Astrid Jarre

Astrid Jarre
University of Cape Town | UCT · Department of Biological Sciences

PhD

About

131
Publications
26,563
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4,719
Citations
Citations since 2017
30 Research Items
1732 Citations
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20172018201920202021202220230100200300
20172018201920202021202220230100200300

Publications

Publications (131)
Article
Full-text available
Scenario-planning, a management tool used for addressing challenges in complex and uncertain social-ecological systems (SES), offers a helpful way to facilitate responses to complex change by stakeholders at all scales of the SES. This is facilitated through imagining possible futures in pursuit of a pre-determined and common goal. Environmental va...
Article
Understanding climate variability and change together with fishing activities through high-resolution scientific information and local observations can help implement and sustain improved coastal marine management strategies. Ethnographic data collected between 2010 and 2016 during previous studies with traditional handline fishers on South Africa'...
Article
Full-text available
The Ecosystem Approach to Fisheries (EAF) management, recognising complexity, aims for the holistic, sustainable management of fisheries to promote healthy marine ecosystems and sustainable livelihoods. Effective implementation of the EAF has been problematic as we continue to grapple with issues of scale, knowledge integration and meaningful stake...
Article
Full-text available
In recent decades, scientists and practitioners have increasingly focused on identifying and codifying the best ways to manage activities in marine systems, leading to the development and implementation of concepts such as the social-ecological systems approach, ecosystem-based management, integrated management, marine spatial planning, participato...
Article
Access to science-based environmental education is critical to improve rural coastal communities’ adaptive capacity and resilience. Based on research in two rural, underprivileged schools in South Africa’s southern Cape coastal region, we describe the process and lessons learnt in developing and deploying a series of integrated teaching modules for...
Article
Full-text available
This paper presents a new, updated, temporally dynamic Ecosim model for the Southern Benguela (1978–2015) by capturing recent advancements in our understanding of the dynamics and newly available data series from an additional decade of research in the region. The paper documents the model development and the thinking behind incorporating a newly a...
Article
Full-text available
Fishers, and the communities they support face a range of challenges brought on by complexity and uncertainty in their social-ecological systems (SESs). This undermines their ability to achieve sustainability whilst hampering proactive planning and decision-making. To capacitate fishers to apply risk aversion strategies at smaller scales of operati...
Article
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Faced with competition from large-scale fisheries and other pressures, many small-scale fisheries are looking to ‘alternative’ seafood marketing options to enhance livelihoods. Based on the findings of participant observation and action research, we discuss opportunities and challenges associated with an attempt to create a novel brand and alternat...
Article
Full-text available
Although an ecosystem approach to fisheries has been recognized as a means of progressing toward sustainable fishing, successful implementation of this approach has been limited. However, one way in which progress has been made is through the use of suites of indicators. Decision tree frameworks can be used to incorporate trends in ecological, fish...
Technical Report
Full-text available
Executive summary To support the implementation of the Ecosystem Based approach to Management (EBM), ICES strives to provide evidence-based scientific advice and relevant management options that also assess potential trade-offs among sectors or between environmental status and human uses. To help achieve this, the Workshop on Challenges, Opportunit...
Article
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Small-scale fisheries face similar challenges and constraints, including marginalization, spatial competition, unequal power relations, limited participation in decision-making processes, and climate stressors. We compare the vulnerability of small-scale fishing communities under pressure from climate change in the southern Cape in South Africa and...
Article
Based on 18-months of ethnographic fieldwork in South Africa’s Western Cape province, we suggest ways in which marine resource law enforcement activities can be evaluated at the level of individual fisheries compliance inspectors, to gain a more accurate understanding of the state of marine resource law enforcement. We show that these individual as...
Article
Avoiding whinges from various and potentially conflicting stakeholders is a major challenge for sustainable development and for the identification of sustainability scenarios or policies for biodiversity and ecosystem services. It turns out that independently complying with whinge thresholds and constraints of these stakeholders is not sufficient b...
Article
Fishers operating on smaller scales are vulnerable to stressors at multiple temporal and spatial scales that drive change in marine social-ecological systems (SES). Apart from natural variability, the effects of anthropogenic change and developmental challenges add to complexity and uncertainty. Fishers need to proactively implement response strate...
Article
A number of ecologically and economically important species in the southern Benguela, including the forage fish sardine Sardinops sagax and anchovy Engraulis encrasicolus, have undergone southward/eastward shifts in their distribution in the 1990s/early 2000s. In addition to the effects of changes in prey availability to top predators, the spatiall...
