Using Post-Release Stratification to Detect Heterogeneity in Mallard Survival

Floods Continue to Disrupt Barge TrafficOn-going highwater conditions continue to disrupt barge traffic on most of the inland waterways.On the Upper Mississippi River there are multiple lock closures.As of May 30, all traffic through St Louis is stopped, as the Mississippi River gauge there was 42.4 feet and rising.The Coast Guard stops all traffic at St. Louis when the river gauge exceeds 38 feet.The National Weather Service's forecast doesn't show the river levels dropping below 38 feet until mid-June.Barge traffic is also stopped on the Lower Illinois River and much of the Arkansas River.The Ohio River and the Lower Mississippi River are open but traffic is delayed by high water conditions.The U.S. Army Corps of Engineers reports saturated soil levels throughout the Mississippi River Valley Basin are at 25-year highs.Additional rain, coupled with the saturated soils, may bring faster runoff and rapid jumps in river stages. Grain Inspections Down Slightly but Corn ReboundsFor the week ending May 23, total inspections of grain (corn, wheat, and soybeans) for export from all major U.S. export regions reached 2.16 million metric tons (mmt).This amount signifies a 3 percent decrease from the previous week, a 22 percent drop from last year, and a 2 percent decrease from the 3-year average.Although inspections of corn and soybeans increased 31 and 7 percent, respectively, from week to week, the increases could not offset the 41 percent drop in inspections of wheat.Compared to the previous week, grain inspections decreased 3 percent in the Mississippi Gulf and 5 percent in the Pacific Northwest (PNW). Ocean Freight Rates Ticked Up Slightly for Two Consecutive WeeksOcean freight rates for shipping bulk grains rose for two consecutive weeks, but they are still below the levels seen at the beginning of the year, and relatively the same as the same period last year.As of May 23, the rate for shipping a metric ton (mt) of grain from the U.S. Gulf to Japan was $43.50.This is a 2 percent increase since the last 2 weeks, but 7 percent less than the beginning of the year, and unchanged from the same period last year.The rate from the Pacific Northwest to Japan was $24.00 per mt.This is a 4 percent increase since the last 2 weeks, but 4 percent less than the beginning of the year, and 1 percent less than the same period last year.According to the May 23 Transportation and Export report by O'Neil Commodity Consulting, rates are expected to continue rise gradually as we move into the fourth quarter.However, the direction of the rates could be impacted by the outcome of the current tariff and trade turmoil. Snapshots by Sector Export SalesFor the week ending May 16, unshipped balances of wheat, corn, and soybeans totaled 24 mmt.This indicates a 19 percent decrease in outstanding sales, compared to the same time last year.Net weekly wheat export sales were .048mmt, down 58 percent from the previous week.Net corn export sales totaled .442mmt, down 20 percent from the previous week.Net soybean export sales totaled .536mmt, up 45 percent from the past week.Rail U.S. Class I railroads originated 23,194 grain carloads for the week ending May 18.This is 4 percent lower than the previous week, up 4 percent from last year, and 6 percent above the 3-year average.Average June shuttle secondary railcar bids/offers (per car) were $22 below tariff for the week ending May 23.This is $136 above last week and $322 lower than last year.There were no non-shuttle bids/offers this week. BargeFor the week ending May 25, barge grain movements totaled 542,150 tons.This is 47 percent more than the previous week and 27 percent lower than the same period last year.For the week ending May 25, 324 grain barges moved down river.This is 114 more barges than the previous week.There were 432 grain barges unloaded in New Orleans.This is 16 percent lower than the previous week. OceanFor the week ending May 23, 36 ocean-going grain vessels were loaded in the Gulf.This is 16 percent more than the same period last year.Forty-two vessels are expected to be loaded within the next 10 days.This is 11 percent more than the same period last year.As of May 23, the rate for shipping a metric ton (mt) of grain from the U.S. Gulf to Japan was $43.50.This is 1 percent more than the previous week.The rate from the Pacific Northwest to Japan was $24.00 per mt, a 2 percent increase from the previous week. FuelFor the week ending May 27, the U.S. average diesel fuel price decreased 1.2 cents, from the previous week, to $3.151 per gallon.This price is 13.7 cents below the same week last year.

