Fishes In South Africa Research Articles

Revalidation of Enteromius karkensis (Gilchrist and Thompson 1913) (Cypriniformes: Smiliogastrinae) from the southern temperate freshwater ecoregion, South Africa.

The chubbyhead barbs, a distinct group of fishes endemic to southern Africa, currently include eight valid species. Historically, Enteromius anoplus was the most widespread freshwater fish in South Africa due to synonymizations in the 1960s. It occurred in nearly every river system except coastal systems in the Cape Fold Ecoregion and the lower Orange River. However, a recent revision utilizing molecular and morphological analyses has led to significant taxonomic updates. Enteromius anoplus is restricted to the Gouritz River system, whereas Enteromius cernuus and Enteromius oraniensis have been revalidated and respectively confined to the Olifants and Orange River systems. Additionally, a new species Enteromius mandelai was described, with its range currently considered to encompass several river systems in the Eastern Cape. Despite these advances, the taxonomic status of fish previously assigned to E. anoplus from KwaZulu-Natal remained uncertain. In this study, an integrative approach, combining genetic analysis, morphological characteristics, and geographic data, was employed to resurrect Enteromius karkensis as a distinct species from E. anoplus. Enteromius karkensis is deeply genetically differentiated (3.99%-8.07% p-distance) from its congeners within the chubbyhead group. Morphologically, E. karkensis is easily distinguishable from its counterparts due to possession of a terminal mouth (vs. inferior in E. amatolicus), one pair of maxillary barbels (vs. two conspicuous pairs in E. motebensis, E. treurensis, and E. gurneyi), and a complete lateral line (vs. incomplete in E. anoplus and E. oraniensis). Furthermore, E. karkensis is differentiated from E. mandelai and E. cernuus by its long maxillary barbels that extend beyond the midpoint of the orbit. These findings highlight a consistent pattern from previous studies that show many freshwater fishes in South Africa have narrow geographic ranges. This emphasizes the importance of targeted conservation and management efforts, and our understanding of the biogeographic and evolutionary history of freshwater fishes in southern Africa.

Ornamental fish in the South African pet shop trade: potential risk to natural aquatic ecosystems

AbstractThe aquarium pet trade is one of the leading pathways for the introduction of invasive species into natural ecosystems. In 2018, we surveyed pet shops across South Africa to obtain a checklist of ornamental fish species in the aquarium pet shop trade and to assess their invasion potential using sourced data (e.g., natural environment, native range, introduction status, impact status and climatic zone). We evaluated selected common aquarium fish species with high invasion potential according to previous invasion history. We highlighted the need for the development of a management strategy for the aquarium pet trade in South Africa. We identified 312 fish species belonging to 77 families and 182 genera. Most pet shops were in Gauteng Province (n = 38), with few in Limpopo Province (n = 3). Gauteng had the highest number of fish species (n = 271), while North West Province had the lowest number (n = 95). Pet shops were dominated by freshwater species (68%), followed by marine species (22%), while the origin of 30 species (10%) was transitional aquatic ecosystems. Most freshwater taxa were native to South America and Asia, while most marine species were from the Pacific and Indo-Pacific Oceans. Most (88%) species were tropical, 10% subtropical, and 1% temperate. Several (n = 28) species had more than 50% frequency of occurrence, representing the most popular ornamental fishes. Several (n = 13) species are invasive in South Africa and other parts of the world. The system of importation of ornamental fish in South Africa is not clear. Although there is a recommendation that these importations must be regulated according to the whitelist and blacklist in South Africa, it is not clear how this is implemented in practice. We demonstrated a high risk of alien fish species introduction in South Africa through the aquarium pet shop trade.

