76 research outputs found

    Conditions and Limitations on Learning in the Adaptive Management of Mallard Harvests

    Get PDF
    In 1995, the United States Fish and Wildlife Service adopted a protocol for the adaptive management of waterfowl hunting regulations (AHM) to help reduce uncertainty about the magnitude of sustainable harvests. To date, the AHM process has focused principally on the midcontinent population of mallards (Anas platyrhynchos), whose dynamics are described by 4 alternative models. Collectively, these models express uncertainty (or disagreement) about whether harvest is an additive or a compensatory form of mortality and whether the reproductive process is weakly or strongly density-dependent. Each model is associated with a probability or weight, which describes its relative ability to predict changes in population size. These Bayesian probabilities are updated annually using a comparison of population size predicted under each model with that observed by a monitoring program. The current AHM process is passively adaptive, in the sense that there is no a priori consideration of how harvest decisions might affect discrimination among models. We contrast this approach with an actively adaptive approach, in which harvest decisions are used in part to produce the learning needed to increase long-term management performance. Our investigation suggests that the passive approach is expected to perform nearly as well as an optimal actively adaptive approach, particularly considering the nature of the model set, management objectives and constraints, and current regulatory alternatives. We offer some comments about the nature of the biological hypotheses being tested and describe some of the inherent limitations on learning in the AHM process

    Conditions and Limitations on Learning in the Adaptive Management of Mallard Harvests

    Get PDF
    In 1995, the United States Fish and Wildlife Service adopted a protocol for the adaptive management of waterfowl hunting regulations (AHM) to help reduce uncertainty about the magnitude of sustainable harvests. To date, the AHM process has focused principally on the midcontinent population of mallards (Anas platyrhynchos), whose dynamics are described by 4 alternative models. Collectively, these models express uncertainty (or disagreement) about whether harvest is an additive or a compensatory form of mortality and whether the reproductive process is weakly or strongly density-dependent. Each model is associated with a probability or weight, which describes its relative ability to predict changes in population size. These Bayesian probabilities are updated annually using a comparison of population size predicted under each model with that observed by a monitoring program. The current AHM process is passively adaptive, in the sense that there is no a priori consideration of how harvest decisions might affect discrimination among models. We contrast this approach with an actively adaptive approach, in which harvest decisions are used in part to produce the learning needed to increase long-term management performance. Our investigation suggests that the passive approach is expected to perform nearly as well as an optimal actively adaptive approach, particularly considering the nature of the model set, management objectives and constraints, and current regulatory alternatives. We offer some comments about the nature of the biological hypotheses being tested and describe some of the inherent limitations on learning in the AHM process

    Wildlife Biologist, Division of Migratory Bird Management, U.S. Fish and Wildlife Service, Denver, Colorado

    Get PDF
    The abundance of the Mid-Continent Population of Sandhill Cranes has been relatively stable since the early 1980s, compared to the increases that were recorded in the 1970s. The Central Platte River Valley, Nebraska spring index for 2004, uncorrected for visibility bias, was 356,850. The photo-corrected 3-year average for 2001-2003 was 370,300, which is within the established population objective range of 343,000-465,000 cranes. All Central Flyway states, except Nebraska, allowed crane hunting in portions of their respective states during 2003- 04. About 7,700 hunters participated in these seasons, which was similar to the number that participated in the previous year’s seasons. Hunters harvested 18,527 in the Central Flyway during the 2003-04 seasons, which was 42% higher than the harvest for the previous year. The retrieved harvest in the Pacific Flyway, Canada, and Mexico combined was estimated at 13,109 during 2003-04. The preliminary estimate for the North American sport harvest, including crippling losses, was 35,706, which is 28% higher than the previous year’s estimate of 27,839 and the second highest harvest recorded. The long-term (1982-2000) trends for the Mid- Continent Population indicate that harvests have been increasing at a higher rate than population growth. The fall 2003 pre-migration survey estimate for the Rocky Mountain Population was 19,523, which was similar to the previous year’s estimate of 18,803. The 3-year average for 2001-2003 is 18,295, which is within established population objectives of 17,000 - 21,000. Hunting seasons during 2003-04 in portions of Arizona, Idaho, Montana, New Mexico, Utah, and Wyoming, resulted in a harvest of 528 cranes, a 17% decrease from the harvest of 639 the year before

    Status and Harvests of Sandhill Cranes: Mid-Continent & Rocky Mountain Populations 2005

