Small pelagic fish have short lives and reproduce in bursts, making their recruitment highly sensitive to climate stress in spawning areas. Yet these species are crucial for food security and heavily fished. Keeping steady catch levels during periods of environmental stress risks overfishing. But there are no simple rules for predicting when this happens, as the risks depend on local factors like pre-event fishing pressure, event severity, habitat changes over time, and how fish populations react. Successful management systems learned to anticipate these risks through years of observing how stocks and fisheries responded to past climate shocks.
In Angola, fisheries targeting sardinella species are crucial for food security and livelihoods, accounting for about 40% of landings, but climate variability historically wasn’t a primary management concern. Decades of assessments suggested sustainable exploitation — a view still reflected in recent global reports (FAO, 2022). Yet over the past decade, reduced fish availability, factory closures, and growing tensions among stakeholders became common, signalling emerging overfishing. At the same time, climate research pointed to intensifying weather extremes along the Angolan coast, raising concerns about potential recruitment failures. Still, the fishery continued business-as-usual until late 2022, when sardinella exploitation became economically unviable and the reality of overfishing could no longer be ignored.
A study on the role of recent climatic variability in the Eastern Tropical Atlantic in the transition from a sustainable to an overfished state in Angolan fisheries was one of the key investigations of the EXEBUS project, coordinated by the Institute of Marine Research.
The study identified two key seasonal physical phenomena driving sardinella reproductive success: intensification of the Congo River discharge during May and remotely forced tropical upwelling from July to September. Both processes provide optimal spawning habitat conditions—temperatures of 21–23°C, abundant plankton, and high retention rates—supporting survival of early life stages. Juveniles born during these periods recruit to the fisheries five to six months later, during the unfavourable conditions of the austral summer, when temperatures exceed 28°C and increased stratification limits nutrient enrichment and plankton production. Still, sardinella is a tropical species well-adapted to surviving these seasonal extremes, relying on consistently favourable winter conditions to sustain reproductive success.
However, in 2016, the Angolan coastal ocean climate reached a tipping point, when the interannual events — the Benguela and Atlantic Niños — superimposed on steady decadal ocean warming of 0.5°C per decade, evolved into prolonged marine heatwave activity lasting from 2016 to 2022 — a phenomenon coined in this study as the CAMPA period (Calor Anômalo Marinho Prolongado em Angola). The CAMPA significantly reduced sardinella reproductive habitat suitability.
During the CAMPA, information on rising climate extremes was not considered relevant to the operational management of sardinella fisheries. The fishery continued exploitation at pre-2016 levels. In 2018 — two years into the CAMPA — landings still did not show a visible decline, as industrial fishing fleets equipped with modern fish-finding equipment and strategies managed to compensate for reduced fish availability by increasing catch-per-unit-effort. However, from 2018 onward, landings started to fall dramatically, as new recruits — born during adverse climatic conditions — became too few to balance the biomass lost to intense fishing.
The significance of the EXEBUS findings lies in the fact that they provide the first evidence that, with the recent warming of the coastal ocean, the fate of Angolan sardinella fisheries has become inextricably linked to the rising intensity of marine heatwaves. These findings indicate that, just as ENSO monitoring and predictions support the management of Eastern Pacific pelagic fisheries, the recently developed capacity to monitor and predict extreme climatic events in the eastern tropical Atlantic can strengthen Angola’s management advice by providing early warning for sardinella fisheries.
Although the study focuses on Angola, similar climate-to-fish impacts may have recently emerged more broadly across West African sardinella fisheries, which have been shown to be similarly exposed to steady ocean warming and an increasing frequency of marine heatwaves.
Reflecting on these results, EXEBUS convened a concluding workshop—the Conferência Internacional Sobre Ciências Marinhas—in Luanda, 24–25 March 2025. Participants, including fisheries industry representatives, Angolan authorities, and international experts, agreed that the CAMPA socio-ecological scenario identified by this research highlights the urgent need to expand existing management regimes to include climate-informed early warning approaches.
Redynamized Benguela Current Commission
an energized Angolan research community taking EXEBUS results forward on the international stage including to the UN Oceans meeting in France,
a series of meetings and workshops in South Africa, Namibia and Angola that reached larger communities who will be impacted by the extremes studied by the project,
a follow-on South African National Research Fund project on the Effect of Coastal Ocean Extremes (ECOE),
interest in the Belmont Forum Oceans 2 proposal related to the Benguela Niño and connections to the fisheries collapse whether a temporary dynamic or permanent regime shift.
The Benguela Upwelling System (BUS) of South Africa, Namibia, and Angola is one four Eastern Boundary Upwelling Systems globally. It is bordered with warm tropical water of the Angola Benguela Front Zone in the north and by the Agulhas Current in the south. Changes in the coupled atmosphere-marine climate, natural or anthropogenic, both within the BUS and beyond, affect ecological and socio-economic important sub-systems, potentially affecting millions of people—residents of the coastline and those who derive their livelihoods and resources from the BUS.Our aim in the EXEBUS project is to understand the drivers of change in the BUS and its contribution to the changing variability of the system, with an emphasis on extreme events. Given that both natural- and human-induced changes to the functioning of the BUS occur at a range of time and space scales (and are also interdependent), we seek to understand the changing envelope of variability, extremes of this variability, and their impact. EXEBUS undertakes an Integrated Ecosystem Assessment (IEA) to establish the roles, trends, and range of variability and the extremities of natural and anthropogenic geophysical, biological, governance, socio- economic features and phenomena, and assess their impact on ecological, sociological, governance, and macroeconomic systems and processes in the BCLME. The goal is to strengthen the rational basis for management on relevant spatial and temporal scales.The work is undertaken by transdisciplinary consortium of international researchers, practitioners, and representatives of the private sector and civil society proposed here brings unique and complementary perspectives for both understanding the changes in this dynamic system, applying, and communicating the importance of these findings. This will enable the development of an Ecosystem Based Management framework for application in the region.
