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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

'n Evaluering van hengelsensusstatistieke van vis in geselekteerde hengelwaters in Transvaal

Malan, Albertus Johannes 04 June 2014 (has links)
M.Sc. (Zoology) / The present investigation was conducted over a period of five years, from 1981 to 1986. The study comprised creel surveys on four selected angling waters in the Transvaal. Information obtained included the fish species caught, the numbers and mass contributed by each species towards the total catches, and the number of anglers who visited the angling waters during each month of the period of survey. This investigation was complemented by fish population studies in 1984 on each of the waterbodies concerned. The information obtained in this way was compared with results on fish populations estimates obtained during earlier studies, when use was made of mark recapture investigations of the angling fish species of these waters. In view of the dramatic changes that took ~lace in the population structures of some of these fish species over a period of 10 to 20 years, supported by recent fish catch statistics on anglers obtained during the creel survey, certain recommendations are made aimed at the improvement of the management of these and other popular angling waters in the Transvaal.
2

The impact of angling on smallmouth and largemouth yellowfish, labeobarbus aeneus and labeobarbus kimberleyensis, in Lake Gariep, South Africa

Ellender, Bruce Robert January 2009 (has links)
A large sportfishery that targets both smallmouth (Labeobarbus aeneus) and largemouth (Labeobarbus kimberleyensis) yellowfish exists in South Africa. Both species have high conservation priority, and no assessments documenting the effect of angling on L. aeneus and L. kimberleyensis have been undertaken. The overall aim of this study was to provide an assessment of the impact of angling on L. aeneus and L. kimberleyensis. The specific objectives of this study were to characterise the sectors utilising Lake Gariep, document catch, effort and total catch for the fishery as well as the locality specific biology of L. aeneus and L. kimberleyensis. The study was undertaken on Lake Gariep, South Africa's largest impoundment, situated on the Orange River system in central South Africa. Subsistence fishers were the dominant user group, constituting 60 % of the fishery, the remainder constituted recreational anglers. Angler catches were dominated by carp (Cyprinus carpio; 74 %), followed by mudfish (Labeo capensis; 13 %) and smallmouth yellowfish (8 %). Catches of largemouth yellowfish contributed < 0.5 % to the total catch. The relative abundance of species by weight differed by area (χ² test of independence: χ² = 182, df = 4, p ≤ 0.05). On any sampling day time fished was the best predictor for differences in probability of capture (PC) (Wald X²(1) = 7.169, p = 0.007). The probability of capturing L. aeneus differed significantly between month (Wald X²(5) = 20.690, p = 0.000) and region (Wald X²(3) = 46.755, p = 0.000). The single best predictor of differences in log abundance and non-zero CPUE was region (Factorial ANOVA p ≤ 0.05). Mean CPUE ranged from 0.21 ± 0.06 kg. man⁻¹.hr⁻¹ to 0.82 ± 0.11 kg. man⁻¹.hr⁻¹ in the OV region and 0.42 ± 0.10 kg. man⁻¹.hr⁻¹ to 1.17 ± 0.24 kg. man⁻¹.hr⁻¹ in the GD region. Angler effort was higher in OV than in GD and ranged from 17 ± 3 anglers/day to 45 ± 9 anglers/day and 6 ± 1 anglers/day to 41 ± 8 anglers/day, respectively. Total catch was higher in the GD 46.0 [95 % CI = 15:102.6] t. period⁻¹ than the OV region 40.0 [95 % CI = 13.9:89.6] t. period⁻¹. The total catch from the Lake Gariep fishery between March and December 2007 was estimated to be 86.0 [95 % CI = 40.4:154.8] t. period⁻¹. Age and growth was determined using whole otoliths. The growth of L. aeneus was best described by the von Bertalanffy growth model as Lt = 481.80 (1- e⁻°·²²⁽t⁺°·⁶¹⁾). Gonadal development for L. aeneus was seasonal, with the gonadosomatic index peaking in January, revealing a distinct spawning season. The length at 50 % maturity for female L. aeneus was attained at a fork length of 354.7 mm. Natural mortality (M) was estimated at 0.55 year⁻¹. The growth of L. kimberleyensis was described by the von Bertalanffy growth model as Lt = 763.22 (1- e⁻°·¹¹⁽t⁺°·⁶³⁾). Only 6 mature female and 15 mature male L. kimberleyensis were recorded during the study period. The smallest mature female was a 390 mm FL stage four female and the earliest recorded mature male was a 337 mm FL, ripe running male. Natural mortality (M) was estimated at 0.08 year⁻¹ for L. kimberleyensis. Per recruit analysis indicated that current fishing mortality reduces the L. aeneus spawner biomass by 7 %, which is considered negligible. Labeobarbus kimberleyensis forms an insignificant proportion of anglers catches and stock status is currently considered pristine.
3

