Classification of hatchery and wild fish using natural geochemical signatures in otoliths, fin rays, and scales of an endangered catostomid

Abstract

Endangered and endemic June sucker (JS, Chasmistes liorus) have been stocked for many years to prevent extinction in Utah Lake, Utah. When unmarked fish appeared in the lake at higher rates than expected from tag loss, we sought to determine if 87Sr/86Sr and Sr/Ca (signatures) in otoliths, fin rays, and scales could be used to identify whether stocking had created a naturally reproducing population. Signatures from otoliths and fin rays suggested that approximately 38% (12 of 31) of unmarked JS probably came from the Fisheries Experimental Station (FES) hatchery in Logan, Utah, and a minimum of 13% (four of 31) of unmarked JS had signatures that strongly indicated that they were of wild origin. The remaining JS (15 of 31) could not be assigned to any particular location because of signature overlap. While scales were not useful for determining fish provenance, we found a nearly 1:1 relationship between pelvic fin and otolith 87Sr/86Sr. Thus, fin sections appear to provide a nonlethal structure for laser ablation microchemical analysis to determine origins of unknown origin JS in the future.