Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Aerial surveys conducted along the Garden Route coastline, South Africa, to determine patterns in shore fishing effort

Coastal environments provide a wide range of leisure opportunities, including recreational fishing. Understanding spatial and temporal fishing patterns is important in ensuring wise management and sustainable use. To provide information on shore angler effort and distribution, randomised aerial surveys of the Garden Route coast between the eastern border of the Tsitsikamma Marine Protected Area and the Kaaimans River mouth in the west were undertaken between December 2008 and November 2009. A total of 15 flights were conducted, with six flights taking place over weekends, two on public holidays and the balance on normal week days. Angler effort was not uniformly distributed along the coastline, and spatial analysis highlighted coastal areas both inside and outside marine protected areas that had increased angler effort. In general, fishing effort was highest around more densely populated areas and concentrated in areas with easy access. Although angler counts were highly variable, the seasonality of shore angling effort showed a slight increase during autumn and winter and angling effort was significantly higher on weekends. Conservation implications: Data obtained during these surveys can assist management with future conservation planning exercises, whilst also guiding daily law enforcement patrols to maximise angler encounters

Movement behaviour of alien largemouth bass Micropterus salmoides in the estuarine headwater region of the Kowie River, South Africa

The movement behaviour of largemouth bass Micropterus salmoides in the estuarine headwater region of the Kowie River, South Africa, was investigated using passive acoustic telemetry. Ten adult fish were tagged and released in four discrete pools below a weir that precluded possible upriver migration. Their residency and movement patterns were monitored using 27 moored acoustic receivers spanning both riverine and estuarine habitats between January and November 2013. Small-scale movements ranging from 50 to 400 m occurred between pools in the headwater region, where tagged fish remained resident (did not leave their tagging pool) during the warmer (summer) months. The onset of autumn and winter correlated with declining water temperatures and half of the tagged largemouth bass made downstream excursions into the slightly warmer upper reaches of the estuary. The penetration of these alien piscivores into estuarine headwaters potentially provide additional predator pressure on the juveniles of migratory estuary-associated native marine fish species, which utilise these areas as nurseries. The presence of the alien fish in South African estuarine headwaters may impair the migration of juvenile fishes between the estuarine and freshwater environments

Fish on the move: Connectivity of an estuary-dependent fishery species evaluated using a large-scale acoustic telemetry array

Connectivity â movements of animals between and among numerous habitats â and the factors (rhythmic cycles and environmental variables) influencing connectivity of juvenile Lichia amia (Teleostei: Carangidae) were assessed in complementary acoustic telemetry studies in two geographically separated estuaries (620 km apart) in South Africa. The studies were conducted within a nationwide array of acoustic receivers moored in estuaries and coastal waters. Tagged fish in both the Kowie (n = 21) and Goukou (n = 17) estuaries displayed high levels of multiple habitat connectivity, with 81% and 76% visiting nearby marine and estuarine environments. The presence of tagged L. amia within the tagging estuaries was significantly influenced by river and sea temperature (Kowie) and river inflow and moon phase (Goukou). Tidal phase, time of day and season were found to significantly influence marine excursions undertaken by Kowie- and Goukou-tagged fish. Our study provides an assessment of connectivity between multiple estuarine, port and marine habitats, relating those movements to rhythmic cycles and environmental variables, and highlights the benefits of tracking animals using an extensive acoustic receiver array that spans multiple habitats.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Movement behaviour of alien largemouth bass Micropterus salmoides in the estuarine headwater region of the Kowie River, South Africa

The movement behaviour of largemouth bass Micropterus salmoides in the estuarine headwater region of the Kowie River, South Africa, was investigated using passive acoustic telemetry. Ten adult fish were tagged and released in four discrete pools below a weir that precluded possible upriver migration. Their residency and movement patterns were monitored using 27 moored acoustic receivers spanning both riverine and estuarine habitats between January and November 2013. Small-scale movements ranging from 50 to 400 m occurred between pools in the headwater region, where tagged fish remained resident (did not leave their tagging pool) during the warmer (summer) months. The onset of autumn and winter correlated with declining water temperatures and half of the tagged largemouth bass made downstream excursions into the slightly warmer upper reaches of the estuary. The penetration of these alien piscivores into estuarine headwaters potentially provide additional predator pressure on the juveniles of migratory estuary-associated native marine fish species, which utilise these areas as nurseries. The presence of the alien fish in South African estuarine headwaters may impair the migration of juvenile fishes between the estuarine and freshwater environments.Keywords: alien invasive, estuary-dependent, estuarine fish, fishway, residency, telemetr

