Degree of Plasticity in Tissue Specific Fatty Acid Signatures of Yellow Perch Fed Natural Diet of Alewife or Round Goby

Fatty acid signature (FAS) analysis becomes a useful tool in food web studies and can be very informative when combined with stable isotope analysis and with traditional stomach content examination. It can provide insights into the long term feeding habits of predators based on the degree of similarity between their FAS and that of their prey. To illustrate the degree of variability in FAS one can expect in a freshwater system, we fed for 9 months two groups of adult yellow perch (Perca flavescens) with a natural diet comprised of either exclusively alewife (Alosa pseudoharengus) or round goby (Neogobius melanostomus); both prey species are commonly consumed by yellow perch in Lake Michigan. By doing so, we mimicked FA transfer up the food chain and established a template for ongoing food web studies related to yellow perch trophic interactions in the natural conditions of Lake Michigan. We will compare and contrast the FAS in yellow perch eggs, liver, muscle, adipose fat, and whole body. In addition, we will assess the degree of FAS similarity among yellow perch tissues and relate fatty acid composition of yellow perch tissues to that of their prey (alewife and round goby). Results will be discussed in the context of fatty acid transfer from prey to predator in freshwater systems.