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Dams commonly restrict fish movements in large rivers but can also help curtail the spread of invasive species, such as invasive bigheaded carps (Hypophthalmichthys spp). To determine how dams in the upper Mississippi River (UMR) affect large-scale invasive and native fish migrations, we tracked American paddlefish (Polyodon spathula) and bigheaded carp across > 600 river km (rkm) and 16 navigation locks and dams (LD) of the UMR during 2 years with contrasting water levels. In 2022, a low-water year, both native paddlefish and invasive bigheaded carp had low passage rates (4% and 0.6% respectively) through LD15, a movement bottleneck being studied for invasive carp control. In contrast, flooding in 2023 led to open-river conditions across multiple dams simultaneously, allowing 53% of paddlefish and 46% of bigheaded carp detected in Pool 16 to move upstream through LD15. Bigheaded carp passed upstream through LD15 rapidly (μ = 32 rkm per day) a maximum of 381 rkm, whereas paddlefish moved an average of 9 upstream rkm per day (maximum of 337 rkm). Our results can inform managers examining trade-offs between actions that enhance native fish passage or deter movements of invasive species. This understanding is critical because current climate change models project increases in flooding events like that observed during 2023. [ABSTRACT FROM AUTHOR]

Abstract Dams commonly restrict fish movements in large rivers but can also help curtail the spread of invasive species, such as invasive bigheaded carps (Hypophthalmichthys spp). To determine how dams in the upper Mississippi River (UMR) affect large-scale invasive and native fish migrations, we tracked American paddlefish (Polyodon spathula) and bigheaded carp across > 600 river km (rkm) and 16 navigation locks and dams (LD) of the UMR during 2 years with contrasting water levels. In 2022, a low-water year, both native paddlefish and invasive bigheaded carp had low passage rates (4% and 0.6% respectively) through LD15, a movement bottleneck being studied for invasive carp control. In contrast, flooding in 2023 led to open-river conditions across multiple dams simultaneously, allowing 53% of paddlefish and 46% of bigheaded carp detected in Pool 16 to move upstream through LD15. Bigheaded carp passed upstream through LD15 rapidly (μ = 32 rkm per day) a maximum of 381 rkm, whereas paddlefish moved an average of 9 upstream rkm per day (maximum of 337 rkm). Our results can inform managers examining trade-offs between actions that enhance native fish passage or deter movements of invasive species. This understanding is critical because current climate change models project increases in flooding events like that observed during 2023.

In electroreceptive jawed vertebrates, embryonic lateral line placodes give rise to electrosensory ampullary organs as well as mechanosensory neuromasts. Previous reports of shared gene expression suggest that conserved mechanisms underlie electroreceptor and mechanosensory hair cell development and that electroreceptors evolved as a transcriptionally related "sister cell type" to hair cells. We previously identified only one transcription factor gene, Neurod4, as ampullary organ-restricted in the developing lateral line system of a chondrostean ray-finned fish, the Mississippi paddlefish (Polyodon spathula). The other 16 transcription factor genes we previously validated in paddlefish were expressed in both ampullary organs and neuromasts. Here, we used our published lateral line organ-enriched gene-set (arising from differential bulk RNA-seq in late-larval paddlefish), together with a candidate gene approach, to identify 25 transcription factor genes expressed in the developing lateral line system of a more experimentally tractable chondrostean, the sterlet (Acipenser ruthenus, a small sturgeon), and/or that of paddlefish. Thirteen are expressed in both ampullary organs and neuromasts, consistent with conservation of molecular mechanisms. Seven are electrosensory-restricted on the head (Irx5, Irx3, Insm1, Sp5, Satb2, Mafa and Rorc), and five are the first-reported mechanosensoryrestricted transcription factor genes (Foxg1, Sox8, Isl1, Hmx2 and Rorb). However, as previously reported, Sox8 is expressed in ampullary organs as well as neuromasts in a catshark (Scyliorhinus canicula), suggesting the existence of lineage-specific differences between cartilaginous and ray-finned fishes. Overall, our results support the hypothesis that ampullary organs and neuromasts develop via largely conserved transcriptional mechanisms, and identify multiple transcription factors potentially involved in the formation of electrosensory versus mechanosensory lateral line organs. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effect of light intensity on the growth performance, hematological profile, and biochemical composition of muscle tissue of paddlefish juveniles, reared in a recirculating aquaculture system (RAS). Two experimental variants were created: V1- where the rearing units have green color, and the average of the light intensity was 105 lx (mean fish weight was 21.65 ± 0.6 g), and V2- where the rearing units have white color, and the average of the light intensity was 30 lx (mean fish weight was 22.15 ± 0.8 g). Fish were fed at an intensity of 2.5% BW for 48 days. Growth of juvenile paddlefish under 30 lx was significantly better than that of paddlefish under 105 lx (p < 0.05), as indicated by final weight (1158.20 ± 21.90 g), specific growth rate (2.18% ± 0.07%/day) and feed conversion coefficient (0.80 ± 0.28 g/g). In conclusion, the paddlefish juveniles can adapt to various light intensities and grow favorably under low light conditions in a recirculating aquaculture system. [ABSTRACT FROM AUTHOR]

Objective: Movement of fish past dams can be facilitated by dedicated fish passage structures, navigational locks, and crested spillways, with the efficacy of a passage structure depending strongly on the nature of the system (height of the dam, flow rate, etc.) and the fish's behavior and swimming capability. However, once the fish have passed a dam, whether by using a mitigation structure or due to active translocation, they encounter a different habitat upstream versus in the tailrace, potentially affecting their ability to continue their upstream migration. Methods: Here, we had two objectives. First, we determined whether Paddlefish Polyodon spathula that successfully passed a structure continued their upstream migration in the Alabama River. Because assuring passage by tagged fish required that we move the fish past the dam, our second objective was to determine whether translocated fish exhibited fallback behavior (downstream drift or movement postrelease that would compromise their continued migration). We used both active and passive telemetry methods to quantify the postpassage movements of tagged and translocated Paddlefish. Result: Fish that were translocated above Claiborne Lock and Dam (CLD) exhibited upriver movements once translocated, and they exhibited no fallback (i.e., downstream movement with delayed or no continuation upstream). Timing of movement relative to spawning periods did not influence initial fish movement or the likelihood of reaching the next upstream dam (Millers Ferry Lock and Dam [MFLD]; ~100 river kilometers upstream) within the first 30 days of observation, but more fish that were tagged and released during the early prespawn period made it to within 4.83 km of MFLD (the location of our closest receiver below MFLD) relative to fish from the prespawn or spawning period. Fish that were released above CLD had a lower probability of being subsequently detected downstream of their release sites compared to fish that were released below CLD. Conclusion: Our findings support that Paddlefish will continue their upstream migration once they have passed a structure, despite changes in habitat. Impact statementDams represent barriers to fish movement in rivers, but the question remains whether fish will continue an upstream migration once they pass a dam given that the upstream habitat differs from the habitat below the dam. We tracked tagged fish that were moved from downstream to upstream of a lock‐and‐dam structure and found that they did continue their upstream migration. [ABSTRACT FROM AUTHOR]