Movement patterns of Lichia amia (Teleostei Carangidae) results from a long-term cooperative tagging project in South Africa

Understanding fish movement patterns and migrations is important for fisheries management as well as the identification and conservation of critical habitats. Data collected by the Oceanographic Research Institute's Cooperative Fish Tagging Project (ORI-CFTP) were used to describe the large-scale movement patterns of Lichia amia along the South African coastline. A total of 10 762 L. amia were tagged between 1984 and 2012, of which 744 (7%) were recaptured. Most tagging effort, mainly on juvenile and subadult individuals, took place along the south-eastern (i.e. Eastern Cape) and south-western (i.e. Western Cape) regions of the country during summer. Conversely, more L. amia were tagged and recaptured (mostly adults) during winter and spring (July to November) along the north-east coast (i.e. KwaZulu-Natal). Movements (dispersal distance in kilometres) by juveniles were restricted and largely confined to estuaries within the south-eastern and south-western regions of the country. There was a significant effect of fish size on distance moved (ANOVA: p0.001), with evidence of a distinct seasonal (winter) longshore migration by adults to KwaZulu-Natal. The consequences of juvenile residency in estuarine habitats and high recapture rate of adults during a directed, seasonal spawning migration are discussed in light of improving current fisheries management

Movement patterns of Lichia amia (Teleostei: Carangidae): results from a long-term cooperative tagging project in South Africa

Understanding fish movement patterns and migrations is important for fisheries management as well as the identification and conservation of critical habitats. Data collected by the Oceanographic Research Institute’s Cooperative Fish Tagging Project (ORI-CFTP) were used to describe the large-scale movement patterns of Lichia amia along the South African coastline. A total of 10 762 L. amia were tagged between 1984 and 2012, of which 744 (7%) were recaptured. Most tagging effort, mainly on juvenile and subadult individuals, took place along the south-eastern (i.e. Eastern Cape) and south-western (i.e. Western Cape) regions of the country during summer. Conversely, more L. amia were tagged and recaptured (mostly adults) during winter and spring (July to November) along the north-east coast (i.e. KwaZulu-Natal). Movements (dispersal distance in kilometres) by juveniles were restricted and largely confined to estuaries within the south-eastern and south-western regions of the country. There was a significant effect of fish size on distance moved (ANOVA: p < 0.001), with evidence of a distinct seasonal (winter) longshore migration by adults to KwaZulu-Natal. The consequences of juvenile residency in estuarine habitats and high recapture rate of adults during a directed, seasonal spawning migration are discussed in light of improving current fisheries management.Keywords: fisheries management, leervis, migration, movement behaviour, tag recaptur

Benchmarking knowledge-based adaptive management of estuarine fisheries in South Africa for sustainable development