The status of COI and 12S rRNA DNA barcode reference libraries for freshwater fish in South Africa: Implications for future eDNA projects

Environmental DNA metabarcoding (eDNA) is a rapidly emerging field in which high-throughput sequencing is used to catalogue the biodiversity of ecosystems through the amplification of DNA extracted from environmental samples (water, air, faeces and soil). Although eDNA has strong links to DNA barcoding, the molecular marker most often used to detect vertebrates in eDNA studies is a portion of the mitochondrial 12S ribosomal RNA (12S rRNA) and not the standard cytochrome oxidase I (COI) marker used in traditional DNA barcoding. eDNA methods rely on a comprehensive reference library to link sequence data to species, which are often lacking in hyper-diverse countries such as South Africa. In this study, we review the present state of DNA barcode reference databases for both 12S rRNA and COI for freshwater fish (native and introduced) found in South African aquatic systems. Analysis of DNA records available on GenBank and the Barcode of Life Database (BOLD) revealed incomplete records of the examined taxa for both markers. Our findings showed that 34 species, 6 genera and 0 families of native South African freshwater fish lack COI barcode records, while 86 species, 22 genera and 8 families lack 12S rRNA records. Unlike the native freshwater fish, the non-native fish all had barcode records available for both COI and 12S rRNA. Producing comprehensive reference libraries for both markers is an important first step in developing an eDNA protocol for the non-invasive monitoring of native and non-native freshwater fish in South Africa.

Molecular characterisation of three species of Coitocaecum (Digenea: Opecoelidae) infecting Clinus superciliosus (Clinidae) in South Africa, with description of Coitocaecum brayi sp. n.

The genus Coitocaecum Nicoll, 1915 is part of the most speciose digenean family, the Opecoelidae Ozaki, 1925, which is found globally in both freshwater and marine fishes. Fifteen opecoelid species have been reported from marine fishes in South Africa, yet only one species of Coitocaecum has been described from this region: Coitocaecum capense Bray, 1987. During an explorative study of the digeneans of the endemic, intertidal fish Clinus superciliosus (Linnaeus) from the Saldanha Bay area, Cape Town harbour, Hermanus, the Tsitsikamma section of the Garden Route National Park and Chintsa East in South Africa, a total of three distinct species of Coitocaecum were identified based on morphological and molecular (28S rDNA, ITS1-5.8S-ITS2 rDNA and COI mtDNA) data: the previously mentioned C. capense, Coitocaecum brayi sp. n. and a third, unnamed species. We provide the first molecular characterisation of species of Coitocaecum from South Africa, accompanied by detailed morphological descriptions. This study illustrates the importance of an integrated taxonomic approach, especially when studying species with similar morphology. These findings further emphasise the lack of information on the true diversity and molecular data for trematodes of marine fishes in South Africa, creating a great capacity for future explorative taxonomic studies and highlighting the use of intertidal areas for conducting such research.

First biomonitoring of microplastic pollution in the Vaal river using Carp fish (Cyprinus carpio) "as a bio-indicator".

Fish inhabiting freshwater environments are susceptible to the ingestion of microplastics (MPs). Knowledge regarding MPs in freshwater fish in South Africa is very limited. In this study, the uptake of MPs by common carp (Cyprinus carpio) in the Vaal River in South Africa was assessed. MPs were detected in all of the twenty-six fish examined, 682 particles of MPs were recovered from the gastrointestinal tracts of the fish with an average of 26.23 ± 12.57 particles/fish, and an average abundance of 41.18 ± 52.81 particles/kg. The examination of the physical properties of MPs revealed a predominance on fibers (69%), small-sized particles of less than 0.5 mm (48%), as well as prevelance of coloured MPs (94%), mostly green, blue, and black. Using Raman Spectroscopy, the following plastic polymers were identified: high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), polyethylene terephthalate (PET), and polytetrafluoroethylene (PTFE). To the best of our knowledge, this study, is the first to report MPs uptake by freshwater biota in the Vaal River using common carp as a target organism. It provided evidence of MP contamination in the Vaal.

Allopatric differentiation in the Enteromius anoplus complex in South Africa, with the revalidation of Enteromius cernuus and Enteromius oraniensis, and description of a new species, Enteromius mandelai (Teleostei: Cyprinidae).

