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Steven J. Zigler - One of the best experts on this subject based on the ideXlab platform.
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hydrologic and hydraulic factors affecting passage of Paddlefish through dams in the upper mississippi river
Transactions of The American Fisheries Society, 2004Co-Authors: Steven J. Zigler, Michael R. Dewey, Brent C. Knights, Ann L. Runstrom, Mark T. SteingraeberAbstract:Abstract Populations of Paddlefish Polyodon spathula have been adversely affected by dams that can block their movements. Unlike high-head dams that preclude fish passage (unless they are equipped with fishways), the dams on the upper Mississippi River are typically low-head dams with bottom release gates that may allow fish passage under certain conditions. We evaluated the relation of dam head and river discharge to the passage of radio-tagged Paddlefish through dams in the upper Mississippi River. Radio transmitters were surgically implanted into 71 Paddlefish from Navigation Pools 5A and 8 of the upper Mississippi River and from two tributary rivers during fall 1994 through fall 1996. We tracked Paddlefish through September 1997 and documented 53 passages through dams, 20 upstream and 33 downstream. Passages occurred mostly during spring (71%) but also occurred sporadically during summer and fall (29%). Spring passages varied among years in response to hydrologic conditions. We evaluated patterns in u...
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movement and habitat use by radio tagged Paddlefish in the upper mississippi river and tributaries
North American Journal of Fisheries Management, 2003Co-Authors: Steven J. Zigler, Michael R. Dewey, Brent C. Knights, Ann L. Runstrom, Mark T. SteingraeberAbstract:Abstract We used radio telemetry to evaluate the movement and habitat use of Paddlefish Polyodon spathula in the upper Mississippi River and two tributary rivers. Radio transmitters were surgically implanted into 71 Paddlefish in Navigation Pools 5A and 8 of the upper Mississippi River, the Chippewa River, and the Wisconsin River during fall 1994 through fall 1996. Radio-tagged Paddlefish were located through summer 1997. The range of Paddlefish movement was typically low during all seasons except spring, but some Paddlefish moved throughout the 420-km extent of the study area. Paddlefish tagged in the Chippewa River were closely linked with the upper Mississippi River, as substantial portions of the population inhabited the adjacent Navigation Pool 4 each spring; Paddlefish in the Wisconsin River, however, rarely ventured out of that tributary. The use of aquatic area types by Paddlefish varied among the study reaches. A cartographic model of Paddlefish habitat suitability was developed for Navigation Po...
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Movement and Habitat Use by Radio‐Tagged Paddlefish in the Upper Mississippi River and Tributaries
North American Journal of Fisheries Management, 2003Co-Authors: Steven J. Zigler, Michael R. Dewey, Brent C. Knights, Ann L. Runstrom, Mark T. SteingraeberAbstract:Abstract We used radio telemetry to evaluate the movement and habitat use of Paddlefish Polyodon spathula in the upper Mississippi River and two tributary rivers. Radio transmitters were surgically implanted into 71 Paddlefish in Navigation Pools 5A and 8 of the upper Mississippi River, the Chippewa River, and the Wisconsin River during fall 1994 through fall 1996. Radio-tagged Paddlefish were located through summer 1997. The range of Paddlefish movement was typically low during all seasons except spring, but some Paddlefish moved throughout the 420-km extent of the study area. Paddlefish tagged in the Chippewa River were closely linked with the upper Mississippi River, as substantial portions of the population inhabited the adjacent Navigation Pool 4 each spring; Paddlefish in the Wisconsin River, however, rarely ventured out of that tributary. The use of aquatic area types by Paddlefish varied among the study reaches. A cartographic model of Paddlefish habitat suitability was developed for Navigation Po...
