Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Deciphering patterns of intraspecies population genetic structuring in commercially important shark species is essential for an integrated fisheries management approach to conservation of regional biodiversity. The common smoothhound shark, Mustelus mustelus, is an overexploited, commercially and recreationally important shark species in South Africa. Considering the vulnerable status of the common smoothhound shark and due to very limited available genetic information, this study aimed to develop molecular markers, assess patterns of genetic diversity and population connectivity along the South African coast using multilocus data generated from 12 microsatellite markers and the mitochondrial gene, NADH dehydrogenase subunit 4 (ND4). The cross-species amplification of microsatellites proved useful for genetic diversity and population genetic analysis of the common smoothhound shark. These microsatellites could aid in the molecular characterisation of other endemic and cosmopolitan species and provide valuable tools for the conservation of potentially threatened or exploited shark species. For the microsatellite data, moderate levels of genetic diversity based on the heterozygosity, allelic richness and haplotype diversity were found in a total of 144 individuals sampled across eight study populations. Estimates for pairwise population differentiation, F-statistics, AMOVA and factorial correspondence analysis (FCA) indicated significant genetic structure within and between west- and east coast populations. Additionally, Bayesian clustering analyses detected two putative ancestral gene pools, supporting the presence of a biogeographic barrier at the Cape Agulhas region and therefore genetic discontinuity between the Indian and Atlantic Ocean samples. On the contrary, mitochondrial data indicated that common smoothhound shark is genetically homogenous with substantial interoceanic gene flow. Such conflicting signals found between nuclear and mitochondrial DNA (mitonuclear discordance) can be attributed to a number of factors and could simply be due to the inherent differences in marker properties or an indication of sex biased dispersal. Despite an indication of an expanding common smoothhound shark population based on both marker types, a contemporary genetic bottleneck may have gone undetected as genetic divergence was very low in some of the study populations. Nonetheless, contemporary restriction to gene flow and historical demographics such as range expansion are proposed as the most likely forces explaining genetic structure in present-day common smoothhound sharks in South Africa. For future sustainable exploitation of common smoothhound shark, the possible existence of two genetically differentiated populations and observed asymmetric gene flow along the South African coast should be taken into consideration. It is also recommended that in the future further evaluations of finescale genetic structure and seasonal migration patterns in this commercially important species are conducted in order to allow integration of this knowledge into existing fisheries management practices. / AFRIKAANSE OPSOMMING: Die ontsyfering van patrone van intraspesie populasie genetiese struktuur in kommersieel belangrike haai spesies is noodsaaklik vir 'n geïntegreerde bestuursbenadering tot visserue en bewaring van plaaslike biodiversiteit. Die hondhaai, Mustelus mustelus, is 'n oorbenutte, kommersiële en sporthengelary belangrike haai spesie in Suid-Afrika. Met inagneming van die kwesbare status van die hondhaai en as gevolg van baie beperkte beskikbare genetiese inligting, het hierdie studie gepoog om molekulêre merkers te ontwikkel, asook om die patrone van genetiese diversiteit en populasie struktuur te ondersoek langs die Suid- Afrikaanse kus deur middel van multilokus data gegenereer uit 12 mikrosatelliet merkers en die mitokondriale geen, NADH dehidrogenase subeenheid 4 (ND4). Die kruis-spesie amplifisering van mikrosatelliete was nuttig vir genetiese diversiteit en populasie genetiese analise van die hondhaai. Hierdie mikrosatelliete kan moontlik help met die molekulêre karakterisering in ander inheemse en kosmopolitaanse spesies en kan as waardevolle hulpmiddels dien in die bewaring van potensieel bedreigde en oorbenutte haai spesies. Vir die mikrosatelliet data is matige vlakke van genetiese diversiteit gevind gebaseer op heterosigositeit, alleliese rykheid en haplotipe diversiteit gevind in 'n totaal van 144 individue getoets oor agt studie populasies. Skattings vir paarsgewyse populasie