Asian Carp in the Missouri River: Analysis from Multiple Missouri River Habitat and Fisheries Programs

Bighead carp Hypophthalmichthys nobilis, silver carp H. molitrix, black carp Mylopharyngodon piceus, and grass carp Ctenopharyngodon idella, collectively referred to as Asian carps, are invasive species that were either accidentally or intentionally introduced into the Mississippi River basin. The expansion of Asian carp into the Missouri River is not well understood and knowledge of population characteristics within this river were lacking. The objectives of this study were to describe the relative abundance, size structure, and spatial and temporal trends of Asian carp using multiple gears from three long-term fish community monitoring programs in the Missouri River downstream of Gavins Point Dam, South Dakota and Nebraska from 2003 to 2007. A total of 1,307 bighead, 1,280 silver, 624 grass, and 0 black carp were captured. The majority of adult bighead carp were captured in overnight hoop nets (38%) and adult silver (14%) and grass carp (23%) were most commonly caught in overnight experimental gill nets. Mini-fyke nets captured almost exclusively, young of the year Asian carp (≤ 80 mm), while gill, trammel, and hoop nets collected a wide length range of fish (81 – 1,200 mm). The relative abundance of all three Asian carp species did not significantly differ among years; however, spatial trends were found as relative abundance was highest in the Missouri River downstream of the Platte River. Short Asian carp weighed less in the Gavins Point reach compared to downstream of the Grand River in Missouri. Conversely, long Asian carp in the Gavins Point reach attained greater weights than fish of similar length downstream. We found that multiple sampling gears are necessary to monitor Asian carp population characteristics in the Missouri River. Asian carp populations appear to be well established in the Missouri River and it is increasingly important to understand the affects these invasive species have on the native fish community

Asian Carp in the Missouri River: Analysis from Multiple Missouri River Habitat and Fisheries Programs

Bighead carp Hypophthalmichthys nobilis, silver carp H. molitrix, black carp Mylopharyngodon piceus, and grass carp Ctenopharyngodon idella, collectively referred to as Asian carps, are invasive species that were either accidentally or intentionally introduced into the Mississippi River basin. The expansion of Asian carp into the Missouri River is not well understood and knowledge of population characteristics within this river were lacking. The objectives of this study were to describe the relative abundance, size structure, and spatial and temporal trends of Asian carp using multiple gears from three long-term fish community monitoring programs in the Missouri River downstream of Gavins Point Dam, South Dakota and Nebraska from 2003 to 2007. A total of 1,307 bighead, 1,280 silver, 624 grass, and 0 black carp were captured. The majority of adult bighead carp were captured in overnight hoop nets (38%) and adult silver (14%) and grass carp (23%) were most commonly caught in overnight experimental gill nets. Mini-fyke nets captured almost exclusively, young of the year Asian carp (≤ 80 mm), while gill, trammel, and hoop nets collected a wide length range of fish (81 – 1,200 mm). The relative abundance of all three Asian carp species did not significantly differ among years; however, spatial trends were found as relative abundance was highest in the Missouri River downstream of the Platte River. Short Asian carp weighed less in the Gavins Point reach compared to downstream of the Grand River in Missouri. Conversely, long Asian carp in the Gavins Point reach attained greater weights than fish of similar length downstream. We found that multiple sampling gears are necessary to monitor Asian carp population characteristics in the Missouri River. Asian carp populations appear to be well established in the Missouri River and it is increasingly important to understand the affects these invasive species have on the native fish community

Common Carp Disrupt Ecosystem Structure and Function Through Middle-out Effects

Middle-out effects or a combination of top-down and bottom-up processes create many theoretical and empirical challenges in the realm of trophic ecology. We propose using specific autecology or species trait (i.e. behavioural) information to help explain and understand trophic dynamics that may involve complicated and nonunidirectional trophic interactions. The common carp (Cyprinus carpio) served as our model species for whole-lake observational and experimental studies; four trophic levels were measured to assess common carp-mediated middle-out effects across multiple lakes. We hypothesised that common carp could influence aquatic ecosystems through multiple pathways (i.e. abiotic and biotic foraging, early life feeding, nutrient). Both studies revealed most trophic levels were affected by common carp, highlighting strong middle-out effects likely caused by common carp foraging activities and abiotic influence (i.e. sediment resuspension). The loss of water transparency, submersed vegetation and a shift in zooplankton dynamics were the strongest effects. Trophic levels furthest from direct pathway effects were also affected (fish life history traits). The present study demonstrates that common carp can exert substantial effects on ecosystem structure and function. Species capable of middle-out effects can greatly modify communities through a variety of available pathways and are not confined to traditional top-down or bottom-up processes

Heart failure in chronic kidney disease: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies conference

