Are the Post-harvest Losses of Nile-perch Value Chain in Lake Victoria in Tanzania a Driver of using Pesticides for Fish Storage?

Abstract

Post-harvest losses are major causes of economic and nutritional losses in the Nile perch value chain. Literatures indicate that the value of the total post- harvest losses on the Nile perch value chain as a percentage of the expected value of all the fish landed is 31%; whereby the quality loss constitutes 12.1% while physical loss accounts for 18.9%. This huge loss has necessitated fisher folks to use different alternatives that are possible to fight such post- harvest losses. This study was conducted in Lake Victoria to assess whether post-harvest losses on the Nile perch value chain are important drivers of using chemical pesticides in fish storage. The study involved fresh fish samples collection from the designated landing sites and processed products (salted- sundried, smoked, deep-fried and trims) from the markets. Samples extraction and cleanup was carried out using a QuEChERS method and analysis using a Gas Chromatography equipped with electron capture detectors (GC- ECDs). The results indicated high levels of organochlorine pesticides in processed Nile perch products than in the fresh fish muscles. The concentrations of organochlorine pesticides (OCPs) in fresh fish muscles ranged from below the limits of detection (<LOD) to 0.4 μg/kg whereas in processed fish products the OCPs concentration ranged from <LOD to 2.20 μg/kg. In this study, only four OCPs (β-HCH, HCB, Dieldrin and Aldrin) were detected in fresh fish muscles while nine OCPs (α- HCH, β- HCH, Lindane, HCB, Dieldrin, Aldrin, p, p- DDE, α- endosulfan, Oxychlordane and α- chlordane) were detected in processed fish products. This suggests use of chemical pesticides in the fish value chain for preventing post-harvest losses and that post-harvest losses could be significant contributors towards use of pesticides during fish processing and storage.