ABSTRACT: Periodic flood disturbance is a well known controlling factor of in channel and floodplain ecosystem function. However, channel manipulations during the last century have potentially altered hydrologic fluctuations, and thus ecosystem function. We examined temporal river stage hydrology, through autocorrelation analysis, at seven gauges along the Mississippi River to quantify flow periodicity and effects of systematic channel modifications on flow periodicity. Intraannual variation follows a strong one‐year cycle of six months higher flow and six months lower flow for the entire Mississippi River drainage, with precipitation as a driving force. Interannual hydrologic variation differs between the upper and lower river segments. A clear quasi‐biennial oscillation pattern was evident throughout the lower river section. The effect of channel alterations was a decreased magnitude of differences between lower and higher flows. The upper section, however, suggests a 12‐to 14‐year periodicity prior to alterations and a decreased duration of lower flow years following systematic modifications. Interannual variograms clearly depict very different temporal hydrology between the upper Mississippi River and the lower Mississippi River, suggesting the simple transfer of knowledge from one segment to the other oversimplifies the complexity of a large river system.

Knowledge of environments used during early life history and movement patterns of Bighead Carp (Hypophthalmichthys nobilis) and Silver Carp (H. molitrix), collectively termed bigheaded carps, in the Upper Mississippi River (UMR) would be valuable for informing control measures to limit further population expansion and impacts of these species. Lock and Dam 19 (LD19) is a high-head dam on the UMR that delineates downriver areas where bigheaded carps are well established from upriver pools where these species are less abundant and evidence of reproduction and recruitment are limited. Principal natal environments supporting recruitment of emerging bigheaded carp populations in the UMR are unknown. The objectives of this study were to (1) infer environments occupied during early-life stages by bigheaded carps collected in UMR Pools 19–21 during 2013–2014 using otolith microchemistry and stable isotope analyses, and (2) use early-life environment assignments and capture location to identify individuals that passed through LD19. Differences in multivariate water chemistry signatures (Sr:Ca, Ba:Ca and δ18O) among the UMR, its tributaries, and the Missouri and Middle Mississippi rivers enabled development of a classification model for inferring early-life environment of bigheaded carps. Multiple sources of recruits, including from tributaries, have contributed to upriver expansion of bigheaded carps in the UMR. Sustainable control of bigheaded carps upstream of LD19 will likely require efforts to control local recruitment and immigration from downriver. The frequency of bigheaded carps collected in Pool 19 that were downstream of LD19 during early life suggests that bigheaded carps upstream of LD19 still predominantly consisted of immigrants from downriver during 2013–2014. Otolith chemistry provides an approach for assessing the extent to which changes in abundance of bigheaded carps upstream of LD19 are associated with local recruitment or immigration from downriver.

Our project sought to determine ecological effects of adding low‐head dams and levees to large rivers by examining potential changes to aquatic food webs over a 70‐year period in the Lower Ohio River (LOR) and Upper Mississippi River (UMR). We employed museum collections of fish and compound specific stable isotope analysis of amino acids to evaluate long‐term changes in primary food sources for multiple species of fish in each river. Fishes in both rivers depended more on autochthonous than allochthonous carbon sources throughout the 70‐year period (based on measurements of isotopic signatures of algae, C3 plants, C4 plants, cyanobacteria, and fungi), but the relative use of different carbon sources differed between the UMR and LOR. Significant but opposite shifts in trophic positions (TP) between rivers over time (higher TP in the UMR; lower in the LOR) were correlated with major anthropogenic changes to habitat structure (e.g. slight decrease in abundance of side channels in the UMR; increase in pool water depth in the LOR) resulting from low‐head dam construction. They may also have been influenced by likely increased primary productivity in the UMR from agricultural nitrogen inputs and by possible shifts in the importance of phytoplankton versus benthic algae in the LOR from changes in water depth. Shifts in trophic position and reliance on various food sources were not correlated with variation in discharge, gage height, or temperature. Although these two rivers have contrasting hydrogeomorphic complexity (UMR is an anastomosing river, while the LOR is a constricted channel river) and different discharge patterns (seasonal versus yearly operation in some cases), both differ substantially from rivers having hydrogeomorphic changes resulting from construction of high dams (>15 m). It is not surprising, therefore, that factors controlling trophic position and reliance on different carbon sources vary among different types of dams and river structures.