The chubbyhead barb, Enteromius anoplus, as currently described, is the most widely distributed freshwater fish in South Africa. The species occurs in almost all the major river systems across the country, with the exception of the small coastal drainages on the south coast. The use of a comprehensive data set of mitochondrial (mtDNA) cytochrome b (cyt b) sequences uncovered the presence of four distinct lineages or operational taxonomic units (OTUs) within E. anoplus: (a) the Gouritz lineage endemic to the Gouritz River system, (b) the Olifants lineage endemic to the Olifants-Doring River system, (c) the Orange lineage endemic to the Orange River system and (d) the Eastern Cape lineage which is distributed across six river systems from the Great Fish to the Buffalo rivers in the Eastern Cape Province of South Africa. The present study provides a new diagnosis for E. anoplus s.s. (the Gouritz lineage), revalidates Enteromius cernuus (the Olifants lineage) and Enteromius oraniensis (the Orange lineage) as distinct species. The study also provides a description for a new species, Enteromius mandelai sp. nov (the Eastern Cape lineage). E. cernuus and E. mandelai differ from both E. anoplus and E. oraniensis by having a complete lateral line (vs. an incomplete lateral line in the latter species). E. cernuus further differs from the other three species by having long maxillary barbels which reach or exceed the vertical through the middle of the eye and the lowest number of circumpendicular scales (10-12 vs. 12-16 for the other three species). E. oraniensis is distinctive from the other three species by having inconspicuous barbels. These findings add to the growing body of literature that shows that the freshwater fishes of the Cape Fold and adjacent freshwater ecoregions have narrow geographic ranges. This has ramifications for conservation planning and management, as well as the understanding of the evolutionary history of the stream fishes in these global endemic hotspots.

Black Soldier Fly Larvae Meal as a Fishmeal Substitute in Juvenile Dusky Kob Diets: Effect on Feed Utilization, Growth Performance, and Blood Parameters

Using black soldier fly larvae meal (BSFM) in place of fishmeal is an ingenious strategy for sustainable fish aquaculture. However, BSFM has not been evaluated for dusky kob (Argyrosomus japonicus), an economically important fish in South Africa. Therefore, this five-week study investigated the effect of partially replacing fishmeal with BSFM on feed utilization, growth performance, and blood parameters of juvenile dusky kob in a recirculating aquaculture system. Four diets were formulated by replacing fishmeal in a commercial dusky kob diet with BSFM at the rate of 0 (BSFM0), 50 (BSFM50), 100 (BSFM100), and 200 g/kg (BSFM200). Fish length and weights were measured weekly, while blood analyses were performed at the end of Week 5. For fish length and weight gain, there were neither linear nor quadratic responses in Weeks 1–4, while quadratic trends (y = 14.77 (± 0.19)−0.11 (± 0.05)x + 0.01 (± 0.00) x2; R2 = 0.35 and y = 49.85 (± 1.53)−1.22 (± 0.39)x + 0.06 (± 0.02) x2; R2 = 0.47, respectively) were observed in Week 5 in response to BSFM levels. Quadratic effects (y = 1.75 (± 0.15) + 0.10 (± 0.04)x − 0.01 (± 0.00) x2; R2 = 0.39) were also observed for feed conversion ratio (FCR) in response to BSFM inclusion levels. Fish fed BSFM200 had a similar overall FCR and specific growth rate as those reared on BSFM0. All blood parameters fell within the normal range for the dusky kob. We concluded that 20% dietary replacement of fishmeal with BSFM does not compromise feed utilization and growth performance of juvenile dusky kob.

Resolution of the identity of three species of Diplostomum (Digenea: Diplostomidae) parasitising freshwater fishes in South Africa, combining molecular and morphological evidence.