The dynamic South African coastline is over 3 000 km long and comprises 290 estuaries and 42 micro-estuaries. These biologically productive habitats provide fishery opportunities for both subsistence and recreational users, making these fisheries important for income creation and food security, especially for vulnerable coastal communities. Unfortunately, most of the sought-after, often large-bodied fish species that are caught in estuaries are overexploited, with some stocks considered as collapsed. The complexity of managing the estuaries in South Africa, together with illegal and unregulated fishing, climate impacts and increased anthropogenic pressures are threatening not only the fisheries but also the livelihoods, and food security in particular, of fishers and their communities. For the past 20 years, researchers from the South African Institute for Aquatic Biodiversity (NRF-SAIAB) and the Norwegian Institute for Nature Research (NINA) have investigated the behaviour and vulnerability of prominent estuarine fish species to provide knowledge for improved sustainable management of the fisheries. However, these findings, although important, have had little direct influence on estuarine fisheries policies and regulations in South Africa. This was the impetus for the South Africa/Norway Cooperation on Ocean Research (SANOCEAN) project ‘Benchmarking knowledge-based adaptive management of estuarine fisheries in South Africa for sustainable development’ financed by the South African National Research Foundation, the Research Council of Norway, NRF-SAIAB, NINA and the Institute for Coastal and Marine Research at Nelson Mandela University (NMU). The project aims to develop recommendations for knowledge-based governance of estuarine fisheries in South Africa to aid sustainable development in this sector. To achieve this goal our interdisciplinary study of estuarine fisheries management included key researchers in the biological, socio-cultural and economic sciences from NRF-SAIAB, NINA, NMU and the University of Strathclyde. We adopt a socio-ecological systems approach that included novel methods that are inclusive of different knowledge systems. Through biological, socio-cultural and socio-economic research, the project aims to guide a more sustainable approach to estuarine management, blue economy policies, resource utilisation and improved resilience of ecosystem services. The purpose of this report is to guide coastal and estuarine managers with key findings and recommendations that will assist in setting fisheries regulations and manage these important systems that benefit communities directly, have high social and cultural value and contribute towards the blue economy in South Africa. With improved regulation and implementation, estuarine resources can be sustainably utilised more equitably and will aid in conserving the estuarine ecosystems and services. This closeout report provides a summary of the findings of our SANOCEAN project and provides recommendations for adaptive estuarine fisheries management that are knowledge-based and interdisciplinary. Project conclusions Estuarine fisheries cannot be managed in isolation by only taking resources and fishers into account. Estuaries must be co-managed as socio-ecological systems that have critical linkages from their catchment areas to the marine environment. A holistic approach to management, supported by multi-disciplinary research that is inclusive of all knowledge systems, is the only way to improve estuarine functioning and allow for the sustainable provision of goods and services. Key areas that need to be addressed to improve management of estuaries and their resources: Consistent integration of scientific, practical, Indigenous and local knowledge systems and knowledge holders for an improved understanding of complex social-ecological estuarine ecosystems. Improved management and law enforcement through capacity development, integration of all stakeholder groups, increased financial resources and funding at all levels of governance. Strengthen current cooperative governance processes, including policy and legislative coherence to ensure a co-ordinated approach to estuary management. All stakeholders need to recognise and understand the complicated dynamics of socio-economic inequalities and apartheid legacy issues that continue to marginalise and exclude certain individuals and communities from equitable access to estuaries and their resources to enable a better response to resource use challenges. Stakeholder processes, methodologies and pathways need to be addressed to allow for users to contribute meaningfully to management processes and stewardship of estuaries. This will reduce tensions and conflict, and build trust. Inclusion and acknowledgement of multiple benefits and services in fisheries management within estuaries is essential. This would include cultural benefits and health. Manage and restore vital ecosystem functions through addressing water quality and quantity as a main driver. This could include wastewater treatment management and ecosystem restoration. Build capacity for research integration in estuarine management to adequately address and manage estuaries as complex socio-ecological systems. Effective implementation of the proposed new fisheries regulations and the establishment of Estuarine Protected Areas, in close collaboration with estuarine stakeholders, with linkages to the marine environment is essential for sustainable estuarine fisheries. Scenario planning and adaptive management approaches to address emerging serious threats to estuarine functioning posed by mining activities, both legal and illegal, and alien and invasive species. Ensure the development and implementation of estuary management plans, which provides a vital tool for facilitating the integrated management of estuaries as socio-ecological systems. A significant opportunity to enhance the protection of estuaries and their resources is provided in the proposed Estuarine Functional Zone expansion detailed in the 2018 National Biodiversity Assessment - Estuarine Realm. Present estuary management The realisation that estuaries are complex systems linked to and affected by catchment and land-use activities, the coastal and marine environment, and human needs and activities, gave rise to the National Estuarine Management Protocol. The effectiveness of any management plan, however, depends on how well it is informed by a range of knowledge systems. A solid knowledge base provides for evidence-based decision-making, and perhaps more importantly allows for flexibility via adaptive management as more knowledge becomes available and/or situations change. This is the key as regime shifts, such as climate change together with ever-increasing demands for resources and other anthropogenic impacts require constant re-evaluation of management objectives and their implementation. Therefore, the perceptions of role players with regards to current strengths and weaknesses of and solutions to estuarine management in general and estuarine fisheries in particular, were considered to be of key importance in laying the foundation for developing knowledge-based adaptive