Recruitment contributions and natal fidelity in tributary rivers of the Grand Lake, Oklahoma, Paddlefish stock

Abstract

Microchemistry of sectioned dentary (lower jaw) bones was used to determine natal river (Neosho, Spring or Elk River) of paddlefish Polyodon spathula (Walbaum) in the economically important snag fishery in Grand Lake, northeastern Oklahoma, and to assess the relative importance of the tributary rivers as sources of recruits to the fishery. Geological differences between the Neosho River and Spring River watersheds resulted in large differences in water strontium:calcium (Sr:Ca) ratios reflected in dentary Sr:Ca for paddlefish from each river. Dentary core Sr:Ca signatures were used to infer natal river for paddlefish harvested over the period 2008–2018. Most harvested fish (87%) were identified as Neosho River origin, and 7% were within the predicted range for Spring River origin (6% undetermined). Relative frequencies of Neosho River and Spring River-origin fish (the latter, all ≤10%) differed among cohorts but did not differ among years, locations or sexes. Results corroborate a sonar survey of spawning substrates that concluded that the Neosho River has higher potential value for paddlefish spawning and recruitment than the Spring River. No evidence of natal river fidelity was found. Results highlight the importance of maintaining habitat conditions and inform harvest management regulations required for paddlefish spawning, recruitment and sustainability.