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We produced pallid sturgeon Scaphirhynchus albus embryos at five pre‐hatch developmental stages and isolated and quantified genomic DNA from four of the stages using four commercial DNA isolation kits. Genomic DNA prepared using the kit that produced the largest yields and concentrations were used for microsatellite DNA analyses of 10–20 embryos at each of the five developmental stages. We attempted to genotype the hatchery‐produced embryos at 19 microsatellite loci and confirmed reliable genotyping by comparing the microsatellite genotypes to those of known parents. Embryos at stages 5 and 8 did not produce reliable genotyping while those at stages 14, 24 and 33 did. We used the same DNA isolation method on 262 wild‐caught acipenseriform embryos collected from the lower Yellowstone River. A total of 200 of the wild embryos were successfully identified to stages 8 to 34 and the rest could not be staged. Using a combination of single nucleotide polymorphism and microsatellite markers, 249 of the wild‐caught embryos were genetically identified as paddlefish Polyodon spathula, five were identified as shovelnose sturgeon Scaphirhynchus platorynchus and eight failed to amplify. None were identified as pallid sturgeon. This study demonstrates that early‐stage wild‐spawned acipenseriform embryos can be genetically identified less than 24 h post‐spawn. This methodology will be useful for recovery efforts for endangered pallid sturgeon and can be applied to other acipenseriform species. [ABSTRACT FROM AUTHOR]

Abstract: Lake of the Ozarks, Harry S. Truman Reservoir, and Table Rock Lake in Missouri contain important recreational fisheries for trophy Paddlefish Polyodon spathula. These three reservoirs were created by damming major rivers. Because of river modifications, Paddlefish natural reproduction is thought to be limited; subsequently, populations have been maintained through supplementation and harvest regulations. However, these fisheries have not been thoroughly assessed, and the applicability of management actions (e.g., supplementation and minimum length limits) has not been fully evaluated. Population simulations indicated that changes in the amount of trophy‐sized Paddlefish and broodstock remaining were similar among the three reservoirs, with larger minimum length limits resulting in a greater proportion of mature and trophy‐sized individuals. However, the number of Paddlefish that could be harvested at Harry S. Truman Reservoir and Lake of the Ozarks was much greater than at Table Rock Lake. These disparities are likely attributable to the amount of supplementation occurring at each reservoir. Based on unmarked fish from each reservoir, the percentage of sampled fish that were considered wild suggested that natural reproduction is occurring in Lake of the Ozarks (51.5%), Harry S. Truman Reservoir (83.9%), and Table Rock Lake (13.7%). Considering the Missouri Department of Conservation's desired management goals for maintaining trophy fisheries, a minimum length limit of at least 864 mm is suggested. If supplementation, natural reproduction, and harvest regulations are inadequate, reductions in Paddlefish abundance, size structure, harvest, and popularity could occur. One motivator for anglers to participate in trophy fisheries is the opportunity to catch a rare, unique, and large fish. Declines in a trophy fishery could cause economic losses to local areas and state agencies; thus, having an adaptive management plan in place to manage trophy fisheries is imperative. [ABSTRACT FROM AUTHOR]

Recent work demonstrates that tributary inputs are important community reorganisation points for river biota; however, no studies have examined the long-term effects of tributary inputs on fish population dynamics. This study examines nearly 40 years of young-of-year (yoy) paddlefish recruitment data to investigate the hypothesis that tributaries influence mainstem fish population dynamics. We generated hydrological variables from daily mean flow data (1965–2007) from an impounded reach of the mainstem Missouri River and from the Niobrara River, a relatively unaltered tributary, using Indicators of Hydrologic Alteration software. Three multiple regression models using natural-log transformed catch per unit effort (log cpue) as the response variable were created using (1) Missouri River-only flow variables, (2) Niobrara River-only flow variables and (3) Missouri River and Niobrara River flow variables. Flow variables from the Niobrara River explain a greater proportion of yoy paddlefish log cpue variability demonstrating that tributaries can positively impact fish population dynamics in altered rivers. [ABSTRACT FROM AUTHOR]

This article presents information on malignant cartilaginous tumours. The only reported case of a malignant cartilaginous tumour from fish is that of a cranial chondrosarcoma in a paddlefish, Polyodon spathula (Walbaum), from south-central Missouri. Diagnosis of the large, focally extensive lesion was based on morphology, radiographic examination, local invasiveness, histochemical staining properties and histologic characteristics. Here, two cases of chondrosarcoma from rivulus, Rivulus marmoratus Poey, the first such neoplasm described from an atheriniform fish, are reported.

The article presents information on Polypodium hydriforme, a common parasite of acipenserids found in large rivers in Russia. In North America, Polypodium species has been found from the eggs of paddlefish Polydon spathula from the Ossage River in Missouri. During a survey conducted by the Michigan Department of Natural Resources (MDNR) in 2008, 97 lake sturgeon were captured; and the sex of only four of them could be determined.