In electroreceptive jawed vertebrates, embryonic lateral line placodes give rise to electrosensory ampullary organs as well as mechanosensory neuromasts. Previous reports of shared gene expression suggest that conserved mechanisms underlie electroreceptor and mechanosensory hair cell development and that electroreceptors evolved as a transcriptionally related “sister cell type” to hair cells. We previously identified only one transcription factor gene, Neurod4, as ampullary organ-restricted in the developing lateral line system of a chondrostean ray-finned fish, the Mississippi paddlefish (Polyodon spathula). The other 16 transcription factor genes we previously validated in paddlefish were expressed in both ampullary organs and neuromasts. Here, we used our published lateral line organ-enriched gene-set (arising from differential bulk RNA-seq in late-larval paddlefish), together with a candidate gene approach, to identify 25 transcription factor genes expressed in the developing lateral line system of a more experimentally tractable chondrostean, the sterlet (Acipenser ruthenus, a small sturgeon), and/or that of paddlefish. Thirteen are expressed in both ampullary organs and neuromasts, consistent with conservation of molecular mechanisms. Seven are electrosensory-restricted on the head (Irx5, Irx3, Insm1, Sp5, Satb2, Mafa and Rorc), and five are the first-reported mechanosensory-restricted transcription factor genes (Foxg1, Sox8, Isl1, Hmx2 and Rorb). However, as previously reported, Sox8 is expressed in ampullary organs as well as neuromasts in a catshark (Scyliorhinus canicula), suggesting the existence of lineage-specific differences between cartilaginous and ray-finned fishes. Overall, our results support the hypothesis that ampullary organs and neuromasts develop via largely conserved transcriptional mechanisms, and identify multiple transcription factors potentially involved in the formation of electrosensory versus mechanosensory lateral line organs.

Interspecific hybridizations among sturgeon species are feasible and often bidirectional. The American paddlefish (Polyodon spathula) from Family Polyodontidae and sturgeon species from Family Acipenseridae were reported capable of hybridization, but viable hybrids have been described only in crosses with the American paddlefish as paternal parents. In the reciprocal cross, the hybrids were not viable however embryos start to develop and reach late gastrula and early neurula stages. The goal of this study was to examine the hybridization between the sterlet sturgeon (Acipenser ruthenus) and the American paddlefish. Hybrid and purebred crosses were produced by artificial fertilization. Viable hybrid offspring were harvested (three month old) and verified in the families produced by female sterlet crossing with male American paddlefish. In the reciprocal hybrid crosses with female American paddlefish and male sterlet, the embryos development did not pass over 120 h post fertilization, indicating the unidirectional hybridization between American paddlefish and sterlet. Chromosome counting showed for the same ploidy level of viable hybrid and parent species. Analysis of three microsatellite markers confirmed the unidirectional hybridization between the American paddlefish and the sterlet species. Overall, the inferred genetic cause suggests that unidirectional hybridization between American paddlefish and sterlet may be the case not only for these two species but likely also between American paddlefish and other sturgeon species.

Objective: We used two approaches, fish hard‐part microchemistry and genetics, to quantify effects of low‐use lock‐and‐dam structures on riverine fish movement. Each approach varied in temporal scope, with microchemistry addressing effects within a lifetime and genetics addressing effects across generations. Methods: Water samples and individuals of two species (Paddlefish Polyodon spathula and Smallmouth Buffalo Ictiobus bubalus) were collected from four river sections that were separated by three low‐use lock‐and‐dam structures on the Alabama River. Quarterly water samples were collected from 15 sites during 2017–2018, and concentrations of Sr, Ba, Mn, Mg, and Ca were quantified using mass spectrometry. Result: Water elemental signatures were spatially variable but temporally consistent. The Sr:Ca ratios in fish hard parts differed significantly among river sections for both species. Additionally, discriminant function analyses classified fish to their river capture section with accuracy between 55% and 74% for Paddlefish (errors nearly always assigned individuals to adjacent river sections) and 37–47% for Smallmouth Buffalo. Population genetic analyses included fish from each river section, as well as from Alabama River tributaries and a neighboring watershed. Genotyping‐by‐sequence techniques identified 1,889 and 3,737 single nucleotide polymorphisms postfiltering in Paddlefish and Smallmouth Buffalo, respectively, which we used to estimate population diversity indices and conduct differentiation analyses. Analysis of molecular variance, discriminant analysis of principal components, Bayesian clustering, and pairwise comparisons of FST values indicated no strong evidence for genetic divergence in either species among river sections. Conclusion: Within‐lifespan results based on hard‐part microchemistry suggested a potential for population isolation. However, longer‐term genetic effects were not apparent, possibly because the life span of these large and relatively long‐lived species means that few generations have passed since dam construction, and there could be sufficient mixing or population connectivity to prevent genetic divergence across river sections, particularly at the most downstream structure. Impact StatementPaddlefish and Smallmouth Buffalo showed evidence of population separation by Alabama River lock‐and‐dams via a within‐generation measure (chemical composition of fish jaw bones and ear stones) but not with a longer‐term metric (genetic isolation). Both species are long lived relative to the age of the dams; effects may be more apparent in shorter‐lived species. [ABSTRACT FROM AUTHOR]

Purpose. To investigate the peculiarities of growth of age-1+ paddlefish depending on water temperature and quantitative parameters of zooplankton development in ponds of the forest-steppe zone of Ukraine. Methodology. Age-1+ paddlefish, a North American zooplanktophagus were reared in polyculture with cyprinids in a 72-hectare pond using semi-intensive technology. The stocking density of age-1 paddlefish with an average weight of 86.5 g was 59 fish/ha, with a total stocking density of 2,402 fish/ha for all objects of polyculture. The intensification measures included fertilization of ponds with traditional organic fertilizers and feeding of carp with feed mixtures based on waste from the processing of agricultural raw materials of plant origin. The study of the intensity of development of the natural food supply and physicochemical parameters of water was carried out according to the methods generally accepted in hydrobiology and hydrochemistry. Determination of piscicultural parameters and growth characteristics of age-1+ paddlefish was carried out using methods common in ichthyology based on the dynamics of body weight gains in absolute and relative values. Findings. The conditions of the pond environment during most of the period of rearing of age-1+ paddlefish met the biological requirements of this species. A periodic decrease in the content of oxygen dissolved in water to 3.3-3.5 mgO2/dm3 was noted, which could negatively affect the growth of fish. Water temperature during the fish breeding period varied between 9.8-26.5oC. The average seasonal biomass of phytoplankton and zooplankton of the pond was 16.49 mg/dm3 and 3.92 g/m3, respectively, with a predominance of Cladocera and Copepoda (respectively, 61.0 and 34.5% in the average seasonal biomass) in the quantitative composition of zooplankton. As a result, age-1+ paddlefish reached an average weight of 1318.3 g with a fish productivity of 45.6 kg/ha and a total pond fish productivity of 1162.6 kg/ha. Maximum relative weight gains of paddlefish of 4.25–4.37% per day were observed during the first half of the growing season (mainly in June) at a water temperature of 22–25oC during the period of increase in zooplankton biomass from 3.79 to 10.11 g/m3. Originality. New data were obtained on the growth characteristics of paddlefish depending on environmental conditions of the ponds of the Forest-Steppe zone of Ukraine. Practical value. The study results can be used in the process of improving pond aquaculture technologies in Ukraine.

