The practice of catch-and-release (C&R) angling is increasingly being integrated into recreational fisheries as a conservation strategy to promote sustainability. However, C&R can still have lethal or sublethal effects owing to various stressors involved in the act of angling. Using a modified rapid-assessment approach, this study evaluated the potential impact of C&R on the health and short-term survival of bronze seabream Pachymetopon grande in the South African marine shore-based recreational fishery. The air-exposure period was found to be a driver of increased physical impairment, with significantly higher reflex action mortality predictor scores for fish exposed for 70 s or 200 s, whereas the low air-exposure time of 10 s, associated with globally recognised best practices, was least impactful. Using a delayed blood sampling technique, fight time was positively linked to increased blood lactate concentrations, which concurs with other findings and highlights the need to reduce the fight time where possible to limit stress from physical exertion during C&R events. Though mortality was low across all treatments (<4%), air-exposure-driven reflex impairment would likely contribute to increased predation risk if the fish were released directly back into the sea. Handling recommendations include well-established methods that mitigate against hooking injury and reduce the handling and air-exposure times. The incorporation of a species-specific delay in blood sampling shows promise for improving the reliability of physiological markers for evaluating stress responses to C&R in wild fishes, but further refinements are required for this new technique.

Sandy beaches provide vital ecosystem services and support diverse ecological communities but are increasingly threatened by anthropogenic pressures. In particular, intertidal mining disrupts sandy beaches and challenges their resilience, yet these ecosystems retain some capacity for environmental recovery. This study assessed the ecological impact of, and potential recovery from, diamond mining on southern Namibia’s sandy beaches within the Restricted Diamond Mining Area, using the isopod Tylos granulatus as a bioindicator. Paired control and impact sites were surveyed before, during and after mining to estimate T. granulatus abundance and population size structure. Mining onset and activity led to significant declines in T. granulatus abundance at all impact sites, including local extirpation in some cases. While overall abundance showed significant recovery within 1–2 years following mining cessation, the population size structure remained substantially altered for at least 4 years on actively rehabilitated beaches, and for at least 7 years where recovery was left to occur naturally. These findings demonstrate the environmental effects of mining on beach ecosystems while demonstrating the recovery potential (albeit gradual) of these habitats. Our results support T. granulatus as a cost-effective indicator of environmental stress on sandy beaches, while offering critical insights for sustainable management of vulnerable shorelines in southern Africa.

Underwater seismic surveys generate high-intensity, low-frequency noise that can negatively affect a range of marine fauna. As a result, countries have implemented mitigation regulations to reduce the potential impacts of this activity. This study examines seismic survey mitigation regulations from Australia, the United States, Brazil, New Zealand, Canada and the United Kingdom, and compares them with the current regulations in South Africa. We focused on setting the radii of exclusion zones, ‘soft-start’ procedures, passive acoustic monitoring, marine mammal observer qualifications and standards, and regulatory oversight. Of the six countries reviewed, Australia and New Zealand have implemented the most robust mitigation measures. Furthermore, Australia stands out for its independent regulatory authority overseeing offshore environmental compliance. We recommend the establishment of an independent regulatory board in South Africa to oversee the development of environmental impact assessment guidelines and mitigation protocols. By adopting these measures and aligning with international best practice, South Africa could become a regional, if not global, leader in science-based environmental regulation and the protection of marine fauna from seismic surveys.

The construction of seawalls is increasing the extent of artificial infrastructure along coastlines globally. Such development compromises substrate complexity of the natural environment which is crucial for major life functions of larvae (invertebrates and fish). Understanding the physical and biological implications of how marine assemblages function within such transformed environments is imperative in view of the role of early life-stages in regulating the population dynamics of coastal species and the structure of coastal ecosystems. Appropriate sampling gear must be ensured for accurate and comparable data collection of plankton forms across various impacted environments, as in high wave-dynamic natural sites versus in sheltered, urbanised areas. Validating the sampling equipment is also warranted when assessing the cost-effectiveness of gear intended for deployment at wave-dynamic locations. This study evaluated the efficiency of two light trap designs (quatrefoil and cylindrical) in assessing photo-positive larval assemblages along the southeast coast of South Africa. The results showed no significant differences in species diversity, abundance or evenness between the two trap designs and among sites. Significant differences were, however, observed in species richness between the trap designs and across sites, and in overall species composition across sites. These differences were primarily attributed to the presence of juveniles or adults of taxa in the orders Cumacea and Amphipoda. Our findings suggest that either light trap design could be deployed at both urban and natural coastal ecosystems to assess the positively phototactic plankton assemblage from the early life stages. This methodological validation is critical for accurately refining scientific data collection and for meticulously monitoring complex life-stages of coastal resources that require management and habitat rehabilitation.

This study investigated sediment dynamics in the Roman Rock area of False Bay, South Africa, by integrating sediment grain size data with hydrodynamic and wave modelling. We examined two significant events: a long-period southwesterly swell in 2008, and a prolonged southeasterly gale in 2009. Using two-way coupled Delft3D FLOW and SWAN models, we assess wave conditions and their ability to mobilise sandy sediments based on established threshold velocities. The 2008 event was linked to a deep low-pressure system located far south of the subcontinent, generating long-period waves with heights exceeding 10 m offshore. These waves entered False Bay maintaining sufficient energy to produce near-bed orbital velocities that surpassed the sediment movement thresholds over much of the study area. In contrast, the 2009 event created higher, short-period waves that were locally generated and produced lower near-bed velocities, which were not enough to initiate widespread sediment transport. Our findings challenge earlier assumptions that summer southeasterly winds are the primary drivers of sediment mobility around Roman Rock. The results emphasise the significance of episodic long-period swell events in shaping the seabed and highlight the limitations of applying quartz-based threshold models to bioclastic carbonate sediments. This study provides a foundation for future studies exploring the sediment dynamics in False Bay.

