Isotope values in fish eye lenses may be useful in differentiating rearing origins. We compared eye lens isotopic values of fall fingerling age‐0 walleye ( Sander vitreus ) reared in a hatchery pond, a recirculating aquaculture system (RAS), and a natural lake. Using 10 fish per rearing source, we delaminated layers from one eye lens per fish to assess temporal changes in carbon (δ 13 C) and nitrogen (δ 15 N) and pulverized th...

Stable isotope analysis is key to understanding trophic relationships, but how different diet components are incorporated into tissues remains unclear. Understanding trophic relationships for omnivorous species is particularly challenging because they consume both plants and animal material that vary in nutritional quality, isotopic composition, and metabolic routing. Carbohydrates can fuel metabolism but may not be incorporat...