differensiasie, Fstatistieke, AMOVA en faktoriale ooreenstemming analise het betekenisvolle genetiese struktuur aangedui binne en tussen wes- en ooskus populasies. Daarbenewens, het Bayesian groepering analise twee potensiele voorvaderlike geenpoele waargeneem, ter ondersteuning van die teenwoordigheid van 'n biogeografiese versperring by die Cape Agulhas gebied en dus genetiese diskontinuïteit tussen die Indiese en Atlantiese Oseaan monsters. In teenstelling het die mitokondriale data aangedui dat hierdie haai spesie geneties homogeen is met aansienlike interoseaniese geenvloei. Sulke teenstrydige tekens tussen kern en mitokondriale DNS (mitokern onenigheid) kan toegeskryf word aan 'n aantal faktore en kan eenvoudig wees as gevolg van die inherente verskille in merker eienskappe of 'n aanduiding van geslags sydigeverspreiding. Ten spyte van 'n aanduiding van 'n groeiende hondhaai populasie gebaseer op beide merker tipes, kon 'n hedendaagse genetiese bottelnek onopgemerk gegaan het aangesien genetiese divergensie baie laag was in sommige van die studie populasies. Nietemin, hedendaagse restriksie van geenvloei en historiese demografie soos verbreding van reeks voorkoming word voorgestel as die mees waarskynlike dryfkragte wat genetiese struktuur in die hedendaagse hondhaaie in Suid-Afrika verduidelik. Vir toekomstige volhoubare benutting van die spesie, moet die moontlike bestaan van twee geneties verskillende populasies en waargenome asimmetriese geenvloei langs die Suid-Afrikaanse kus in ag geneem word. Vir die toekoms word dit ook aanbeveel dat verdere evaluerings van fyn-skaal genetiese struktuur en seisoenale migrasie patrone in hierdie kommersiël belangrike spesie uitgevoer word om die integrasie van hierdie kennis in die bestaande bestuur van visserye praktyke toe te laat. / National Research Foundation (NRF)

Mustelus schmitti (Chondrichthyes, Triakidae) llamado comúnmente gatuso o gatuzo, constituye la especie más común de tiburones en la pesca argentina. Este proyecto investiga algunos aspectos de la biología reproductiva de la hembra de M. schmitti con el fin de asesorar manejos pesqueros para prevenir la sobreexplotación. Normalmente, las muestras de peces son medidas, pesadas y sexadas de manera de conocer la condición reproductiva de una especie pesquera pero un conocimiento cabal requiere de un análisis detallado basado en técnicas histológicas, las cuales proveen datos sobre cambios a nivel celular. En consecuencia, el conocimiento del desarrollo del ovocito y del espermatozoide es necesario para evaluar la condición reproductiva de la especie bajo estudio en este trabajo. El aparato reproductor de este pez está compuesto por un solo ovario izquierdo, un par de glándulas oviductales y un útero par que finaliza en un conducto cloacal. El ovario, las glándulas oviductales y el útero fueron examinados por microscopía óptica y electrónica en diferentes estados a lo largo del ciclo reproductivo. El ovario está formado por un epitelio germinal simple cúbico que descansa sobre una fina capa de tejido conectivo. Los folículos contienen desde el interior hacia el exterior, un ovocito, la zona pelúcida, un epitelio folicular y capa tecal formada por tejido conectivo. El epitelio folicular se origina simple con células planas, continúa con células cúbicas y finalmente, se transforma en un epitelio cilíndrico durante la foliculogénesis y vitelogénesis. Se observaron algunos folículos atrésicos y cuerpos lúteos. La capa tecal no se diferencia en interna y externa. Las glándulas oviductales muestran las cuatro zonas características: club, baffle, papilar y terminal, similares a las de otros condrictios. El almacenamiento espermático es observado en los túbulos de la zona terminal de hembras sexualmente maduras y preñadas. El útero par desarrolla distintos epitelios en el istmo, partes anterior y posterior uterinas, y cérvix. Durante la preñez, los embriones se sitúan en compartimentos uterinos sin placenta. El esperma preparado para fertilizar sería aquel que primero interactúa con el epitelio uterino y luego se almacena en los túbulos de la zona terminal. Esta estrategia aseguraría la unión entre el ovocito y el espermatozoide debido a que se pueden encontrar a pesar de estar la hembra preñada. Uno de los objetivos principales de esta tesis es presentar un amplio rango de modificaciones histológicas para ser empleadas en una mayor comprensión de la dinámica reproductiva de los condrictios en particular, y de los peces en general, y promover la discusión sobre temas críticos para pesca sustentable dentro de un contexto histológico.