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 Pool 8 based on geographic information systems (GIS) coverages of bathymetry and current velocity. The value of paddlefish habitat in the cartographic model increased with depth and decreased with current velocity. For example, areas modeled as excellent corresponded to regions classified as having both deep water (≥6.0 m) and negligible (<5 cm/s) current velocities. Our study suggests that aquatic area types are an inadequate basis for making sound management decisions regarding the critical habitats of paddlefish in complex riverine systems because such strata rely on gross geomorpological features rather than on the physicochemical variables that fish use to choose habitats. The development of systemic GIS coverages of such variables could improve the understanding of fish habitat selection and management in the upper Mississippi River.

Floodplain systems in the Driftless Area have experienced widespread historical transformations in hydrologic and sediment characteristics as well as rates of hydrogeomorphic processes. These changes exceed natural variability experienced during the Holocene and are driven by nearly two centuries of major land-cover alterations coupled with shifting precipitation patterns. On the pre–Euro-American landscape, tributaries to the Upper Mississippi River had clear, constant base flow and low sedimentation rates due to a protective cover of prairie, oak savanna, and woodland. The Upper Mississippi River was sandy and braided, with geomorphologically diverse backwaters, side channels, and vegetated islands. Soil erosion and gullying caused by agriculture-related land clearance have had the largest historical effects on Upper Mississippi River tributary stream morphology and floodplain sedimentation. Floodplain sedimentation rates for tributaries and the Upper Mississippi River were 0.2 and 0.9 mm/yr, respectively, before Euro-American settlement, compared to 2–20 and 5–20 mm/yr after Euro-American settlement, respectively. The soil conservation movement had its birthplace in the Driftless Area in the 1920s because of the region’s widespread landscape degradation. As soil erosion decreased and gullies were stabilized in the middle to late twentieth century, land management efforts turned toward the lingering problem of fine-grained, phosphorus-rich sediment stored in tributary floodplains and channels. This trend has been complicated by a climatic shift in the late twentieth century toward increased annual precipitation, increased flood variability, and more floods in late fall and winter months, when bare fields are vulnerable to runoff. Floods are major contributors to channel erosion and deposition, and variability in magnitudes and frequency will likely continue in the early twenty-first century. Restoration efforts in tributaries have included reducing bank erosion, reconnecting floodplains, and adding trout habitat features. Lock and dam structures have altered sediment transport and erosion processes within the Upper Mississippi River, and restoration efforts there have focused on creation and rehabilitation of islands and protection of remnant off-channel backwater habitats.

Since its escapement into the Upper Mississippi River (UMR) and rapid expansion in the late 1900's, the common carp, Cyprinus carpio, has become a major component of the river fishery. Mean annual harvest value for this species was $270000 between 1953 and 1977. Recent evidence suggests that common carp may not be as abundant in the river as they have been in the past. We summarized historical commerical information on common carp in the UMR to put its current harvest levels in perspective. A major factor responsible for recent low annual harvests has been PCB contamination of the river in the Lake Pepin area. Market and biological factors probably have also contributed to declining harvests. To help explain why common carp populations in the UMR may be declining, we reviewed literature pertaining to the ecology of the species, particularly that from the river, its tributaries, or midwestern lakes. We included information on how common carp are controlled by environmental factors, and how they interact with other biota. Most aspects of carp ecology in the UMR and other areas are similar. Exceptions relate primarily to their response to annual water level regimes of the river. We postulate that population declines and absent year classes in the UMR may be related to poor recruitment during high- or variable-water years.

