Final report of the targeted research on Indian mackerel and sharks and national plan of action for conservation and management of shark resources, Thailand

Research included: population structure of Indian mackerel (Rastrelliger kanagurta); a National Plan of Action for the conservation and management of sharks; levels of heavy metals in shark products; and a database on rays.

The effect of artisanal preservation methods on nutritional security of “Mukene” Rastrineobola argentea caught from Lakes Victoria and Kyoga in Uganda

The artisanal fish preservation methods in Uganda are characterized by extreme operating conditions. Consequently, vital nutritional components diminish in value and quantity which renders fish consumer nutritionally insecure. To establish the magnitude of nutritional loss, duplicate samples of Mukene Rastrineobola argentea were collected from Kiyindi landing site on L. Victoria and Moone landing site on L. Kyoga. Each set of duplicate samples was divided into five portions and kept on ice. For each preservation method a portion was processed into respective products at Food Bioscience and Agri-Business Laboratories aside from the control (fresh) sample. Both preserved and control samples were analysed for nutrient loss at Department of Chemistry, Makerere University using AOAC methods. The composition of fatty acids was determined by methanolysis gas chromatography and Mass spectrophotometry of the resultant methyl esters. The results indicate that nutrients of all preserved samples did not vary significantly from the control except for some fatty acids. The Eicosapentaenoic acid (EPA) in fresh samples declined from 6.72% to 1.08% in deep-fried samples constituting 83.93% nutrient loss. The sum ratio w3:w6 as well as EPA: DHA (Docosahexaenoic) ratio in fried samples also varied significantly (p<0.5) lower than 0.668 and 0.20 for the average of either preservation methods and experts recommended ratio respectively. Further research has been recommended to ascertain the causative factor, since Mukene frying is being promoted in the Great lakes region as alternative method to sun-drying. In conclusion, regular consumers of fried Mukene do not benefit much from the nutritional and health attributes of Omega 3 and 6.

The preservation of some East African freshwater fish

Quality changes during storage were investigated for several commercially important East African freshwater fish. Lates, Bagrus, Protopterus, Tilapia esculenta and T. nilotica were examined during storage in ice and at ambient temperature (250•C). After 24 hours at ambient temperature Lates and Bagrus were completely spoilt but Protopterus was still edible. In iced storage most fish were acceptable for at least 20 days. Organoleptic examination showed that T. nilotica was acceptable after 22 days storage in ice and that gutting was only marginally beneficial. Changes in physical appearance, which could form the basis of a fish inspection system, were recorded during storage. Possible chemical quality control indices were also investigated. It was found that total volatile bases and hypoxanthine are unlikely to be useful quality indices for the species studied with the possible exception of Lates. The bacterial counts of the flesh and skin of T. esculenta and T. niloticus were found to be low (a maximum of 10 organisms per sq cm of skin or per g of flesh) after 22 days storage in ice.