Can fish have too much fat? Connections between fat content and Thiamine Deficiency in Lake Ontario

Session: Thiamine Deficiency in the Great Lakes (2)

Matthew Futia, The University of Vermont, [email protected]
Michael Connerton, SUNY ESF, [email protected]
Brian Weidel, U.S. Geological Survey, Great Lakes Science Center, [email protected]
Jacques Rinchard, The College at Brockport, State University of New York, [email protected]

Abstract

Natural salmonine recruitment has been greatly limited in Lake Ontario, potentially due to Thiamine Deficiency Complex (TDC). Research shows consumption of alewife is frequently associated with TDC; however, the specific mechanisms involved remain unknown. Studies have suggested thiaminase as the cause of TDC, but this hypothesis remains to be confirmed. High fat content of prey may cause TDC by increasing predator thiamine requirements for lipid metabolism and/or protection from lipid peroxidation as an antioxidant. In the present study, we investigated correlations between salmonine thiamine concentrations and (1) lipid content as well as (2) proportions of fatty acids based on degrees of saturation. Negative correlations were observed between lipid content and thiamine concentrations; however, significant correlations were restricted to brown trout, which did not experience TDC. Significant negative correlations between the proportions of polyunsaturated fatty acids (PUFAs) and thiamine concentrations in salmonine tissue were observed for lake and brown trout. However, it is unlikely that PUFA proportions alone accounted for TDC as much of the variance in thiamine concentrations remained unexplained and other species experienced weak, but positive correlations. Thus, consuming prey with relatively high fat content is unlikely to be the main cause of TDC in Lake Ontario salmonines.