Application of fin tissue for nonlethal stable isotope analysis of small-bodied fishes

Stable isotopes are commonly used to characterize food web structure and resource use by aquatic organisms. White muscle is generally preferred for stable isotope analysis of fishes. However, obtaining white muscle tissue typically requires lethal take or invasive sampling techniques, which are undesirable for small-bodied species or those of conservation concern. We assessed the use of fish fin as a nonlethal alternative to muscle tissue for stable isotope analysis of four small-bodied fishes native to the upper Red River drainage of Texas and Oklahoma, USA: plains minnow Hybognathus placitus, prairie chub Macrhybopsis australis, Red River shiner Alburnops bairdi, and Red River pupfish Cyprinodon rubrofluviatilis. Fin isotope values were strong predictors of both δ¹⁵N and δ¹³C muscle isotope values (ANCOVA: δ¹⁵N: F_1,451 = 5312.09, P