Assessing Percid Populations In The Ohio River
Scott A. Schell, Ohio Department of Natural Resources, Athens, OH 45701; (740) 594-2211; FAX (740) 594-1626; scott.schell@dnr.state.oh.us
R. Scott Hale, Ohio Department of Natural Resources, Hebron, OH 43025
Stacy M. Xenakis, Ohio Department of Natural Resources, Hebron, OH 43025
Kenneth K. Cunningham, Ohio Department of Natural Resources, Hebron, OH 43025
Douglas T. Henley, Kentucky Department of Fish and Wildlife Resources, Frankfort, KY 40601
Les D. Frankland, Illinois Department of Natural Resources, Fairfield, IL 62837
Thomas C. Stefanavage, Indiana Department of Natural Resources, Winslow, IN 47598
Christopher J. O'Bara, West Virginia Division of Natural Resources, Parkersburg, WV 26101
The Ohio River Fisheries Management Team (ORFMT) assessed sauger Stizostedion canadense and walleye Stizostedion vitreum populations during 1998-2003 to develop interjurisdictional management strategies. Population composition, abundance, size and age structure, growth, condition, and mortality were assessed with standardized shoreline electrofishing surveys at seven tailwaters. Inter-pool movement and exploitation were estimated with mark and recapture studies. Fishery characteristics including angler effort, catch, and harvest were estimated with creel surveys. Genetic analyses of sauger, walleye and their hybrids (saugeye) were contracted independently to two universities. Sauger comprised 91% of all percids sampled with walleye abundance higher in the upper pools. Over 80% of sauger and 75% of walleye collected during fall were <33cm and few fish survive beyond age 3. Relative weight of sauger and walleye consistently exceeded 90% riverside. Total annual mortality for sauger between ages 1-2 ranges from 63-98%, and generally exceeded 90% in most study tailwaters. The tagging study revealed that most of the 3,131 tagged sauger and 432 tagged walleye were recovered in the same pool where tagged. Movement was primarily upstream and limited to one or two pools, but some fish were recovered seven pools upstream from their tagging location. Exploitation calculated from tag returns ranged from 4% at R.C. Byrd to 42% at J. T. Meyer tailwaters, and averaged 14% river wide. Creel surveys demonstrated that 58% of anglers keep and eat their catch and 84% of these fish are sauger. Angler effort ranged from 6,972 angler hours at New Cumberland tailwater to 26,152 angler hours at Greenup tailwater. Greater than 50% of all anglers were seeking sauger. Sauger catch rates ranged from 0.67 f/h (Pike Island) to 2.88 f/h (Willow Island). Angler harvest ranged from 1,080 fish at New Cumberland to 8,463 at Markland. Harvested sauger were primarily 300-400 mm (ages 1-3). Genetic analysis confirmed that percid field identification can be inaccurate. Two independent genetic studies documented the presence of a unique walleye haplotype, suggesting a remnant native population in Hannibal and Pike Island pools. High levels of Great Lakes strain MtDNA were found in hybrids collected from Belleville and Meldahl pools, implicating stocking programs and suggesting that broodstock should not be collected from these areas. Sauger is the primary percid of the Ohio River sport fishery, with walleye predominantly found in the uppermost pools. Although abundant, the sauger population has truncated size and age structure and high mortality indicative of overharvest. Overharvest cannot be substantiated until total annual mortality is accurately partitioned into fishing and natural mortality. When mortality components are adequately quantified, fisheries options can be explored to maximize yield, size at harvest, or numbers of fish harvested.