• Main changes to the manuscript were the restructuring of the model description sections, particularly the descriptions of the study system/population and rearranging the submodel information. • We switched the order of Figures 3 and 4, and removed Figure 5 and the associated experiment. • Otherwise, we have thoroughly checked the manuscript for clarity on the terminology we used pertaining to "metapopulations" and "connectivity", as requested by the reviewer. The persistence of fish population segments that are isolated by dams may be directly related to passage rates (both upstream and downstream) across the dams that isolate them. In anticipation of proposed bypass structures at two dams currently fragmenting the Alabama River, we programmed an individual-based model (Alabama River Paddlefish Passage Model; ARPPAM) to simulate the effects of increasing connectivity between population segments of a migratory fish species on the likelihood of segment extirpation within 100 years. We designed six different realistic passage efficiency scenarios to account for uncertainty in the ultimate efficacy of the bypass structures, and to test the effect of increasing segment connectivity (fish passage) on the overall metapopulation. We used the Paddlefish Polyodon spathula as our model species and programmed detailed life history information and movement dynamics according to measured quantities (although several demographic and movement rates for the metapopulation were uncertain or unknown). We used a simulation to see how a range of values would affect our inference about the influence of increased connectivity. Higher juvenile entrainment probability and associated mortality increased the probability of segment extirpation. These effects were lessened by increasing segment connectivity. Our model has broad applicability and provides a flexible framework to test a variety of hypotheses about metapopulation dynamics of potamodromous species in fragmented systems globally. Furthermore, fish passage facilities are costly, so modeling population consequences at early stages of development can save money and help formulate criteria for their design. [ABSTRACT FROM AUTHOR]

Movement and dispersal of migratory fish species is an important life-history character-istics that can be impeded by navigation dams. Although habitat fragmentation may be detrimental to native fish species, it might act as an effective and economical barrier for controlling the spread of invasive species in riverine systems. Various technologies have been proposed as potential fish deterrents at locks and dams to reduce bigheaded carp (i.e., silver carp and bighead carp (Hypophthalmichthys spp.)) range expansion in the Upper Mississippi River (UMR). Lock and Dam (LD) 15 is infrequently at open-river condition (spillway gates completely open; hydraulic head across the dam <0.4 m) and has been identified as a potential location for fish deterrent implementation. We used acoustic telemetry to evaluate paddlefish passage at UMR dams and to evaluate seasonal and diel movement of paddlefish and bigheaded carp relative to environmental conditions and lock operations at LD 15. We observed successful paddlefish passage at all dams, with the highest number of passages occurring at LDs 17 and 16. Paddlefish residency events in the downstream lock approach of LD 15 occurred more frequently and for longer durations than residency events of bigheaded carp. We documented upstream passages completed by two individual paddlefish through the lock chamber at LD 15, and a single bighead carp completed upstream passage through the lock chamber during two separate years of this study. We identified four bigheaded carp and 19 paddlefish that made upstream passages through the spillway gates at LD 15 during this study. The majority of the upstream passages through the spillway gates for both species occurred during open river conditions. When hydraulic head was approximately 1-m or greater, we observed these taxa opt for upstream passage through the lock chamber more often than the dam gates. In years with infrequent open-river condition, a deterrent placed in the downstream lock approach may assist in meeting the management goal of reducing upstream passage of bigheaded carps but could also potentially affect paddlefish residency and passage. Continued study to understand the effects of deterrents on native fish could be beneficial for implementing an integrated bigheaded carp control strategy. Understanding fish behavior at UMR dams is a critical information need for river managers as they evaluate potential tools or technologies to control upstream expansion of bigheaded carp in the UMR. [ABSTRACT FROM AUTHOR]

Movement and dispersal of migratory fish species is an important life-history characteristics that can be impeded by navigation dams. Although habitat fragmentation may be detrimental to native fish species, it might act as an effective and economical barrier for controlling the spread of invasive species in riverine systems. Various technologies have been proposed as potential fish deterrents at locks and dams to reduce bigheaded carp (i.e., silver carp and bighead carp (Hypophthalmichthys spp.)) range expansion in the Upper Mississippi River (UMR). Lock and Dam (LD) 15 is infrequently at open-river condition (spillway gates completely open; hydraulic head across the dam

Purpose. To investigate peculiarities of feeding of paddlefish during the second year of life in polyculture with carp fish in ponds of Ukrainian Polissia. Methodology. A North American zooplanktophage belonging to sturgeons, the paddlefish was reared in polyculture with carp, hybrids of silver and bighead carps, as well as grass carp in pond with areas of 1 hectare on natural food supply. Development of the natural food supply was stimulated by applying cattle manure into ponds at an amount of 1 ton/ha. The stocking density of age‒1 paddlefish with an average weight of 143 g was 150 ind./ha, The total stocking density of all polyculture objects was 520 ind./ha. The determination of the nutritional and growth characteristics of fish, the qualitative composition of forage aquatic organisms and their biomass was carried out using well‒known methods. The main physicochemical parameters of water quality were investigated during fish rearing using generally accepted recommendations in fish farming and hydrochemistry. Findings. The environmental conditions of the pond mainly met the biological requirements for the studied aquaculture objects. A periodic decrease in dissolved oxygen concentration to 1.5‒2.0 mgO2/dm3 was observed, which could slow down fish growth. During sampling to determine the feeding habits of paddlefish, the zooplankton biomass in the pond varied within 1.11‒6.44 g/m3, with the predominance of Cladocera and Copepoda. At the end of the study period, age‒1+ paddlefish reached an average weight of 979.0 g with a fish production of 120.4 kg/ha and a survival rate of 82.0%. The total fish production for all polyculture objects was 502.3 kg/ha. The average digestive tract fullness index of paddlefish varied within 199.72‒459.0030/000. The diet of paddlefish was dominated by lower crustaceans with a predominance of Cladocera (65.28‒86.23%). The role of Copepoda in paddlefish nutrition increased at the end of the culture season (up to 32.76%). Rotifera and other forage aquatic organisms did not have a significant value in the paddlefish diet (up to 3.85%). A significant amount of detritus swallowed by fish was observed (13.43‒31.31% of the digestive tract content). A selectivity in the consumption of paddlefish of various groups of zooplankton organisms was noted with the selectivity index for Cladocera at the level of 1.23‒1.48. Originality. New data were obtained on the feeding habits of paddlefish in Ukrainian Polissia. Practical value. The study results are an integral part of the database for the development of improved technologies for pond fish farming in Ukraine.

Purpose. Assessing the results of winter keeping of paddlefish young-of-the-year in ponds of the Forest-steppe and Polesye of Ukraine. Methodology. The study was carried out using 0.05-1.0 ha ponds intended for winter keeping of carps. The stocking density of paddlefish young-of-the-year with an average weight of 94.2-147.2 g in wintering ponds was 4.10-16.63 thousand fish/ha. The study of the physicochemical parameters of the aquatic environment was carried out according to the methods generally accepted in hydrochemistry and fish farming. The main piscicultural-biological parameters during the wintering period of fish were assessed using methods commonly used in ichthyology and fish farming according to the level of survival and body weight loss of paddlefish. Findings. The environmental conditions in the ponds during most of the wintering period of fish met the biological requirements of the studied object of cultivation. The water temperature varied within 0.9-6.50C. The dissolved oxygen content in water did not fall below 3.6-3.8 mgO2/dm3 and was mainly at the level of 3.9-7.9 3.9-7.2 mgO2/dm3. Other hydrochemical parameters were within acceptable values ​​for wintering fish in pond conditions. As a result, the survival rate of paddlefish young-of-the-year during the wintering period was 81.5-89.7%. The body weight loss of fish during the winter keeping was on average in the range of 6.41-8.17%. A conclusion was made on the need to conduct additional studies of physiological and biochemical parameters of paddlefish during the wintering period. Originality. New data were obtained on the peculiarities of wintering of paddlefish seeds in ponds of the Forest-steppe and Polesye of Ukraine. Practical value. The study results are part of the database for the development of improved technologies for sturgeon breeding in Ukraine.

