Aquaculture and Fisheries Commons^™

Quantifying The Adaptive Cycle, David G. Angeler, Craig R. Allen, Ahjond S. Garmestani, Lance H. Gunderson, Olle Hjerne, Monika Winder

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

The adaptive cycle was proposed as a conceptual model to portray patterns of change in complex systems. Despite the model having potential for elucidating change across systems, it has been used mainly as a metaphor, describing system dynamics qualitatively. We use a quantitative approach for testing premises (reorganisation, conservatism, adaptation) in the adaptive cycle, using Baltic Sea phytoplankton communities as an example of such complex system dynamics. Phytoplankton organizes in recurring spring and summer blooms, a well-established paradigm in planktology and succession theory, with characteristic temporal trajectories during blooms that may be consistent with adaptive cycle phases. We used long-term …

The Status Of Fishes In The Missouri River, Nebraska: Selected Ancient Fishes, Kirk D. Steffensen

Transactions of the Nebraska Academy of Sciences and Affiliated Societies

Several ancient fish species have inhabited the Missouri River and its tributaries for thousands of years prior to major mainstem modifications and fragmentation. However post-anthropogenic modifications, populations of these ancient fish species have been highly diminished. Therefore, the objective of this study was to use historic and current ichthyological records to determine the past and present status for Chestnut Lamprey Ichthyomyzon castaneus, Silver Lamprey Ichthyomyzon unicuspis, Bowfin Amia calva, American Eel Anguilla rostrata, and Burbot Lota lota. Currently, these species are rarely captured and perhaps extirpated from Nebraska waters.

Population Dynamics And Movement Of Channel Catfish In The Red River Of The North, Stephen F. Siddons

School of Natural Resources: Dissertations, Theses, and Student Research

Channel Catfish are widely distributed across North America and highly valued as a sport fish and for food. While most Channel Catfish fisheries are managed under liberal harvest regulations, the Red River of the North (Red River) in Manitoba, Canada is managed with restrictive harvest regulations to promote a trophy fishery. Two barriers (dams) are present on the main stem of the Red River and may fragment the population to some degree. My objectives were to: 1) analyze population dynamics of the trophy Channel Catfish population on the lower Red River, 2) compare population characteristics of Channel Catfish in selected …

Spreading Holiday Spirit And Northwestern Salamanders, Ambystoma Gracile (Baird 1859) (Caudata: Ambystomatidae), Across The Usa, Michael R. Rochford, Jeffrey M. Lemm, Kenneth Krysko, Louis A. Somma, Robert W. Hansen, Frank J. Mazzotti

Papers in Herpetology

Introduced species of amphibians and reptiles are of growing conservation concern (Bury and Luckenbach 1976; Krysko et al. 2011; Meshaka 2011). Unintentional introductions result largely from individuals escaping from enclosures or hitch-hiking in cargo or on vehicles, whereas intentional introductions occur primarily because a species is perceived to be of value to humans or from deliberately releasing sick or unwanted animals, including pets (Kraus 2009; Krysko et al. 2011). In Florida, most known introductions are directly related to the pet trade, but about 12% are related to the cargo pathway (Krysko et al. 2011). In this paper, we report the …

Blow-Up Of Positive Solutions To Wave Equations In High Space Dimensions, Mohammad A. Rammaha, Hiroyuki Takamura, Hiroshi Uesaka, Kyouhei Wakasa

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

This paper is concerned with the Cauchy problem for the semilinear wave equation:

utt - u = F(u) in Rn X [0;1);

where the space dimension n >2, F(u) = jujp or F(u) = up-1u with p>1. Here, the Cauchy data are non-zero and non-compactly supported. Our results on the blow-up of positive radial solutions (not necessarily radial in low dimensions n=2,3) generalize and extend the results of Takamura [19] for zero initial position and Takamura, Uesaka and Wakasa [21] for zero intitial velocity. The main technical difficulty in the paper lies in obtaining the lower bounds for for …

Bioenergetics And Habitat Suitability Models For The Chinese Mystery Snail (Bellamya Chinensis), Danielle M. Haak

School of Natural Resources: Dissertations, Theses, and Student Research

Relatively little is known about the invasive Chinese mystery snail (Bellamya chinensis). This research aims to elucidate some of the mystery surrounding this species. First, we place the species in context with other invasive freshwater snails of the USA and Canada, identifying current information gaps, categorizing shared characteristics among families and species, and comparing functional roles and ecological effects of freshwater snails. We conclude that more focus needs to be directed to regulating the aquarium, pet, and food trades if we are serious about preventing future invasions. Next, we develop a bioenergetics model for the species by quantifying …

