Otolith chemistry indicates walleye movement and entrainment in a large serial reservoir system

Abstract

Understanding fish movement in impounded river systems is important for fisheries management. Otolith chemistry was used to examine walleye Sander vitreus (Mitchill) intra‐ and inter‐reservoir movement in four Missouri River impoundments. Age‐0 individuals were reclassified with 75%–93% accuracy to known natal sites, allowing for reliable evaluation of movement patterns of age‐1 and older fish. Nearly half of walleye occupied the same location annually (i.e. site residency) between 2009 and 2010. In 2011, during the largest flood on record since 1898, downstream movement (49% of age‐1 and older fish) exceeded upstream movement (7%) and site residency (33%) across the study area. After the flood, most walleye moved downstream within reservoirs (45%) or were site residents (37%). Entrainment occurred most frequently during the flood year and was proportionally greatest in downstream reservoirs. Otolith chemistry is useful for understanding walleye movement and entrainment and is a tool for fisheries management with applications such as informing reservoir water releases, harvest regulations and habitat protection and rehabilitation within and outside the Missouri River reservoir system.

Otolith chemistry as a fisheries management tool after flooding: The case of Missouri River gizzard shad

“…Moreover, aquatic resource professionals should also recognize that main channels and other comparatively large habitats with low natal contributions relative to their size contribute considerable numbers of gizzard shad and should thus be incorporated into habitat management approaches. Although most gizzard shad hatched in floodplain environments separated from the main channel, 21% of gizzard shad originated in main‐channel habitats, where otolith chemistry research indicates Lake Sharpe walleye predominately hatch and are abundant as adults (Carlson, Fincel, & Graeb, , ). This finding is important for understanding predator–prey dynamics (e.g., spatial overlap of walleye and gizzard shad and walleye consumption of gizzard shad) in main‐channel environments and developing multispecies fisheries management strategies in Lake Sharpe.…”

“…Water chemistry in large rivers is influenced primarily by surficial and bedrock geology (Gibbs, ); thus, it was predicted that water signatures would be temporally stable, as demonstrated in previous Missouri River otolith chemistry studies (Carlson, Bailey, et al, ; Carlson, Fincel, & Graeb, , ). To verify this idea, current (2014) Ba:Ca and Sr:Ca signatures collected in the Lake Sharpe main channel were compared to historical signatures (Ba:Ca, 1978–1986 and 1997–1998; Sr:Ca, 1983–1986 and 1997–2000) collected at the same location during the same time of year (i.e., late summer).…”

“…Along with biochronological markers (i.e., annuli and circuli), otoliths accrete permanent signatures of strontium (Sr), barium (Ba), and other trace elements in proportion to their water column concentrations (Campana, Chouinard, Hanson, Frechet, & Brattey, ). Thus, if water chemistry is spatially variable and temporally consistent, otoliths can be used as natural tags to assess natal origins, habitat use, and other aspects of environmental history (e.g., movement and entrainment; Carlson, Fincel, & Graeb, ). Otolith chemistry has been used to assess walleye natal origins ( Sander vitreus ) in Missouri River reservoirs (Carlson, Fincel, & Graeb, ) and movement in Lake Oahe (Carlson, Bailey, Fincel, & Graeb, ), the largest Missouri River impoundment.…”

“…Our objectives were to (a) evaluate spatiotemporal patterns in the water chemistry of Lake Sharpe habitats (e.g., main channel, embayment, and tributary); (b) quantify the relationship between water and gizzard shad otolith chemistry across habitat types; (c) assess the natal contributions of Lake Sharpe habitats; and (d) evaluate the importance of Hipple Lake for gizzard shad spawning relative to other floodplain habitats (i.e., tributary, canal, and stilling basin) to inform sediment and water management in Lake Sharpe. *We hypothesized that water signatures would be spatially heterogeneous, temporally consistent, and proportional to otolith signatures as previously documented within and outside Lake Sharpe (Carlson, Fincel, & Graeb, , ), making otolith chemistry an effective environmental history method and a fisheries management tool after floods.…”

Species‐ and habitat‐specific otolith chemistry patterns inform riverine fisheries management

“…Although other techniques for quantifying hard‐part signatures (e.g., X‐ray fluorescence) do not require a data reduction step, studies involving laser ablation ICP‐MS can be made more efficient if researchers have the ability to predict which elemental ratios will best satisfy requirements for hard‐part chemistry research prior to data collection. This is particularly true in Missouri River reservoirs, where otolith and fin ray chemistry are increasingly used to inform fisheries and aquatic resource management (Carlson, Bailey, Fincel, & Graeb, ; Carlson, Fincel, & Graeb, ; Carlson, Fincel, & Graeb, ; Phelps et al, ), yet research logistics (e.g., water sampling and fish sampling) are inherently costly due to the basin's large size (1,371,017 km 2 ; Galat et al, ). The goal of this investigation was to develop a predictive methodology whereby Missouri River aquatic resource professionals can use known study attributes (i.e., species and habitat identity) to efficiently design otolith chemistry investigations and avoid unnecessary resource expenditure (e.g., time, money, and personnel) associated with water and fish sampling.…”