Variable δ15N Diet-Tissue Discrimination Factors among Sharks: Implications for Trophic Position, Diet and Food Web Models

The application of stable isotopes to characterize the complexities of a species foraging behavior and trophic relationships is dependent on assumptions of δ15N diet-tissue discrimination factors (∆15N). As ∆15N values have been experimentally shown to vary amongst consumers, tissues and diet composition, resolving appropriate speciesspecific ∆15N values can be complex. Given the logistical and ethical challenges of controlled feeding experiments for determining ∆ 15N values for large and/or endangered species, our objective was to conduct an assessment of a range of reported ∆ 15N values that can hypothetically serve as surrogates for describing the predator-prey relationships of four shark species that feed on prey from different trophic levels (i.e., different mean δ 15N dietary values). Overall, the most suitable species-specific ∆ 15N values decreased with increasing dietary-δ 15N values based on stable isotope Bayesian ellipse overlap estimates of shark and the principal prey functional groups contributing to the diet determined from stomach content analyses. Thus, a single ∆ 15N value was not supported for this speciose group of marine predatory fishes. For example, the ∆ 15N value of 3.7‰ provided the highest percent overlap between prey and predator isotope ellipses for the bonnethead shark (mean diet δ 15N = 9‰) whereas a ∆ 15N value \u3c 2.3‰ provided the highest percent overlap between prey and predator isotope ellipses for the white shark (mean diet δ 15N = 15‰). These data corroborate the previously reported inverse ∆ 15N-dietary δ 15N relationship when both isotope ellipses of principal prey functional groups and the broader identified diet of each species were considered supporting the adoption of different ∆ 15N values that reflect the predators’ δ 15N-dietary value. These findings are critical for refining the application of stable isotope modeling approaches as inferences regarding a species’ ecological role in their community will be influenced with consequences for conservation and management actions

Estimating population size of largemouth bass and black crappie at The Nature Conservancy's Emiquon Preserve prior to reconnection to the Illinois River

Prior to completion of the water control structure at The Nature Conservancy’s Emiquon Nature Preserve (Emiquon), a mark-recapture study was conducted on largemouth bass Micropterus salmoides and black crappie Pomoxis nigromaculatus to estimate the populations of both species. Largemouth bass > 150 mm and black crappie > 100 mm were captured using pulsed-DC electrofishing, fyke nets, and tandem fyke nets and double tagged using T-bar style clear tags. Results of this study show very large populations of both species, with populations of largemouth bass estimated at 21,090 (17,110-27,484) and black crappie estimated at 205,042 (91,198-490,563). Information gained in this study will allow Nature Conservancy managers to make informed decisions on future management actions and allow for potential evaluation of those management actions on two major components of the recreational fishery at Emiquon.Ope

The long-term Illinois rivers fish population monitoring program 2014

This report presents a summary of those data collected during segment 26(2014-15) of the Long-term Illinois Rivers Fish Population Monitoring Program(LTEF), an annual survey executed by members of the Illinois Natural History Survey with funds administered by the U.S. Fish and Wildlife Service and the Illinois Department of Natural Resources. Sampling for the LTEF program was conducted on: six reaches of the Illinois River Waterway, six segments or pools of the Mississippi River, and navigable portions of the Iroquois and Kankakee Rives. In all segments of the LTEF program, all fish species collected were accurately identified, tallied, measured, and weighed. The catch rates of sportfish species were calculated as the number of individuals collected per hour (CPUEN± standard error). Structural indices [Proportional Size Distribution (PSD) and Relative Weight (Wr)] were also calculated for species of interest to regional managers. Catch rates and species richness varied greatly among all sampling locations and sampling periods. Emerald Shiners and Gizzard Shad comprised the majority of the individuals caught, and Silver Carp and Common Carp accounted for the greatest proportion of the biomass collected in most sampling areas of the survey. The analysis of CPUEN and PSD trends in sportfish populations sampled by the program may indicate inter-annual recruitment patterns in sportfish populations around the state. Both Shovelnose Sturgeon and Blue Catfish were the two species most commonly encountered in the gill net surveys.IDNR Division of Fisheries Project F-101-R, Segment 26unpublishednot peer reviewe

Over 50 years of fish community monitoring in Illinois’ large rivers: The evolution of methods used by the Illinois Natural History Survey’s Long-term Survey and Assessment of Large-River Fishes in Illinois

Federal Aid in Sport Fish Restoration Act (F-101-R), administered by the U.S. Fish and Wildlife Service and Illinois Department of Natural Resourcesis peer reviewedOpe