Purpose. To investigate the growth characteristics and determine the productivity of paddlefish grown to marketable weight in ponds of the Forest-steppe and Polesia of Ukraine. Methodology. The cultivation of the North American zooplanktophage, a representative of sturgeons, the paddlefish, was carried out in polyculture with cyprinids in ponds with areas ranging from 0.2 to 74.0 ha with the use of semi-intensive and extensive technologies. The stocking density of age-1-2 paddlefish with an average weight of 86.5 to 1017.0 g varied within 59-150 ind./ha with a total stocking density for all polyculture objects of 515-2402 ind./ha. Intensification measures included application of traditional organic fertilizers into ponds and feeding of carp with feed mixtures based on wastes from the processing of agricultural raw materials of vegetable origin in some ponds. Studies of the intensity of development of the natural food supply of ponds and physicochemical parameters of the aquatic environment were carried out according to the methods generally accepted in hydrobiology and hydrochemistry. The peculiarities of fish growth were studied with the use of common ichthyological methods for the dynamics of body weight gains in absolute and relative values. Findings. The environmental conditions in ponds during most of the growing period met the biological requirements of the studied aquaculture objects. A periodic decrease in the oxygen concentration in water to 1.5-2.2 mg O2/dm3 was noted, which could have a negative effect on fish growth. The average seasonal biomass of zooplankon in ponds was in the range of 3.8-5.8 g/m3 with predominance of Cladocera and Copepoda. As a result, paddlefish production was 48.8-256.4 kg/ha in total fish production in ponds ranging from 502.3 to 1249.0 kg/ha. Average seasonal weight gain of paddlefish, depending on growing conditions, was 0.84-1.49 kg. The maximum daily increments of this species were observed during the first half of the growing period at a water temperature of 18-25°C, when zooplankton biomass in ponds varied within 3.7-17.4 g/m3. Originality. New data have been obtained on the peculiarities of paddlefish growth in the conditions of ponds of the Forest-steppe and Polesia of Ukraine. Practical value. The study results are an integral part of the database for the development of improved sturgeon breeding technologies in Ukraine.

Polyodon spathula is a valuable species of sturgeon native to North America that has acclimatized very well in Europe. Detailed knowledge of the quantitative and qualitative productive performance of paddlefish meat is of interest. Through this article, we aimed to highlight the chemical composition, cholesterol, and collagen content of fillets issued from paddlefish aged two and three summers and to highlight, as well as the nutritional value, the profile of fatty acids and amino acids, the sanogenic indices and the biological value of proteins for the epaxial and hypaxial muscle groups. The chemical analysis of the fillets by age indicated slightly higher values in summer three, compared to summer two: +5.32% dry matter, +0.89% protein, +41.21% fat, therefore +10.94% gross energy and for collagen by 2.94%; instead, for water, minerals and the W/P ratio the values were lower by 1.52%, 10.08%, and 2.29%. The nutritional assessment revealed that paddlefish has a meat with high PUFA content (approx. 22% of total fatty acids) and good values of sanogenic indices (Polyunsaturation Index = 7.01–8.77; Atherogenic Index = 0.57; Thrombogenic Index = 0.38–0.39; Hypocholesterolemic Fatty Acids = 33.01–41.34; Hypocholesteromic/Hypercolesteromic Fatty Acids ratio = 1.9). Also, the proteins of these fish are of good quality for young and adult consumers (EAA index = 156.11; Biological Value = 158.46; Nutritional Index (%) = 28.30) and good enough for children (Essential Amino Acids Index = 96.41; Biological Value = 93.39; Nutritional Index (%) = 17.45).

In derived bony vertebrates, activation of the melanocortin-2 receptor (Mc2r) by its ACTH ligand requires chaperoning by the Mc2r accessory protein (Mrap1). The N-terminal domain of the non-mammalian tetrapod MRAP1 from chicken (c; Gallus gallus) has the putative activation motif, W18D19Y20I21, and the N-terminal domain in the neopterygian ray-finned fish Mrap1 from bowfin (bf; Amia calva) has the putative activation motif, Y18D19Y20I21. The current study used an alanine-substitution paradigm to test the hypothesis that only the Y20 position in the Mrap1 ortholog of these non-mammalian vertebrates is required for activation of the respective Mc2r ortholog. Instead, we found that for cMRAP1, single alanine-substitution resulted in a gradient of inhibition of activation (Y20 >> D19 = W18 > I21). For bfMrap1, single alanine-substitution also resulted in a gradient of inhibition of activation (Y20 >> D19 > I21 > Y18). This study also included an analysis of Mc2r activation in an older lineage of ray-finned fish, the paddlefish (p), Polyodon spathula (subclass Chondronstei). Currently no mrap1 gene has been found in the paddlefish genome. When pmc2r was expressed alone in our CHO cell/cAMP reporter gene assay, no activation was observed following stimulation with ACTH. However, when pmc2r was co-expressed with either cmrap1 or bfmrap1 robust dose response curves were generated. These results indicate that the formation of an Mc2r/Mrap1 heterodimer emerged early in the radiation of the bony vertebrates.

The abilities of the long-acting, dual-agonist anti-diabetic peptides [D-Ala2]palmitoyllamprey GLP-1 and [D-Ser²]palmitoyl-paddlefish glucagon to induce α-cell to β-cell transdifferentiation were investigated in GluCreERT2;ROSA26-eYFP mice. These animals have been genetically engineered so that yellow fluorescent protein is specifically expressed in glucagon-producing α-cells, thereby allowing cell lineage tracing. Insulin deficiency was produced by treatment of the mice with multiple low doses of streptozotocin. Administration of the peptides (twice daily intraperitoneal injections of 25 nmol/kg body weight over 10 days) to streptozotocin-treated mice produced significant (P < 0.05) increases in pancreatic insulin content and plasma insulin concentrations compared with control mice. Immunohistochemical studies demonstrated a significant (P < 0.05) increase in the % of cells staining for both insulin and fluorescent protein in islets located in the head region of the pancreas (from 10.0 ± 1.3% of total cells in untreated mice to 20.0 ± 3.85% in mice treated with D-Ala2]palmitoyllamprey GLP-1 and to 17.3 ± 1.1% in mice treated with [D-Ser2]palmitoyl-paddlefish glucagon). Corresponding effects upon islets in the tail region were not significant. The data indicate an improvement in β-cell mass and positive effects on transdifferentiation of glucagon-producing to insulin-producing cells. The study provides further evidence that proglucagon-derived peptides from phylogenetical ancient fish show therapeutic potential for treatment of diabetes. [ABSTRACT FROM AUTHOR]

