Consumption of Forage Fish Alters Fatty Acids of Brown Trout Eggs

In an effort to better understand the effects diet composition has on salmonid species we feed captive brown trout diets consisting of mixtures of two invasive species. Alewife and round goby were offered to brown trout in isolation and in 70:30 mixtures based on wet weight for a period of 11 months. Fatty acid profiles of belly flaps and eggs were analyzed along with the thiamine content of eggs. In samples of belly flap proportions of oleic acid (18:1n-9) and fatty acids of the n-3 family in both belly flap and eggs proportions increased with increasing consumption of alewife. Conversely, fatty acids in the n-7 family and branched-chain fatty acids increased in both tissue types when round goby comprised larger portions of the diet composition. We noted that a diet of only round goby produced higher and more variable concentrations of free thiamine in brown trout eggs compared to other treatments. Our data indicates that diet compositions influence the supply of essential nutrients to brown trout embryos. Furthermore, our data indicates that thiamine deficiency complex could be related to a diet supplying a high concentration of n-3 fatty acid depleting maternal thiamine reserves.