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Ecology and biology of Paddlefish in North America: historical perspectives, management approaches, and research priorities
Reviews in Fish Biology and Fisheries, 2000Co-Authors: Cecil A. Jennings, Steven J. ZiglerAbstract:Paddlefish ( Polyodon spathula , Polyodontidae)are large, mostly-riverine fish that once wereabundant in medium- to large-sized river systemsthroughout much of the central United States. Concernfor Paddlefish populations has grown from a regionalfisheries issue to one of national importance for theUnited States. In 1989, the U.S. Fish and WildlifeService (USFWS) was petitioned to list Paddlefish asa federally threatened species under the EndangeredSpecies Act. The petition was not granted, primarilybecause of a lack of empirical data on Paddlefishpopulation size, age structure, growth, or harvestrates across the present 22-state range. Nonetheless,concern for Paddlefish populations prompted the USFWSto recommend that Paddlefish be protected through theConvention on International Trade in EndangeredSpecies of Wild Fauna and Flora (CITES). The additionof Paddlefish to Appendix II of CITES, which wasapproved in March 1992, provides a mechanism tocurtail illegal trade in Paddlefish and their partsand supports a variety of conservation plans. Paddlefish populations have been negatively affectedby overharvest, river modifications, and pollution,but the Paddlefish still occupies much of its historicrange and most extant populations seem to be stable. Although many facets of Paddlefish biology andecology are well understood, the lack of informationon larval and juvenile ecology, mechanisms thatdetermine recruitment, population size and vitalrates, interjurisdictional movements, and the effectsof anthropogenic activities present significantobstacles for managing Paddlefish populations. Questions about the size and structure of localpopulations, and how such populations are affected bynavigation traffic, dams, and pollution are regardedas medium priority areas for future research. Theavailability of suitable spawning habitat and overallreproductive success in impounded rivers are unknownand represent critical areas for future research. Research on reproductive and recruitment success inimpounded rivers have significant implications formanaging Paddlefish, as rivers are modified furtherfor human use.
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Ecology and biology of Paddlefish in North America: historical perspectives, management approaches, and research priorities
Reviews in Fish Biology and Fisheries, 2000Co-Authors: Cecil A. Jennings, Steven J. ZiglerAbstract:Paddlefish ( Polyodon spathula , Polyodontidae)are large, mostly-riverine fish that once wereabundant in medium- to large-sized river systemsthroughout much of the central United States. Concernfor Paddlefish populations has grown from a regionalfisheries issue to one of national importance for theUnited States. In 1989, the U.S. Fish and WildlifeService (USFWS) was petitioned to list Paddlefish asa federally threatened species under the EndangeredSpecies Act. The petition was not granted, primarilybecause of a lack of empirical data on Paddlefishpopulation size, age structure, growth, or harvestrates across the present 22-state range. Nonetheless,concern for Paddlefish populations prompted the USFWSto recommend that Paddlefish be protected through theConvention on International Trade in EndangeredSpecies of Wild Fauna and Flora (CITES). The additionof Paddlefish to Appendix II of CITES, which wasapproved in March 1992, provides a mechanism tocurtail illegal trade in Paddlefish and their partsand supports a variety of conservation plans. Paddlefish populations have been negatively affectedby overharvest, river modifications, and pollution,but the Paddlefish still occupies much of its historicrange and most extant populations seem to be stable. Although many facets of Paddlefish biology andecology are well understood, the lack of informationon larval and juvenile ecology, mechanisms thatdetermine recruitment, population size and vitalrates, interjurisdictional movements, and the effectsof anthropogenic activities present significantobstacles for managing Paddlefish populations. Questions about the size and structure of localpopulations, and how such populations are affected bynavigation traffic, dams, and pollution are regardedas medium priority areas for future research. Theavailability of suitable spawning habitat and overallreproductive success in impounded rivers are unknownand represent critical areas for future research. Research on reproductive and recruitment success inimpounded rivers have significant implications formanaging Paddlefish, as rivers are modified furtherfor human use.
Steven D. Mims - One of the best experts on this subject based on the ideXlab platform.