Article
The historical approach of sector-specific, largely top-down management in favor of highly capitalized industry sectors has seemingly left southern Benguela fisheries management in a Gordian knot. The modern systems approach to management of human activities in the oceans forbids cutting through the knot, making it necessary to develop methodology...
Article
As one of the most economically important marine ecosystems, the North Sea has been impacted by numerous anthropogenic activities. A move towards an ecosystem approach to fisheries is key in developing sustainable fisheries in marine ecosystems. The application of a previously tested decision tree framework that employs a suite of indicators sugges...
Article
In South Africa's most valuable fishery, the offshore demersal hake trawl, participant companies differ in their rightsholdings, product streams, core business structure and their numbers and types of vessels. HakeSim, an agent-based model of this fishing industry, is used to explore these interactions, how companies could cope with increased fuel...
Article
The most valuable component in South Africa's fishing industry is its hake fishery, which targets two species, the shallow-water (Merluccius capensis) and deep-water (M. paradoxus) Cape hakes. Modelling provides a means to assist in understanding the dynamics of the economic system of this fishery and identify potential links to the ecological syst...
Article
Full-text available
Understanding and validating annual structures in fish otoliths are important for stock assessments and fisheries ecology. Biannual translucent zone formation has been demonstrated for 3-21. months old Namibian shallow-water hake Merluccius capensis. This paper addresses the hypothesis that the pattern continues in older fish. Otolith zone periodic...
Article
Full-text available
viter la contestation d'acteurs aux objectifs divers et parfois contradictoires est un défi majeur pour le développement durable et pour l'identification de politique pour la biodiversité et les services éco-systémiques. De plus, respecter les seuils d'acceptation des différents acteurs indépendamment n'est pas suffisant parce que des interactions,...
Article
Full-text available
Variability on multiple temporal and spatial scales exposes fishers and fishing communities to multiple stressors. The impact and interplay of these stressors need to be considered to improve our understanding of social-ecological linkages if sustainable livelihoods are to be promoted. To this end, participant-led research was conducted in the smal...
Article
Full-text available
Fishers in the small-scale, commercial linefishery in the southern Cape, South Africa, are exposed to variability and change in the marine social-ecological system of which they are a part. Faced with multi-scalar changes within this complex system, fishers employ a wide range of strategies in reaction to change. As part of a broader study of stres...
Article
Indicators have been recognised as a useful tool aiding the implementation of an ecosystem approach to fisheries in marine ecosystems. Studies, such as the IndiSeas project (www.indiseas.org), use a suite of indicators as a method of assessing the state and trends of several of the world's marine ecosystems. While it is well known that both fishing...
Article
Full-text available
Fisheries have had major negative impacts on marine ecosystems, and effective fisheries management and governance are needed to achieve sustainable fisheries, biodiversity conservation goals and thus good ecosystem status. To date, the IndiS-eas programme (Indicators for the Seas) has focussed on assessing the ecological impacts of fishing at the e...
Article
Full-text available
Several commercially and ecologically important species in the southern Benguela have undergone southward and eastward shifts in their distributions over previous decades, most notably the small pelagic fish sardine Sardinops sagax and anchovy Engraulis encrasicolus. Understanding these changes and their implications is essential in implementing an...
Data
Overlap in area (ROA) and biomass (ROB) between M. capensis, M. paradoxus and horse mackerel, and all other species, east and west of Cape Agulhas. (TIF)
Data
Overlap in area (ROA) and biomass (ROB) between chub mackerel, kingklip and chokka squid, and all other species, east and west of Cape Agulhas. (TIF)
Data
Overlap in area (ROA) and biomass (ROB) between yellowtail and geelbek, and all other species, east and west of Cape Agulhas. (TIF)
Data
Overlap in area (ROA) and biomass (ROB) between sardine, anchovy and redeye and all other species, east and west of Cape Agulhas. (TIF)
Data
Average distribution of sardine, anchovy and redeye recruits (May) and spawner biomass (Nov) during each period, based on pelagic survey data. (TIF)
Data
Overlap in area (ROA) and biomass (ROB) between Silver kob, snoek and yellowfin tuna, and all other species, east and west of Cape Agulhas. (TIF)
Article
Full-text available
The three countries of the Benguela Current Large Marine Ecosystem (BCLME), namely Angola, Namibia and South Africa, have committed to implementing ecosystem-based management (EBM) including an ecosystem approach to fisheries (EAF) in the region, to put in practice the principles of sustainable development in ocean-related matters. There is also re...