The incidence and prevalence of heart failure (HF) and chronic kidney disease (CKD) are increasing, and as such a better understanding of the interface between both conditions is imperative for developing optimal strategies for their detection, prevention, diagnosis, and management. To this end, Kidney Disease: Improving Global Outcomes (KDIGO) convened an international, multidisciplinary Controversies Conference titled Heart Failure in CKD. Breakout group discussions included (i) HF with preserved ejection fraction (HFpEF) and nondialysis CKD, (ii) HF with reduced ejection fraction (HFrEF) and nondialysis CKD, (iii) HFpEF and dialysis-dependent CKD, (iv) HFrEF and dialysis-dependent CKD, and (v) HF in kidney transplant patients. The questions that formed the basis of discussions are available on the KDIGO website http://kdigo.org/conferences/heart-failure-in-ckd/, and the deliberations from the conference are summarized here

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

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

Spatial and temporal patterns and the influence of abiotic factors on larval fish catches in the lower Niobrara River, Nebraska

The Niobrara River has a natural hydrograph and temperature regime with the lower 32 km protected under the National Wild and Scenic River system managed by the National Park Service. The largest threat to this river is decreased instream flows due to water withdrawals for agriculture. The Niobrara River a large tributary to the Missouri River may positively influence fish production. However, no information exists regarding phenology of fish spawning or what abiotic factors may influence spawning. Our objectives were to examine the taxonomic composition and the spatial and temporal patterns of the larval fish assemblage in relation to environmental variables in the lower Niobrara River. Larval fish sampling occurred weekly from April to August in 2008 and May to August 2009 with drift nets set in the Niobrara River at two sites: the mouth and 63 kilometers upstream. Each year, larval fish first appeared in the drift during the second week of May and were collected until the third week of August. Larval river carpsuckers Carpiodes carpio were the most abundant species in the drift during early-June, followed by red shiners Notropis lutrensis and sand shiners Notropis stramineus in late-June to mid-August, with Lepomis spp. appearing during late-June to late-July. No diel cycle in occurrence of larval fish in the drift was observed and likely resulted from the naturally high turbidity (mean nephelometric turbidity unit [NTU] \u3e 74). Larval fish densities were 24% higher in 2009 compared to 2008. Spatially, the greatest numbers of larval fish for most fish species were collected at our upstream site located immediately downstream of Spencer Dam. Differences in environmental variables were found among sites and years as mean water temperature, velocity, and turbidity were higher and dissolved oxygen was lowest at the mouth site in 2009. The results of canonical correspondence analysis found red shiners and sand shiners were associated with high water temperatures with low stable flows found late summer. Larval flathead chubs Platygobio gracilis and common carp Cyprinus carpio abundance was positively related to dissolved oxygen and water velocity and negatively with water temperature. River carpsuckers were associated with high water velocities and moderate water temperatures while Lepomis spp. were positively associated with high conductivity and high water temperatures. Fish species that successfully spawned in the lower Niobrara River are adapted to extreme temperatures, high variability in discharge, turbidity, and sediment load. Based on the importance of abiotic factors affecting larval fish abundances, a reduction in in-stream flows would likely jeopardize native fish populations and eliminate some productivity of fish in this river

Common carp abundance, biomass, and removal from Dewey and Clear lakes on the Valentine National Wildlife Refuge: Does trapping and removing carp payoff?