In the wild, overfishing, habitat loss, industrial and agriculture activity has led to the degradation of freshwater habitats and, therefore, dramatically declines the Mississippi paddlefish (Polyodon spathula) stocks (Stone 2007). Paddlefish gain a growing commercial interest in the USSR/Russian Federation due to its ability to produce high-quality caviar. Also, it can be reared in polyculture ponds and a wide range of temperate reservoirs. Therefore, aquaculture of these valuable fish is necessary to meet consumer demand in Eastern European markets with flesh and caviar. Published information about the culture of paddlefish in the USSR/Russian Federation is scarce and not permanently available. Regarding our study, data were collected from English reports and translated Russian official statistics and studies. Also, FAO fisheries data from 1880 up to 2010 for paddle sh were included. Moreover, caviar production data and prices were surveyed from companies. The collected data could briefly represent the historical and current status of paddlefish aquaculture and provide insight into the expected future production in the Russian Federation. Besides, it investigates the drawbacks of paddlefish aquaculture development and the potential challenges in Russian territories. Also, it discusses potential impacts related to the preservation of the breeding stocks, population naturalization and invasiveness of the species in the southern parts of Russia (i.e., in the Volga-Caspian basin): Saratov, Rostov, Astrakhan Oblast and Krasnodar regions. Furthermore, this review aimed to gather the available data and the latest final findings that may address the welfare of paddlefish data to fill the knowledge gap towards improving the management of this species. In addition, future development prospects can be supported by government oversight through accurate accounting and financing for private farm activity. [ABSTRACT FROM AUTHOR]

Sturgeons and paddlefishes (Acipenseriformes) occupy the basal position of ray-finned fishes, although they have cartilaginous skeletons as in Chondrichthyes. This evolutionary status and their morphological specializations make them a research focus, but their complex genomes (polyploidy and the presence of microchromosomes) bring obstacles and challenges to molecular studies. Here, we generated the first high-quality genome assembly of the American paddlefish (Polyodon spathula) at a chromosome level. Comparative genomic analyses revealed a recent species-specific whole-genome duplication event, and extensive chromosomal changes, including head-to-head fusions of pairs of intact, large ancestral chromosomes within the paddlefish. We also provide an overview of the paddlefish SCPP (secretory calcium-binding phosphoprotein) repertoire that is responsible for tissue mineralization, demonstrating that the earliest flourishing of SCPP members occurred at least before the split between Acipenseriformes and teleosts. In summary, this genome assembly provides a genetic resource for understanding chromosomal evolution in polyploid nonteleost fishes and bone mineralization in early vertebrates. [ABSTRACT FROM AUTHOR]

Interspecific hybridizations among sturgeon species are feasible and often bidirectional. The American paddlefish ( Polyodon spathula ) from Family Polyodontidae and sturgeon species from Family Acipenseridae were reported capable of hybridization, but viable hybrids have been described only in crosses with the American paddlefish as paternal parents. In the reciprocal cross, the hybrids were not viable however embryos start to develop and reach late gastrula and early neurula stages. The goal of this study was to examine the hybridization between the sterlet sturgeon ( Acipenser ruthenus ) and the American paddlefish. Hybrid and purebred crosses were produced by artificial fertilization. Viable hybrid offspring were harvested (three month old) and verified in the families produced by female sterlet crossing with male American paddlefish. In the reciprocal hybrid crosses with female American paddlefish and male sterlet, the embryos development did not pass over 120 h post fertilization, indicating the unidirectional hybridization between American paddlefish and sterlet. Chromosome counting showed for the same ploidy level of viable hybrid and parent species. Analysis of three microsatellite markers confirmed the unidirectional hybridization between the American paddlefish and the sterlet species. Overall, the inferred genetic cause suggests that unidirectional hybridization between American paddlefish and sterlet may be the case not only for these two species but likely also between American paddlefish and other sturgeon species., Competing Interests: The authors declare there are no competing interests., (©2024 Káldy et al.)

Purpose. To determine the effects of specific elements of biotechnologies used for rearing sterlet and paddlefish seeds for the optimization of rearing technology and their rational use in pond fish facilities of Southern Ukraine. Methodology. Rearing of young-of-the-year sterlet and paddlefish was conducted in experimental ponds (2 ha and 3 ha). In order to develop appropriate natural food supply, we added mineral and organic fertilizers (5 tons/ha). Rearing of YOY sterlet was conducted with different stocking densities (65000 and 95000 fish/ha), the control variant had 100000 fish/ha. Rearing of YOY paddlefish was conducted with a stocking density of 500 and 1500 fish/ha. Mean individual body weight while stocking experimental ponds was 69–75 mg (sterlet) and 600–700 mg (paddlefish). Findings. Results of rearing were analyzed and fishery performance of sterlet (Acipenser ruthenus L.) and paddlefish (Polyodon spathula (Walbaum)) reared according to the combined technology were analyzed. We examined pond food supply composition (phytoplankton, zooplankton, zoobenthos), growth and nutrition of YOY sterlet and paddlefish. It was found that a stocking density of 79000 fish/ha and abundant food supply for YOY sterlet can result in mean individual body weight of 3.60–4.40 g, survival rate –– 70.32– 82.78%, fish productivity –– 238.09 kg/ha. Stocking ponds with paddlefish with individual body weight of 600–700 mg and stocking density of 500-1500 fish/ha resulted in obtaining young-of-the-year with mean individual body weight of 278.0-409.8 g, survival rate –– 25.4–31.2%. Scientific novelty. Our experiment allowed better understanding of the correlation between stocking density and results of the rearing of sterlet and paddlefish seeds. We found a clear correlation between mean individual body weight, stocking density and duration of rearing for YOY sterlet. We found an effect for some biotechnological aspects on biochemical indicators of YOY sterlet. Practical value. The obtained data enriches and refines existing representation of the correlation between technological factors and efficiency of rearing viable sterlet and paddlefish seeds in the conditions of southern Ukraine and contributes to finding optimal parameters of rearing in terms of modern aquaculture.

Purpose. To investigate the peculiarities of heavy metal (Fe, Zn, Mn, Cu, Ni, Co, Pb, Cd) accumulation in organs and tissues of the North American paddlefish Polyodon spathula (Walbaum) introduced into inland water bodies of Ukraine. Methodology. The objects of the study were age-4-7 paddlefish reared in ponds of the forest-steppe and forest area of Ukraine. Age-3 carp as well as hybrids between the bighead and silver carps reared in polyculture with experimental groups of the paddlefish were used for comparative evaluation of the peculiarities of heavy metal accumulation in fish muscular tissues. The studies of the heavy metal content in pond water, fish organs and tissues were performed with the use of generally accepted toxicological methods. The quantitative contents of heavy metals were determined with the aid of the atomic-absorption spectrophotometer C-115-M1. Findings. The toxicological state of the experimental ponds was characterized by elevated values of the contents of Mn (by 8.5-8.9 times), Cu (by 2.1-3.9 times) and Pb (by 1.5-1.80 in water. The concentration of other heavy metals in water did not exceed the allowed values. Similar patterns were found regarding the heavy metal distribution and accumulation in paddlefish organs and tissues as for carps. No maximum allowable concentrations of heavy metals were detected in the muscular tissues of the paddlefish. Among all studied fish reared in polyculture, the paddlefish had the lowest content of Cu, Co, Pb and Cd in muscles. The mean heavy metal contents in paddlefish muscles in the studied ponds of forest-steppe and forest area were: Fe (4.64-29.60), Zn (1.20-5.54), Mn (0.10-0.23), Cu (0.09-0.44), Ni (0.28-2.15), Co (0.10-0.13), Pb (0.63-0.94), Cd (0.031-0.037). Originality. The peculiarities of the distribution and accumulation of heavy metals in organ and tissues of the North American paddlefish reared in the conditions of pond farms of Ukraine have been studied for the first time. Practical value. The study results is an essential component of the material for the creation of a database for the determination of product quality of domestic sturgeon culture, in particular regarding the peculiarities of heavy metal accumulation in fish.

