Greg A. Wanner

Poststocking Movements and Habitat Use of Hatchery-Reared Juvenile Pallid Sturgeon in the Missouri River below Fort Randall Dam, South Dakota and Nebraska

Abstract Telemetry was used to evaluate seasonal and diel movement patterns, general habitat use, survival, and spatial distributions of hatchery-reared juvenile pallid sturgeon Scaphirhynchus albus stocked in the Missouri River below Fort Randall Dam, South Dakota and Nebraska. Sampling occurred at about 2-week intervals during spring through fall. Of 22 ultrasonically tagged fish, 13 were intensively followed to assess hourly diel movement rates. A total of 258 relocations were made for the 22 tagged fish; 19 fish were relocated at least once, and 16 were relocated multiple times. At least 68% of tagged fish survived for 2.5 years. In 2000, fish were found mainly upstream of the stocking site, whereas in 2001 and 2002 the entire reach was used. Juveniles were found primarily in the main channel at depths exceeding 80% of the maximum channel cross-section depth, where bottom current velocities ranged from 0.1 to 0.9 m/s. Clusters of juvenile pallid sturgeon (i.e., two or more fish) within 750 m of each o...

Food Habits of Juvenile Pallid Sturgeon and Adult Shovelnose Sturgeon in the Missouri River Downstream of Fort Randall Dam, South Dakota

ABSTRACT We examined the seasonal food habits and diet overlap of juvenile pallid sturgeon (Scaphirhynchus albus) and adult shovelnose sturgeon (S. platorynchus) in the Missouri River downstream of Fort Randall Dam, South Dakota. Seasonal trends were found for both sturgeon species as chironomids were consumed in the greatest numbers and dry weights during early summer, ephemeropterans dominated during late summer, and trichopterans were most abundant in early spring and late fall diets. However, diet overlap between juvenile pallid sturgeon and adult shovelnose sturgeon was low based on a Schoener index value of 0.53 in 2003 and 0.21 in 2004. Juvenile pallid sturgeon consumed a greater proportion of fish in 2003 and Ephemeroptera in 2004 compared to shovelnose sturgeon. Shovelnose sturgeon consumed a greater proportion of Chironomidae in both years compared to juvenile pallid sturgeon. These results illustrate that shovelnose sturgeon is not an acceptable surrogate for the endangered pallid sturgeon based on food habits.

Evaluation of a Gastric Lavage Method on Juvenile Pallid Sturgeon

Abstract Because of the endangered status and limited knowledge of the early life history of the pallid sturgeon Scaphirhynchus albus, I tested the safety and efficiency of a nonlethal method for investigating the food habits of age-2 juvenile pallid sturgeon. Pallid sturgeon were fed a mixture of live prey items, including earthworms Lumbricus terrestris, red worms Alloloborpha calliginosa, meal worms Tenebrio molitor, and wax worms Galleria mellonella. Gastric lavage was performed on two test groups; a third group did not undergo gastric lavage but was held as a control (N = 30 fish per group). Over a 60-d test period, no mortality was observed. No significant differences were detected in relative condition and growth in length between the two lavaged groups and the control group over the 60-d test period. The efficiency of the gastric lavage procedure was tested on 29 age-2 juveniles, and food items were recovered from 100% of the fish with food in their stomachs. The average recovery rate for all food...

Length-Weight Relationships for Three Asian Carp Species in the Missouri River

ABSTRACT Bighead carp (Hypophthalmichthys nobilis), silver carp (Hypophthalmichthys molitrix), and grass carp (Ctenopharyngodon idella), collectively referred to as Asian carp, are invasive species that have been introduced into the Mississippi River basin. The expansion of Asian carp into the Missouri River is not well understood and knowledge of population characteristics within this river are lacking. The objectives of this study were to describe the length-weight relationships (condition) of Asian carp from 2003 to 2007 in the Missouri River downstream of Gavins Point Dam, South Dakota and Nebraska to St. Louis, Missouri. All total, 388 bighead, 75 silver, and 111 grass carp were measured and weighed. Short bighead weighed significantly less in the upper Missouri River from Gavins Point Dam to the Platte River compared to fish of the lower Missouri River from the Grand River to the Mississippi River. Conversely, long bighead carp in the upper Missouri River attained greater weights than fish of similar length downstream. Though not significant, condition similarly varied between the upper and lower Missouri River for silver carp and grass carp.

Comparison of Green and White Mesh Trammel Nets and Gill Nets to Assess the Fish Community in a Large River

Abstract Standardized monitoring programs in great rivers need to identify and minimize the bias in the estimates of fish population characteristics to enable fishery managers to make informed decisions. We compared the effectiveness of green and white mesh in drifted trammel and anchored gill nets in capturing fish in the Missouri River from downstream of Fort Randall Dam, South Dakota, to the mouth of the river near St. Louis, Missouri. Sampling occurred from March to November 2006 and from April to May 2007. Paired green and white trammel net drifts (N = 383) caught 28 fish species from 12 families. Pairs of anchored gill nets set overnight (N = 193) caught 24 fish species from 12 families. Chi-square tests indicated that for most species there were no significant differences in occurrence between mesh colors in both the trammel and gill nets. However, occurrence was significantly higher in white mesh nets for goldeye Hiodon alosoides and blue sucker Cycleptus elongatus in trammel nets and for river ca...