Differences in Paddlefish Populations among Impoundments of the Arkansas River, Arkansas

Abstract

Most large rivers within the range of paddlefish Polyodon spathula are fragmented by dams. However, little research has been done to determine if population characteristics (e.g., growth, mortality, density) vary among impoundments within river systems and how this may influence the risk of overfishing. Population characteristics and the potential for commercial overfishing were assessed for paddlefish in three impoundments of the Arkansas River, Arkansas (Pool 13, Ozark Lake, and Lake Dardanelle). Paddlefish (n = 751) were collected with gill nets from November 2003 to March 2005. Paddlefish from the most lentic and most heavily fished pool, Lake Dardanelle, had the lowest catch rate, grew fastest, and had the highest mean condition factor, weight, fecundity, and total annual mortality (67%). In contrast, paddlefish from the most lotic impoundment that was less intensively fished, Pool 13, had the highest catch rate, slowest growth, and the lowest mean condition, weight, fecundity, and total annual mortality (53%). The Lake Dardanelle paddlefish fishery appeared to show signs of commercial overfishing when managed with a 914-mm eye fork length minimum length limit and a 151-d season. Beverton–Holt population simulations modeled by impoundment indicated Lake Dardanelle was more sensitive to overfishing than the other pools. Although there was limited movement among pools, results of this study indicate that population characteristics vary among the three adjacent impoundments on the Arkansas River and that they should be managed as separate management units.

Received November 15, 2011; accepted April 13, 2012

ACKNOWLEDGMENTS

We thank Drs. J. Jackson and C. Gagen for reviewing earlier versions of the manuscript. G. Kremers and Z. Watson assisted with field collections and spent many hours analyzing specimens in the laboratory. We thank Mike Jezierski for making the study site map. M. Armstrong, R. Limbird, and E. Leone provided logistical support for this project.