Ecology And Management Of Superabundant Fish Populations, Nathaniel T. Stewart

School of Natural Resources: Dissertations, Theses, and Student Research

Fish population biomasses can reach extreme levels; we term these populations superabundant fish populations. Superabundant fish populations may negatively affect aquatic communities and anglers, necessitating the effective management of the superabundant fish populations. However, there are gaps in our understanding of these populations. The gaps in our understanding hamper our ability to predict effects on valuable sportfisheries and to effectively manage superabundant fish populations. The overall goal of my thesis research is to provide further insight into the ecology of superabundant fish populations and to provide information that will aid in their effective management. First, we described a new method …

Genetic And Morphological Variation In Ecuadorian Astroblepid Catfishes, Katherine M. Lawry

School of Natural Resources: Dissertations, Theses, and Student Research

The Andean ichthyofauna remains a poorly understood component of Neotropical biodiversity, and stands in stark contrast to the lowland ichthyofauna in terms of number of species and range of distribution. The Climate Variability Hypothesis (CVH) predicts rapid turnover of species along elevational gradients in tropical climates, but it remains unclear whether stream fishes follow this pattern. Astroblepid catfishes represent a distinctive assemblage of species that inhabit high elevation streams throughout the Andes from Panama to Bolivia, and constitute the only native fish family present in the Ecuadorian highland region. In this research, population samples of Astroblepids collected throughout Ecuador’s Napo …

Fertilizers In Aquaculture, Bartholomew Green

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Pond fertilization is an important component of semi-intensive to intensive aquaculture pond management that supports successful production of the culture organism. Semi-intensive and intensive aquaculture pond management fall along the extensive to hyper-intensive management continuum and are characterized by high stocking rate of the culture animal, limited use of fertilizers, use of compound or complete feeds, and water quality monitoring and management, including use of mechanical aeration. Fertilization contributes to establishing and maintaining a pond environment that allows the culture organism to utilize efficiently the compound or complete feeds offered. This chapter presents information on pond food webs, sources and …

Hypoxia Affects Performance Traits And Body Composition Of Juvenile Hybrid Striped Bass (Morone Chrysops X M. Saxatilis), Bartholomew W. Green, Steven D. Rawles, Sidney A. Fuller, Benjamin H. Beck, Matthew E. Mcentire

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Performance traits and body composition of juvenile hybrid striped bass (Morone chrysops x M. saxatilis) in response to hypoxia were evaluated in replicate tanks maintained at constant dissolved oxygen concentrations that averaged 23.0 ± 2.3%, 39.7 ± 3.0%, and 105.5 ± 9.5% dissolved oxygen saturation. Fish were fed a commercially formulated feed daily to apparent satiation. Total feed intake and fish growth and yield increased linearly in response to increased dissolved oxygen concentration. Nutrient utilization was reduced significantly only at the greatest level of hypoxia. With the exception of whole-body protein content, whole body compositional indices and nutrient …

Nile Tilapia And Blue Tilapia Fry Production In A Subtropical Climate Based On Degree Days, Bartholomew W. Green, Esam H. Rizkalla

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The relationship between production in subtropical earthen ponds of fry suitable for hormonal sex inversion and degree days was quantified for Nile tilapia (Oreochromis niloticus; Egypt strain) and blue tilapia (O. aureus). Degree days were calculated for each trial as the sum of mean daily water column temperature minus the reference temperature, 15◦C. No fry from either species were harvested at fewer than 124–126 degree days. Total fry production for each increased linearly as cumulative degree days increased from 129 to 281 degree days. Production of fry suitable for hormonal sex inversion was positively related to …

Reservoir Area Of Influence And Implications For Fisheries Management, Dustin R. Martin, Christopher J. Chizinski, Kevin L. Pope

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Understanding the spatial area that a reservoir draws anglers from, defined as the reservoir’s area of influence, and the potential overlap of that area of influence between reservoirs is important for fishery managers. Our objective was to define the area of influence for reservoirs of the Salt Valley regional fishery in southeastern Nebraska using kernel density estimation. We used angler survey data obtained from in-person interviews at 17 reservoirs during 2009–2012. The area of influence, defined by the 95% kernel density, for reservoirs within the Salt Valley regional fishery varied, indicating that anglers use reservoirs differently across the regional fishery. …