Thesis (MSc)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: Smoothhound sharks Mustelus mustelus (Chondrichthyes: Triakidae) were conditioned to associate a compound auditory and electrical conditioned stimulus (CS) using the presentation of food as the unconditioned stimulus (US). This was done to investigate the general conditioning process of sharks, specifically the use of conditioned stimuli, the time frame required for conditioning, the retention of conditioned responses and the individual learning capabilities of sharks in classical conditioning experiments. Conditioning was done in two CS experiment replicates, in which the CS and the US were paired to elicit a conditioned response (CR: entering of a feeding area). Shark behaviour in these replicates was compared with those of sharks in a CS control. In the CS control, the CS and US were not paired; consequently no CS-US association was formed. In contrast, half of the sharks in the 1st and 2nd CS replicates formed the conditioned CS-US association after five and six days of conditioning training, respectively. This conditioned association was also retained over a two-month rest period. However the rate of conditioning of sharks varied, which was thought to be due to differences in motivational drives, particularly hunger. These experiments demonstrated that classical conditioning could provide a mechanism whereby smooth hound sharks can adapt to utilise new food sources. However these experiments could not demonstrate whether auditory or electrical cues are more biological relevant signallers of the presence of food for smooth hound sharks. According to the "belonging ness" phenomenon, for conditioning to be successful, the CS should be biologically relevant to the US. Therefore by comparisons of the conditioning success with different conditioned stimuli, the biological relevance of each CS can be determined. To determine the biological relevance of each component of the compound CS, an auditory or electrical CS was paired with the presentation of food (US), in separate experiments. The conditioned CS-US association formed in the majority of the sharks after 60 and 57 conditioning trials in the auditory CS and electrical CS experiment, respectively. This suggests that both auditory and electrical cues are biologically relevant signallers of food, facilitating the oppurtunistic feeding behaviour of smoothhound sharks. However, after five days of conditioning, conditioning with the electrical CS had proceeded further and the electrical CS-US association was stronger than the auditory CS-US association. This indicates that electrical cues are more biologically relevant due to past feeding experiences. Thus, classical conditioning during past feeding experiences can influence the feeding behaviour of smooth hound sharks. / AFRIKAANSE OPSOMMING: Gladde-hondhaaie Muste/us muste/us (Chondrichthyes: Triakidae) is gekonditioneer om "n gekombineerde klank en elektriese konditionerings stimulus (CS) met voedsel, die ongekonditioneerde stimulus (US) te assosieer. Dit is gedoen om die konditionerings proses, spesifiek die gebruik van konditionerings stimuli, tyd benodig vir konditionering, behoud van die gekonditioneerde gedrag en individuele leer-vermoëens van haaie in klassieke konditionerings eksperimente te ondersoek. Konditionering is gedoen in twee CS eksperiment replikate, waarin die CS en die US saam aangebied is, om "n konditionerings reaksie (CR: om in 'n voedings area in te beweeg) teweeg te bring. Die gedrag van haaie in die CS replikate is vergelyk met die van haaie in "n CS kontrole. In die CS kontrole is die CS en die US nie saam aangebied nie en gevolglik is geen gekonditioneerde CS-US assosiasie gevorm nie. Daarenteen is die CS-US assosiasie by die helfte van die haaie in die 1st en 2de CS replikate gevorm, na vyf en ses dae, onderskeidelik. Hierdie gekonditioneerde CS-US assosiasie het selfs behoue gebly na 'n twee maande rus periode. Die tempo van konditionering het egter verskil, moontlik a. g. v. motiverings verskille, veral hongerte. Hierdie eksperimente het gedemonstreer dat klassieke konditionering kan dien as 'n meganisme waarmee gladde-hondhaaie kan aanpas om nuwe voedsel bronne te benut. Hierdie eksperimente kon egter nie demonstreer óf klank stimuli óf elektriese stimuli meer biologiese relevante seine van die teenwoordighied van voesel is vir gladdehondhaaie nie. Volgens die "belonging ness" verskynsel, moet die CS biologies relevant to die US wees, vir konditionering om suksesvol te wees. Dus kan die biologiese relevansie van verskillende konditionerings stimuli bepaal word deur die konditionerings sukses van elke CS te vegelyk. Om die meer biologiese relevante komponent van die gekombineerde CS te bepaal, is 'n klank of elektriese CS saam met voedsel aangebied in aparte eksperimente. Die gekonditioneerse CS-US assosiasie is gevorm by die meeste van die haaie na 60 en 57 konditionerings proeflopies in die klank en elektriese CS eksperimente, onderskeidelik. Hierdie resultate dui daarop dat beide klank en elektriese stimuli biologies relevante siene van voedsel is, wat die oppurtunistiese voedings wyse van gladde-hondhaaie fasiliteer. Konditionering met die elektriese CS het egter verder gevorder en die elektriese CS-US assosiasie was sterker as die klank CSUS assosiasie na vyf dae van konditionering. Dus, mag elektriese stimuli meer biologies relevant wees weens vorige voedings ervaringe. Dit illustreer dat klasseke konditionering tydens vorige voedings ervaringe die voedings gedrag van gladde-hondhaaie kan beinvloed.

