Scaphirhynchus Conference: Alabama, Pallid, and Shovelnose Sturgeon

St. Louis, Missouri, 11-13 January 2005

13.  EFFECTIVENESS OF NON- AND MINIMALLY INVASIVE METHODS FOR ESTIMATING REPRODUCTIVE STAGE AND FECUNDITY OF SHOVELNOSE AND PALLID STURGEONS

Janice L. Bryan*, U.S.G.S. Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO 65201; Phone 573-441-2953; Fax 573-876-1896; jbryan@usgs.gov

Mark L. Wildhaber, U.S.G.S. Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO 65201; Phone 573-876-1847; Fax 573-876-1896; mwildhaber@usgs.gov

Diana M. Papoulias, U.S.G.S. Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO 65201; Phone 573-876-1902; Fax 573-876-1896; dpapoulias@usgs.gov

Aaron J. DeLonay, U.S.G.S. Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO 65201; Phone 573-876-1878; Fax 573-876-1896; adelonay@usgs.gov

Donald E. Tillitt, U.S.G.S. Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO 65201; Phone 573-876-1886; Fax 573-876-1896; dtillitt@usgs.gov

Mandy L. Annis, U.S.G.S. Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO 65201; Phone 573-441-2940; Fax 573-876-1896; mannis@usgs.gov

Understanding the reproductive cycle of sturgeon in the Missouri River is important in evaluating the status and viability of the population. Using non- and minimally invasive methods for examining fish permits a nonconsumptive procedure to collect reproductive data. To evaluate the reproductive status of shovelnose sturgeon and pallid sturgeon, we used ultrasound to estimate fecundity, egg size, and gonad size and an endoscope to estimate egg stage. To estimate gonad volume we took three equa-distant transverse ultrasound images and one longitudinal external length measurement. Gonad area in each cross section and egg diameters were measured using image analysis software. Fecundity was estimated by dividing the calculated gonad volume by the mean calculated egg volume. Ultrasound-measured fecundity, gonad volume and egg diameters were conservative compared to actual measurements. By viewing egg color through the oviduct or an abdominal incision, the endoscope technique determined egg stage within one reproductive stage. In addition, 16 pallid sturgeons were examined and we found that ultrasound could be used to determine fecundity but stage determination with the endoscope was limited due to their opaque oviducts. Overall, ultrasound and endoscopic examination were effective tools for evaluating the reproductive status of sturgeons.