The economic contribution of trout fly-fishing to the economy of the rhodes region

Gatogang, Ballbo Patric January 2009 (has links)
Approximately 24 alien fish species, equivalent to 9 percent of all South African freshwater fish species, were introduced and established into South African waters during the 19th and 20th Centuries (Skelton, 2001). Of the 24 species introduced, the Rainbow trout and the Brown trout have over time become South Africa's most widely spread and used freshwater fish species (Bainbridge, Alletson, Davies, Lax and Mills, 2005). The National Environmental Management: Biodiversity Act, no.10 of 2004 has, however, cast considerable doubt on the future of trout as a food source and a recreational fishing resource in South Africa. More specifically, Section 64 of the Act has the following aims: “(a) to prevent the unauthorized introduction and spread of alien species and invasive species to ecosystems and habitats where they do not naturally occur; (b) to manage and control alien species and invasive species to prevent or minimize harm to the environment and to biodiversity in particular; and (c) to eradicate alien species and invasive species from ecosystems and habitats where they may harm such ecosystems or habitats.” The uncertainty surrounding the future of trout in South Africa is mainly underpinned by aim (c) of Section 64 of the Act. Regarding the eradication of trout and in keeping with aim (c) of Section 64 of the Act, three remarks can be made. First, there exists a paucity of published studies which offer validated proof of the impacts which may be ascribed entirely to the introduction of alien trout in South Africa, since no pre-stocking assessments were conducted (Bainbridge et al., 2005). Second, the elimination of trout is feasible in a few limited closed ecosystems, such as small dams, but is highly impractical and untenable from an environmental and cost perspective where open and established river systems are concerned (Bainbridge et al., x 2005). More specifically, there are no efficient or adequate eradication measures which may be used in wide-ranging open ecosystems, which selectively target alien fish species. Moreover, most, if not all, measures have the potential to cause considerable adverse impacts on indigenous aquafaunal species. Finally, the elimination of trout could undermine the tourism appeal of many upper catchment areas in South Africa. The trout fishing industry is well established and is a source of local and foreign income, as well as a job creator in the South African economy (Bainbridge et al., 2005; Hlatswako, 2000; Rogerson, 2002). In particular, the industry provides a two-tier service: first, in food production at the subsistence as well as commercial levels, and second, as an angling resource. Recreational angling, including fly-fishing for trout, is one of the fastest growing tourism attractions in South Africa. Furthermore, the trout fishing industry is sustained and underpinned by a considerable infrastructure consisting of tackle manufacturers and retailers, tourist operators, professional guides, hotels, lodges and B&Bs. The economic case for the trout fishing industry in South Africa has, however, not been convincingly made. The economic benefit provided by trout and trout fly-fishing is priced directly in the market place by expenditures made by fly-fishers, and indirectly in property values, which provide access to fly-fishing opportunities. The benefit of trout and trout fly-fishing can also be valued through non-market valuation techniques. Non-market valuation is used to calculate values for items that are not traded in markets, such as environmental services. There are several non-market valuation methods available to the researcher, namely those based on revealed preference and those based on stated preference. The former includes the hedonic pricing method and the travel cost method, while the latter includes the contingent valuation method and the choice modelling method. Of the available non-market valuation techniques, the travel cost method is the most suitable method for determining the value of trout and the trout fishing industry because travel cost is often the main expenditure incurred. xi The aim of this study is threefold: first, to value the economic contribution of trout and trout fly-fishing to the Rhodes region, North Eastern Cape; second, to determine the willingness-to-pay for a project that entails the rehabilitation and maintenance of trout streams and rivers in and around Rhodes village so as to increase their trout carrying capacity by 10 percent; third, to determine the willingness-to-pay for a project aimed at eradicating trout from streams and rivers in and around Rhodes village so as to prevent trout from harming the indigenous yellowfish habitat. The first aim was achieved by applying the travel cost method, whereas the second and third aims were achieved by applying the contingent valuation method. The study aimed to provide policy makers with information regarding the value of trout fishing in the Rhodes region, so as to create an awareness of the economic trade-offs associated with alien fish eradication. Through the application of the travel cost method, the consumer surplus per trout fly-fishermen was estimated to be R19 677.69, while the total consumer surplus was estimated to be R13 774 384.40. The median willingness-to-pay for a project to rehabilitate trout habitat was estimated to be R248.95, while the total willingness-to-pay amounted to R199 462.20. The median willingness-to-pay for a project to eradicate alien trout from the Rhodes region rivers and streams was estimated to be R41.18, while the total willingness-to-pay amounted to R28 829.36. This study concludes that trout and trout fly-fishing make a valuable economic contribution to the Rhodes region. The extent of the economic benefit provided by trout and trout fly-fishing services in the Rhodes region should be carefully considered in any stream management project.
4

