The flapnose houndshark Scylliogaleus quecketti is an endemic, range-restricted houndshark species found within a similar to 625 km stretch of coast between East London and Richards Bay on the east coast of South Africa. Little is known about the biology and ecology of this species, and it is listed as Vulnerable on the IUCN Red List. This species was the most common elasmobranch caught in a long-term monitoring project conducted in the Pondoland Marine Protected Area (MPA) from 2006 to 2022. To obtain an understanding of their movement behaviour, individuals were externally dart-tagged (n = 168), and acoustic transmitters were inserted into a small sample of sub-adult and adult individuals (n = 13). A total of 32 (19%) dart-tag recaptures were made with an average distance moved of 213 m. Based on these data, linear home range length was calculated at between 503 and 574 m. Movements of acoustically tagged males and females were localised, with most detections recorded on acoustic receivers in close proximity to the tagging site, thus confirming high residency and site fidelity over multiple years. These findings highlight the value of spatial protection for this species in no-take MPAs within its distribution. Ongoing efforts are required to encourage careful handling and release of individuals by anglers, as well as enforcement of no-take MPAs within the species' distribution. Consideration should also be given to decommercializing this species as a precautionary approach.

Guitarfish species (genus Acroteriobatus) display restricted distributions in undermanaged regions of intense fishing pressure. The importance of accurate specimen identification is well established, especially in the context of conservation management. However, guitarfishes remain poorly understood, which is exacerbated by taxonomic uncertainty due to morphological similarity. We therefore aimed (1) to identify molecular operational taxonomic units (MOTUs) within Acroteriobatus by analysing sampled specimens as well as publicly available sequence data for the cytochrome c oxidase subunit I (COI) and nicotinamide adenine dehydrogenase subunit 2 (ND2) genes, and (2) to augment and review the representation of these sequences on public databases. A molecular taxonomic approach integrating species delimitation and specimen assignment methods revealed 14 MOTUs. These MOTUs aligned with current species descriptions, displaying no evidence of cryptic diversity. Both genes demonstrated similar interspecific relationships that broadly reflected current distribution ranges, underscoring sub-regional endemism. Moreover, discrepancies in public sequence repositories were identified, attributed to misidentified specimens and the usage of outdated taxonomic nomenclature. Genetic diversity indices were substantially inflated when specimens were grouped based on reported species versus delimited MOTUs, thus overestimating genetic diversity. We highlight the need for extensive, curated DNA reference libraries, including revising earlier sequence entries in light of new taxonomic insights, to enable reliable identification of morphologically conserved species. The molecular resolution illustrated in this study can aid in clarifying taxonomic uncertainties in the genus Acroteriobatus.

Wedgefishes represent a threatened group of elasmobranchs with limited knowledge on their ecology and habitat use. To improve our understanding on their movement ecology, 28 Whitespotted Wedgefish Rhynchobatus djiddensis were acoustically tracked for up to 7 years along similar to 900 km of the South African and Mozambican coastline. While detection rates were low, some site fidelity was evident (most detections occurred within 50 km of tagging location). However, there was intraspecific variability in the scales of movement, with individuals tagged in the northern extent of the study region displaying restricted movements (<100 km), while individuals tagged in the southern extent made significant longshore movements (up to similar to 500 km). Movements lacked seasonal trends in directionality, suggesting they were not migrations, and the drivers of these movements remain unresolved. This study confirmed for the first time that Whitespotted Wedgefish undertake transboundary movements between South Africa and Mozambique, highlighting the need for international cooperation between the countries that have neighboring Marine Protected Areas.

Pomadasys furcatus is a relatively common inshore fish species caught in the shore-based linefishery in northern KwaZulu-Natal (KZN), South Africa, yet relatively little is known about the biology and ecology of this species. Movement patterns of this species were studied based on data obtained from a 20-year tag-recapture study conducted in the iSimangaliso Marine Protected Area in northern KZN from 2001 to 2021. A total of 4 983 fish were caught, of which 1 302 were tagged and released and 74 were recaptured. Results showed that P. furcatus is a highly resident species with a linear coastal home-range size of 250-540 m. None of the fish recaptured moved out of the protected area no-take zones in which they were tagged, suggesting limited adult spillover. Based on their residency, options for the future conservation and management of this species are discussed.