Reservoir Rehabilitations: Seeking The Fountain Of Youth, Mark A. Pegg, Kevin L. Pope, Larkin A. Powell, Kelly C. Turek, Jonathan J. Spurgeon, Nathaniel T. Stewart, Nick P. Hogberg, Mark T. Porath

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Aging of reservoirs alters the functions, and associated services, of these systems through time. The goal of habitat rehabilitation is often to alter the trajectory of the aging process such that the duration of the desired state is prolonged. There are two important characteristics in alteration of the trajectory—the amplitude relative to current state and the subsequent rate of change, or aging—that ultimately determine the duration of extension for the desired state. Rehabilitation processes largely fall into three main categories: fish community manipulation, water quality manipulation, and physical habitat manipulation. We can slow aging of reservoirs through carefully implemented management …

The Global Status Of Freshwater Fish Age Validation Studies And A Prioritization Framework For Further Research, Jonathan J. Spurgeon, Martin J. Hamel, Kevin L. Pope, Mark A. Pegg

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Age information derived from calcified structures is commonly used to estimate recruitment, growth, and mortality for fish populations. Validation of daily or annual marks on age structures is often assumed, presumably due to a lack of general knowledge concerning the status of age validation studies. Therefore, the current status of freshwater fish age validation studies was summarized to show where additional effort is needed, and increase the accessibility of validation studies to researchers. In total, 1351 original peer-reviewed articles were reviewed from freshwater systems that studied age in fish. Periodicity and age validation studies were found for 88 freshwater species …

Barriers And Bridges To The Integration Of Social–Ecological Resilience And Law, Olivia Odom Green, Ahjond S. Garmestani, Craig R. Allen, Lance H. Gunderson, J.B. Ruhl, Craig A. Arnold, Nicholas A.J. Graham, Barbara Cosens, David G. Angeler, Brian C. Chaffin, C.S. Holling

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

There is a fundamental difference between the ways in which ecologists and lawyers view uncertainty: in the study of ecology, uncertainty provides a catalyst for exploration, whereas uncertainty is antithetical to the rule of law. This issue is particularly troubling in environmental management, where the tensions between law and ecology become apparent. Rather than acknowledge uncertainties in management actions, legal frameworks often force a false sense of certainty in linking cause and effect. While adaptive management has been developed to deal with uncertainty, laws and legal wrangling can be obstacles to implementation. In this article, we recommend resilience-based governance – …

Quantifying The Adaptive Cycle, David G. Angeler, Craig R. Allen, Ahjond S. Garmestani, Lance H. Gunderson

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

The adaptive cycle was proposed as a conceptual model to portray patterns of change in complex systems. Despite the model having potential for elucidating change across systems, it has been used mainly as a metaphor, describing system dynamics qualitatively. We use a quantitative approach for testing premises (reorganisation, conservatism, adaptation) in the adaptive cycle, using Baltic Sea phytoplankton communities as an example of such complex system dynamics. Phytoplankton organizes in recurring spring and summer blooms, a well-established paradigm in planktology and succession theory, with characteristic temporal trajectories during blooms that may be consistent with adaptive cycle phases. We used long-term …

Across-Ecoregion Analysis Suggests A Hierarchy Of Ecological Filters That Regulate Recruitment Of A Globally Invasive Fish, Przemek G. Bajer, Timothy K. Cross, Joseph D. Lechelt, Christopher J. Chizinski, Michael J. Weber, Peter W. Sorensen

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Aim -- Even successful invaders are abundant only in a fraction of locales they inhabit. One of the main challenges in invasion ecology is explaining processes that drive these patterns. We investigated recruitment of a globally invasive fish, common carp (Cyprinus carpio), across three ecoregions to determine the role of environmental characteristics, predatory communities and propagule pressure on the invasion process at coarse and fine spatial scales.

Location -- Lakes across Northern Forest, Temperate Forest and Great Plains ecoregions of North America.

Methods -- We used data from 567 lakes to model presence or absence of carp recruitment …

The Importance Of Scaling For Detecting Community Patterns: Success And Failure In Assemblages Of Introduced Species, Craig R. Allen, David G. Angeler, Michael P. Moulton, Crawford S. Holling

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Community saturation can help to explain why biological invasions fail. However, previous research has documented inconsistent relationships between failed invasions (i.e., an invasive species colonizes but goes extinct) and the number of species present in the invaded community. We use data from bird communities of the Hawaiian island of Oahu, which supports a community of 38 successfully established introduced birds and where 37 species were introduced but went extinct (failed invasions). We develop a modified approach to evaluate the effects of community saturation on invasion failure. Our method accounts (1) for the number of species present (NSP) when the species …

