A risk assessment for managing fishing impacts in the southern Benguela system, South Africa скачать в хорошем качестве

A risk assessment for managing fishing impacts in the southern Benguela system, South Africa

Kelly Ortega-Cisneros 1, Lynne Shannon 1 1 Department of Biological Sciences, University of Cape Town, South Africa Contact: [email protected] The analysis of risks posed by anthropogenic drivers, including climate change, is key to the sustainable management of marine ecosystems. However, ecosystem assessments are usually confounded by different uncertainty sources such as natural variability, cumulative impacts and limited knowledge of a system. We use a Bayesian Belief Network (BBN) to conduct a risk assessment of key vulnerabilities in the southern Benguela system. A previous study used a hierarchical approach, where key sectors, pressures and ecosystem components contributing most towards the risk of ecosystem degradation were identified using the Options for Delivering Ecosystem-Based Marine Management (ODEMM) approach, through a review of available literature and stakeholder consultations. In that study, fishing was identified as the sector exerting the highest pressures on ecological components of the southern Benguela. Here, we develop a BBN to investigate changes in risk levels from this sector on ecosystem structure and services. The BBN is parameterised using quantitative data such as observations, and ecosystem and ocean model outputs. The BBN consists of 17 variables, two of which (e.g. temperature, primary production) represent environmental factors to which six key ecological components (e.g., demersal fish, elasmobranchs, marine mammals) are exposed to. Three variables represent selected ecosystem services provided by the southern Benguela system. Climate scenarios and potential management strategies are evaluated, while accounting for the uncertainty in predictions for the southern Benguela system. The probability of minimising fishing-related risks while achieving socio-ecological objectives is estimated. Keywords: Marine ecosystems, Economic activities during degradation, Risk assessment and uncertainty