The movement and growth of spotted gully sharks Triakis megalopterus (family Triakidae) along the coast of South Africa were investigated using external dart tagging. Of a total of 7 211 sharks tagged, 657 (9.1%) were recaptured over a 37-year period, from 1984 to 2021. Average distance moved by recaptured sharks was 31 (SD 82) km, with a maximum distance moved of 911 km. The longest time at liberty was 6 332 days (17.3 years). Most recaptures (66.9%) displayed resident, philopatric behaviour, although adults moved significantly more than juveniles. There was strong seasonality in the catches, with more individuals caught during summer months (October-March); however, there was no evidence to suggest that adults undertook seasonal migrations to and from mating or pupping areas. Similarly, the findings suggested that pupping likely takes place throughout their distribution and is not confined to a particular region. Growth of recaptured individuals was slow, with an average growth rate of 50 mm year(-1). This was similar to the growth rate determined by vertebral band counts but suggested that individuals could reach a theoretical maximum age of 41 years. Based on the species' resident behaviour and slow growth rate, we advocate for maintenance of the current fishing regulations and greater protection in no-take marine protected areas with suitable habitat within their distribution. Further research using acoustic telemetry is also recommended.

The Critically Endangered seventy-four seabream Polysteganus undulosus, a slow-growing sparid that forms spawning aggregations off South Africa, faced heavy exploitation from 1910 until a fishery moratorium was put in place in 1998. Utilising temporal samples from 1962/1963 (mid-collapse) and 2005/2006 (post-collapse), we assessed genetic diversity at six microsatellite loci. Amplification success for archived samples was low (43%), necessitating a rarefaction approach, revealing a 40% decrease in allelic diversity. Significant genetic differences between recent and archived samples confirmed the impact of overfishing. Simulation studies indicated that missing genotypes did not affect these tests, validating the genetic differences. Using a coalescent-based approach, a 10-fold decrease in effective population size (Ne) was estimated over this 43-year period (Ne = 43.88 to 4.76). Simulations provided corrected Ne of 36.86, accounting for missing genotypes that were responsible for inflated values. Assuming 25% of pristine levels in the 1960s, pristine Ne values ranged from 147 to 176 in 1910, suggesting a 96.8-98.3% genetic decline over 88 years of exploitation. This study emphasises severe genetic consequences of overfishing on P. undulosus diversity and effective population size. The results provide vital genetic baseline data for recovery assessment and conservation efforts, as well as an analytical framework to evaluate the stock decline using partial genotyping data gathered from degraded archived samples.

Giant trevally Caranx ignobilis are iconic, apex marine predators globally distributed in tropical to subtropical regions, where they are of high importance to ecosystems and fisheries. During summer, adults aggregate for spawning, making them vulnerable to overfishing. The world's largest C. ignobilis aggregation has been recorded in southern Mozambique, but the year-round movements of these fish required further investigation. To assess movement patterns of C. ignobilis along the southern African coast, 36 adult fish were acoustically tagged and monitored along the east coast between Santa Maria in southern Mozambique and Port St Johns in the Eastern Cape, South Africa, for over 5 yr using an extensive passive acoustic receiver array. All acoustically tagged C. ignobilis were recorded in southern Mozambique between November and January each year (with minor exceptions), moving distances up to a maximum of 632 km in one direction. These movements were fast and direct, with maximum travelling speeds of up to 130 km d-1. When not migrating, South African-based fish showed consistent inter-annual fidelity to individual linear areas of space use equivalent to home ranges. Although the coastal length of these areas varied considerably between individuals, even the mean length (92 km) was greater than any previously recorded C. ignobilis home range, globally. Findings from this study, including the value of no-take marine protected areas, are of global ecological interest and have implications for local fisheries management. Protecting these vulnerable aggregations is of the utmost importance for the future of this species in southern African waters and elsewhere.

High-latitude coral reefs (HLCRs) are unique ecosystems with diverse biological assemblages, including many low latitude species on their distribution margins. These ecosystems are threatened by fisheries exploitation, habitat destruction and climate change; however, relative to low latitude coral ecosystems, our understanding of their structure and functioning is limited. This is particularly true for sharks and rays. In this study, we used baited remote underwater stereo-video systems to determine the effect of habitat and management on the assemblage structure of elasmobranchs on the HLCRs of southern Africa (26-28 degrees S; iSimangaliso Marine Protected Area [MPA], South Africa, and the adjoining Ponta do Ouro Partial Marine Reserve, Mozambique). We recorded a total of 12 species of shark (142 individuals) and 9 species of ray (40 individuals) over 2 brief time frames (November 2016 and June 2017). All species were tropical with many on the southern limit of their known distributions. Sharks increased in diversity with depth and showed a preference for the reef and mosaic habitats, relative to sand. The occurrence of rays was predominantly influenced by the presence of low relief habitats. These findings highlight the need for MPAs to encompass both sand and reef habitats over broad depth ranges to effectively protect elasmobranch assemblages. We found evidence to support the high average abundance and diversity of sharks and rays within MPAs of South Africa and southern Mozambique. The results highlight the importance of marginal HLCRs, particularly those within MPAs, for the management and conservation of tropical elasmobranch species.