    Get PDF
    Annual indices to abundance of the Mid-Continent Population of Sandhill Cranes has been relatively stable since the early 1980s, compared to the increases that were recorded in the 1970s. The Central Platte River Valley, Nebraska spring index for 2005, uncorrected for visibility bias, was 412,000. The photo-corrected 3-year average for 2002-2004 was 363,167, which is within the established population-objective range of 343,000- 465,000 cranes. All Central Flyway states, except Nebraska, allowed crane hunting in portions of their respective states during 2004-05. About 9,300 hunters participated in these seasons, which was 12% higher than the number that participated in the previous year’s seasons. Hunters harvested 15,124 cranes in the U.S. portion of the Central Flyway during the 2004-05 seasons, which was 18% lower than the estimated harvest for the previous year. The retrieved harvest of Mid-Continent Population sandhill cranes in hunt areas for the Rocky Mountain Population of sandhill cranes (Arizona & New Mexico), Alaska, Canada, and Mexico combined was estimated at 14,528 during 2004-05. The preliminary estimate for the North American sport harvest, including crippling losses, was 33,847, which is 5% lower than the previous year’s estimate of 35,671. The long-term (1982-2004) trends for the Mid-Continent Population indicate that harvests have been increasing at a higher rate than population growth. The fall 2004 pre-migration survey estimate for the Rocky Mountain Population was 18,510, which was 5.5% lower than the previous year’s estimate of 19,523. The 3-year average for 2002-2004 is 18,945, which is within established population objectives of 17,000 - 21,000. Hunting seasons during 2004-05 in portions of Arizona, Idaho, Montana, New Mexico, Utah, and Wyoming, resulted in a harvest of 594 cranes, a 13% increase from the harvest of 528 the year before

    Blood Stage Malaria Vaccine Eliciting High Antigen-Specific Antibody Concentrations Confers No Protection to Young Children in Western Kenya

    Get PDF
    The antigen, falciparum malaria protein 1 (FMP1), represents the 42-kDa C-terminal fragment of merozoite surface protein-1 (MSP-1) of the 3D7 clone of P. falciparum. Formulated with AS02 (a proprietary Adjuvant System), it constitutes the FMP1/AS02 candidate malaria vaccine. We evaluated this vaccine's safety, immunogenicity, and efficacy in African children.A randomised, double-blind, Phase IIb, comparator-controlled trial.The trial was conducted in 13 field stations of one mile radii within Kombewa Division, Nyanza Province, Western Kenya, an area of holoendemic transmission of P. falciparum. We enrolled 400 children aged 12-47 months in general good health.Children were randomised in a 1ratio1 fashion to receive either FMP1/AS02 (50 microg) or Rabipur(R) rabies vaccine. Vaccinations were administered on a 0, 1, and 2 month schedule. The primary study endpoint was time to first clinical episode of P. falciparum malaria (temperature >/=37.5 degrees C with asexual parasitaemia of >/=50,000 parasites/microL of blood) occurring between 14 days and six months after a third dose. Case detection was both active and passive. Safety and immunogenicity were evaluated for eight months after first immunisations; vaccine efficacy (VE) was measured over a six-month period following third vaccinations.374 of 400 children received all three doses and completed six months of follow-up. FMP1/AS02 had a good safety profile and was well-tolerated but more reactogenic than the comparator. Geometric mean anti-MSP-1(42) antibody concentrations increased from1.3 microg/mL to 27.3 microg/mL in the FMP1/AS02 recipients, but were unchanged in controls. 97 children in the FMP1/AS02 group and 98 controls had a primary endpoint episode. Overall VE was 5.1% (95% CI: -26% to +28%; p-value = 0.7).FMP1/AS02 is not a promising candidate for further development as a monovalent malaria vaccine. Future MSP-1(42) vaccine development should focus on other formulations and antigen constructs.Clinicaltrials.gov NCT00223990

    Measurement of the inclusive isolated-photon cross section in pp collisions at √s = 13 TeV using 36 fb−1 of ATLAS data

    Get PDF
    The differential cross section for isolated-photon production in pp collisions is measured at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC using an integrated luminosity of 36.1 fb. The differential cross section is presented as a function of the photon transverse energy in different regions of photon pseudorapidity. The differential cross section as a function of the absolute value of the photon pseudorapidity is also presented in different regions of photon transverse energy. Next-to-leading-order QCD calculations from Jetphox and Sherpa as well as next-to-next-to-leading-order QCD calculations from Nnlojet are compared with the measurement, using several parameterisations of the proton parton distribution functions. The predictions provide a good description of the data within the experimental and theoretical uncertainties. [Figure not available: see fulltext.
    corecore