The Effects Of Harvest Regulations On Behaviors Of Duck Hunters, Matthew T. Haugen, Larkin A. Powell, Mark P. Vrtiska, Kevin L. Pope

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Uncertainty exists as to how duck harvest regulations influence waterfowl hunter behavior. We used the U.S. Fish and Wildlife Service’s Parts Collection Survey to examine how harvest regulations affected behaviors of Central Flyway duck hunters. We stratified hunters into ranked groups based on seasonal harvest and identified three periods (1975–1984, 1988–1993, 2002–2011) that represented different harvest regulations (moderate, restrictive, and liberal, respectively; season length and daily bag limits smallest in restrictive seasons and largest in liberal seasons). We examined variability of seven measures of duck hunter behaviors across the periods: days harvesting ducks, daily harvest, hunter mobility, mallard (Anas platyrhynchos …

Masked Expression Of Life- History Traits In A Highly Variable Environment, Jason A. Deboer, Joseph J. Fontaine, Christopher J. Chizinski, Kevin L. Pope

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Differing life-history strategies may act as a constraint on reproductive expression that ultimately limits the ability of individual species to respond to changes in the magnitude or frequency of environmental variation, and potentially underlies the variation oft en inherent in phenotypic and evolved responses to anthropogenic change. Alternatively, if there are environmental cues that predict reproductive potential, differential expression of life-history strategies may represent differences in the adaptive capacity to optimize current reproductive value given variation in environmental conditions. We compared several aspects of walleye Sander vitreus spawning ecology at two reservoirs that diff er in environmental variability (i.e., annual …

Accuracy Or Precision: Implications Of Sample Design And Methodology On Abundance Estimation, Lucas K. Kowalewski, Christopher J. Chizinski, Larkin A. Powell, Kevin L. Pope, Mark A. Pegg

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Sampling by spatially replicated counts (point-count) is an increasingly popular method of estimating population size of organisms. Challenges exist when sampling by point-count method, and it is often impractical to sample entire area of interest and impossible to detect every individual present. Ecologists encounter logistical limitations that force them to sample either few large-sample units or many small sample-units, introducing biases to sample counts. We generated a computer environment and simulated sampling scenarios to test the role of number of samples, sample unit area, number of organisms, and distribution of organisms in the estimation of population sizes using N-mixture …

Experimental Evaluation Of Rainbow Trout Oncorhynchus Mykiss Predation On Longnose Dace Rhinichthys Cataractae, Kelly C. Turek, Mark A. Pegg, Kevin L. Pope

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Laboratory and in-stream enclosure experiments were used to determine whether rainbow trout Oncorhynchus mykiss influence survival of longnose dace Rhinichthys cataractae. In the laboratory, adult rainbow trout preyed on longnose dace in 42% of trials and juvenile rainbow trout did not prey on longnose dace during the first 6 h after rainbow trout introduction. Survival of longnose dace did not differ in the presence of adult rainbow trout previously exposed to active prey and those not previously exposed to active prey (x²₁ = 0.28, P = 0.60). In field enclosures, the number of longnose dace decreased at …

Predictions Of Future Ephemeral Springtime Waterbird Stopover Habitat Availability Under Global Change, Daniel R. Uden, Craig R. Allen, Andrew A. Bishop, Roger Grosse, Christopher F. Jorgensen, Theodore G. Lagrange, Randy G. Stutheit, Mark P. Vrtiska

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

In the present period of rapid, worldwide change in climate and landuse (i.e., global change), successful biodiversity conservation warrants proactive management responses, especially for long-distance migratory species. However, the development and implementation of management strategies can be impeded by high levels of uncertainty and low levels of control over potentially impactful future events and their effects. Scenario planning and modeling are useful tools for expanding perspectives and informing decisions under these conditions. We coupled scenario planning and statistical modeling to explain and predict playa wetland inundation (i.e., presence/absence of water) and ponded area (i.e., extent of water) in the Rainwater …

Effects Of Alternative Framing On The Publics Perceived Importance Of Environmental Conservation, Amanda E. Sorensen, Daniel Clark, Rebecca C. Jordan

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Effective communication of science to the general public is important for numerous reasons, including support for policy, funding, informed public decision making, among others. Prior research has found that scientists participating in public policy and public communication must frame their communication efforts in order to connect with audiences. A frame is the mechanism that individuals use to understand and interpret the world around them. Framing can encourage specific interpretations and reference points for a particular issue or event; especially when meaning is negotiated between the media and public audiences. In this study, we looked at the effect of framing within …