ABSTRACT
Stable isotope analysis of fi sh tissue is now an established tool to identify the origin or to trace migration patterns of freshwater, estuarine, and marine fi shes. Studies of fi sh origins, migrations, and other movements are undertaken to better understand the ecology and ecological connectivity of fi shes, provide habitat use information for conservation, assess potential exposure to ecotoxicological threats, and support environmental assessments. In early studies of migration and movement, spatial patterns were inferred from marking and tagging of fi sh, or else by the use of intrinsic markers found in meristic characters, scales, or otoliths that were location-or stockspecifi c (Jones 1968). Such techniques are still used and effective; fi ndings from these studies, however, are limited by the ability to recapture tagged fi sh or to those stocks for which intrinsic markers have been studied and determined reliable. Recent developments in electronic tagging technologies (e.g., archival tags, acoustic and radio telemetry tags; see Schaefer 2016, this book) have greatly expanded our ability to track individual fi sh over varied spatial domains. Nevertheless, these tagging methods are not feasible or economical for many fi shes.
