A Comparative Analysis of Content of omega-3 Polyunsaturated Fatty Acids in Food and Muscle Tissue of Fish from Aquaculture and Natural Habitats
M. I. GLADYSHEV1,2, L. A. GLUSHCHENKO2, O. N. MAKHUTOVA1,2, A. E. RUDCHENKO2, S. P. SHULEPINA2, O. P. DUBOVSKAYA1,2, I. V. ZUYEV2, V. I. KOLMAKOV1,2, N. N. SUSHCHIK1,2
1Institute of Biophysics of Federal Research Center, 660036, Krasnoyarsk, Akademgorodok, 50/50
2Siberian Federal University, 660041, Krasnoyarsk, Svobodny ave., 79
Keywords: жирные кислоты, аквакультура, пищевая цепь, биоаккумуляция, fatty acids, aquaculture, food chain, bioaccumulation
Abstract
Two fish species, reared in aquaculture, pink salmon Oncorhynchus gorbuscha and whitefish Coregonus lavaretus , as well as ten species from natural habitats, whitefish C. lavaretus , tugun Coregonus tugun , broad whitefish Coregonus nasus , least cisco Coregonus sardinella , vendace Coregonus albula , boganid charr Salvelinus boganidae , charr Salvelinus alpinus complex, northern pike Esox lucius , sharp-snouted lenok Brachymystax lenok and taimen Hucho taimen were studied. The content of two long-chain polyunsaturated omega-3 fatty acids (PUFA), eicosapentaenoic (20:5n-3, EPA) and docosahexaenoic (22:6n-3, DHA) in muscle tissue of fish and in their food (intestine contents) was compared. In the aquacultures of whitefish and pink salmon, the content of the sum of EPA and DHA in food was significantly higher, than that in muscle tissue of the fish, which indicated losses of PUFA in the two-link food chain of aquaculture during their transfer to the upper trophic level. The losses of EPA and DHA in aquaculture, supported by numerous literature data, meant an inefficient usage of given sources of PUFA and an aggravation of a global deficit of these biochemicals in human diet. When studying natural fish populations, in many cases an accumulation of EPA and DHA in the biomass compared to the food was found, although contrary phenomena also took place. Basing on our and literature data, an existence of certain optimal physiologically adequate species-specific level of PUFA in fish muscle tissue was supposed. If a level of PUFA in the muscles was lower than the optimal one, their storing (bioaccumulation) from the food and/or de novo synthesis took place. In a case of exceeding the optimal level, the content of EPA and DHA in biomass approached to maximum species-specific values, but a part of these PUFA, obtained from food, either was not assimilated, or was catabolized. According to the data obtained, species from order Salmoniformes had the optimal level of 2-6 mg g-1 wet weight. As found, in aquaculture the approach to maximum values of EPA + DHA content was accompanied by their losses (scattering) in the food chains, while in natural ecosystems the maximum values of PUFA content in fish biomass were achieved by their accumulation from lower trophic levels. For boganid charr S. boganidae , the highest content of EPA + DHA in muscle tissue among all known fish species, 32.78 mg g-1 of wet weight, was recorded.
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