Agricultural influence on landscape sensitivity in the Upper Mississippi River Valley

The Mississippi River and other large rivers have the potential to regulate nitrogen export from terrestrial landscapes, and thus mitigate eutrophication in downstream aquatic ecosystems. In large rivers, human-constructed impoundments and connected backwaters may facilitate nitrogen removal; however, the capacity of these features is poorly quantified and incompletely incorporated into model frameworks. Using a high-resolution and spatially intensive sampling technique, we assessed the contribution of individual navigation pools, as well as impounded open waters and backwater wetlands within them, to overall nitrate retention by mapping the entire length (1370 km) of the Upper Mississippi River (UMR) main channel. Based on this single spatial survey of water chemistry, the river appeared to act primarily as a passive nitrate transporter, retaining only 12.5% of the incoming load, most of which occurred in the upper 150 km of the river, which includes the largest and only naturally impounded reach of the river. Although reservoirs typically are nitrogen sinks, our data indicate that UMR dams do not impede river flows to the extent necessary to promote substantial changes in water residence times and subsequent nitrogen removal. Backwaters routinely had lower nitrate concentrations than the main channel, but their limited hydrologic connectivity to the through-flowing river channel constrained their influence on downstream export. As a whole, the UMR did not remove a substantial proportion of its nitrate load despite optimal N removal conditions, numerous impoundments, and the presence of extensive backwater habitats. These results suggest that efforts to reduce delivery of nitrogen to the Gulf of Mexico should emphasize mitigation strategies that target upland nutrient sources rather than relying on removal within the Mississippi River.

Floodplain sedimentation in the Upper Mississippi Valley: Natural versus human accelerated

Zooplankton samples were collected in main channel and adjacent channel border habitat at eight transects in navigation Pool 19, Mississippi River. Rotifers dominated the system with the most abundant organism being Brachionus calyciflorus. Zooplankton densities were statistically higher at both the upper and lower ends of the pool. The lower end of the pool was lacustrine in nature, thus supporting higher zooplankton densities. These high densities are transferred to the upper part of the succeeding pool Such a sequence of populations may be typical of pool systems that result from navigation structures such as those on the upper Mississippi River.

The quagga mussel (Dreissena bugensis) was first found in the Ohio River and the upper Mississippi River in the mid-1990s. It has since gone unreported in the Mississippi River system possibly due in part to its phenotypic variability and close morphological resemblance to the more commonly occurring zebra mussel (Dreissena polymorpha). Sampling of the upper Mississippi River system during 2004–2006 revealed that the quagga mussel occurred at several localities outside its previously reported distribution in the Ohio River and upper Mississippi River. Few zebra and no quagga mussels were found in the Missouri River. Quagga mussels were not abundant in our survey, comprising less than 1% of identifiable Dreissena specimens.