Long-term Survey and Assessment of Large-River Fishes in Illinois, 2015

This report presents a summary of those data collected during segment 26 (2014-15) of the Long-term Survey and Assessment of Large-River Fishes in Illinois (LTEF), an annual survey executed by members of the Illinois Natural History Survey with funds administered by the U.S. Fish and Wildlife Service and the Illinois Department of Natural Resources. Sampling for the LTEF program was conducted on: six reaches of the Illinois River Waterway, six segments or pools of the Mississippi River, and navigable portions of the Iroquois and Kankakee Rivers. In all segments of the LTEF program, all fish species collected were accurately identified, tallied, measured, and weighed. The catch rates of sportfish species were calculated as the number of individuals collected per hour (CPUEN± standard error). Structural indices [Proportional Size Distribution (PSD) and Relative Weight (Wr)] were also calculated for species of interest to regional managers. Catch rates and species richness varied greatly among all sampling locations and sampling periods. Emerald Shiners and Gizzard Shad comprised the majority of the individuals caught, and Silver Carpand Common Carp accounted for the greatest proportion of the biomass collected in most sampling areas of the survey. The analysis of CPUEN and PSD trends in sportfish populations sampled by the program may indicate inter-annual recruitment patterns or long-term trends in sportfish populations around the state. Shovelnose Sturgeon was the species most commonly encountered in the gill net surveys; sampling was substantially reduced during the 2015-2016 winter season relative to previous years due to moderate to major flooding during the majority of the field season.IDNR Division of Fisheries U.S. Fish & Wildlife Service F-101-R, Segment 27unpublishednot peer reviewe

SNAPSHOT USA 2019 : a coordinated national camera trap survey of the United States

This article is protected by copyright. All rights reserved.With the accelerating pace of global change, it is imperative that we obtain rapid inventories of the status and distribution of wildlife for ecological inferences and conservation planning. To address this challenge, we launched the SNAPSHOT USA project, a collaborative survey of terrestrial wildlife populations using camera traps across the United States. For our first annual survey, we compiled data across all 50 states during a 14-week period (17 August - 24 November of 2019). We sampled wildlife at 1509 camera trap sites from 110 camera trap arrays covering 12 different ecoregions across four development zones. This effort resulted in 166,036 unique detections of 83 species of mammals and 17 species of birds. All images were processed through the Smithsonian's eMammal camera trap data repository and included an expert review phase to ensure taxonomic accuracy of data, resulting in each picture being reviewed at least twice. The results represent a timely and standardized camera trap survey of the USA. All of the 2019 survey data are made available herein. We are currently repeating surveys in fall 2020, opening up the opportunity to other institutions and cooperators to expand coverage of all the urban-wild gradients and ecophysiographic regions of the country. Future data will be available as the database is updated at eMammal.si.edu/snapshot-usa, as well as future data paper submissions. These data will be useful for local and macroecological research including the examination of community assembly, effects of environmental and anthropogenic landscape variables, effects of fragmentation and extinction debt dynamics, as well as species-specific population dynamics and conservation action plans. There are no copyright restrictions; please cite this paper when using the data for publication.Publisher PDFPeer reviewe

Mammal responses to global changes in human activity vary by trophic group and landscape

Wildlife must adapt to human presence to survive in the Anthropocene, so it is critical to understand species responses to humans in different contexts. We used camera trapping as a lens to view mammal responses to changes in human activity during the COVID-19 pandemic. Across 163 species sampled in 102 projects around the world, changes in the amount and timing of animal activity varied widely. Under higher human activity, mammals were less active in undeveloped areas but unexpectedly more active in developed areas while exhibiting greater nocturnality. Carnivores were most sensitive, showing the strongest decreases in activity and greatest increases in nocturnality. Wildlife managers must consider how habituation and uneven sensitivity across species may cause fundamental differences in human–wildlife interactions along gradients of human influence.Peer reviewe

Sublethal Effects of Acoustic Dummy Tag Implantation and External Tags in Silver Carp

Telemetry data collected via internally implanted transmitters are commonly used to monitor and manage invasive Silver Carp Hypophthalmichthys molitrix. However, the extent to which posttagging effects may influence fish behavior is generally overlooked in telemetry studies. Moreover, internal telemetry tags are often combined with an external tag that can also affect fish growth and survival. This study used two pond experiments to (1) evaluate the temporal effects of internal telemetry tags, external jaw tags, and the combination of the two tags on survival, relative weight, growth, and inflammation; and (2) compare the effects of two external tag types (jaw and loop tags) on Silver Carp. Response variables were evaluated at three time points: 1, 2, and 5 months posttagging. Growth and relative weight were lower in fish that received jaw tags than in the control group or in fish that received internal tags only; however, growth was different at 1 month posttagging but not at 2 months posttagging, indicating potential compensatory growth. Shedding rate of internal tags was 14%; after 5 months, inflammation was absent and tags were encapsulated in tissue. Survival was similar between loop- and jaw-tagged fish (73%), although growth was lower in jaw-tagged fish. Results indicate that survival effects and sublethal effects of telemetry tagging may be temporary, and researchers should examine detection data from within 1–2 months of tagging for possible postsurgery effects. Jaw tags reduced growth, and loop tags had reduced retention; therefore, further evaluation of alternative external tags is needed to optimize telemetry studies focused on Silver Carp. Additionally, researchers need to carefully evaluate which external tag to use to facilitate the returns of more expensive acoustic telemetry tags and whether external tags are necessary in a particular case