Reliable data on the diversity of the genus Diplostomum (Digenea: Diplostomidae) parasitising freshwater fishes in South Africa, as well as in Africa, is almost non-existent. Most of the morphology-based identifications of species within this genus reported from Africa require critical revision. The aim of the present study was to determine the diversity of Diplostomum metacercariae in South African fishes applying molecular and traditional morphological techniques. To achieve this aim, a total of 216 fishes belonging to 21 species collected in the Rivers Phongolo, Riet, Usuthu and Mooi in three provinces of South Africa were examined. Metacercariae of Diplostomum were recovered from the eye lenses of 38 fishes belonging to five species of the families Anguillidae, Cichilidae and Mochokidae, with an overall low prevalence of infection (18%). Metacercariae were subjected to morphological study and molecular sequencing of the partial mithochondrial cox1 and ribosomal 28S rDNA genes as well as of ribosomal ITS1-5.8S-ITS2 region. Morphological and phylogenetic analyses revealed the presence of three species which matched those previously reported from Nigeria, Iraq and China, therefore those from Tilapia sparrmanii and Synodontis zambezensis were named Diplostomum sp.; those from Anguilla labiata, Oreochromis mossambicus and S. zambezensis were named Diplostomum sp. 14; and those from Pseudocrenilabrus philander were named Diplostomum sp. 16. Geographic distribution of several species of Diplostomum appeared to be wider than expected. Morphological description and novel sequence data generated during this study will contribute to the elucidation of the life cycles of Diplostomum sp., Diplostomum sp. 14 and Diplostomum sp. 16 and advance further research of diplostomids in Africa.

Variation in thermal tolerances of native freshwater fishes in South Africa's Cape Fold Ecoregion: examining the east-west gradient in species' sensitivity to climate warming.

The Cape Fold Ecoregion (CFE) is a biodiversity hotspot with high levels of endemism in its freshwater fish fauna. This study examined inter and intra-specific variation in critical thermal maxima (TCmax ) for eight native species of freshwater fish from the CFE. Cape galaxias Galaxias zebratus, Breede River redfin Pseudobarbus burchelli, Berg River redfin Pseudobarbus burgi, Clanwilliam redfin Pseudobarbus calidus and fiery redfin Pseudobarbus phlegethon were the most thermally sensitive (TCmax = 29.8-32.8°C). Clanwilliam rock-catfish Austroglanis gilli, Eastern Cape redfin Pseudobarbus afer and Cape kurper Sandelia capensis were moderately sensitive (TCmax = 33.0-36.8°C). An increase in intra-specific thermal sensitivity of S. capensis was observed from east to west. The results were related to in situ water temperature, which influenced TCmax for all species, suggesting that thermal history is a major driver of variation in thermal tolerance amongst populations. These thermal tolerance data for freshwater fishes in the CFE demonstrate that resilience to climate warming follows a geographical cline and that the more sensitive western species and regions are conservation priorities.

Evidence for diet partitioning among three coexisting native freshwater fishes in South Africa's Cape Fold Ecoregion

The partitioning of limited resources commonly explains how different species can coexist within the same ecological community. In this 2010 study, the diets of three coexisting freshwater fishes (Cape galaxias Galaxias zebratus, n = 27; Cape kurper Sandelia capensis, n = 60; Breede River redfin Pseudobarbus burchelli, n = 77) were characterised and compared in three headwater streams in South Africa's Cape Fold Ecoregion using gut contents and stable isotope analyses. These data were analysed to ascertain whether the three species exploit distinct trophic niches. Both approaches provided evidence that these species occupy different trophic niches, though with some overlap. However, dietary differences among sites were not consistent and were probably influenced by site-specific factors like resource availability. Pseudobarbus burchelli had a broader niche breadth at Tierkloof Stream than the other two species, but not at Waaihoek or Tierstel Streams. Our results also suggest that P. burchelli consumed a more omnivorous diet than do the other two species, whereas S. capensis occupied a higher trophic position than the other two species and consumed vertebrates. Our findings suggest that these species occupy non-equivalent feeding niches in Cape Fold Ecoregion headwater streams, and that diet partitioning might facilitate their coexistence in these systems.