management recommendations. Lessons learned: South Africa has good legislation related to estuary and fisheries management, but a combination of limited capacity (manpower, infrastructure, funding, knowledge) and poor governance (includes poor cooperative governance) mean that mandates and responsibilities are not fulfilled to their full potential. Non-compliance or lack of self-regulation across the board erodes management efforts. Estuary management plans (EMPs) are an essential enabler and provide a legally binding framework that facilitates cooperative governance to achieve the management of estuaries as complex socio-ecological systems. They should be simple, clear and concise and indicate the What, Who, Where, When and How of estuary issues and management interventions. As a lever for change, EMPs should be developed for priority systems identified in the National Biodiversity Assessment - Estuarine Realm (NBA), and small rural systems with similar characteristics (physical, functional and socio-economic) can be clustered. In the absence of EMPs, protection of the Estuarine Functional Zone (EFZ) via the Environmental Impact Assessment (EIA) process and the use of tools such as the NBA to classify estuaries as Critical Biodiversity Areas or Critically Endangered Ecosystems will reduce the threat to health and functioning. The identification and appointment of key driven people in key positions (champions) is needed to prioritise and implement estuary management efforts. Estuaries are complex systems and management interventions, and research needs to adopt an integrated socio-ecological systems approach that takes connectivity (catchment to coast), ecological and biological interactions, and socio-cultural-economic values into account. Indigenous and local knowledge systems are under-utilised in developing knowledge-based management actions and this leads to the exclusion of communities and end users with the result that trust in government and management authorities is undermined. Weak institutional functioning resulting from governance challenges and limited capacity means estuary management is not prioritised, there is a lack of institutional memory, bureaucratic delays hamper management efforts and management bodies such as Estuary Management Forums and Coastal Committees are neither representative nor functioning optimally. Key to resolving this is the appointment of champions in key positions, the recognition of the socio-economic importance of estuaries and representative participation in management. Poor understanding of the importance of estuaries to biodiversity and, more importantly, to social well-being, means that management is not prioritised. Raising awareness amongst all role players via two-way communication and the integration of knowledge from all knowledge systems could help focus government efforts to manage estuaries and encourage compliance amongst end users. The impact of mining activities needs to be assessed and the environmental authorisation process revisited. Impacts from land-use and development, including mining, urban development, infrastructure and agricultural practices can be reduced by formal recognition of the expanded EFZ proposed in the NBA and strict application of the EIA process in the zone. Compliance with regulations and standards for improved water quality is essential. The reduction of contaminated agricultural return flows and discharges from wastewater treatment works alone will go a long way in improving the situation. The development and implementation of Resource Directed Measures for the NBA-prioritised estuaries should be a priority. Estuary mouth manipulation may only be done after authorisation of Mouth Management & Maintenance Plans, or under emergency situations. Making the EFZ a no-go area in terms of land-use and development would preclude the necessity or frequency of artificial breaching. Despite the pending kob species and estuary night-fishing ban, more stringent regulations for key linefish species are needed in combination with formal protected areas and no-take zones, established through meaningful stakeholder engagement processes. However, the efficacy of these actions is reliant on enforcement, for which there is limited capacity, and compliance or self-regulation by end users, which is also in short supply. The extent of the impact of biological invasions needs to be brought to the attention of authorities so eradication measures can be implemented, and the aquaculture industry and aquarium trade must be better regulated. Thirteen management themes that encompass the levers for change to address the dominant challenges were identified, namely: 1. Increase capacity to govern 2. Improved compliance 3. Effective governance 4. Institutional functioning 5. Enhanced knowledge sharing and communication 6. Reducing impact of mining 7. Amendment and improved implementation of legislation and frameworks 8. Improved water quality and decreased pollution 9. Water quantity 10. Mouth manipulation 11. Sustainable resource use 12. Responsible land-use and development 13. Control of invasive species. Fisheries resources The biological importance of estuaries cannot be overestimated, and immeasurable numbers of larval and juvenile fishes recruit and thrive in these systems. Amongst these are species valuable to estuarine subsistence, small-scale and recreational fisheries, with some being targeted more than others. Most species are distributed throughout South Africa, fall under various International Union for Conservation of Nature Red List categories, are in varying stages of collapse, and have their own management regulations. The objectives of the estuarine fisheries resources studies have been to gain policy relevant knowledge to address the adaptive management needs of the important estuarine fisheries in South Africa. This has been done by evaluating a series of management options by quantifying patterns of movements, area use and seasonal distributions of fisheries species using data from previous and ongoing studies. Lessons learned: South Africa has at least eleven important estuarine fishery species utilised in subsistence, small-scale commercial and recreational fisheries. Species composition and area use of the species varies among estuaries. Estuary-dependent fish species are important food and economic resources, which contribute significantly to the socio-cultural-economic sector. The present fisheries management of important estuary-dependent species must be improved to secure fish stocks and avoid further population depletion and worsened status. Most fishes targeted in estuarine fisheries are estuary-associated species, spending a large portion of their juvenile life in estuaries, showing a relatively high, but varying, degree of residency to specific estuaries. While in their estuarine nursery habitat, fish use varying lengths of the estuary with some species being more resident to certain areas (e.g. spotted grunter, Cape stumpnose, white steenbras) than others (e.g. dusky kob, leervis). Sub-adults and adults of estuarine fishery species, including dusky kob, spotted grunter and leervis, have all been shown to spend more