Scaphirhynchus Conference: Alabama, Pallid, and Shovelnose Sturgeon

St. Louis, Missouri, 11-13 January 2005

24.  POPULATION CHARACTERISTICS OF SHOVELNOSE STURGEON FROM AN EXPLOITED AND UNEXPLOITED REACH OF THE WABASH RIVER, INDIANA

Anthony J. Kennedy, Purdue University, Department of Forestry and Natural Resources, 175 Marsteller Street, West Lafayette, Indiana 47907, USA; telephone: (765) 494-5040; FAX: (765) 494-2422; email: kennedya@purdue.edu

Trent M. Sutton, Purdue University, Department of Forestry and Natural Resources, 195 Marsteller Street, West Lafayette, Indiana 47907, USA; telephone: (765) 496-6266; FAX: (765) 496-2422; email: tsutton@purdue.edu

Thomas C. Stefanavage, Indiana Department of Natural Resources, Sugar Ridge Fish and Wildlife Area, 2310 E. SR 364, Winslow, IN 47598, USA; telephone: (812) 789-2724; FAX: (812) 789-9453; email: tstefanavage@dnr.state.in.us

Brant E. Fisher, Indiana Department of Natural Resources, Atterbury Fish and Wildlife Area, 7970 South Rowe Street, P.O. Box 3000, Edinburgh, Indiana 46124, USA; telephone: (812) 526-5816; FAX: (812) 526-2892; email: bfisher@dnr.state.in.us

Leslie D. Frankland, Illinois Department of Natural Resources, RR#1 Box 165, Albion, IL 62806, USA; telephone: (618) 842-2179; FAX: (618) 842-5107; email: lfrankland@dnrmail.state.il.us

Shovelnose sturgeon Scaphirhynchus platorynchus are one of the few North American sturgeon species that currently support a commercial fishery.  As a result, there is concern that global declines in sturgeon populations due to the high demand for caviar may result in increased exploitation rates and population-level effects on shovelnose sturgeon.  We examined the population attributes of shovelnose sturgeon in an exploited and unexploited reach of the upper Wabash River, Indiana.  Fish were captured from April through December 2003 and February through October 2004 between Wabash and Terre Haute, Indiana, using DC electrofishing and experimental gill nets (N = 4,908).  Electrofishing catch-per-unit-effort was greater in the unexploited reach (35 fish/hr) than the exploited reach (14 fish/hr).  Catch rates were highest for both reaches during March through May, and approached 500 fish/hr in early May when fish became concentrated in spawning aggregations.  Fork length ranged from 273 to 858 mm, but small shovelnose sturgeon (< 500 mm) were not captured during the study period in appreciable numbers.  Median fork length and wet weight were greater in the unexploited reach (683 mm and 1181 g, respectively; range = 535 to 858 mm and 549 to 3381 g, respectively) than the exploited reach (673 mm and 1102 g, respectively; range = 273 to 842 mm and 52 to 2715 g, respectively).  However, relative weight of shovelnose sturgeon was not significantly different between the exploited (mean = 83.5) and unexploited reach (mean = 83.9).  Empirical growth rates were slow and 74% of fish showed negative or no growth while at-large for up to 3 years.  Mark-recapture data included several fish that crossed the demarcation of the exploited and unexploited section of the river, with some upstream movements greater than 200 km.  Our results indicate that biological characteristics of shovelnose sturgeon may not differ between exploited and unexploited reaches of the Wabash River.