Saccostrea cucullata is the dominant species of rock oyster (family Ostreidae) in southeastern Madagascar. Despite its economic and ecological importance, information on its biology and ecology is scarce. This study investigated the growth, shell length–weight relationship, and condition index (tissue dry weight/shell dry weight) of S. cucullata in the Ambinanibe coastal lagoon system. Oysters were placed in cages and deployed at four sites: one site at the Efaho River mouth emptying into the main lagoon, two sites within the main lagoon (Ambinanibe lagoon), and one site out of river influence (Andranasy lagoon). Shell length, shell weight and the condition index were monitored at each site over one year. The results show significant increases in shell length and shell weight during the study period. The relationship between shell length and weight was nonlinear and best described by a power equation. The b value of the length–weight relationship ranged between 1.01 and 1.76, which is comparable to values reported in other studies. Oysters from the site at the river mouth exhibited the highest condition index (4.50 ± 2.82%), while those from the site out of river influence had the lowest (0.72 ± 0.55%), suggesting that freshwater inflow creates favourable environmental conditions for producing high-quality, marketable oysters. Overall, this study makes an important contribution to the current knowledge on the morphometric characteristics and growth parameters of S. cucullata in coastal zones. The findings provide valuable insights for developing effective conservation strategy and optimising the farming of this species, in this region and beyond.

The leopard whipray Himantura leoparda (family Dasyatidae) is globally assessed as Endangered on the IUCN Red List of Threatened Species owing to the species’ inherent vulnerability and declining population trends. In this study we assessed the population found off the coast of South Africa by modelling probability-of-capture using a comprehensive recreational shore-angling competition dataset covering a 46-year period (1977–2022, except not 2020). Although partially biased by ‘effort creep’, the results of JARA (Just Another Red-List Assessment) suggested that the population in South African waters is stable, and thus it was assessed as Least Concern. Decreased fishing effort, introduction of catch-and-release by competition anglers, and the establishment of large no-take marine protected areas within the core range of the species are the likely reasons for this conservation success. However, heavy fishing pressure on the population in southern Mozambique is cause for concern, and ongoing monitoring and careful management are required to ensure sustainable use of this resource.

The concept of ‘other effective area-based conservation measures’ (OECMs) and its technical guidance provide opportunities for recognising a broader range of area-based management measures that contribute to biodiversity conservation outside of protected areas. However, progress towards the recognition of OECMs for the marine environment is less advanced than for terrestrial processes. In response, South Africa developed a systematic approach to establish coherence on the OECM concept in the marine, coastal and estuarine context through rapid trial assessments of 14 management measures against six simplified OECM criteria. The objectives included identifying measures with the greatest potential as OECMs, identifying information gaps and highlighting issues that are unique to the marine context, framed within the OECM definition and assessment criteria. Among the assessed measures, only two (both restricted areas for fishing) were considered unsuitable overall owing to being short-term measures, and in one case because of its single-species focus and weak contribution to broader biodiversity outcomes. Other measures varied in their suitability, with ‘biosphere reserve marine buffer zone’ and ‘closed fishing areas adjacent to African penguin colonies’ being among the existing measures that show the most potential, aligning with five and four of the six simplified criteria for OECMs, respectively. There is substantial work needed to advance marine OECMs in South Africa and to negotiate complexities brought about by the overlapping nature of jurisdictions, management measures, rights and stakeholder interests in the marine realm, and the need for equitable and effective marine governance and management. The approach and recommendations from this exercise may be useful to other countries undertaking similar efforts.

Abandoned, lost or otherwise discarded fishing gear (ALDFG), also known as ghost gear, represents one of the most under-addressed environmental threats. ALDFG is a problem because it is often non-biodegradable and continues to trap marine life long after the gear (nets, lines, traps) has been abandoned. Subsequently, this poses ecological, economic and social consequences to marine ecosystems and coastal economies worldwide. Despite significant research on the environmental impacts of ghost gear, gaps remain in our understanding of the key factors that contribute to its accumulation, the full scope of its consequences and sustainable mitigation measures. Using the drivers–pressures–state–impacts–responses (DPSIR) analytical framework, this review undertakes a comprehensive analysis of the drivers, pressures, state, impacts and responses to ALDFG. For this review, we considered 152 studies produced between 2000 and 2024. We surmise that key factors driving ALDFG accumulation include rapid fishing industry expansion, severe economic constraints, and acute regulatory gaps. Collectively, these driving forces intensify the pressure on marine ecosystems through ALDFG entanglements and the ‘self-baiting cycle’. The impacts can be profound as long-term ecological damage caused by the persistence of ALDFG can result in socio-economic losses for fishers and coastal populations. Current responses to this emerging threat highlight the potential of technological innovations in reducing the prevalence of ALDFG, such as biodegradable gear and gear tracking systems. Future research should explore the application of circular economy principles in gear manufacturing in efforts to combat the ghost gear crisis. This review ultimately underscores an urgent need for a holistic approach to effectively mitigate ALDFG.