Common carp Cyprinus carpio is a nonnative invasive nuisance species to North America. Many authors have documented the detrimental affects of common carp invasions on waterfowl habitats (Chamberlain 1948; Robel 1961), game fish habitat (Cahn 1929), and the overall decline in native fishes (Bernstein and Olson 2001; Koehn 2004). Common carp reduce water quality by mobilizing nutrients and increasing turbidity; therefore, increasing phytoplankton biomass and reducing zooplankton biomass and rooted aquatic vegetation (Lougheed et al. 1998). Common carp are capable of rapidly colonizing shallow lakes and altering a body of water from a clear stable state, dominated by submergent vegetation to a more turbid state, dominated by phytoplankton (Northcote 1988; Parkos et al. 2003). Management and control of common carp has been well documented through much of North America (Meronek et al. 1996; Wydoski and Wiley 1999) with millions of dollars invested on research and control (Pimentel et al. 2000). Removal projects included mechanical harvest by netting (Ritz 1987; Pinto et al. 2005), water level manipulation to disrupt spawning (Summerfelt 1999), exclusion from spawning habitat (Lougheed and Chow-Fraser 2001), and piscicide application (Meronek et al. 1996). Northern pike Esox lucius have additionally been used as a biological tool to control common carp recruitment in the Sandhill lakes in Nebraska (Paukert et al. 2003). All methods of carp control have had varying degrees of success (Meronek et al. 1996). Common carp gained access to the U.S. Fish and Wildlife Service (USFWS), Valentine National Wildlife Refuge (NWR) lake system through Gordon Ditch, which was dug during the 1930\u27s (Wanner 2009). The ditch was plugged shortly after completion to eliminate fish movement onto the Refuge. Refuge lakes have a long history of chemical renovation to remove common carp (Wanner 2009). For approximately five years after renovation and the re-stocking of game fish, angling is excellent, waterfowl use is high; however, both decline soon after carp recolonization and subsequent habitat degradation (M. Lindvall, Valentine NWR, personal communication). Fisheries biologists from the USFWS and Nebraska Game and Parks Commission (NGPC) have also experimented with the use of northern pike and largemouth bass Micropterus salmoides to control common carp recruitment. Early attempts were unsuccessful because northern pike were introduced after carp populations were well established and subsequently the population and individual fish were too large to be controlled by predation (Wanner 2009). Common carp recruitment in the Refuge lakes is low due to predation or other abiotic factors (Phelps et al. 2008). Common carp have also been physically removed on Valentine NWR lakes by releasing water through control structures between lakes, luring fish into ditches during spawning migrations where they are subsequently trapped. In the ditches between Whitewater and Dewey lakes and Dewey and Clear lakes (Figure 1), thousands of common carp, with an estimated biomass of several tons, were trapped in 1993 and 2008 (Wanner 2009). Trapping was also attempted in 2003 with little success due to scour holes around the trap that allowed carp to escape (M. Nenneman, unpublished data). These methods of controlling common carp have never been thoroughly evaluated; therefore, the objectives of this study were to 1) estimate abundance, biomass, and size structure of common carp in Dewey Lake, 2) estimate the proportion of the abundance, biomass, and size structure of the common carp removed from the lake during the trapping operation, and 3) monitor water quality and carp relative abundance before and after carp removal

River geomorphology and fish barriers affect on spatial and temporal patterns of fish assemblages in the Niobrara River, Nebraska

The Niobrara River in northern Nebraska traverses the heart of the Great Plains with portions of the river protected under the National Wild and Scenic River system managed by the National Park Service. The Niobrara River changes from a narrow, entrenched stream to a wide, highly braided river with four fish barriers and 36 distinct geomorphic segments in the lower 531 river kilometers (rkm). Our objectives were to examine the spatial and temporal patterns of fish assemblages in the Niobrara River related to environmental variables, fish barriers, and river geomorphology. Tote-barge electrofishing occurred monthly from June to September in 2009 at 17 sites downstream of Dunlap Diversion Dam near Hemingford, Nebraska (river kilometer [rkm] 531) to the mouth (rkm 0) where the Niobrara River meets the Missouri River. In all, we collected 33,888 fish from 42 species and 11 families. Species richness was greatest near the mouth (rkm 4) and subsequently declined sharply upstream of the first fish barrier (Spencer Dam; rkm 63). Monthly changes in the fish assemblages were generally low with most differences due to young of the year, large-bodied fish recruiting to the electrofishing gear. Fish barriers, both anthropomorphic and natural, had significant impacts on the fish community by blocking fish migration, creating high abundances downstream of the structures, and species absent above the barriers. Bray-Curtis dissimilarity values between sample sites ranged from 45.4 to 96.5, which indicated high variation in the fish assemblage as river geomorphic features changed. Norden Chute (rkm 193), a natural fish barrier, marked a sharp change in geomorphic structure from a highly braided river with heterogeneous diversity of habitats downstream to a single river channel with a reduced floodplain upstream. Above the chute, the fish assemblage was dominated by insectivores fish species, while downstream occurrence of piscivores increased. Based on our results, fish barriers affected the diversity and abundances of fish both upstream and downstream

Common Carp Disrupt Ecosystem Structure and Function Through Middle-out Effects

Middle-out effects or a combination of top-down and bottom-up processes create many theoretical and empirical challenges in the realm of trophic ecology. We propose using specific autecology or species trait (i.e. behavioural) information to help explain and understand trophic dynamics that may involve complicated and nonunidirectional trophic interactions. The common carp (Cyprinus carpio) served as our model species for whole-lake observational and experimental studies; four trophic levels were measured to assess common carp-mediated middle-out effects across multiple lakes. We hypothesised that common carp could influence aquatic ecosystems through multiple pathways (i.e. abiotic and biotic foraging, early life feeding, nutrient). Both studies revealed most trophic levels were affected by common carp, highlighting strong middle-out effects likely caused by common carp foraging activities and abiotic influence (i.e. sediment resuspension). The loss of water transparency, submersed vegetation and a shift in zooplankton dynamics were the strongest effects. Trophic levels furthest from direct pathway effects were also affected (fish life history traits). The present study demonstrates that common carp can exert substantial effects on ecosystem structure and function. Species capable of middle-out effects can greatly modify communities through a variety of available pathways and are not confined to traditional top-down or bottom-up processes