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Investigation in Reuse of Decommissioned Wastewater Facility and Reclaimed Water for Culturing Paddlefish Fingerlings
Journal of the World Aquaculture Society, 2014Co-Authors: Rafael Cuevas-uribe, Steven D. MimsAbstract:Reclaimed water is treated wastewater that has received at least secondary treatment and basic disinfection and is reused for beneficial purposes. The goal of this study was to develop a safe and reliable sustainable aquaculture system for producing stocker fish using reclaimed water in decommissioned wastewater treatment plants (WWTP) in Kentucky. The specific objectives were (1) to monitor Paddlefish, Polyodon spathula, growth and survival and water quality in experimental tanks with static or flow-through reclaimed water, (2) to evaluate the use of decommissioned tanks for large-scale production of phase II Paddlefish, and (3) to biomonitor Paddlefish grown in reclaimed water for contaminants. Phase I Paddlefish (11 ± 2.6 g) were produced by feeding live Daphnia collected daily from the clarifier tanks with hand-pulled nets for 27 d. Phase II Paddlefish were produced in four replicated 5600-L experimental tanks with static and flow-through reclaimed water. Paddlefish from the flow-through system were significantly larger (199.2 ± 61 g) and had better feed conversion ratios (2.8 ± 2.1) than those from the static system (135.5 ± 51 g; 4.1 ± 1.6). For the large-scale trial, two 1125 m3 decommissioned digester tanks were stocked with 50,000 Paddlefish larvae per tank. One tank was treated as a flow-through system with reclaimed water flowing at a rate of 280 L/min, while the other tank was treated as a static system where water was just added to replace that lost by evaporation. Survival rate (40%) and weight (194.1 ± 25.4 g) from the flow-through system were significantly different from those of the static system (31%; 147.1 ± 6.5 g). This difference could be linked to better water quality in the flow-through systems. Analyses for 38 contaminants were conducted on Daphnia, prepared diets, and Paddlefish. All the concentration levels detected were at levels well below the FDA action limits and their permissible limits in edible food. The result from this project showed that Paddlefish can be successfully produced in large-scale as stocker fish using reclaimed water in decommissioned tanks at WWTP.
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Reservoir Ranching of Paddlefish, Polyodon spathula
Journal of Applied Aquaculture, 2008Co-Authors: Siddhartha Dasgupta, Steven D. Mims, Richard J. OndersAbstract:Abstract Reservoir ranching is an extensive aquaculture practice which stocks young fish that feed on naturally available foods, and are harvested after a period of time. Paddlefish, Polyodon spathulaare filter feeders on zooplankton and are valued for their boneless meat and roe that can be processed into caviar. The goal of this study was to report the perceptions that Kentuckians have of Paddlefish reservoir ranching in public waters. Our results show that over 80% of surveyed respondents (N = 478) were in favor of this practice. However, almost 20% of respondents indicated that reservoir ranching of Paddlefish might be deleterious for sport fishing in the reservoirs selected for this aquaculture method. A similar proportion of the surveyed sample was against instituting reservoir ranching of Paddlefish in public waters. Other results showed that respondent characteristics, such as fishing license ownership and education level, systematically affected their opinion of reservoir ranching. Individuals wi...
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growth condition and size distribution of Paddlefish polyodon spathula juveniles reared in ponds at three densities
Journal of The World Aquaculture Society, 2008Co-Authors: Richard J. Onders, Steven D. Mims, Siddhartha DasguptaAbstract:.— A study was conducted to determine the effect of increasing density on growth and size distribution of Paddlefish, Polyodon spathula, juveniles reared in ponds. Feed-trained Paddlefish of mean weight (±SE) 25.8 ± 1.1 g were randomly stocked into nine 0.02-ha ponds at 12,355, 18,533, and 24,710 Paddlefish/ha, three replications per treatment. The fish were fed daily in excess of what they would eat for 97 d, beginning with a floating trout diet containing 45% protein and 16% lipid and then transferring to a floating catfish diet containing 32% protein and 4.5% lipid. Survival at harvest was not significantly different (P > 0.05) among treatments and averaged 90%. Mean final weights (±SD) for the low-, middle-, and high-density treatments were 205.2 ± 54.1, 174.8 ± 53.2, and 178.6 ± 51.4 g, respectively. Best-fit distributions centered on these means were lognormal. The low-density distribution was significantly different (P 0.05). Paddlefish weight at the minimum target length of 35 cm was estimated to be 100 g by regression analysis. The probability of Paddlefish reaching or exceeding 100 g was 90% for the low-density treatment. For the two higher densities, probabilities were 79 and 78%, respectively. Mean Fulton’s condition factors (FCFs) (±SD) were 250 ± 19, 242 ± 4, and 256 ± 37 for the low-, middle-, and high-density treatments, respectively. The FCF for the middle-density treatment was significantly lower than for the low- and high-density treatments (P 0.05). CV, feed conversion ratio, and relative growth were not significantly different (P > 0.05) among treatments and averaged 0.43, 1.50, and 5.45, respectively. Monoculture of Paddlefish juveniles in ponds results in a hierarchic size structure when density is at least greater than 12,355 Paddlefish/ha. The effect is enhanced with increasing density but becomes asymptotic as density approaches 18,533 Paddlefish/ha. Feeding in excess does not ameliorate the effect.
