ungwana Bay, Kenya

Abstract

Unpredictable weather patterns has affected both the agriculural and fisheries production worldwide coupled with increased conflict in resource use. The Malindi-Ungwana Bay, Kenya in Tana Delta has multiple socio-economic uses and therefore, has been a subject of resource use conflict for a long time. This present study identifies resource use overlap and conflict by comparing species composition, distribution patterns and abundance of bottom trawl fish bycatches and artisanal fish catches in the bay. Bottom trawl surveys were undertaken during the dry Northeast Monsoon (NEM) season and during the wet Southeast Monsoon (SEM) season in 2011, and artisanal catches were sampled along the bay between 2009 and 2011. Bottom trawl fish bycatches consisted of a total of 223 species against a total of 177 species for artisanal catches. Higher species diversity was associated with the bottom trawl bycatches and was significantly higher in the wet SEM season and in the inshore area of the bay. Trawl bycatch rates and biomass were significantly higher in inshore than offshore areas and distinct in composition but less differing between the seasons.  Similarity in catch composition was evident between the artisanal catches and bottom trawl bycatches in the inshore area. This similarity was attributed mainly to 7 common and most abundant fish species associated with the artisanal and bottom trawl sub-sectors confirming the existence of a potential but localised inshore resource use overlap. Furthermore, significantly smaller sized individuals of these 7 species occurred in the trawl bycatches which may affect fish recruitment with continued trawling. Artisanal fishing activity in the bay is envisaged to increase due to decreased agricultural production. Sustainable artisanal fisheries will therefore, depend on the full implementation of the shrimp fishery management plan in the bay.