The survival of Elasmobranch fishes (sharks, skates and rays) depends critically on their ability to sense odor cues. The outstanding question of detection thresholds to food odors in the shark is investigated in this study. The tracking behavior of Mustelus canis (the smooth dogfish) was analyzed using a binary choice flume designed specifically for testing odor preferences of aquatic animals. To determine threshold, odor was serially diluted until no tracking responses were observed. Sharks spent significantly more time in the odor side of the flume, regardless of their individual side bias, until the "squid juice" was diluted several orders of magnitude. For the whole flume the two greatest dilutions (10-4-10-5 at the odor source) did not cause significant choice and for the upstream flume half, all but the greatest dilution (10-5 at the odor source) caused significant odor side preference. To interpret these results fully we need to consider the structure of odor plumes and the function of the sharks' olfactory responses. Nonetheless, assuming that M. canis represent sharks in general, these findings demonstrate that their extraordinary sensitivity to food attractants may indicate aspects still unknown about life history of elasmobranch fishes including the ranges that benthic elasmobranchs are capable of traveling to feed.

Thesis (MSc Food Sc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The aim of this study was to determine the proximate composition of five individual body sites of the Mustelus mustelus shark in order to evaluate the cross carcass variation of the individual proximate components (moisture, protein, lipid, ash) of the meat. This variation was determined in order to find a representative sample of the edible part of the shark (fillet and body flap). Secondly, this sample representing the entire shark fillet was used to investigate the endogenous factors (gender, size and life cycle stage) and their effects on the individual proximate components and other meat components (amino acids, fatty acids, minerals, histamine and mercury contents). Finally, all this data was combined to describe the average chemical composition and nutritional value of M. mustelus meat. None of the proximate components showed any variation between the different fillet positions. This indicated that the fillet is homogenous and samples for chemical analyses can be taken anywhere on the fillet as representative of the entire fillet. It was found that all three main effects (gender, size and life cycle stage) did not have major influences on most of the components of the chemical composition of M. mustelus meat analysed. Higher fatty acid levels (SFA, MUFA and PUFA) were observed in large females than in large males as well as in non-pregnant large females compared to pregnant large females. According to statistical analysis, large males had higher total mercury levels than large females. The only component affected by size variation was the fatty acids, showing a trend to decrease in quantity before maturity was reached. Variation due to life cycle stages was mostly evident in the fatty acid component with some small effects on two mineral components, aluminium and copper, which had slightly higher levels in pregnant large females than in non-pregnant large females. M. mustelus meat has an average proximate composition of 75% moisture, 23% protein, 1.6% lipids and 1.4% ash (weight per wet weight). The protein is, however, an over-estimation of the true protein value as the meat contains significant amounts of non-protein nitrogen (NPN) in the form of urea which contributes to the N concentration. M. mustelus meat is a good source of some essential amino acids, especially lysine and threonine (78% of the daily requirements for an adult in a 100g portion), but low in minerals. The meat has a healthy lipid content with a good ratio (>0.45) of PUFA:SFA (0.83) as well as a healthy (<4) n-6:n-3 fatty acid ratio of 0.39. The histamine content was very low or not detectable but some samples contained total mercury values above the maximum safe limit. Although further research is needed for some meat components, these results are a valuable contribution to the new South African Food Composition Tables being compiled. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die proksimale samestelling van die vleis vanaf vyf afsonderlike posisies op die liggaam van die Mustelus mustelus haai te bepaal. Sodoende is die variasie, met betrekking tot die verskillende proksimale komponente (vog, proteïen, lipiede en as), in terme van die totale karkas, bepaal. Die proksimale variasie is bepaal om vas te stel hoe ʼn verteenwoordigende monster van die totale karkas geneem kan word. Gevolglik is hierdie verteenwoordigende monster gebruik om die effek van geslag, grootte en die verskillende fases van die lewens-siklus op die afsonderlike proksimale komponente asook ander vleis komponente (aminosure, vetsure, minerale, histamien en kwik inhoud) te ondersoek. Laastens is al hierdie inligting gebruik om die algemene samestelling en voedingswaarde van M. mustelus vleis te bespreek. Geen van die proksimale komponente het enige variasie getoon tussen afsonderlike liggaamsposisies