Scoping an Integrated Ecosystem Assessment for the southern Benguela: fisheries still biggest risk

Abstract

The southern Benguela ecosystem faces complex pressures from anthropogenic activities and climate change, leading to structural and functional changes. To counter ecosystem service losses, intergovernmental marine science organizations propose integrated management. However, predictions to evaluate alternative strategies are challenging due to multifaceted sector interactions affecting ecological components. Scoping phases of Integrated Ecosystem Assessments (IEA), such as the Options for Delivering Ecosystem-Based Marine Management (ODEMM), identify priority sectors and pressures for management using linkage chains and impact risk scores. This study expands a South African-wide ODEMM assessment to investigate dependent sectors in the southern Benguela. Fishing emerged as the primary sector, exhibiting high connectance and impact risk on ecological components. Disaggregation of the fishing sector into sub-sectors and over three 21-year time periods revealed the demersal trawl and mixed species inshore trawl sectors to still have the greatest impact despite recent mitigation efforts, driven by species extraction, bycatch, and ‘incidental loss’. Research gaps, such as the effects of recreational fisheries and underwater noise, were identified and need to be addressed to improve future ecosystem assessments. Additionally, the effects of climate on long-term, ecosystem-scale variability and change need more attention in IEAs and should be incorporated into frameworks such as ODEMM.