Barychka, Tatsiana; (2019) Model-based approaches to understanding wild meat harvesting in Central Africa: uncertainty, yields and ecosystem impacts. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

The current levels of bushmeat harvesting, combined with other human-made pressures, are likely to drive many African species to extinction and disrupt ecological processes. However, reliably predicting what the appropriate harvesting levels might be is a challenge. Existing methods for assessing sustainability of harvesting rely heavily on species observational data, despite the widely-recognised limitations (such as geographical and taxonomic biases) of these data. In addition, population models can be employed; however, these necessitate parameter estimates which are often lacking. This thesis investigates new model-based approaches to overcoming these data and modelling limitations, in particular, high parameter uncertainty and simplistic population models which ignore many of ecological complexities (such as multi-trophic interactions). The first two chapters investigate proportional and quota-based harvesting in single-species population models of duiker antelope, but extended to include (1) an explicit consideration of parameter uncertainty, which revealed a trade-off between yield and population survival probability not apparent when ignoring uncertainty; and (2) model-based adaptive harvesting, which was predicted to increase yields and survival, particularly when combined with parameter updating. Chapters 3 and 4 employ the Madingley General Ecosystem Model, which can simulate a wide range of scenarios without any species-specific data. The Madingley Model predictions for duiker harvesting were similar to those from the single-species model, but the Madingley could also predict (1) wider ecosystem impacts of duiker harvesting (which were minimal); (2) yields and impacts for multiple species harvesting (both yields and impacts were greater than for duiker, with large reductions in target functional groups and increases in smaller-bodied animals); and (3) variation in yield and impacts among ecosystems (yields varied by a factor of ten; impacts varied quantitatively, but not qualitatively). These findings highlight the potential value of model-based approaches for informing bushmeat harvesting policies, given existing limitations in data and systems understanding.

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