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Summary: Historically, management of fish populations has been achieved through the use of age‐derived estimates of growth and mortality. For long‐lived species such as the paddlefish, Polyodon spathula, the validation of calcified structures is necessary to correct for the presence of false annuli or the absence of growth rings. Regardless, numerous studies on paddlefish populations throughout their range have continued the use of un‐validated age estimates to evaluate dynamic rate functions. The use of mark‐recapture studies has been applied widely to evaluate growth of short‐lived fishes, but only recently to a few long‐lived freshwater fishes (i.e. white sturgeon, shovelnose sturgeon, and pallid sturgeon). This study provides the first simultaneous evaluation of both mark‐recapture and age‐estimate information in determining population characteristics for paddlefish. In doing so, this study has determined that the P. spathula population in the Black River below Clearwater Dam, Missouri is sustainable. Additionally, mark‐recapture information is sufficient to produce accurate and reliable assessments of paddlefish populations in lieu of validated aging structures; future management should be centered on accurate scientific methods, which is not the case when using un‐validated aging structures (e.g. scales, otoliths, fin rays, dentary bones) to determine population parameters. Mark‐recapture information can provide an accurate, alternative source of growth and mortality information for use in evaluating and managing paddlefish populations throughout their range. [ABSTRACT FROM AUTHOR]

Summary: Concern over exploitation rates of the American paddlefish Polyodon spathula from sport and commercial fisheries has increased in recent decades and the Convention on International Trade of Endangered Species is now seeking information from state agencies regarding the sustainability of commercially harvested paddlefish populations. The Missouri Department of Conservation is addressing this through the implementation of a 5‐year tagging study on exploitation of paddlefish in the Mississippi River. The first 2 years of this project found that minimal exploitation of paddlefish along Missouri's eastern border was equal to 4.01% (SE = 0.02). After updating previously constructed spawning potential ratio modeling completed in 2016 with the more accurate estimates of exploitation determined in this study it becomes apparent that paddlefish populations of the Mississippi River are currently at sustainable levels. However, precautionary adjustment of regulations is advised to protect paddlefish through maturation and to counteract the possibility of increased harvest intensity resulting from increased demand of domestic caviar. [ABSTRACT FROM AUTHOR]

The Pallid Sturgeon is listed as federally endangered under the Endangered Species Act in the United States. When the species was listed in 1990 it was considered extremely rare and was poorly understood. Habitat alteration, commercial harvest, environmental contaminants, and other factors were identified as threats. Today our scientific understanding of the species and its life history requirements have increased greatly as summarized below. [ABSTRACT FROM AUTHOR]

Lake sturgeon Acipenser fulvescens are considered rare and were nearly extirpated in the Mississippi River in Missouri by 1931 as a result of overfishing and habitat fragmentation. Propagation efforts have been implemented by the Missouri Department of Conservation since 1984 as means to restore the lake sturgeon population. Although recent population increases have been observed, a formalized evaluation to determine if lake sturgeon are self-sustaining in the Missouri portion of the Mississippi River has not been completed. Therefore, the objectives of this study were to: (i) determine the proportion of reproductive individuals, (ii) evaluate seasonal movement patterns of adults, and (iii) validate purported spawning locations within the Mississippi River in Missouri. Lake sturgeon catch data indicated that approximately 11 percent of the population are reproductively mature. Additionally, telemetry data confirms that the greatest movement by adult lake sturgeon occurs during spring, which suggests spawning behavior. Finally, it was possible to document lake sturgeon embryos and emergent fry larvae below Melvin Price Locks and Dam 26 in the Upper Mississippi River near St. Louis, Missouri. Water velocity, depth, and substrate size were measured at this location and embryos were collected and hatched in the laboratory. River gage data suggest that spawning behavior may have been elicited by a large influx of water during a drawdown period of water above the dam. This study represents the first documented spawning of A. fulvescens in the Mississippi River and highlights the success of recovery efforts in Missouri. [ABSTRACT FROM AUTHOR]

The diet composition was quantified of year-0 Scaphirhynchus sturgeons during sampling years (2004-2008) from the Middle Mississippi River to evaluate trends in diet. River stage height varied among years and seasons. Water temperature differed among seasons but did not differ among years. The presence of empty stomachs was evident across years, seasons, and size classes of sturgeon. The overall Multivariate Analysis of Variance for frequency of occurrence was significant, suggesting that macroinvertebrate taxa (e.g. Ephemeroptera, Diptera pupae, Chironomidae, ' Other') differed among size classes of sturgeon, but not seasons or years. Furthermore, Tukey's pairwise comparisons indicated Ephemeroptera frequency of occurrence differed between medium and large size classes; Diptera pupae differed between small and medium size classes and small and large size classes; Chironomidae differed between small and large size classes and medium and large size classes; the macroinvertebrate taxa category ' Other' differed between small and large size classes. Ultimately, because of the link between diet and growth of year-0 Scaphirhynchus sturgeon, the early life history may affect eventual recruitment to adult stages. [ABSTRACT FROM AUTHOR]