time in estuaries than previously thought. Juveniles of most species show relatively high levels of residency to their tagging estuaries, with some actively moving between the estuary and adjacent marine environment, as well as to other neighbouring estuaries. Recaptures of tagged fish show that some of the species are heavily targeted in estuaries, and that fish below the legal size-limits were often retained. Effective and sustainable management regulations may vary for different species, and to some extent also among estuaries. Management regulations must therefore be tailor-made for the species in question and based on knowledge of the species behaviour and area use. The threatened status of some of the important estuary-dependent species calls for immediate implementation of effective regulations to secure sustainable use of these valuable resources. Without sustainable use, future fisheries resources are threatened, with especially severe implications for more marginalised and poor fisher groups. In the present situation with restricted law enforcement of, and compliance with, fisheries regulations, our studies indicate that no-take estuarine area closures are likely to benefit important coastal fishery species; at least the more resident species, during their obligatory estuary-dependent life-history phase. However, the size, proportion and part of the estuary closed to fisheries will determine the effectiveness of the protected area. Resource economics of estuarine ecosystem services Estuaries provide ecosystem services to humans. Ecosystem services are both material (provisioning ecosystem services) and non-material (cultural ecosystem services). Material benefits humans receive from estuaries include food, freshwater, and genetic resources, while the non-material benefits include recreation, aesthetic enjoyment, spiritual experiences, and physical and mental benefits. Fishing occurs in estuaries and sustains local economies and traditions as well as providing basic food. Estuaries also generate employment through tourists who are drawn to estuaries because of the aesthetics and the water sporting activities that they offer. The objective of this part of the project has been to assess the value of provisioning ecosystem services from the estuaries, including both bait collection and fishing by subsistence and recreational users. Lessons learned: Estuarine ecosystem services face significant threats and challenges, the majority of which are caused by anthropogenic activities, while others are caused by climate change. Estuaries provide benefits to humans and help them maintain their livelihoods. These benefits can be monetary (provisioning ecosystem services) or non-monetary (cultural ecosystem services), which are valued for the contributions they make to livelihoods and societal well-being. Most of the research on the value of estuarine ecosystem services is conducted globally, with only a few studies conducted in South Africa, which highlights a significant research gap. This emphasises the importance of increased research effort into the value and conservation of the estuarine ecosystem services in understudied geographic areas. Our economic valuation estimates provide reliable examples of the economic benefits of keeping estuaries intact, and indirectly pinpoints the value of well-managed estuarine ecosystems to maintain or improve connectivity for fish populations and ecological production, in combination with sustainable utilisation of natural resources in estuaries. Socio-cultural aspects of estuaries Another important objective of the project has been to identify the constraints and enablers to management of estuarine fisheries as well as to identify and understand the socio-cultural components that impact the governance of these resources. Recognising that fisheries management is located within estuarine management, we acknowledge the need to approach this work with a social-ecological systems perspective. This component of the study responds to a lack of research on the social-cultural dimensions of estuarine management and aims to identify key social and cultural benefits of estuaries. To advance towards more integrated approaches to estuarine management, which acknowledges economic, social, and cultural priorities alongside biophysical and environmental objectives, this aspect of the research explores the opportunities for alternative knowledge integration into estuarine management, ensuring Indigenous and local knowledge systems inform future estuarine management processes and implementation. Social-ecological systems approaches to environmental management highlights the need to identify and analyse the links between estuarine ecosystems, estuarine users and environmental challenges. We specifically focus on the specific estuarine resource users and estuarine uses, and their interlinkages with estuarine resources and ecosystems. Lessons learned: Estuarine fisheries management is informed primarily by scientific knowledge (over other knowledge systems). Estuarine fisheries systems, as complex social-ecological systems, require a consistent integration of different knowledge systems and knowledge holders to manage them effectively, adaptively and sustainably including not only scientific knowledge, but practical, Indigenous and local knowledge. Resource users’ connections with estuarine fisheries are complex, multidimensional and often overlap to the extent that understanding users goes beyond the simplified motivations of subsistence or recreation. Socio-economic inequalities and apartheid legacy issues continue to exclude certain users from equitable estuary access and use. Estuary management needs to recognize and understand these complicated dynamics in order to better respond to resource use challenges. Structural racism within government institutions and society more broadly, continues to constrain estuarine management measures and sometimes leads to marginalisation and exclusion of certain individuals and communities. It is at times challenging for local estuarine managers to fulfil their mandates due to limited capacity, executive sponsorship, leadership and poor communication from superiors. There is a lack of realistic opportunities and support from authorities for estuarine users to engage meaningfully in the management process. Users feel sidelined, which erodes confidence in government and management interventions and processes. The strong cultural connections that users have to estuaries must be acknowledged, understood and viewed holistically with other uses in order to better inform management. Social science data fails to inform estuarine management processes and policy due to limited capacity and knowledge flow structures to integrate such data. There are limited governance structures and capacity to engage stakeholders in a meaningful and inclusive way, which can result in increased social tensions rather than shared knowledge, trust and stewardship of estuaries. Meaningful and inclusive stakeholder engagement is hampered by bureaucracy and ineffective knowledge flow structures, leading to social tensions, lack of knowledge sharing and the inability of estuar