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reservoir ranching of Paddlefish polyodon spathula results of a public opinion survey in kentucky
Journal of Applied Aquaculture, 2006Co-Authors: Siddhartha Dasgupta, Steven D. Mims, Richard J. OndersAbstract:Reservoir ranching is an extensive aquaculture practice which stocks young fish that feed on naturally available foods, and are harvested after a period of time. Paddlefish, Polyodon spathulaare filter feeders on zooplankton and are valued for their boneless meat and roe that can be processed into caviar. The goal of this study was to report the perceptions that Kentuckians have of Paddlefish reservoir ranching in public waters. Our results show that over 80% of surveyed respondents (N = 478) were in favor of this practice. However, almost 20% of respondents indicated that reservoir ranching of Paddlefish might be deleterious for sport fishing in the reservoirs selected for this aquaculture method. A similar proportion of the surveyed sample was against instituting reservoir ranching of Paddlefish in public waters. Other results showed that respondent characteristics, such as fishing license ownership and education level, systematically affected their opinion of reservoir ranching. Individuals wi...
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Methylmercury Concentrations Found in Wild and Farm-raised Paddlefish
Journal of Food Science, 2006Co-Authors: Siddhartha Dasgupta, Richard J. Onders, D. T. Gunderson, Steven D. MimsAbstract:: Paddlefish (Polyodon spathula) were collected from 4 sites in Kentucky: the Ohio River, Lake Cumberland, and 2 aquaculture sources (private reservoir and catfish ponds). They were tested for methylmer-cury concentrations in their flesh. Paddlefish from all sources had methylmercury levels below the 1 part per million Food and Drug Administration-mandated action limit for seafood. However, using the U.S. Environmental Protection Agency reference dose for methylmercury, only Paddlefish from the Ohio River exceeded the reference dose for unrestricted consumption. Some Ohio River and Lake Cumberland Paddlefish had higher-than-average methylmercury concentrations, whereas aquacultured Paddlefish had low concentrations of methylm-ercury. There was a direct proportionality between fish age and methylmercury concentration; older Paddlefish tended to have higher amounts of methylmercury in their meat.
Dennis L. Scarnecchia - One of the best experts on this subject based on the ideXlab platform.
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Evidence of Positive Phototaxis in Paddlefish: Implications for Larval Sampling
Transactions of the Kansas Academy of Science, 2020Co-Authors: Jason D. Schooley, Adam Geik, Willis Sontheimer, Dennis L. ScarnecchiaAbstract:Paired lit and unlit quatrefoil traps were used to examine the photic response of Paddlefish Polyodon spathula yolk-sac larvae (YSL) and exogenous-feeding larvae (EFL) under controlled conditions in a hatchery. One lit and one unlit trap were placed in two identical circular raceways containing approximately 10,000 YSL and EFL for 20 2-min trials. Lit traps captured nearly 10x more larvae than unlit traps for each cohort and accounted for 91% and 94% of total catch for YSL and EFL, respectively. This is the first documentation of this photic response in Paddlefish. A slight increasing trend in capture with length was noted for YSL, whereas EFL demonstrated a strong decreasing trend in capture, indicating a possible behavioral shift at 15-16 mm TL. The high proportional catch of lit traps among 1-mm length classes evaluated (≥79%) suggests that Paddlefish exhibit positive phototaxis and light trapping for Paddlefish larvae
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energy acquisition and retention by age 0 and age 1 Paddlefish polyodon spathula walbaum 1792 in relation to size growth and rearing conditions in two great plains reservoirs and hatchery ponds