Wedgefishes (Rhinidae) are threatened by unsustainable fishing globally, and especially in the Southwest Indian Ocean (SWIO), due to their high-value fins in the shark trade. The whitespotted wedgefish Rhynchobatus djiddensis and the bottlenose wedgefish R. australiae are both classified as Critically Endangered on the IUCN Red List of Threatened Species, yet a lack of species-specific knowledge and taxonomic uncertainty still exists within this genus. Genetic approaches aid in taxonomic classification and identifying distinct populations for targeted conservation. Morphological specimen identification of samples (n = 189) collected across the SWIO was confirmed based on the cytochrome oxidase c subunit I (COI) and/or nicotinamide adenine dehydrogenase subunit 2 (ND2) gene regions. The genetic diversity and population structure within and between species and sampling locations were investigated using a dual marker approach: (1) 2 concatenated mitochondrial gene regions, namely COI and the control region (n = 117), and (2) 9 nuclear microsatellite markers (n = 146). The overall genetic diversity was moderate, with an indication that different evolutionary forces are at play on a mitochondrial versus nuclear level. The 2 species were delineated based on both marker types, and for R. djiddensis, the sampling locations of South Africa and Mozambique were genetically homogeneous. For R. australiae, significant differentiation was found between sampling locations, with Madagascar and Tanzania being genetically the most similar. This information provides critical insights into the distribution range and population structure of the whitespotted wedgefish species complex that can support the sustainable management of wedgefishes.

The African blackspot shark Carcharhinus humani (until now commonly known as Human's whaler shark) is a small-sized requiem shark (family Carcharhinidae) found in tropical coastal waters of the western Indian Ocean as far south as Port St Johns on the east coast of South Africa. It was only recently recognised as being distinct from the blackspot shark C. sealei, which occurs elsewhere in the Indo-Pacific. This study utilised four datasets to investigate the movements, temporal and geographic distributions, life history and population status of this species in South African waters. The recapture of eight individuals of 294 that were tagged by shore anglers revealed an average distance moved of 33 km (range 1-192 km). Competitive shore anglers caught an average of 39 C. humani per annum along the entire KwaZulu-Natal (KZN) coast, with no marked trend in catch rate over time. Catches in the KZN bather protection programme were extremely low but included 30 pregnant females which displayed a highly seasonal pattern of embryo development. Sightings of C. humani on stereo baited remote underwater video systems (stereo-BRUVS) in the iSimangaliso Marine Protected Area were dominated by females (7.7:1) and were mostly in deeper water of 26-35 m. In all datasets most of the individuals were mature and were present year-round, but with a clear peak in summer and autumn, especially in the catches taken by shore anglers. Competitive shore-angling catch data were used to conduct a risk assessment for the South African population, and, based on values of probability of encounter, the sampled population satisfies the IUCN Red List criteria for Least Concern.

Migration is a critical aspect of ocean ecosystems, and understanding this phenomenon answers ecological and management questions. Given the difficulty in tracking ocean animals across large distances, the extent to which different ray species perform long-distance movements, such as migrations, remains unknown. This study used passive acoustic telemetry to track the movements of endemic diamond Gymnura natalensis and critically endangered duckbill Aetomylaeus bovinus rays along the South African coastline using a collaborative nationwide network of coastal acoustic receivers for up to 7 years. Duckbill rays were detected significantly more frequently than diamond rays, but both species moved between the south and east coasts of South Africa (traveling up to 1167 km). Tagged individuals were detected significantly more often in their tagging locations during summer months but traveled significantly further distances during winter months. Furthermore, movement models fitted to individual duckbill rays' annual net-squared displacement identified most individual annual movements as migratory. This evidence suggests that both diamond and duckbill rays make eastward winter migrations and return to specific areas along the coastline during the summer months. The exceptions to this were diamond rays tagged on the east coast that were not found to migrate seasonally, which supports previous research that there is intraspecific variability in migrations for ray species. These findings have implications for understanding ray migration not only on a global scale but also locally for spatial management interventions and population delineation.

