Participatory assessment of the South African abalone resource and its impact on predicted population trajectories

Illegal harvesting is a cause for concern in many of the world's fisheries. Over the last decade, the abalone resource in South Africa has come under severe fishing pressure, largely because of increased and unmitigated levels of poaching. The unquantified illegal exploitation of this resource is a major impediment to management, because understanding of abalone population dynamics is affected. Incorrect assessments of population abundance could lead to inadequate attempts by management to stem the decline. Here, population trends along the west coast of South Africa are investigated. A simple discrete-time logistic model was used to estimate parameters within a maximum likelihood statistical framework by fitting to available catch rate data. To address the problem of unknown levels of illegal catch, interview data were collected on non-commercial catch trends and the model was structured to allow this catch to be estimated during the fitting process. The results show that such a participatory approach to stock assessment can lead to an improved understanding of resource dynamics, illustrating the benefit this approach may have for management

Reconciliation of data from the lobster fisheries on Inaccessible, Nightingale and Gough Islands

For the years between 1997 and the present, a number of different data sources exist for the Tristan lobster (Jasus tristani) fisheries on the islands surrounding Tristan da Cunha . In an accompanying document (MARAM/Tristan/07/Dec/05), the sources of fisheries related data for Inaccessible, Nightingale and Gough, and the limitations of that data are described in detail. Catch and effort values from these sources had been shown previously to exhibit major differences. Here we relate progress made on reconciling these differences

Towards standardisation of the longline CPUE series from the lobster fisheries around Inaccessible, Nightingale and Gough islands

Two CPUE indicies exist for the tristan lobster (Jasus tristani ) fisheries surrounding Inaccessible, Nightingale and Gough islands. Here the nominal indicies are presented, alongside descriptions of how they will be standardised to ensure they each provide a more accurate index of population density

The numerical solution of linear multi-term fractional differential equations: Systems of equations

This is a PDF version of a preprint submitted to Elsevier. The definitive version was published in the Journal of computational and applied mathematics and is available at www.elsevier.comThis article discusses how the numerical approximation of a linear multi-term fractional differential equation can be calculated by the reduction of the problem to a system of ordinary and fractional differential equations each of order at most unity.This article was submitted to the RAE2008 for the University of Chester - Applied Mathematics

Biotope mapping to compare and contrast Columbia, Missouri neighborhoods

Abstract only availableHow people manage their property can ultimately have an affect on biodiversity, and ecosystem services. Our project seeks to understand the relationship of socioeconomic status to property management and how it affects biodiversity and ecosystem services. Our project compares neighborhoods with different socioeconomic characteristics by studying vegetation pattern and structure at three different scales: neighborhood, block, and lot. In this poster we compare vegetation pattern at a neighborhood scale. Our objectives are to classify vegetation in eight Columbia, Missouri neighborhoods and to determine if there are associated with socioeconomic differences. We defined neighborhoods as eight census block groups, and used data from the 2000 census to group the eight block groups into four socioeconomic categories. We used biotope mapping, a method of vegetation classification, to describe the different vegetation types in each block group. We used a similarity analysis to group the block groups based on biotope (vegetation) type. We used percent cover of the dominant biotope types to test for differences among the four socioeconomic groups. We identified 46 biotope types among the eight neighborhoods. Residential biotope types with lawn, trees and shrubs were dominant. These were divided into two subtypes, yard trees and fence rows, based on location of trees. Fence row were most common in the inner city area where the income is much lower than the areas with yard trees. The classification of the eight block groups based on the percentage of each biotope type in the block group did not match the classification based on socioeconomic data. The biotope classification did join the two block groups dominated by renters, Black residents, and low median income, a relationship supported by census data.NSF Undergraduate Mentoring in Environmental Biolog

Inefficient Cytotoxic T Lymphocyte–Mediated Killing of HIV-1–Infected Cells In Vivo

Understanding the role of cytotoxic T lymphocytes (CTLs) in controlling HIV-1 infection is vital for vaccine design. However, it is difficult to assess the importance of CTLs in natural infection. Different human leukocyte antigen (HLA) class I alleles are associated with different rates of progression to AIDS, indicating that CTLs play a protective role. Yet virus clearance rates following antiretroviral therapy are not impaired in individuals with advanced HIV disease, suggesting that weakening of the CTL response is not the major underlying cause of disease progression and that CTLs do not have an important protective role. Here we reconcile these apparently conflicting studies. We estimate the selection pressure exerted by CTL responses that drive the emergence of immune escape variants, thereby directly quantifying the efficiency of HIV-1–specific CTLs in vivo. We estimate that only 2% of productively infected CD4þ cell death is attributable to CTLs recognising a single epitope. We suggest that CTLs kill a large number of infected cells (about 107) per day but are not responsible for the majority of infected cell death

Incentivizing monitoring and compliance in trophy hunting

Conservation scientists are increasingly focusing on the drivers of human behavior and on the implications of various sources of uncertainty for management decision making. Trophy hunting has been suggested as a conservation tool because it gives economic value to wildlife, but recent examples show that overharvesting is a substantial problem and that data limitations are rife. We use a case study of trophy hunting of an endangered antelope, the mountain nyala (Tragelaphus buxtoni), to explore how uncertainties generated by population monitoring and poaching interact with decision making by 2 key stakeholders: the safari companies and the government. We built a management strategy evaluation model that encompasses the population dynamics of mountain nyala, a monitoring model, and a company decision making model. We investigated scenarios of investment into antipoaching and monitoring by governments and safari companies. Harvest strategy was robust to the uncertainty in the population estimates obtained from monitoring, but poaching had a much stronger effect on quota and sustainability. Hence, reducing poaching is in the interests of companies wishing to increase the profitability of their enterprises, for example by engaging community members as game scouts. There is a threshold level of uncertainty in the population estimates beyond which the year-to-year variation in the trophy quota prevented planning by the safari companies. This suggests a role for government in ensuring that a baseline level of population monitoring is carried out such that this level is not exceeded. Our results illustrate the importance of considering the incentives of multiple stakeholders when designing frameworks for resource use and when designing management frameworks to address the particular sources of uncertainty that affect system sustainability most heavily

Development of a boundary setting algorithm based on migration rates estimated using BayesAss and its preliminary application to TOSSM datasets

A Boundary Setting Algorithm (BSA) is developed that utilises migration rates estimated by the program BayesAss. It is subjected to preliminary testing through application of the BSA to a subset of TOSSM datasets from Archetypes I and II. Two Fully Internally Mixed Areas (FIMAs) are considered, connected by varying rates of migration. The objective of the BSA, implemented through the run.tossm control program, is to decide whether to manage FIMAs as one or two units. Performance is assessed using the depletion and catch statistics produced by run.tossm. Although BayesAss has the potential to provide information relevant to management, performance of the BSA was found to be poor, apparently due to inconsistent and unreliable estimation of the migration rate