Delta-carbon-13 and delta-nitrogen-15 signatures in salmonid muscle and fin tissues: Non-lethal sampling methods for stable isotope analysis of fish

Stable isotope analysis has emerged as an important tool in ecology. Traditionally, dorsal muscle from sacrificed fish has been used in stable isotope studies; however, there are many instances when lethal sampling is undesirable. The objectives of my research were to evaluate a biopsy procedure for obtaining dorsal muscle non-lethally from rainbow trout and to assess the viability of adipose and caudal fin clips from five species of salmonids as alternatives to muscle in stable isotope studies. Muscle biopsy proved to be a low mortality sampling method. Isotope signatures of both adipose and caudal fins were strongly correlated with signatures of muscle in the salmonid species studied, and in some cases, were not different from the signatures of muscle. Muscle biopsy should eliminate lethal sampling in fish large enough to tolerate the procedure and fin clips should be considered good surrogates for muscle in stable isotope studies of salmonids.