nie. Hierdie resultaat dui daarop dat die vleis van ʼn M. mustelus haai homogeen is regoor die karkas en dat ʼn vleis monster vanaf enige posisie op die karkas geneem kan word as ʼn verteenwoordigende monster. Daar is gevind dat geslag, grootte en fase van die lewens-siklus geen merkwaardige invloed het op die vleis se samestelling nie. Hoër vetsuur konsentrasies (versadigde, monoonversadigde en poli-onversadigde vetsure) is gevind in groot vroulike haaie en nie-dragtige vroulike haaie as in groot manlike haaie en dragtige vroulike haaie onderskeidelik. Statisties, het groot manlike haaie hoër vlakke van totale kwik as groot vroulike haaie. Die enigste vleis komponent wat beïnvloed is deur die grootte van die haai, is die vetsure, wat verminder het voor volwassenheid bereik is en dan weer vermeerder soos die haai groter word. Variasie as gevolg van die verskillende fases van die lewens-siklus is meestal gevind in die vetsuursamestelling, en die minimale het ook gevarieer ten opsigte van die elemente aluminium en boor wat effense hoër vlakke getoon het in dragtige haaie as in nie-dragtige haaie. M. mustelus vleis het ʼn gemiddelde proksimale samestelling van 75% vog, 23% proteïen, 1.6% lipiede en 1.4% as (nat massa). Die proteïen waarde is ʼn oorskatting van die ware proteïen waarde as gevolg van hoë nie-proteïen stikstof in die vorm van ureum wat bydra tot die totale stikstof inhoud. M. mustelus vleis blyk ʼn goeie bron van sommige essensiële aminosure soos lisien en treonien (78% van die daaglikse aanbevole dosis), maar laag in mineraal inhoud. Die vleis het ʼn gesonde vet inhoud met ʼn goeie (>0.045) poli-onversadigde:versadigde vetsuur verhouding (0.83) asook ʼn gesonde (<4) omega 6 tot omega 3 vetsuur verhouding van 0.39. Die histamien inhoud van die vleis was baie laag of onder die meetbare limiet, maar sekere monsters het ʼn totale kwik inhoud getoon wat bo die maksimum veilige limiet is. Hoewel verdere navorsing ten opsigte van sekere van die vleis komponente vereis word, lewer hierdie resultate ʼn waardevolle bydrae tot die nuwe Suid-Afrikaanse voedsel samestellings tabelle wat tans opgestel word.

Living elasmobranchs occupy every major aquatic ecosystem throughout the world (Compagno 2003; Compagno et al. 2005). Sensory ecology can be a good determinant in comprehending the processes occurring between an organism and its natural environment (Weissburg and Browman 2005). By utilizing ecophysiological tools, insight into the adaptive responses of the sensory systems to their ever-changing ecological niche can help explain behavioral and life history characteristics (Hueter 1991; Litherland 2009). Aquatic animals show structural and physiological adaptations in their visual sense specific to the ecological requirements of their habitat (Hart et al. 2004), implying that vision is an important modality. The visual system of the smooth dogfish (Mustelus canis, family Triakidae) was examined using corneal electrophysiological methods to determine the visual spectral range, irradiance sensitivity, and speed of vision (flicker fusion frequency, FFF). The smooth dogfish, a shallow water bottom feeder inhabiting inshore waters along the eastern United States, was found to be extremely sensitive to dim light (-3.1- 0.1 log light intensity), and have a slow FFF (13 Hz), thus being well adapted to the scotopic conditions of the turbid coastal inshore waters. This prompted a second set of experiments focusing on the chromatic adaptations of the photoreceptor cells and retina function following light adaptation. Light adaptation increased the photopic threshold by 2.0 log light units of intensity (LLI). However, the temporal resolution was not dramatically increased (to 17 Hz), indicating that the retinal integration time is very slow for this species under all circumstances. The spectral sensitivity peak for M. canis (470 nm) was found to be significantly blue-shifted in comparison to other members of the Triakidae family (Crescitelli et al. 1995; Sillman et al. 1996). Smooth dogfish appear to forgo high spatial and temporal resolution for the enhancement of photon capture. The sandbar shark inhabits the same inshore estuaries during the summer months but has a visual system with a higher temporal resolution (FFF, 54 Hz) and a brighter photopic threshold (1.2 LLI-50% max) (Litherland 2009). Furthermore, other elasmobranch or telelost species inhabiting similar photic environments also exhibit faster temporal resolution; little skate (FFF, 30 Hz), weakfish (FFF, 40 Hz), red drum (FFF, 50 Hz), spotted sea trout (FFF, 60 Hz), and Atlantic croaker (FFF, 58 Hz) (Horodysky et al. 2008; McComb et al. 2010). Coastal seas tend to contain more dissolved organics and particulates than the clear oceanic waters of the epipelagic and pelagic zones (McFarland 1986), therefore the retina of smooth dogfish has adapted to be extremely sensitive to dim light, has a long integration time, a low flicker fusion frequency and temporal resolution, and retinal cells that are able to adjust to changing light conditions. All of these factors contribute to the visual system to provide optimal visual ability to enable smooth dogfish to accurately exploit its surroundings.