Journal of Applied Ichthyology, 2017Co-Authors: Rulon James Hemingway, Dennis L. ScarnecchiaAbstract:Summary The objective of this study was to investigate lipid accumulation and storage in age-0 and age-1 Paddlefish Polyodon spathula (Walbaum, 1792) in relation to age, stock, year, and growth. Juvenile Paddlefish were collected from three locations in North Dakota and Montana, USA, during July and August of 2011 and 2012 and proximate analysis was used to determine lipid content. RNA/DNA ratios were used as an index of growth rates. Differences in age-based lipid accumulation and storage in juvenile Paddlefish suggest a split allocation between growth and lipid storage, with growth being the highest initial priority and emphasis on energy storage occurring at a larger size, later in life. Differences in lipid allocation between stocks indicate that allocation is influenced by hatchery/wild rearing conditions. Differences within and between year-classes are consistent with field evidence observed in 2012 of a strong 2011 year-class, and indicate that during productive times, Paddlefish may allocate energy to both body growth and lipid reserves, and that allocation differs among years. The lack of a relationship between RNA/DNA ratio and lipid does not support a physiologically exclusive allocation strategy between growth and lipid. Evidence from this and other studies suggests rather that an emphasis on growth, some energy storage, and a large rostrum size in relation to overall fish length in age-0 and age-1 fish, may be adaptive in avoiding predation while accruing necessary energy reserves for overwintering. Although this study also provides reference information regarding proximate composition of wild and hatchery origin juvenile Paddlefish, much more study is needed into the relationships among growth, low and high lipid groups, lipid allocation in juvenile Paddlefish as well as the existence and timing of allocation changes between growth and storage. To aid in understanding Paddlefish survival and year-class strengths, these relationships also need to be linked to inter-annual differences in early rearing environments for age-0 and age-1 fish.
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spring migratory movements by Paddlefish in natural and regulated river segments of the missouri and yellowstone rivers north dakota and montana
Transactions of The American Fisheries Society, 2006Co-Authors: Jon A Firehammer, Dennis L. ScarnecchiaAbstract:Abstract Paddlefish Polyodon spathula of the Yellowstone–Sakakawea stock, Missouri and Yellowstone rivers, Montana and North Dakota, were radio-tagged to assess movement patterns during spawning migrations in 1999–2002. Sixty-three of the 69 tagged fish provided useful data on migratory movements during the study period. Paddlefish exhibited repeated directional changes in movement during the spring, traveling extensively upriver and downriver in association with increasing and decreasing levels of river discharge and suspended sediment. This behavior resulted in their widespread distribution along the lower 50 km of the Yellowstone River during late spring of all 4 years. The choice of river ascended (Missouri or Yellowstone) was also associated with increasing levels of discharge and turbidity. Paddlefish ascended the unregulated Yellowstone River rather than the regulated Missouri River more than four of every five times when moving above the confluence of the two rivers. Although Paddlefish were also ...
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Predation on Age-0 Paddlefish by Walleye and Sauger in a Great Plains Reservoir
North American Journal of Fisheries Management, 2002Co-Authors: Charles K. Parken, Dennis L. ScarnecchiaAbstract:Abstract From July to October 1994 and 1995, the food habits of walleye Stizostedion vitreum, sauger S. canadense, northern pike Esox lucius, and channel catfish Ictalurus punctatus were studied in Lake Sakakawea, a Missouri River main-stem reservoir in North Dakota. In 1994, no Paddlefish Polyodon spathula were found in stomachs of these predators. In 1995, 3% of the walleyes, 12% of the saugers, and 1% of the channel catfish with identifiable prey ate wild age-0 Paddlefish. Walleyes ate Paddlefish from August to October, with the highest proportions in September, whereas saugers ate Paddlefish from July to October in equal proportions. Walleye and sauger stomachs contained wild age-0 Paddlefish as large as 167 mm body length (BL; 305 mm total length, TL), and one channel catfish stomach contained a 142-mm-BL (269-mm-TL) Paddlefish. Predators were also sampled after 8,000 hatchery-reared, age-0 Paddlefish (mean BL = 189 mm) were released in White Earth Bay, Lake Sakakawea. Hatchery-reared Paddlefish were...