This study reports the first cases of intersex (abnormal development of both male and female reproductive tissues in a gonad) paddlefish Polyodon spathula, an Acipenseriform species of large rivers in the central U.S. and in aquaculture worldwide. Despite a large, multi‐decadal data set in Oklahoma, Montana, and North Dakota, intersex development was not observed until 2019, when two individuals were harvested from the Grand Lake/Neosho River stock in Oklahoma. This suggests that intersex development in mid‐water, zooplanktivorous paddlefish is rarer than in bottom‐dwelling sturgeons for which intersex development is regularly observed. Although contaminants are implicated in causing intersex development in other Acipenseriformes, more investigation is needed. [ABSTRACT FROM AUTHOR]

The study aims to study the impact of the diet shift and feeding behavior of the paddlefish different age groups on the growth during the spawning season. Habitat affected paddlefish prey selection or foraging success is a striking force that promotes either dominance or submissiveness of brood fish to reproductive or growth performance under Russian aquaculture conditions. Four age groups were studied depending on years of commissioning (age composition: 23, 18, 17, 16; for years 1997, 2002, 2003 and 2004, respectively) and registered divergence in their growth rates throughout spawning season 2020. Growth patterns of 59 mature paddlefish were studied based on length-weight relationship, length frequency, and the growth coefficient (K). The results revealed that moderate growth pattern was observed in the 2nd group Isometric (b = 3), whereas the rest groups recorded negative allometric growth (b < 3). The data obtained from gut contents were consistent with the previous growth performance results. Major five prey categories (benthic macro-invertebrates, macro-invertebrate larvae, detritus, zooplankton and phytoplankton) were observed within fish stomach, which exposed through natural feeding in the rearing ponds. The values of chisquare test (χ²) results showed that frequencies in one or more prey items of a four age were strong significance (p-value = 8.93E-17 & χ² = 1.219, 1.051, 1.066 & 1.032; for 2nd, 3rd, 4th and 1st, respectively). Overall results propose maternal paddlefish prey election and growth patterns can be highly variable, and merely heavily reliant on feeding habitat and swimming behavior across spawning season. [ABSTRACT FROM AUTHOR]

While invasions of large rivers by exotic fish species are well documented, assessing actual or potential impacts on native species is a challenge. Rapid assessments may be possible through the application of a combination of bioenergetic and population dynamic models.Paddlefish (Polyodon spathula) is a native species in the central USA with a history of population decline due to waterway development and overharvesting for roe. It is not known whether paddlefish are impacted by resource competition from invasive bigheaded carp populations, including silver (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis), which have expanded dramatically in the Mississippi River.We used bioenergetic models to project the potential impact of invasive silver and bighead carp on zooplankton density and paddlefish somatic growth in backwater habitat. Bioenergetic outputs were translated to impacts on fecundity, becoming inputs for 50‐year metapopulation simulations of backwater habitat connected to the main‐stem Mississippi River by episodic flood events.Competition with carp reduced growth and increased the risk of population decline for paddlefish. Impacts increased disproportionately with increased carp abundance and were further exacerbated in scenarios with increased diet overlap or decreased zooplankton abundance.We also analysed paddlefish condition data collected at sites near the lower Mississippi River with varying histories of carp invasion. These data give credence to the bioenergetic model output; paddlefish had reduced body condition at sites with long‐established, high‐density carp populations.We conclude that invasive bigheaded carps have great potential to reduce paddlefish growth, fecundity, and abundance. The pairing of bioenergetics and population models is likely to be broadly useful in assessing the risks posed by other invasive species. [ABSTRACT FROM AUTHOR]

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]

Purpose. Paddlefish is commercially important species owing to its biological features and consumer characteristics, namely it produces valuable and delicious fish products, such as high quality meat and black caviar. Consequently, its cultivation under Ukrainian fish farm conditions and further realization in domestic and foreign markets are economically efficient. However, the paddlefish broodstock in Ukraine requires the efficient solution of increasing its productivity, identification and assessment of its genetic variation. Thus, the aim of our study was to develop and implement a multiplex PCR-analysis of paddlefish (Polyodon spathula) for population-genetic monitoring of its artificial broodstocks in Ukraine. Methodology. A multiplex PCR was used for the study. The multiplex PCR development was performed for four microsatellite DNA markers: Psp12, Psp21, Psp26 and Psp28. Each investigated DNA loci, for which the multiplex PCR was optimized, was selected in such a way that the colored PCR products labeled with fluorescent dye did not overlap the length of the amplified fragments. Evaluation of the multiplex PCR effectiveness and processing of the data were performed by fragment analysis of DNA on the genetic analyzer ABI Prism 3130 (Applied Biosystem, USA). The size of the identified alleles was determined using the "Gene Mapper 3.7" program (Applied Biosystems, USA) and LIZ-500 size standard (Applied Biosystems, USA). Results. Based on the results of capillary electrophoresis of multiplex PCR products, it was found that the amplified fragments for each of the four studied loci: Psp12, Psp21, Psp26 and Psp28 in one PCR reaction were within the expected size range. Data analysis on the electrophoregram demonstrated that Psp21 had the highest peak intensity at 611 fluorescent units (FU) and the lowest peak intensity at 105 FU was observed for Psp26 locus. In the multiplex PCR after proper interpretation of the data we identified heterozygous allelic variants for Psp12 (218/220 bp), Psp26 (144/146 bp) and Psp28 (256/258 bp). Herewith, the Psp21 locus (150/150 bp) is identified in the homozygous state. Originality. The optimization was conducted and a multiplex PCR was developed for paddlefish genotyping using microsatellite DNA markers. Practical value. The obtained results can be used for paddlefish genotyping within selective-breeding programs for artificial reproduction of this fish species.

Seasonal rhythms affect paddlefish farming practices due to the interactions among internal and external environmental factors in the aquatic ecosystem, including different types of biological, chemical, or physical stressors. In the present study, seasonal variations and the succession of the seasons during the farming periods represent a striking force that reflects the reality of sustainable paddlefish development under Russian aquaculture conditions. Five age groups (28, 29, 30; 26, 27, 28; 24, 25, 26; 19, 20, 21; and 18, 19, 20) were studied based on years of commissioning (1993, 1995, 1997, 2002 and 2003, respectively) and showed different growth rates throughout the seasons during 2017, 2018, and 2019. Consequently, rapid growth rate changes; increasing and decreasing, were observed, as demonstrated in weight gain and specific growth rate parameters. All the growth parameter variables, knowledge base and inference in the growth monitoring analysis model were carried out through computation of weight gain, growth rate, and specific growth rate related to age groups. The results revealed that the descriptive analysis of seasonal variability agreed with the statistical growth performance analysis. Moreover, the findings show that 2017 and 2018 winter and 2017 summer seasons recorded the lowest values of significance (30: 55%, SGR) among the five age groups. In contrast, high values were obtained for 2018 and 2019 winter and 2018 summer seasons (55: 80%, SGR), despite sustainable production. However, it is insufficient to determine the value of the seasonal response in growth rates over four seasons. Therefore, we need to create simulation programmes to predict the impact of seasonal patterns instead of spending more effort and cost on other methods. [ABSTRACT FROM AUTHOR]