Temperature mediates the impact of non-native rainbow trout on native freshwater fishes in South Africa’s Cape Fold Ecoregion

Introduced rainbow trout Oncorhynchus mykiss have invaded many headwater streams in South Africa’s Cape Fold Ecoregion (CFE) and pose arguably the greatest threat to several species of threatened native fishes. Trout impacts in these systems appear to be density-dependent; we hypothesized that temperature is a key factor determining trout density and corresponding impacts on native fishes. We took advantage of natural spatial and temporal thermal heterogeneity in two CFE headwater streams to investigate the influence of temperature and other environmental factors on trout density and impacts on native fish assemblages. Temperature limited trout density (negative relationship) during summer surveys (hottest months), but not during spring and autumn (cooler months). During summer, the highest trout densities were recorded at sites that remained relatively cool (7-day moving average of the daily maximum temperature (Max_7) 27 °C). Native fish density was best explained by trout density (inverse relationship) during summer, but by other environmental variables such as habitat complexity and current flow velocity during autumn and spring. Trout distributions expand during cooler seasons when thermal heterogeneity and maximum temperatures are relatively low, but contract into thermal refugia (habitat patches that remain relatively cool) as temperatures and thermal heterogeneity increase over summer, leaving warmer habitat patches vacant and able to function as predation refugia for native fish. We hypothesize that climate warming could reduce trout density and distribution, and associated impacts on native fish, in CFE headwater streams, but may increase the potential for invasions by other warm-adapted non-native predatory fish already established in downstream river reaches in the region.

Sir Andrew Smith – his contributions and connections to freshwater ichthyology in southern Africa

Sir Andrew Smith (1797–1875), a medical officer in the British Army, was posted to South Africa from 1821 to 1837. During that time, he founded the South African Museum and made many valuable scientific contributions to a range of disciplines; however, his contributions to the discovery of freshwater fishes have not been specifically discussed. Smith was the first to publish descriptions of southern African freshwater fishes in South Africa. He described seven new species in his famed publication of “Illustrations”, a significant step forward in the knowledge of southern African freshwater fishes at the time. This article explores the contributions made by Sir Andrew Smith to freshwater ichthyology in South Africa.

DNA barcoding of South Africa’s ornamental freshwater fish – are the names reliable?

Trade in freshwater ornamental fish in South Africa is currently regulated by a ‘blacklist’ to prevent potentially invasive taxa from establishing in the country. Because its effective implementation requires accurate identification, the aim of the present study was to test whether DNA barcoding is a useful tool to identify freshwater fishes in the South African pet trade. A total of 351 aquarium fish specimens, representing 185 traded taxa, were sequenced for the mitochondrial COI barcoding marker in 2011 and 2012. Lake Malawi cichlids were treated as a single group due to a lack of resolution in their COI marker, resulting in a data set of 137 successfully sequenced taxa. The Barcode Of Life Database (BOLD) and GenBank were used for taxonomic assignment comparisons. The genetic identification matched the scientific name inferred from the trade name for 60 taxa (43.8%) using BOLD, and for 67 taxa (48.9%) using GenBank. A genetic ID could not be assigned in 47 (34.3%) cases using BOLD and in 37 cases (27%) using GenBank. Whereas DNA barcoding can be a useful tool to help identify imported freshwater fishes, it requires further development of publicly available databases to become a reliable means of identification.

Evaluating invasion risk for freshwater fishes in South Africa

Background: South Africa, as a signatory of the Convention on Biological Diversity, has an obligation to identify, prioritise and manage invasive species and their introduction pathways. However, this requires knowledge of the introduction pathways, factors influencing establishment success, invasive potential, current distributions and ecological impacts. Objectives: To evaluate the Fish Invasiveness Screening Kit (FISK) to predict the invasion risk posed by fish species proposed for introduction into South Africa. Method: FISK assessments were compiled for species whose invasion status in South Africa was known. A Receiver operating characteristic (ROC) analysis was conducted to calibrate the FISK for South Africa. The calibrated FISK was used to evaluate the risk that three species recently proposed for importation for aquaculture could become invasive in South Africa. Results: A FISK score of 14 was identified as the threshold to delineate between species that could become invasive in South Africa and those that are unlikely to become invasive. Of the three species evaluated, Silurus glanis had a high risk of becoming invasive in South Africa, Lates calcarifer was likely to be invasive and Oncorhynchus tshawytscha was unlikely to be invasive in South Africa. Conclusion: FISK was demonstrated to be a useful risk assessment tool to evaluate the invasion risk posed by species proposed for use in aquaculture. For the large number of fish imported for the pet trade, a rapid screening assessment to flag potentially high risk species was recommended prior to a full FISK assessment for flagged species.

