Ecological and social strategies for managing fisheries using the Resist-Accept- Direct (RAD) framework

Fisheries management is a complex task made even more challenging by rapid and unprecedented socioecological transformations associated with climate change. The Resist-Accept- Direct (RAD) framework can be a useful tool to support fisheries management in facing the high uncertainty and variability associated with aquatic ecosystem transformations. Here, RAD strategies are presented to address ecological goals for aquatic ecosystems and social goals for fisheries. These strategies are mapped on a controllability matrix which explores the ability to guide a system\u27s behaviour towards a desired state based on ecological responsiveness and societal receptivity to change. Understanding and improving the controllability of aquatic systems and fisheries can help managers to maintain the broadest suite of available RAD management strategies

Managing for RADical ecosystem change: applying the Resist-Accept- Direct (RAD) framework

Ecosystem transformation involves the emergence of persistent ecological or social–ecological systems that diverge, dramatically and irreversibly, from prior ecosystem structure and function. Such transformations are occurring at increasing rates across the planet in response to changes in climate, land use, and other factors. Consequently, a dynamic view of ecosystem processes that accommodates rapid, irreversible change will be critical for effectively conserving fish, wildlife, and other natural resources, and maintaining ecosystem services. However, managing ecosystems toward states with novel structure and function is an inherently unpredictable and difficult task. Managers navigating ecosystem transformation can benefit from considering broader objectives, beyond a traditional focus on resisting ecosystem change, by also considering whether accepting inevitable change or directing it along some desirable pathway is more feasible (that is, practical and appropriate) under some circumstances (the RAD framework). By explicitly acknowledging transformation and implementing an iterative RAD approach, natural resource managers can be deliberate and strategic in addressing profound ecosystem change

Evidence That SOX2 Overexpression Is Oncogenic in the Lung

BACKGROUND: SOX2 (Sry-box 2) is required to maintain a variety of stem cells, is overexpressed in some solid tumors, and is expressed in epithelial cells of the lung. METHODOLOGY/PRINCIPAL FINDINGS: We show that SOX2 is overexpressed in human squamous cell lung tumors and some adenocarcinomas. We have generated mouse models in which Sox2 is upregulated in epithelial cells of the lung during development and in the adult. In both cases, overexpression leads to extensive hyperplasia. In the terminal bronchioles, a trachea-like pseudostratified epithelium develops with p63-positive cells underlying columnar cells. Over 12-34 weeks, about half of the mice expressing the highest levels of Sox2 develop carcinoma. These tumors resemble adenocarcinoma but express the squamous marker, Trp63 (p63). CONCLUSIONS: These findings demonstrate that Sox2 overexpression both induces a proximal phenotype in the distal airways/alveoli and leads to cancer

Climate and Habitat Factors Related to a Localized Extirpation of Gizzard Shad (\u3ci\u3eDorosoma cepedianum\u3c/i\u3e)

Gizzard shad are a riverine species commonly transplanted into man-made reservoir systems to provide prey for predatory game fish. Thermally limited, the range of their native distribution extends into the midwestern Great Plains. Following the harsh winter conditions of 2000-2001, numerous incidents of extensive gizzard shad die-offs were reported in eastern Nebraska during spring ice-out. In an effort to determine the breadth and extent of mortality, statewide fish population surveys conducted between 1994 and 2004 were examined, and it was found that gizzard shad were extirpated from seven flood-control reservoirs in a localized area of eastern Nebraska. Meteorological data confirmed that extreme cold and windy conditions were prevalent in the area during early December 2000, and may have been correlated to this unique extirpation event. Hydrologic connection to groundwater and wind sheltering may have protected smaller waterbodies from extirpation

Using standardized fishery data to inform rehabilitation efforts

Lakes and reservoirs progress through an aging process often accelerated by human activities, resulting in degradation or loss of ecosystem services. Resource managers thus attempt to slow or reverse the negative effects of aging using a myriad of rehabilitation strategies. Sustained monitoring programs to assess the efficacy of rehabilitation strategies are often limited; however, long-term standardized fishery surveys may be a valuable data source from which to begin evaluation.We present 3 case studies using standardized fishery survey data to assess rehabilitation efforts stemming from the Nebraska Aquatic Habitat Plan, a large-scale program with the mission to rehabilitate waterbodies within the state. The case studies highlight that biotic responses to rehabilitation efforts can be assessed, to an extent, using standardized fishery data; however, there were specific areas where minor increases in effort would clarify the effectiveness of rehabilitation techniques. Management of lakes and reservoirs can be streamlined by maximizing the utility of such datasets to work smarter, not harder. To facilitate such efforts, we stress collecting both biotic (e.g., fish lengths and weight) and abiotic (e.g., dissolved oxygen, pH, and turbidity) data during standardized fishery surveys and designing rehabilitation actions with an appropriate experimental design