Paddlefish Polyodon spathula and three sturgeon species are present in the upper Mississippi River; of these four species, two are commercially and recreationally important (Paddlefish and Shovelnose Sturgeon Scaphirhynchus platorynchus), and two are protected under federal or state endangered species laws (Pallid Sturgeon S. albus and Lake Sturgeon Acipenser fulvescens). Before management strategies can be implemented, quantification of movement patterns is necessary to determine the appropriate spatial scale for management. To increase the available relevant information, we investigated broad‐scale movement patterns of the above species in the upper Mississippi River by using telemetry. All four species were capable of long‐range (>300‐km) movements, and these movements were cued by the changing river stages and water temperature. Ultimately, our data suggest that sturgeon and Paddlefish movement patterns are highly variable, with fish moving freely among rivers (e.g., the Mississippi, Missouri, Illinois, Ohio, and Des Moines rivers) across many political boundaries and encompassing multiple regulatory agencies. This migratory nature can lead to portions of the population being subject to harvest in multiple management units, affecting population dynamics, biology, harvest, and management/recovery in both the natal area and in the harvest areas. To effectively manage or recover these highly mobile fish populations, interjurisdictional collaboration will be necessary. [ABSTRACT FROM AUTHOR]

Large‐river fishes (e.g., sturgeons [Acipenseridae] and Paddlefish Polyodon spathula) that inhabit reservoir systems are potentially unable to sense environmental cues that elicit typical life history behaviors. These cues can be masked by altered hydrology and temperature regimes. In many reservoirs throughout North America, Paddlefish populations are potentially affected by these unnatural conditions. In an attempt to understand and identify the potential mechanisms that limit Paddlefish reproduction in reservoir systems, we selected Harry S. Truman Reservoir (Truman Lake), Missouri, as our study area of focus. This population is supplemented by stocking, and although anecdotal evidence of potential natural reproduction exists, spawning has never been documented. We implanted ultrasonic transmitters into 113 reproductively mature Paddlefish, and the movements of these fish were tracked over 2 years. Paddlefish migratory behavior was significantly related to water temperature and gauge height, and differences in movement behaviors existed between sexes. Spring aggregations were located in the riverine portion of the Osage River, and embryos and larvae were sampled in 2015 and 2016 near said aggregations. Using acoustic telemetry and egg mats, we acquired evidence suggesting that the Truman Lake Paddlefish are spawning. Our technique can likely be applied to determine spawning locations for Paddlefish inhabiting other large reservoirs. [ABSTRACT FROM AUTHOR]

Abstract Melatonin (MLT) is a well-known antioxidant and can improve sperm quality during storage in many species. In the present study, the effects of different concentration of MLT (0.1, 0.5, 1 and 5 μM) on paddlefish sperm quality and ATP content in sperm were evaluated during semen storage at 4 °C. Compared with other groups, 0.5 μM MLT supplement in semen could be more effective to improve the plasma membrane integrity, maintain the steady reactive oxygen species (ROS) level and inhibit decrease of mitochondrial membrane potential of the non-activated sperm during whole storage. To the activated sperm, the total motility, progressive motility, beat cross frequency of sperm in semen with 0.5 μM MLT was significant higher (p <.05) than other groups at 30 s after activation. And the motility duration of sperm was also prolonged in semen with 0.5 μM MLT after 24 h storage (p <.05). Furthermore, 0.5 μM MLT in semen could maintain a higher ATP content of sperm before and after sperm activation. Compared with the morphology of the non-activated sperm with 0.5 μM MLT, the head and midpiece of the activated sperm with 0.5 μM MLT displayed deformation in hypotonic condition at 24 h storage. The same morphology changes were also appeared in the non-activated and activated sperm at 0 h storage. In conclusion, 0.5 μM MLT in semen is an optimal concentration to maintain the normal physiological function of paddlefish sperm during storage at 4 °C. Highlights • The 0.5 μM melatonin could maintain a relatively steady physiologic function of paddlefish sperm. • The best period of an efficient insemination could be the first 30 s after paddlefish sperm activation. • The morphology changes of paddlefish sperm are independent of the time of semen storage and additive melatonin during hypotonic activation. [ABSTRACT FROM AUTHOR]

Summary: The paddlefish (Polyodon spathula) was first introduced to Europe in 1974, mainly due to its potential for rearing in natural polyculture ponds and large temperate reservoirs. The information on the history of paddlefish aquaculture efforts in Europe is scarce, as well as data on current paddlefish aquaculture status and trends. In addition, there is a lack of data on its presence and potential establishment in the wild, while its invasive potential and associated risks and impacts are largely unknown. In order to evaluate its current status in Europe, we conducted a survey among scientists, aquaculture producers and other stakeholders, and reviewed literature and data on the Internet. Based on the results obtained, we discuss the potential and the challenges in European paddlefish aquaculture development, and analyze paddlefish invasive potential and risks associated with its naturalization. Paddlefish aquaculture is well established only regionally in Europe, but offers relatively high potential for further development in pond farms. Nevertheless, future development will require careful planning, especially regarding market development and improved marketing strategies. While paddlefish likely represents a low‐risk invader, improved control and reporting on trade and intentional and unintentional releases will be required. Given the lack of knowledge on potential impacts following its introduction, due caution seems highly advisable. [ABSTRACT FROM AUTHOR]

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]

Abstract Glucagon-like peptides-1 (GLP-1)from phylogenetically ancient fish (lamprey, dogfish, ratfish, paddlefish and bowfin) and from a teleost, the rainbow trout produced concentration-dependent stimulations of insulin release from clonal β-cells and isolated mouse islets. Lamprey and paddlefish GLP-1 were the most potent and effective. Incubation of BRIN-BD11 cells with GLP-1 receptor (GLP1R) antagonist, exendin-4 (9–39) attenuated insulinotropic activity of all peptides whereas glucagon receptor (GCGR) antagonist [des-His1,Pro4,Glu9] glucagon amide significantly decreased the activities of lamprey and paddlefish GLP-1 only. The GIP receptor antagonist GIP (6–30) Cex-K40 [Pal] attenuated the activity of bowfin GLP-1. All peptides (1 μM) produced significant increases in cAMP concentration in CHL cells transfected with GLP1R but only lamprey and paddlefish GLP-1 stimulated cAMP production in HEK293 cells transfected with GCGR. Intraperitoneal administration of lamprey and paddlefish GLP-1 (25 nmol/kg body weight) in mice produced significant decreases in blood glucose and increased insulin concentrations comparable to the effects of human GLP-1. Lamprey and paddlefish GLP-1 display potent insulinotropic activity in vitro and glucose-lowering activity in vivo that is mediated through GLP1R and GCGR so that these peptides may constitute templates for design of new antidiabetic drugs. Highlights • Lamprey, dogfish, ratfish, paddlefish, bowfin and trout GLP-1 stimulated insulin release from clonal β-cells and islets. • Insulinotropic activity of lamprey and paddlefish GLP-1 was attenuated by a GCGR antagonist. • All peptides stimulated cAMP production in CHL cells transfected with GLP1R. • Lamprey and paddlefish GLP-1 stimulated cAMP production in HEK293 cells transfected with GCGR. • All peptides improved glucose tolerance in mice with lamprey and paddlefish GLP-1 as effective as human GLP-1. [ABSTRACT FROM AUTHOR]