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Use of Surface Visual Counts for Estimating Relative Abundance of Age-0 Paddlefish in Lake Sakakawea
North American Journal of Fisheries Management, 1997Co-Authors: James P. Fredericks, Dennis L. ScarnecchiaAbstract:Abstract We describe a method for assessing relative reproductive success and year-class strength of Paddlefish Polyodon spathula in reservoirs based on visual surface counts of age-0 fish in late summer and early fall. In 1992 and 1993, we visually counted age-0 Paddlefish and trawled the surface over a series of transects in upper Lake Sakakawea, a Missouri River main-stem reservoir in North Dakota. The visual counts were strongly correlated with the trawl catches. Compared with trawling, counts provided less variability in year-class estimates, required less personnel and equipment, and avoided handling mortality. Surface counts could be useful for assessing relative year-class strength of Paddlefish in areas where significant numbers and densities of age-0 Paddlefish exist.
Cecil A. Jennings - One of the best experts on this subject based on the ideXlab platform.
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Population Statistics for Paddlefish in the Wisconsin River
Transactions of the American Fisheries Society, 2001Co-Authors: Ann L. Runstrom, Bruce Vondracek, Cecil A. JenningsAbstract:Abstract Although Paddlefish Polyodon spathula are protected in Wisconsin and Minnesota, limited information exists on the status of populations in the upper Mississippi River. Paddlefish populations in the upper Mississippi River probably have never fully recovered from declines that occurred in the late 1800s and early 1900s following habitat loss and extensive fishing. In our study, we estimated population size, size and age structure, and mortality for a Paddlefish population in the Wisconsin River, a tributary of the upper Mississippi River, during 1993 and 1994. We tagged 337 Paddlefish and recaptured 33. Unequal probability of capture and small sample sizes violated the assumptions of published population models. To improve interpretation of results, data were adjusted for assumption violations, and estimates were generated using three widely used models (modified Jolly–Seber, adjusted Petersen, and Chapman's modified Schnabel). Based on Chapman's modified Schnabel adjusted for mortality and estima...
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Ecology and biology of Paddlefish in North America: historical perspectives, management approaches, and research priorities
Reviews in Fish Biology and Fisheries, 2000Co-Authors: Cecil A. Jennings, Steven J. ZiglerAbstract:Paddlefish ( Polyodon spathula , Polyodontidae)are large, mostly-riverine fish that once wereabundant in medium- to large-sized river systemsthroughout much of the central United States. Concernfor Paddlefish populations has grown from a regionalfisheries issue to one of national importance for theUnited States. In 1989, the U.S. Fish and WildlifeService (USFWS) was petitioned to list Paddlefish asa federally threatened species under the EndangeredSpecies Act. The petition was not granted, primarilybecause of a lack of empirical data on Paddlefishpopulation size, age structure, growth, or harvestrates across the present 22-state range. Nonetheless,concern for Paddlefish populations prompted the USFWSto recommend that Paddlefish be protected through theConvention on International Trade in EndangeredSpecies of Wild Fauna and Flora (CITES). The additionof Paddlefish to Appendix II of CITES, which wasapproved in March 1992, provides a mechanism tocurtail illegal trade in Paddlefish and their partsand supports a variety of conservation plans. Paddlefish populations have been negatively affectedby overharvest, river modifications, and pollution,but the Paddlefish still occupies much of its historicrange and most extant populations seem to be stable. Although many facets of Paddlefish biology andecology are well understood, the lack of informationon larval and juvenile ecology, mechanisms thatdetermine recruitment, population size and vitalrates, interjurisdictional movements, and the effectsof anthropogenic activities present significantobstacles for managing Paddlefish populations. Questions about the size and structure of localpopulations, and how such populations are affected bynavigation traffic, dams, and pollution are regardedas medium priority areas for future research. Theavailability of suitable spawning habitat and overallreproductive success in impounded rivers are unknownand represent critical areas for future research. Research on reproductive and recruitment success inimpounded rivers have significant implications formanaging Paddlefish, as rivers are modified furtherfor human use.
