Stock Identification of Walleye via Otolith Chemistry in the Eleven Point River, Arkansas

Abstract

Otolith chemistry was used to identify two hatchery stocks (Missouri State Hatchery and Arkansas Federal Hatchery) and a possible wild stock of walleye Sander vitreus in the Eleven Point River in northeastern Arkansas. Previous population estimates by the Arkansas Game and Fish Commission using traditional tag-and-release techniques failed to identify the relative survival of these stocks or their spatial and temporal persistence. Using chemical analysis of otoliths combined with a priori knowledge of the hatchery source, we identified otolith chemical signatures unique to each stock. We collected 51 walleyes that bore the physical tag of a known hatchery, along with 46 nontagged walleyes. The efficacy of otolith chemistry in classifying walleyes to known stocks was assessed by analyzing unknowns via discriminant function analysis. Fish were classified to their respective stocks based on otolith chemistry, and 92% were assigned to known stocks. Fishery managers can assess the persistence of individual stocks and the success rates of stocking practices in riverine systems using this technique.