Threatened Endemic Fishes in South Africa's Cape Floristic Region: A New Beginning for the Rondegat River

ABSTRACTNonnative fishes threaten native fish communities in many rivers of the world. In South Africa's Cape Floristic Region, predation by nonnative fishes has severely impacted native fish populations and more than half of the 17 endemic fish species are endangered. To preserve the unique endemic fish fauna, removal of nonnative fish from conservation areas is a priority in this region. In February 2012, South Africa's first nonnative fish eradication using rotenone took place in the Rondegat River, a small headwater stream that had been invaded by Smallmouth Bass (Micropterus dolomieu). The successful treatment culminated from a decade‐long process that was facilitated through collaboration among a South African nature conservation authority (CapeNature), the South African Institute for Aquatic Biodiversity, and the American Fisheries Society Fish Management Chemicals Subcommittee. The successful removal of alien fish and almost instantaneous increase in biodiversity is anticipated to encourage more endemic fish restorations in South Africa.

Fragmented participation in management of the fishery for small pelagic fish in South Africa – inclusion of small-rights holders is a complex matter

The reasons why most small-rights holders do not participate in management of the fishery for small pelagic fish (‘small pelagics’) in South Africa, despite legislation and policy encouraging their participation, were analysed. Membership of the Small Pelagics Management Working Group (SPMWG), the main participatory governance organ, is limited to representatives of recognised stakeholder associations. Rights holders therefore have to belong to a stakeholder association, which then selects a member or members to represent them on the SPMWG. Small quotas and the difficulties of sourcing capital mean that small-rights holders are not able to invest in infrastructure. Besides, most of the small-rights holders and their companies lack experience and management skills to survive independently in this highly competitive industry, which is based on high volume and low profit margins. As a result, most of the small-rights holders have no option but to enter into complex catching and processing agreements with vessel- and factory owners belonging to the existing recognised stakeholder associations. For the small-rights holders, it does not make sense to join these associations or even to form their own if they cannot actively participate in the industry independently. Greater participation by small-rights holders should start with their genuine integration into the industry through improved ability to invest in infrastructure and through management skills development. Most likely, this will require an interventionist approach by government.

Fish distributions in the Rondegat River, Cape Floristic Region, South Africa, and the immediate impact of rotenone treatment in an invaded reach

Alien fishes are considered the most serious threat to native headwater stream fishes in South Africa. A 4 km reach of the Rondegat River is the first section of a South African river to be rehabilitated through the attempted removal of alien fish by using the piscicide rotenone. The objectives of the current study were to establish the distribution and relative abundance of native and alien fish prior to treatment, and to assess the immediate impact of the treatment on the fish population. Forty-three sites were sampled using backpack electrofishing, snorkel transects and underwater video analysis. In the invaded lower reaches, native Labeobarbus capensis was detected only at very low densities, while three other native fish species were not detected. Alien fish were not detected above a barrier waterfall 5 km upstream of the river's confluence with a reservoir. The fish density of 97 fish per 100 m2 in non-invaded reaches was more than an order of magnitude higher than that of 7 fish per 100 m2 in the invaded reach. A total of 470 Micropterus dolomieu and 139 L. capensis were removed from a 4 km treatment zone during the rotenone operation. No fish were detected in this area after the rotenone treatment.