Acoustic tracking of a threatened juvenile shark species, the smooth hammerhead (Sphyrna zygaena), reveals vulnerability to exploitation at the boundary of a marine reserve

The coastal waters of South Africa are habitat to a diverse composition of sharks that are vulnerable to exploitation, many of which are endemic and/or classified by the International Union for Conservation of Nature (IUCN) Red List as Threatened or Data Deficient. Accordingly, this region has been identified as a global research and conservation priority for elasmobranchs. The De Hoop Marine Protected Area (MPA), in the Western Cape Province of South Africa, provides 288 km2 of no-take protection within its boundaries. However, the region experiences heavy commercial fishing, with two vessels actively operating as dedicated shark longliners (as of 2022). When crossing MPA boundaries, sharks are susceptible to capture by these vessels. Utilizing passive acoustic telemetry, the present study evaluated the movements of a threatened juvenile shark species, the smooth hammerhead (Sphyrna zygaena), both inside and adjacent to the De Hoop MPA, and along the greater coastline. Movement data from 20 tagged sharks were used to explore the effects of spatial, environmental, and management variables on their residency and movement patterns. Results indicate a high reliance of sharks on unprotected waters immediately adjacent to the MPA’s eastern boundary, an area of high biological productivity due to its proximity to the mouth of an estuary. Although some tagged sharks did move regionally along the South African coastline, individuals spent 95% of their days detected just outside the eastern boundary of the MPA, rendering them vulnerable to commercial shark longlining occurring there. These findings have conservation implications for smooth hammerhead sharks in South Africa and present an opportunity to revisit management practices that may optimize spatial protection for an important life stage of this threatened species