Article
Many coastal communities rely on living marine resources for livelihoods and food security. These resources are commonly under stress from overfishing, pollution, coastal development and habitat degradation. Climate change is an additional stressor beginning to impact coastal systems and communities, but may also lead to opportunities for some spec...
Chapter
Full-text available
Two hake species co-occur along the Namibian coast: the shallow-water hake (Merluccius capensis) in 100–450-m bottom depth and deep-water hake (Merluccius paradoxus) in 300–1000-m bottom depth. They form Namibia's most valuable commercial fishery, contributing to half of the fisheries sector, which contributes about 5% to the gross domestic product...
Article
This study classifies coastal time-series data according to subsurface phytoplankton vertical distributions to be able to capture the variability of primary production at fine spatial and temporal scales. Our method uses algorithms developed to extract patterns in large datasets of time-sequential data. We use short time-series of QuikSCAT surface...
Conference Paper
Full-text available
CONSIDERING ONE’S OPTIONS WHEN THE FISH LEAVE: A CASE STUDY OF THE TRADITIONAL COMMERCIAL HAND LINE FISHERY OF SOUTH AFRICA’S SOUTHERN CAPE REGION Louise Gammage1,*, Charles Mather2 and Astrid Jarre1 1 Marine Research (MA-RE) Institute and Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch, 7701, South Africa...
Article
Full-text available
Otoliths collected at least monthly from scat samples of Cape fur seals Arctocephalus pusillus are used to show that shallow-water hake Merluccius capensis from the northern Benguela develop three translucent zones in their first 1·5 years of life. The novel sampling approach provided otoliths that belonged to four M. capensis cohorts of approximat...
Article
Full-text available
Overfishing and human-induced climate change are putting severe pressure on marine ecosystems. In the southern Benguela, most of South Africa's commercial fisheries have a long history of exploitation and this, coupled with spatio-temporal changes in key species over the last three decades has severely impacted some of South Africa's fisheries and...
Article
Full-text available
The NansClim project (2010-2013) represented a regional collaboration to assess the effects of climate on Benguela dynamics. Based on in situ (since the 1960s in Namibia and South Africa and 1985 in Angola) and satellite (since the 1980s) observations, the project focussed on four subsystems, namely the Angola subtropical, northern Benguela upwelli...
Article
Full-text available
We investigate the spatial distributions of juvenile and adult hake Merluccius capensis on the Namibian continental shelf using data from 25 biomass surveys (1990–2007) to identify (i) nursery/spawning areas, their spatial or temporal separation and change and (ii) length, depth and latitude preference patterns. The density of fish (number-of-fish...
Article
As part of the southern Benguela upwelling ecosystem, South Africa's west coast represents a very productive marine habitat. Decadal-scale environmental and ecosystem regime shifts have been documented based on wind and ocean temperature data, as well as biota. This study analyses the variability of oxygen-depleted (<2 mL L−1) bottom waters on Sout...
Data
Full-text available
Figure S1 M. capensis survey density (no of fish 30-mins trawled -1) surfaces (right panel) with respect to fish total length (cm) and latitude (°S) 1990-2007 (a-y) for fish <20 cm total length. The profiles (left and middle panels) represent maxima on each plane of the surface plots with respect to fish total length and latitude respectively. Figu...
Article
Full-text available
The hake (Merluccius capensis and M. paradoxus) directed offshore demersal trawl is the most economically important fishing sector in South Africa, generating 30,000 jobs and comprising more than 50% of fisheries value. The industry changed to long term rights (LTRA), allocated in 2006 for a 15 year period. This study investigates the structure of...
Article
Full-text available
An updated trophic model of the southern Benguela ecosystem in the period 2004-2008 was constructed, complementing trophic models for earlier periods. The model represents the trophic structure of the system after a southward shift of major resources. There was an increase in biomass of small pelagic fish and cephalopods between the 1980s and 2004-...
Conference Paper
A knowledge-based system (expert system) was developed to evaluate the effectiveness of implementation towards an ecosystem approach in the South African small pelagics fishery, the largest fishery by volume in the country. The knowledge-based system models the ecological well-being dimension of an ecosystem approach (EAF) in the S.A. sardine-direc...
Conference Paper
The marine pelagic social-ecological system in the southern Benguela, which supports important forage fisheries, has been undergoing both human-induced and environmentally-induced long-term, system-scale changes. While people have learnt to adapt to the high interannual variability in the natural system, the effects of long-term changes have largel...
Conference Paper
A number of ecologically and economically important species in the southern Benguela, including sardine Sardinops sagax and anchovy Engraulis encrasicolus, have undergone southward/eastward shifts in their distribution in recent decades. In addition to the effects of changes in prey availability to top predators, the spatially-distinct nature of th...