Highlights • Glucagons and oxyntomodulins from phylogenetic ancient fish stimulate insulin release from clonal β-cells and mouse islets. • Insulinotropic activities of paddlefish and lamprey glucagons were attenuated by a GLP1R antagonist and a GCGR antagonist. • Paddlefish and lamprey glucagon stimulate cAMP production in cells transfected with GLP1R and also with GCGR. • Administration of the fish peptides improved glucose tolerance and stimulated insulin release in mice. Abstract The insulinotropic and antihyperglycaemic properties of glucagons from the sea lamprey (Petromyzontiformes), paddlefish (Acipenseriformes) and trout (Teleostei) and oxyntomodulin from dogfish (Elasmobranchii) and ratfish (Holocephali) were compared with those of human glucagon and GLP-1 in mammalian test systems. All fish peptides produced concentration-dependent stimulation of insulin release from BRIN-BD11 rat and 1.1 B4 human clonal β-cells and isolated mouse islets. Paddlefish glucagon was the most potent and effective peptide. The insulinotropic activity of paddlefish glucagon was significantly (P < 0.01) decreased after incubating BRIN-BD11 cells with the GLP1R antagonist, exendin-4(9-39) and the GCGR antagonist [des-His1,Pro4, Glu9] glucagon amide but GIPR antagonist, GIP(6-30)Cex-K40[palmitate] was without effect. Paddlefish and lamprey glucagons and dogfish oxyntomodulin (10 nmol L−1) produced significant (P < 0.01) increases in cAMP concentration in Chinese hamster lung (CHL) cells transfected with GLP1R and human embryonic kidney (HEK293) cells transfected with GCGR. The insulinotropic activity of paddlefish glucagon was attenuated in CRISPR/Cas9-engineered GLP1R knock-out INS-1 cells but not in GIPR knock-out cells. Intraperitoneal administration of all fish peptides, except ratfish oxyntomodulin, to mice together with a glucose load produced significant (P < 0.05) decreases in plasma glucose concentrations and paddlefish glucagon produced a greater release of insulin compared with GLP-1. Paddlefish glucagon shares the sequences Glu15-Glu16 and Glu24-Trp25-Leu26-Lys27-Asn28-Gly29 with the potent GLP1R agonist, exendin-4 so may be regarded as a naturally occurring, dual-agonist hybrid peptide that may serve as a template design of new drugs for type 2 diabetes therapy. [ABSTRACT FROM AUTHOR]

The American paddlefish, Polyodon spathula (Walbaum), is an endangered acipenserid fish. Its wild populations are supplemented with stocking material that is obtained by conducting artificial spawning in aquaculture conditions. When fish are bred in captivity, it is important to select breeding pairs that will produce the most genetically diverse progeny, since this permits maintaining the fitness of wild populations. Breeding pairs of land animals are selected successfully based on the polymorphism of their microsatellite loci. This theoretical paper asks how to adapt this technique to fish so that American paddlefish spawners can be paired with the aim of producing restocking material in aquaculture that maintains genetic variation. To test our calculating techniques, we used actual data on the polymorphism of the microsatellites from paddlefish broodstock at the Pogorze fish farm (Poland). The data enabled us to do calculations that showed which spawner pairs would create the most genetically diverse offspring and how to assemble sets of spawning pairs that would be best for maintaining genetic variation. The method presented in this paper can be used for breeding fish in aquaculture to help conserve species. It could also be used in a computer program which would automate calculations and present them in easy-to-read tables and graphs.

The long fingers' paddlefish carpometacarpal (CMC) dislocation is exceptional. Most dislocations occur after high energy trauma. Untreated, these lesions can result in chronic instability of the CMC joints and early osteoarthritis. We report the case of a 20-year-old patient presenting with an ulnar paddlefish CMC fracture-dislocation of the three lesser fingers resulting from a hand trauma in the context of an occupational accident. Treatment is usually surgical though no strict consensus can be found upon literature review. If diagnosed early and no associated fractures are found, CMC dislocation could benefit from conservative treatment.

Due to the high amounts of harvest of natural fish populations, overexploitation can occur and subsequently lead to depleted fisheries. This is especially true for commercially exploited roe-bearing species that exhibit late age at maturation and intermittent spawning. Overexploitation can create an imbalance in natural ecosystem function and in turn jeopardize the livelihood of commercial fishers. Despite the problems created by overexploitation, trends of commercial harvest on large inland river roe-bearing populations have received minimal attention. As such, we evaluated trends in commercial fishing data from 1945-2010 for two roe-bearing species (paddlefish Polyodon spathula and shovelnose sturgeon Scaphirhynchus platorynchus) from two of the largest inland rivers in North America (Mississippi River and Missouri River) adjacent to Missouri. Commercial sturgeon and paddlefish catch has varied from ~160 to 35,150 kg over the course of the 55-year duration. Abnormally high catches corresponded to initiation of worldwide caviar markets, onset of extensive regulations on the Missouri and Mississippi rivers, and the Caspian Sea fishery collapse; respectively. Further, our results suggest that the harvest of sturgeon and paddlefish have increased since 1945 and may be influenced by local, regional, and international events. Despite the increase in harvest and the possibility of overharvest, commercial fishing regulations have not been thoroughly evaluated for effectiveness. Further evaluation of current management and regulations of these paddlefish and sturgeon fisheries is suggested, especially considering these fisheries may be influenced by local, regional, and international events. Taking potentially influential events into consideration when evaluating and implementing regulations and authorizing commercial harvest permits are vital in sustaining a long term commercial fishery and protecting the livelihood of commercial fishers. [ABSTRACT FROM AUTHOR]

This paper presents research on recreational paddlefish anglers’ preferences for catch-and-release fishing. We used stated preference (SP) data from a choice experiment to identify the effect of a hypothetical catch-and-release regulation on fishing preferences, and revealed preference (RP) data to measure the desirability of actual paddlefish fishing locations. We then modeled the effects of catch-and-release regulations on location choice and participation in the Oklahoma fishery. Our results indicate that although anglers dislike catch-and-release, most directly affected by regulations will either continue fishing at their preferred site or switch to a site where harvesting is permitted. Our preferred model predicts two-thirds will continue to participate even if catch-and-release fishing is required statewide. [ABSTRACT FROM AUTHOR]

Short-term movements of adult Polyodon spathula (Paddlefish) are well-documented, but long-term movements are underreported. In this study, we describe extraordinary distances traveled by 4 Paddlefish that were captured, tagged, and released in Moon Lake, a remote oxbow lake in Coahoma County, MS. After 8–24 months at large, the 4 fish were recaptured in the Missouri, Mississippi, and Ohio rivers, having traversed 1408–2433 km from Moon Lake through multiple waterways downstream to the Mississippi River at Vicksburg, MS, and then upriver to 4 geographically disparate locations. The multiple waterways used by these fish and the extensive distances traveled demonstrate the potential importance of backwater habitats located away from the mainstem river, and also underscore the need for interstate cooperation to protect Paddlefish populations. [ABSTRACT FROM AUTHOR]