The Long-term Illinois, Mississippi, Ohio, And Wabash Rivers Fish Population Monitoring Program 2012

This report presents a summary of those data collected during segment 24 (2012-13) of the Long-term Illinois, Mississippi, Ohio, and Wabash Rivers Fish Population Monitoring Program (LTEF), an annual survey executed by members of the Illinois Natural History Survey with funds administered by the U.S. Fish and Wildlife Service and the Illinois Department of Natural Resources. Sampling for the LTEF program was conducted in twenty study areas: six reaches of the Illinois River Waterway, six segments or pools of the Mississippi River, four segments or pools of the Ohio River, and five segments of the Wabash River. Six reaches of the Illinois River Waterway were sampled from Aug-Oct 2012 using boat-mounted AC electrofishing arrays at 28 fixed sites. Sampling was conducted during June-October2012in five reaches of the Illinois River Waterway, six segments or pools of the Mississippi River, four segments or pools of the Ohio River, and five segments of the Wabash Riverusing boat-mounted pulsed DC electrofishing gears. Gill net collections were conducted in two sections of the Mississippi River during fall 2012 and spring 2013. In all segments of the LTEF program, all fish species collected were accurately identified, tallied, measured, and weighed. The capture rates of each species were calculated as the number of individuals collected per hour (CPUEN) and the weight of a given species collected per hour (CPUEW). Samples collected using AC electrofishing were characterized by high species richness and relatively high capture rates of notable fish species (e.g. bluegill, smallmouth bass, smallmouth buffalo, silver carp, and common carp). Over 39,000 fishes were captured in the larger-scale pulsed DC electrofishing survey, although capture rates and species richness varied greatly among all sampling locations and time periods. Emerald shiners and gizzard shad comprised the majority of the individuals captured, while silver carp and common carp accounted for the greatest proportion of the biomass collected in all segments of the DC electrofishing surveys. Both shovelnose sturgeon and blue catfish were the two species most commonly encountered in the gill net surveys. An analysis of gill netting data suggests that sampling at randomly selected wing-dam habitats may be the most effective strategy for long-term monitoring of shovelnose sturgeon and blue catfish abundances in future years. While the factors controlling the annual variations in the relative abundances of fishes in Midwestern Rivers may be difficult to measure, our ability to detect and possibly explain such changes is dependent upon the execution of well-designed fisheries surveys. The operation and maintenance of the LTEF program and the data it generates can contribute to more complex and nuanced understandings that can, in turn, aid in the development of more effective and sustainable management policies for the rivers of Illinois.IDNR Division of Fisheries U.S. Fish & Wildlife Serviceunpublishednot peer reviewe

Status and Genetic Character of Atlantic Sturgeon in the Satilla River, Georgia

<p>The Atlantic Sturgeon <i>Acipenser oxyrinchus oxyrinchus</i> is an important component of biodiversity along the Atlantic coast of North America, but most populations have been decimated by habitat degradation and chronic overfishing. Historically, spawning populations existed in all major Atlantic coast rivers from the St. Lawrence River, Quebec, to the St. Johns River, Florida, but fisheries surveys conducted in the past two decades suggest that several populations at the southern extent of this range are now extirpated or have declined to remnant status. Our objective was to assess the abundance and genetic character of Atlantic Sturgeon in the Satilla River, Georgia. Using entanglement gears, we expended over 2,800 h of sampling effort and captured a total of 193 Atlantic Sturgeon in tidally influenced reaches of the river during 2008–2010. Of the 157 fish that were collected in 2010, 72 were identified as river-resident juveniles (ages 0–1). Genetic analyses of a subset (<i>n</i> = 61) of these juveniles revealed (1) depauperate levels of mitochondrial DNA (mtDNA) haplotype diversity and (2) the presence of large family units based on microsatellite DNA multilocus genotypes, collectively suggesting that very few parents produced the 2008 year-class. The mtDNA and microsatellite analyses both indicated that juveniles in the Satilla River population were genetically distinct from other populations in the South Atlantic Distinct Population Segment. Atlantic Sturgeon life history characteristics and the present results suggest that sampled juveniles from the 2008 year-class were the offspring of a small remnant pool of Satilla River adults; however, a full description of the population's genetic character and origin will require additional juvenile samples from future year-classes.</p> <p>Received May 15, 2015; accepted September 9, 2015</p