Walleye Trophic Position Before and After a Gizzard Shad Extirpation

Walleye (Sander vitreus) are an ecologically and recreationally important sport fish species. Reduced growth and condition in walleye can occur when prey availability is limited. In two Nebraska reservoirs, walleye consumed gizzard shad (Dorosoma cepedianum) as their primary prey until a winterkill extirpated the gizzard shad in 2001. Because of the winterkill, walleye in the two reservoirs had to change to alternative prey items. Our objective was to determine if stable isotope analysis on archived walleye scales can be used to detect a known food web shift in two reservoir food webs. We quantified the changes in walleye trophic position following the loss of gizzard shad using stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) from archived scales. Walleye δ15N decreased and δ13C increased in both reservoirs after the extirpation of gizzard shad, indicating walleye likely fed at a lower trophic level on more benthic or littoral prey resources post winterkill. A replacement of gizzard shad by white perch (Morone americana) in Pawnee Reservoir may have ameliorated the loss of gizzard shad; in the other system, walleye appeared to feed on a wider variety of prey items as indexed by increased δ13C variability. Our results indicated that walleye were robust to gizzard shad extirpation

Influence of Throat Configuration and Fish Density on Escapement of Channel Catfish from Hoop Nets

In recent years, several state agencies have adopted the use of baited, tandemset hoop nets to assess lentic channel catfish Ictalurus punctatus populations. Some level of escapement from the net is expected because an opening exists in each throat of the net, although factors infl uencing rates of escapement from hoop nets have not been quantified. We conducted experiments to quantify rates of escapement and to determine the infl uence of throat configuration and fish density within the net on escapement rates. An initial experiment to determine the rate of escapement from each net compartment utilized individually tagged channel catfish placed within the entrance (between the two throats) and cod (within the second throat) compartments of a single hoop net for overnight sets. From this experiment, the mean rate (±SE) of channel catfish escaping was 4.2% (±1.5) from the cod (cod throat was additionally restricted from the traditionally manufactured product), and 74% (±4.2) from the entrance compartments. In a subsequent experiment, channel catfish were placed only in the cod compartment with different throat configurations (restricted or unrestricted) and at two densities (low [6 fish per net] and high [60 fish per net]) for overnight sets to determine the infl uence of fish density and throat configuration on escapement rates. Escapement rates between throat configurations were doubled at low fish density (13.3 ± 5.4% restricted versus 26.7 ± 5.6% unrestricted) and tripled at high fish density (14.3 ± 4.9% restricted versus 51.9 ± 5.0% unrestricted). These results suggest that retention efficiency is high from cod compartments with restricted throat entrances. However, managers and researchers need to be aware that modification to the cod throats (restrictions) is needed for hoop nets ordered from manufacturers. Managers need to be consistent in their use and reporting of cod end throat configurations when using this gear

Reservoir Rehabilitations: Seeking the Fountain of Youth

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 actions, perhaps even turning back the hands of time, but we cannot stop aging. We call for new, innovative perspectives that incorporate an understanding of aging processes in all steps of rehabilitation of reservoirs, especially in planning and assessing. El envejecimiento de los reservorios altera las funciones y los servicios que están asociados a estos ecosistemas. El objetivo de la rehabilitación de hábitats suele ser alterar la trayectoria del proceso de envejecimiento de manera tal que prolonga la duración de un estado deseable del sistema. Existen dos características importantes cuando se altera dicha trayectoria -amplitud relativa del estado actual y la subsecuente tasa de cambio, o envejecimiento- que últimamente determinan la duración del estado deseado. La mayoría de los procesos de rehabilitación caen en tres grandes categorías: manipulación de comunidades ícticas, manipulación de la calidad del agua y manipulación del hábitat físico. Es posible retardar el envejecimiento de los reservorios implementando cuidadosamente medidas de manejo, e incluso tal vez regresando el tiempo, pero no es posible detener el envejecimiento. Aquí se hace referencia a perspectivas novedosas que incorporan la comprensión del proceso de envejecimiento en todos los pasos de la rehabilitación de reservorios, particularmente en lo que se refiere a planeación y evaluación