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Ecology and biology of Paddlefish in North America: historical perspectives, management approaches, and research priorities
Reviews in Fish Biology and Fisheries, 2000Co-Authors: Cecil A. Jennings, Steven J. ZiglerAbstract:Paddlefish ( Polyodon spathula , Polyodontidae)are large, mostly-riverine fish that once wereabundant in medium- to large-sized river systemsthroughout much of the central United States. Concernfor Paddlefish populations has grown from a regionalfisheries issue to one of national importance for theUnited States. In 1989, the U.S. Fish and WildlifeService (USFWS) was petitioned to list Paddlefish asa federally threatened species under the EndangeredSpecies Act. The petition was not granted, primarilybecause of a lack of empirical data on Paddlefishpopulation size, age structure, growth, or harvestrates across the present 22-state range. Nonetheless,concern for Paddlefish populations prompted the USFWSto recommend that Paddlefish be protected through theConvention on International Trade in EndangeredSpecies of Wild Fauna and Flora (CITES). The additionof Paddlefish to Appendix II of CITES, which wasapproved in March 1992, provides a mechanism tocurtail illegal trade in Paddlefish and their partsand supports a variety of conservation plans. Paddlefish populations have been negatively affectedby overharvest, river modifications, and pollution,but the Paddlefish still occupies much of its historicrange and most extant populations seem to be stable. Although many facets of Paddlefish biology andecology are well understood, the lack of informationon larval and juvenile ecology, mechanisms thatdetermine recruitment, population size and vitalrates, interjurisdictional movements, and the effectsof anthropogenic activities present significantobstacles for managing Paddlefish populations. Questions about the size and structure of localpopulations, and how such populations are affected bynavigation traffic, dams, and pollution are regardedas medium priority areas for future research. Theavailability of suitable spawning habitat and overallreproductive success in impounded rivers are unknownand represent critical areas for future research. Research on reproductive and recruitment success inimpounded rivers have significant implications formanaging Paddlefish, as rivers are modified furtherfor human use.
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Spawning Activity of Paddlefish (Polyodon spathula) In the Lower Black River, Wisconsin
Journal of Freshwater Ecology, 1993Co-Authors: Cecil A. Jennings, Donna M. WilsonAbstract:ABSTRACT We present indirect evidence of successful Paddlefish (Polyodon spathula reproduction in 1989 and 1991 in the lower Black River, Wisconsin, about 5 km upstream of the confluence with the upper Mississippi River. This is the first indication of successful reproduction by Paddlefish at the northern end of its range in the central United States. Attempts to document Paddlefish Polyodon spathula reproduction by sampling eggs and larvae began in the early 1900s (e.g., Stockard 1907), but the exact timing and location of fish spawning were unknown until the early 1960s. Actual spawning by Paddlefish was first observed over gravel bars in the Osage River, Missouri, by Purkett (1961), who then collected eggs and larvae. Paddlefish eggs and larvae have since been collected below dams on the Missouri (Ruelle and Hudson 1977, Unkenholz 1982), Cumberland, and Tennessee Rivers (Pasch et al. 1980, Wall us 1986). However, the spawning areas for most Paddlefish populations remain unknown. Because larval paddlefi...
Phillip W. Bettoli - One of the best experts on this subject based on the ideXlab platform.
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Status of Paddlefish in the United States
2009Co-Authors: Phillip W. BettoliAbstract:The status of Paddlefish Polyodon spathula in the United States was first described in two surveys published in 1986 and 1997; in this paper, we report the results of a similar survey of state and federal agency person- nel that we conducted in 2006. From the 1970s through the 1990s, the sta- tus of Paddlefish stocks was on a downward trend throughout much of the species' range. The 2006 survey results suggest that the status of Paddlefish stocks has improved since the first survey was conducted; 17 of 26 states in 2006 reported that their Paddlefish populations were stable or increas- ing, compared to only 14 states in 1983 and 1994. The number of states with closed fisheries (i.e., no commercial or sport harvest) increased to 12 in 2006 from 8 in 1983. The number of states reporting declining or stable/declin- ing Paddlefish populations dropped from seven states in 1983 to only three states in 2006. The two principal reasons cited for reported declines have remained the same for more than three decades: habitat loss and overfishing. Two states where Paddlefish were listed as extirpated (New York and Penn- sylvania) have begun restoration efforts that may one day allow the status of Paddlefish in those states to be changed. As long as the demand for caviar remains strong, pressure on Paddlefish stocks will undoubtedly remain high in the seven states where they are commercially exploited. However, earlier fears of a basin-wide collapse in Paddlefish stocks should continue to dimin- ish if resource managers are successful in combating overfishing and contin- ued habitat destruction, which will always threaten the long-term viability of Paddlefish stocks throughout the Mississippi River basin.