Global trends in commercially valuable teleost fisheries point to substantial deterioration in population size, offering limited potential for increased harvests. Consequently a shift in focus towards alternative fisheries has increased fishing effort towards targeting chondrichthyans as a possible solution to meet global demands. The life-history traits of chondrichthyans make them poor candidates for resolving economic and nutritional security as these make them particularly vulnerable to anthromorphic influences. Current fisheries management approaches based on centralized government intervention have proved inadequate. This failure of current management approaches is often linked with poor co-operation by industry with government when collecting fishery-dependent data. As management decisions are based on quantitative estimates from fishery assessment modes data collected are often of poor quality. Co-management with its implied power-sharing arrangement between government and fishing communities has been proposed as a more realistic alternative. The motivation within industry to collect high quality data can only be created with a feeling of ownership. The decline in linefish species in South Africa has led to increased exploitation of demersal sharks such as Mustelus mustelus. Their status as one of the target and by-catch species of South Africa's shark fisheries necessitated resource assessment. Age, growth, maturity and mortality calculations for M mustelus were made from data collected from 1983-2006. The maximum observed age for M mustelus was 25 years. Estimated von Bertalanffy growth parameters from observed length-at-age for combined sexes, females and males were L∞ = 1946.16 mm TL, K = 0.08 year⁻' , to = -3.63 year⁻'; L∞ = 2202.21mm, K = 0.05 year⁻', to = 4.67 years; and L∞ = 1713.19 mm TL, K = 0.08 year⁻' and to = -4.36 years, respectively. Instantaneous total mortality (Z) was estimated at 0.16 y⁻', whilst natural mortality (M) for M mustelus was estimated at 0.05 y⁻'. The age and length at 50% maturity was determined for combined sexes, females and males at 1216 mm TL corresponding to an age of 9.93 years, 1234 mm (TL) and 10.75 years, and 1106 mm TL and 9.1 years respectively. The smoothhound shark resource off the south-eastern and south-western Cape coast was assessed by three dynamic pool models; yield per recruit, spawner biomass per recruit and an extended yield and spawner biomass per recruit. Due to the longevity of elasmobranches the per-recruit model was extended over a 20 year time-frame to simulate resource responses to management options. Fo.1 was estimated as 0.034 year⁻' and F MAX was estimated as 0.045 year⁻'. FsB50 was estimated as 0.031. The extended per-recruit model tested the outcome of different management scenarios, Size and effort control showed the least probability of pristine biomass falling below 20% of current levels in 20 years (where selectivity was set at 3 years). The replacement yield model showed that the average catches over the past decade are 2.5 times higher than the replacement yield is on the South Coast and 1.30 on the West Coast. A more realistic level optimising yield would be at 0.05 with a selection pattern at 3 years, where the probability of the biomass falling to below 20% of pristine pre-exploited levels in twenty years becomes negligible. A comparison of the models showed that current catches need to be halved for exploitation of smoothhound sharks to be sustainable. The results of this study indicate a need for a management intervention for M mustelus in South Africa with regards to potential overexploitation and collection of quality data for further assessments. A demersal identification key was developed as part of this study, which should aid monitoring officials in accurately identifying shark logs for collecting data. This study showed how adopting a management plan with the inclusion of comanagement concepts would improve the quality of data collected and increase monitoring of fishing activities. The inclusion of co-management is possible due to the unique bottle neck created by few demersal shark processing facilities actively exporting shark. A fishery management plan was compiled proposing several management options including size and effort controls.