Influence of local and regional prey availability on breeding performance of African penguins Spheniscus demersus

Population trends of African penguins Spheniscus demersus in the Western Cape, South Africa, and their breeding success have been linked to the abundance of their main prey, sardine Sardinops sagax and anchovy Engraulis encrasicolus. During the late 1990s and early 2000s, both fish species increased markedly in abundance, but after 2004, sardine biomass decreased to below average levels. In addition, adults of both stocks were principally located to the east of Cape Agulhas from 2001 to 2009 and were thus distant from seabird colonies on South Africa's West Coast. The number of African penguin pairs counted at Robben Island from 2001 to 2009 and the fledging period of chicks from successful nests increased and decreased in apparent response to the biomass of sardine prior to each breeding season, possibly linked through adult condition at the onset of breeding. Breeding success and chick-fledging rates increased during the study period and showed positive relationships with local food availability, indexed through the annual industrial catch of anchovy made within 56 km (30 nautical miles) of the colony. In addi- tion, chick-fledging rates were depressed in 2-chick broods during years when anchovy con- tributed <75% by mass to the diet of breeding birds. Previously reported relationships between the overall abundance of forage fish in South Africa and penguin breeding success were not sup- ported. Taken together, these results highlight the combined importance of ensuring adequate local food availability for seabirds during the reproductive cycle and safeguarding regional prey abundance during the non-breeding season.

DNA barcoding reveals a high incidence of fish species misrepresentation and substitution on the South African market

The mislabelling of fishery products has emerged as a serious problem on global markets, raising the need for the development of analytical tools for species authentication. DNA barcoding, based on the sequencing of a standardised region of the cytochrome c oxidase I (COI) gene, has received considerable attention as an accurate and broadly applicable tool for animal species identifications. The aim of this study was to investigate the utility of DNA barcoding for the identification of a variety of commercial fish in South Africa and, in so doing, to estimate the prevalence of species substitution and fraud prevailing on this market. A ca. 650 base pair (bp) region of the COI gene was sequenced from 248 fish samples collected from seafood wholesalers and retail outlets in South Africa, following which species identifications were made in the Barcode of Life Database (BOLD) and in GenBank. DNA barcoding was able to provide unambiguous species-level identifications for 235 of 248 (95%) samples analysed. Overall, 10 of 108 (9%) samples from wholesalers and 43 of 140 (31%) from retailers were identified as different species to the ones indicated at the point of sale. Although some cases of mislabelling were potentially unintentional due to misapplied market nomenclature, a far greater proportion represented serious and seemingly deliberate acts of fraud for the sake of increased profits. This study has highlighted that the existing legislation pertaining to seafood marketing in South Africa is inadequate or poorly enforced and requires urgent revision. In the light of the results presented here, DNA barcoding appears to hold great potential for fish authentication monitoring by both regulatory bodies and industry, the utilisation of which could enhance transparency and fair trade on the domestic fisheries market.

Evaluating the availability of fish species on the South African market and the factors undermining sustainability and consumer choice

Information pertaining to the commercial availability of fish species in South Africa remains sparse, even though it is crucial for consumers to make informed purchasing decisions in favour of their own well being and the well being of the environment. The aim of this study was to determine the most commonly available fish species in South Africa by means of surveys of restaurants ( n = 215) and retail outlets ( n = 200) and to assess the conservation statuses of the observed species. Furthermore, the processing states in which fish were mostly sold (fresh, frozen, whole or filleted) and the quality of information available to consumers on fish at the point of sale were evaluated. Kingklip was found to be the most commonly marketed fish species in restaurants, while hake was observed most frequently in retail outlets. More than 30% of the observed species were of conservation concern and included, amongst others, kingklip, kabeljou (kob), east- and west coast soles and geelbek. Specially-protected, illegal-to-sell fish in South Africa, such as white steenbras, white musselcracker and Natal stumpnose, were marketed in restaurants and retail outlets. This study highlighted the poor ability of fish purveyors in South Africa to provide information on the identity, origin, production method and sustainability of fish being sold. Additionally, the labelling of many packaged fish products in retail outlets was in contravention with South African regulations. Poor vendor awareness, disparate naming practices and the highly processed nature of fishery products provide an opportunity for unintentional or deliberate mislabelling of fish in South Africa.