This review explores the similarities and differences in the life-history styles of eight morphologically similar sparid species that occupy the nearshore coastal waters around South Africa. All eight species spawn at sea with two taxa, Acanthopagrus vagus and Rhabdosargus holubi, being dependent on estuaries as primary nursery areas. Two of the species, Rhabdosargus globiceps and Rhabdosargus sarba, have a high proportion of their juveniles in estuaries but are not completely dependent on these systems as nurseries. The remaining four species, Rhabdosargus thorpei, Diplodus capensis, Diplodus hottentotus and Sarpa salpa, have a major proportion of their juveniles on the coastal shelf, with only a small percentage in estuaries. Four of the species (D. capensis, D. hottentotus, R. holubi and S. salpa) occur in all four biogeographic regions, three (A. vagus, R. sarba and R. thorpei) are primarily found in the tropical and subtropical waters and one species (R. globiceps) primarily in temperate areas. All eight species have relatively fast growth rates and a small size at reproductive maturity when compared to other larger sparids, which occupy offshore reef systems and are not found in South African estuaries at any stage of their life cycle. By adopting different life-history styles, the fishes belonging to the family Sparidae have successfully colonised all South African estuaries and the adjacent coastal shelf waters in all four marine biogeographic provinces and are ranked as a dominant marine fish family in terms of both number and biomass in estuaries on the subcontinent.

A tag-recapture study was undertaken on Polysteganus praeorbitalis in the Pondoland Marine Protected Area (PMPA) on the east coast of South Africa. A total of 1 042 fish were tagged over a period of 16 years and 255 individuals (24.5%) were recaptured, some of them on multiple occasions. Data analysis showed that 84.7% of recaptured fish remained in relatively small home ranges (-750 m linear distance), while 13.3% abandoned their home ranges and undertook unidirectional movements (of 21-1 211 km) along the KwaZulu-Natal coast in a north-easterly direction, most likely to spawn. While the no-take area of the PMPA provides effective protection for resident fish, the export of adult P. praearbitalis provides strong evidence of the benefits that no-take MPAs can offer to adjacent fisheries. Based on the tag-recapture length data, the growth rate was found to be relatively slow, averaging 46 mm y-1. This growth rate was similar to that determined by a study of ageing using sectioned otoliths. Reliable tag-recapture data can thus be used to provide a valuable means of validating growth rates determined by other methods.

This review examines the changing status of 10 estuary-dependent marine fish species in 10 South African estuarine systems, ranging from the Kosi Estuary in the northeast to the Berg Estuary in the southwest. In all of these systems, the selected fish species were found to be in population decline, but the causes of the declines varied from one system to another. Recreational and small-scale/subsistence fishing was a common pressure on fish stocks in most of the reviewed estuaries, but environmental degradation and pollution were the prime drivers for major population declines in the St Lucia and uMhlanga estuaries, respectively. Of six primary linefish species that have been well studied, two species are categorised as having an overexploited stock status and four species have reached a collapsed level where the spawner biomass per recruit (SBR) is now <25% of the original unimpacted level. Furthermore, two of those species (dusky kob Argyrosomus japonicus and white steenbras Lithognathus lithognathus) are in the 4-6% SBR range and have been officially categorised as Endangered on the IUCN Red List. Unless definite steps are taken to reduce fishing pressure on the species discussed in this review, and successful policies put in place to promote healthy estuarine environments around the coast, estuarydependent fish stocks will continue to decline-to the detriment of the fish populations and the people who depend on fish for food, recreation and/or employment.

Giant trevally Caranx ignobilis, the largest species in the genus Caranx, are global icons as apex marine predators and contribute substantially to global fisheries. Understanding their movement patterns is critical for effective management, especially in the case of transboundary stocks. In southern Africa, there is limited published movement data for the species, apart from studies at the world’s largest recorded aggregation of C. ignobilis globally, in southern Mozambique. Therefore, the broad aim of this study was to describe the coastal movements of C. ignobilis from southern Africa using data from South Africa’s longest-running citizen science tag-recapture project. A total of 3 729 fish were dart tagged between 1984 and 2020, producing 144 recaptures. While 74% of recaptures were recorded < 1 km from the tagging location, long-distance movements of up to 419 km were also recorded (mean = 15 km). Although adults moved significantly (p < 0.01) greater distances than juveniles, they also displayed high levels of site fidelity. Seasonal trends included evidence of a summer migration from South Africa to southern Mozambique; but surprisingly, no transboundary movements were recorded. The data suggest long-term site fidelity with interspersed return migrations, likely for spawning. However, for the purposes of management, further research would be required to determine the proportion of the population that undertakes transboundary migration, rendering them potentially vulnerable to overfishing in foreign waters.