Muskrats (Ondatra zibethicus) were marked from 1981 through 1984 and recovered for 5 years in Pool 9, Upper Mississippi River to determine survival and harvest rates by using banding methodology. Tag reporting rate, estimated from trapper interviews, averaged 83 ? 1% and was constant among years. Survival and recovery rates did not vary significantly between sexes but were significantly different between birth-year (BY) and after-birth-year (ABY) animals. Data best fit a model assuming constant age-specific survival and year-specific recovery rates. Constant annual survival rate of BY animals was 15.7 ? 2.3%, whereas survival of ABY animals was 5.8 ? 1.5%. Harvest rates ranged from 17% in 1982 to 45% in 1981, and averaged 32 ? 2% of the fall population in all years and habitats combined. Maximum sustained yield in backwaters was 20% of yield in openwaters although annual survival was not different between habitats. There was a density-dependent increase in nonharvest, birth-to-trapping season survival of juveniles, which compensated for increases in harvest mortality. J. WILDL. MANAGE. 51(2):265-272 The effects of exploitation on populations of vertebrates remains one of the important theoretical and applied questions in wildlife ecology. Originally, basic theory on the intercompensatory nature of mortality factors emerged from studies by Errington (1946, 1956, 1963) on the effects of natural predation in influencing abundance of prey species, particularly muskrats. His concepts on predation were extended to include effects of harvest on populations as a basis for management (Allen 1954, Hickey 1955). Wagner (1969:269) later concluded that the evidence that game populations can exist under heavy hunting pressure without obvious effects on their density was equivocal. Much recent research and discussion has focussed on migratory waterfowl (Anderson and Burnham 1976, Burnham and Anderson 1984, Nichols et al. 1984). Anderson and Burnham (1976:5-9) examined the effect of harvest on annual survival of mallards (Anas platyrhynchos) and defined the competing hypotheses of to a threshold point and totally additive, which form the basis for much of this paper. Despite the interest and importance of the effects of harvest on survival, details about mechanisms involved in the relationship between exploitation and population dynamics are poorly known. Therefore, in 1981, I began studies on muskrats on the Upper Mississippi River Fish and Wildlife Refuge (UMRFWR) to examine population responses to exploitation. Muskrats are an ideal study species because: large samples of muskrats are easily captured and marked, population densities vary substantially (Clay and Clark 1985), harvest effort varies in response to changes in trapping conditions (Clark 1986), and they provide a contrast to the studies on migratory waterfowl. Furthermore, practical management of muskrats rests on whether populations respond to changes in harvest in an inversity-compensatory manne (sensu Roseberry [1979]). Clay and Clark (1985) have previously shown density-dependent reproduction (inversity) in Pool 9 populations of muskrats. The task of demonstrating whether compensatory interactions exist between natural mortality and harvest remains. In this paper I examine the effects of harvest on survival, with the goal of contributing to both the theoretical basis for harvesting populations and the management of muskrats. A series of consequences of compensatory theory (Nichols et al. 1984) was examined in light of the Pool 9 studies. These results are an extension and, to some degree, a re-examination of previous results (Clay and Clark 1985) using more data and new techniques. The field work was funded through the Iowa Coop. Wildl. Res. Unit by the Upper Miss. River Basin Comm., U.S. Fish and Wildl. Serv., Iowa Conserv. Comm., and Wis. Dep. Nat. Resour. This is Paper J-12181 of the Iowa Agric. and Home Econ. Exp. Stn., Proj. 2401. R. T. Clay, K. L. Johnson, R. J. Munkel, K. R. Utterson, and R. E. Young conducted the marking and M. M. Anderson and J. Lyons facilitated tag recovery and contact with trappers. J. D. Nichols was particularly helpful with suggestions on parameter and variance estimation and interpretation. K. J. Koehler and H. D. Baker

Silver Carp Hypophthalmichthys molitrix is an invasive species found throughout the Mississippi River basin. Efforts have been made to control Silver Carp populations through removal programs and movement barrier implementation. Up to date information on diel, seasonal, and annual movements and habitat use by Silver Carp will benefit these efforts. Studies of Silver Carp movement are prevalent in the upper Mississippi River, Ohio River, and tributaries, but rare in tributaries of the lower Mississippi River. Between June 2021 and May 2022, we quantified average movement rates and residency periods of 48 Silver Carp in the free-flowing lower White River and lock-and-dam fragmented lower Arkansas River using passive acoustic telemetry arrays and internal implant acoustic transmitters. We also manually tracked Silver Carp in the two rivers during the four seasons to estimate diel movement rates and use of different habitats. On an annual scale, Silver Carp in the White River moved at faster rates than Silver Carp in the Arkansas River and were recorded more times by acoustic receivers. Diel movement rates varied by season in both rivers but were low overall. Silver Carp used lentic habitats more often than lotic habitats. Overall, results suggest the numerous locks and dams of the McClellan-Kerr Arkansas River Navigation System may limit large-scale, annual movement of Silver Carp in the Arkansas River compared to the White River. Low hourly diel movement rates and high occupancy of lentic habitats also should enable effective harvest of Silver Carp using active gears in those lentic habitats.

The usually abundant slow soaking rain systems and evening thunderstorms that characterize the Great Plains climate from May through August (Hoerling 2013) were absent in 2012. As a result, the Ohio and Mississippi rivers dropped to near record levels from July of 2012 through January of 2013, and the US Army Corps of Engineers (USACE) faced a new challenge to their ability to control the Mississippi River. The 2012 drought reduced the channel depths on the upper Mississippi River between Cairo, Illinois, and St. Louis, Missouri, to only 0.3 to 1.8 m (1 to 6 ft) above the 2.7 m (9 ft) deep navigation shipping channel created by USACE in response to the 1930 Rivers and Harbors Act. Of greatest concern was the bedrock-lined river shipping channel near Thebes, Illinois, which threatened to ground barge traffic transporting critical agricultural supplies, including fertilizers and grain.