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Lack of size selectivity for Paddlefish captured in hobbled gillnets
Fisheries Research, 2006Co-Authors: George D. Scholten, Phillip W. BettoliAbstract:Abstract A commercial fishery for Paddlefish Polyodon spathula caviar exists in Kentucky Lake, a reservoir on the lower Tennessee River. A 152-mm (bar-measure) minimum mesh size restriction on entanglement gear was enacted in 2002 and the minimum size limit was increased to 864 mm eye-fork length to reduce the possibility of recruitment overfishing. Paddlefish were sampled in 2003–2004 using experimental monofilament gillnets with panels of 89, 102, 127, 152, 178, and 203-mm meshes and the efficacy of the mesh size restriction was evaluated. Following the standards of commercial gear used in that fishery, nets were “hobbled” (i.e., 128 m × 3.6 m nets were tied down to 2.4 m; 91 m × 9.1 m nets were tied down to 7.6 m). The mean lengths of Paddlefish ( N total = 576 fish) captured in each mesh were similar among most meshes and bycatch rates of sublegal fish did not vary with mesh size. Selectivity curves could not be modeled because the mean and modal lengths of fish captured in each mesh did not increase with mesh size. Ratios of fish girth to mesh perimeter ( G : P ) for individual fish were often less than 1.0 as a result of the largest meshes capturing small Paddlefish. It is unclear whether lack of size selectivity for Paddlefish was because the gillnets were hobbled, the unique morphology of Paddlefish, or the fact that they swim with their mouths agape when filter feeding. The lack of size selectivity by hobbled gillnets fished in Kentucky Lake means that managers cannot influence the size of Paddlefish captured by commercial gillnet gear by changing minimum mesh size regulations.
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population characteristics and assessment of overfishing for an exploited Paddlefish population in the lower tennessee river
Transactions of The American Fisheries Society, 2005Co-Authors: George D. Scholten, Phillip W. BettoliAbstract:Abstract Paddlefish Polyodon spathula (n = 576) were collected from Kentucky Lake, Kentucky–Tennessee, with experimental gill nets in 2003–2004 to assess population characteristics and the potential for commercial overfishing. Additional data were collected from 1,039 Paddlefish caught by commercial gillnetters in this impoundment. Since the most recent study in 1991, size and age structure have been reduced and annual mortality has tripled. In the 1991 study, 37% of the fish collected were older than the maximum age we observed (age 11), and in 2003 annual mortality for Paddlefish age 7 and older was high (A = 68%). Natural mortality is presumably low (<10%) for Paddlefish; therefore, exploitation in recent years is high. Estimates of total annual mortality were negatively related to river discharge in the years preceding each estimate. The number of Paddlefish harvested since 1999 was also negatively related to river discharge because gill nets cannot be easily deployed when discharge exceeds approximat...
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Population Characteristics and Assessment of Overfishing for an Exploited Paddlefish Population in the Lower Tennessee River
Transactions of the American Fisheries Society, 2005Co-Authors: George D. Scholten, Phillip W. BettoliAbstract:Abstract Paddlefish Polyodon spathula (n = 576) were collected from Kentucky Lake, Kentucky–Tennessee, with experimental gill nets in 2003–2004 to assess population characteristics and the potential for commercial overfishing. Additional data were collected from 1,039 Paddlefish caught by commercial gillnetters in this impoundment. Since the most recent study in 1991, size and age structure have been reduced and annual mortality has tripled. In the 1991 study, 37% of the fish collected were older than the maximum age we observed (age 11), and in 2003 annual mortality for Paddlefish age 7 and older was high (A = 68%). Natural mortality is presumably low (