A tag-recapture study was undertaken on the Natal seacatfish Galeichthys troworum in the Pondoland Marine Protected Area (PMPA) on the east coast of South Africa. A total of 473 fish were tagged over a period of 8 years, and 136 individuals (28.8%) were recaptured over a period of 16 years, some of them on multiple occasions. Most recaptures (82%) were caught within 200 m of their release site, with movements ranging between 0 and 617 m, and time-at-liberty ranging between 0 and 3 407 days (9.3 years). Data analysis showed that all recaptured fish remained in relatively small home ranges (of similar to 360 m linear distance) and none of them abandoned their home range and moved out of the 2-km(2) sampling blocks. While the no-take area of the PMPA provided effective protection for these fish, their relative abundance was similar in an adjacent exploited area. This is likely because G. troworum is not a desired linefish species, with most individuals caught being released, coupled with high post-release survival.

Migratory sharks play a key ecological role through movements within and among marine ecosystems, yet many populations are declining. Addressing the decline is especially challenging for wide-ranging species, as they may undertake movements between countries with disparate conservation priorities. To investigate the transboundary migrations of threatened sharks between neighbouring South Africa and Mozambique, we tracked 4 commonly occurring carcharhinid species (bull, blacktip, tiger and grey reef sharks). A total of 102 individuals were fitted with long-life acoustic transmitters and monitored for 4 yr (2018-2022) on an acoustic receiver network of 350 receivers. During this period, 63% of tagged bull sharks (n = 19), 87% of blacktips (n = 13), 94% of tiger (n = 16) and 25% of grey reef sharks (n = 3) undertook transboundary movements. The frequency of mean transboundary movements per year ranged between 1.3 ± 1.5 (SD) for grey reef sharks and 81 ± 35.6 for tiger sharks. Blacktip, bull and tiger sharks all undertook long-distance transboundary migrations ranging from 980 to 2256 km. These data confirm high connectivity between neighbouring countries by threatened sharks undertaking persistent transboundary movements. This study emphasizes the need for collaborative transboundary cooperation between the 2 countries and the alignment of regional management plans and interventions to address declining shark populations in this region of the Western Indian Ocean.

Marine Protected Areas (MPAs) regulate human behaviour within their boundaries to support long-term conservation of marine ecosystems and associated human benefits. As complex socio-ecological systems, the success of MPAs is fundamentally reliant upon community and stakeholder engagement, support, and compliance. Using the Aliwal Shoal MPA in South Africa as a case study, 48 stakeholder interviews were conducted to explore perceptions of existing challenges and potential solutions relating to management of the MPA. Analysis identified several challenges including: i) non-compliance with existing laws; ii) insufficient marine law enforcement; iii) national corruption; iv) poor physical infrastructure, and v) perceived racially biased MPA regulations. To address these challenges, interviewees highlighted the following potential solutions: i) development of awareness raising initiatives to foster marine stewardship and support for the MPA; ii) improving the visibility of marine conservation and MPA management activities; iii) investing finances generated by the Aliwal Shoal MPA regulations (such as diving permit fees) directly into MPA management; iv) identifying and enhancing local skills and knowledge that could contribute to enhancing conservation activities; and v) exploring innovative technical solutions that can improve community awareness and compliance with MPA regulations. While not representative of the entire spectrum of stakeholders, this paper provides useful insights that can be used by national MPA implementing agencies, local management bodies and conservation organisations as they try to improve engagement with local stakeholders to optimise social, economic, and ecological benefits, and contribute to improved governance. Additionally, the paper contributes to the global call for improved communication and engagement with stakeholders about MPAs, especially considering the increased emphasis placed on protected areas for global conservation.

Fishers' ecological knowledge (FEK) has become a popular method for collecting fisheries data. Yet, standard biological sampling by researchers is still the most commonly used method. South Africa's recreational fishing sector currently has a wealth of biological and demographic information on species captured with hook and line, while several species targeted in the spearfishery are data limited. The aim of this study was to incorporate specialised spearfisher FEK to improve the understanding of the reproductive biology of Oplegnathus conwayi in South Africa. This was achieved using standard biological sampling and FEK data collected from specialist spearfishers using a questionnaire. A total of 305 O. conwayi were collected along the South African coastline. Fish were dissected, sexed and staged macroscopically and gonad staging was verified histologically. One hundred and three survey responses were received, of which 90 were regarded as being from specialised spearfishers. The combination of both traditional sampling and FEK data complemented each other well, with key reproductive data such as spawning season, length-at-maturity and spawning locality being collected. The combination of these methods is strongly advised for future life history studies, particularly, in countries with data-deficient species and limited research funding.