Experimental and field evaluation of otolith strontium as a marker to discriminate between river-spawning populations of walleye in Lake Erie

Abstract

Otolith microchemistry is a commonly used tool for stock discrimination in fisheries management. Two key questions remain with respect to its effectiveness in discriminating among river-spawning populations. First, do larvae remain in their natal river long enough for their otoliths to pick up that system’s characteristic chemical signature? Second, are larval otolith microchemical differences between natal rivers sufficiently large to overcome spatiotemporal variation in water chemistry? We quantified how larval age, the ratio of ambient strontium to calcium concentrations (Sr:Ca), and water temperature influence otolith Sr in both lab-reared and wild-collected Lake Erie walleye (Sander vitreus). Otolith microchemistry shows promise as a spawning stock discrimination tool, given that otolith Sr in larval walleye (i) is more strongly influenced by ambient Sr:Ca than by temperature; (ii) reflects Sr:Ca levels in the natal environment, even in larvae as young as 2 days old; and (iii) can effectively discriminate between larvae captured in two key Lake Erie spawning tributaries, even in the face of short larval river residence times and within-year and across-year variation in ambient Sr:Ca.

RAD‐Seq Refines Previous Estimates of Genetic Structure in Lake Erie Walleye

“…These panels could then be used independently (if the resolution is high enough) or in conjunction with other techniques, such as otolith microchemistry, to successfully delineate populations (Chen et al. ). Therefore, further assessment of Walleye with higher‐coverage RAD‐seq or full‐genome resequencing could be highly valuable for developing tools to conduct mixed‐stock analysis of Walleye in the Great Lakes.…”

“…Therefore, delineation may be possible using a combination of environmental markers (e.g., parasites and otolith microchemistry) and molecular markers (MacKenzie and Abaunza ; Chen et al. , ).…”

“…) and knowledge of the relative recruitment of each stock to the broader commercial and recreational fisheries (Chen et al. ; Faust et al. ).…”

“…; Chen et al. ). Walleye is an economically important species that serves as the cornerstone to a large commercial fishery in Canadian waters of Lake Erie and an equally important recreational fishery in U.S. waters (Roseman et al.…”

“…Likewise, the use of otolith microchemistry to determine natal origins was limited by interannual variation in water chemistry, and this approach has been only useful for differentiating individuals originating in the Sandusky River from other western basin spawning stocks (i.e., the Maumee River and Ohio reef complex could not be resolved; Chen ; Chen et al. ).…”