Article
Full-text available
We set out to explore some of the impediments which hinder effective communication among fishers, fisheries researchers and managers using detailed ethnographic research amongst commercial handline fishers from two sites- one on the southern Cape coast and the other on the west coast of South Africa. Rather than assuming that the knowledge of fishe...
Article
This paper assesses changes in the southern Humboldt system (33–39 °S) in the 20th century by constructing and comparing food web models representing four historical periods: (i) lightly exploited (<1900s), (ii) altered by removal of marine mammals (1950), (iii) development of industrial fisheries (1992), and (iv) the more recent state (2005) when...
Article
Full-text available
Dyer Island, South Africa, supported the largest African penguin Spheniscus demersus colony in 1979 (22 655 breeding pairs), but population dynamics of the species have not followed the trends of adjacent colonies in years of high fish abundance or shifts in prey distribution. Less than 1 500 pairs were breeding on Dyer Island in 2013. Available kn...
Article
Based on ethnographic fieldwork amongst a group of commercial handline fishers in the town of Stilbaai in South Africa's southern Cape region, this paper presents a range of flexible, adaptive and evolving strategies through which fishers negotiate constantly shifting variability in weather patterns, fish stocks, fisheries policies, and economic co...
Article
Full-text available
The South African abalone Haliotis midae is a commercially valuable species, but its numbers are seriously depleted due to illegal fishing. Overfishing not only affects the targeted species, but also potentially influences the integrity and functioning of the ecosystem through associated changes in community composition. We assessed the herbivorous...
Article
South Africa's small pelagics fishery is currently the largest in volume and second largest in value in the southern Benguela. It exploits short-lived, small pelagic fishes such as anchovy (for reduction into fish meal and oil) and sardine (for reduction as well as human consumption through canned products), and to a lesser extent redeye round herr...
Article
Full-text available
Wilhelm, M. R., Roux, J-P., Moloney, C. L., and Jarre, A. 2013. Data from fur seal scats reveal when Namibian Merluccius capensis are hatched and how fast they grow. – ICES Journal of Marine Science, 70: . Scat samples were collected regularly at several breeding colonies of Cape fur seals along the Namibian coast. Merluccius capensis otoliths were...
Article
This paper examines the increasingly close interaction between natural and social scientists, non-governmental organizations (NGO) and industry, in pursuit of responsible ecosystem-based management of fisheries. South Africa has committed to implementing an ecosystem approach to fisheries management. Management advice stems from multi-stakeholder r...
Article
Full-text available
An index of upwelling and temperature profiles (indicating the dynamics of the upper mixed layer) gave a good qualitative prediction of the dominance of either small (410 m) or intermediate-to-large (1074 m) phytoplankton cells in surface waters of St Helena Bay, a semi-enclosed bay in the Southern Benguela upwelling region on the west coast of Sou...
Article
Full-text available
The development of suitable reference states for ecosystem-based management requires documentation of changes in structure and functioning of marine ecosystems, including assessment of the relative mportance of bottom-up and top-down processes as drivers of change. We used monitoring data available from St Helena Bay, the most productive bay and an...
Article
Full-text available
Over the past two decades, several species have undergone distributional shifts in the southern Benguela. The commercially-important West Coast rock lobster Jasus lalandii is one of these, and its shift in distribution has had profound effects on the rest of the ecosystem along the south-west coast. Reasons for these shifts are not fully understood...
Article
Research survey data collected over 24 years (1986–2009) were used to explore long-term changes in demersal fish assemblages on the west coast of South Africa. Differences in spatial (latitude and depth) and temporal (seasonal and annual) factors were examined using multivariate analyses. Fish assemblages are clearly influenced by depth, with a dis...
Article
This study explores the usefulness of a frame-based modelling approach in the southern Benguela upwelling ecosystem, with four frames describing observed small pelagic fish dominance patterns. We modelled the dynamics of sardine Sardinops sagax and anchovy Engraulis encrasicolus populations under the influence of the small pelagic fishery and clima...
Chapter
Interdisciplinary research to address global change is essential but inherently difficult. Modeling is a necessary component of many interdisciplinary projects; the way in which modelers approach their work and think about modeling can have a profound effect on the success of the project as a whole. This contribution discusses crucial consideration...
Article
South Africa’s commitment to implementation of the ecosystem approach to fishing (EAF) requires a solid scientific basis comprised of a toolkit assembled through concerted efforts from which management measures can be carefully considered and put into place. A series of workshops was held to assist in the identification of issues in South Africa’s...