Exploitation patterns of the multi species/gear hake (Merluccius capensis and paradoxus) fishery on South Africa's southeast coast

Sutton, Glen Robert January 2000 (has links)
The motivation for this study was to examine the exploitation patterns of the M. capensis and M. paradoxus hake fisheries on the Southeast Coast, and determine the size and species of hake caught in each of the hand-line, long-line, and trawl methods. The handline hake fishery has increased substantially over the last several years and concerns are beginning to emerge about the impact this will have on the inshore resource collected on the South Coast between August 1998 and July 1999 was used to describe the hand-line method and estimate annual landings. Data on the size and species in longline catches of hake caught during 1997 were already available for this study. Size distributions in trawl catches were determined from commercial category landing data reported by catch weight and depth. The species composition in these catches determined by comparison using RV Afrikana survey data collected in the same depth regions. Location plays a significant role in determining the sizes and species of hake caught by each gear. Hand-lines catch smaller sizes on average than do long-lines, inshore trawls target mainly M. capensis while offshore trawls catch both hake species. A substantial amount of the hand-line hake caught on the South Coast is not reported. Examination of the exploitation patterns reveal that intense trawling pressure is directed at the smaller sized M. paradoxus inhabiting the depth region between 160-400-meters. Inshore trawls discard a large amount of small sized M. capensis within the 100-meter isobath. A preliminary stock assessment on the status of each hake species found that M. paradoxus appears to be over-exploited while M. capensis was in better shape. However, length-based pseudo-cohort analysis, used in this assessment, is critically reliant on having length frequency data from a steady state population in equilibrium. This limits the application of this model for management purposes and this finding is purely theoretical at this stage. Results suggest that each hake species is under a different pattern and level of exploitation and the multi-species nature of hake stocks on the South Coast should be considered in developing optimum management policies. Future work should focus on developing appropriate age/length keys so that an age-based VPA, which is more powerful than the length-based approach, can be applied towards stock assessments on the South Coast. Alternatively, length-data covering a longer period should be compiled and the equilibrium assumption further investigated so that the results from length-based models can be used with more confidence.
5

The exploitation of fish during the Holocene in the South-Western Cape, South Africa

Poggenpoel, Cedric Alan January 1996 (has links)
Bibliography: pages 202-225. / This thesis describes the fish remains recovered from a number of sites in three different localities in South Africa; Elands Bay and Langebaan Lagoon on the west coast, and False Bay on the Cape Peninsula. Chapter One is an introductory account of ichthyology, its usefulness in archaeological research and the range of analytical work done in South Africa, whilst Chapter Two is an attempt to show the history and development of the study of fish bones recovered from prehistoric sites in South Africa. Chapter Three gives an account of the southern Oceans, the Benguela Current and fishing habitats. Chapters Four and Five give accounts of the fishing habitats within the Elands Bay area and of the identification and interpretation of fish assemblages excavated at four sites and their implications in relation to habitat and palaeoenvironmental changes at Elands Bay. This information is used first to show that the presence or absence of certain species and the size of those species in the archaeological record can be used as an alternative means to interpret late Pleistocene and Holocene sea level fluctuations and to understand to what extent local fishing habitats have been influenced by those changes. An important observation made was the relative surplus or deficit of vertebrae compared to cranial parts through the sequence. The over-representation or under-representation of fish vertebrae in the fish assemblages points to changes in the procurement strategy employed. The consistency between cranial:vertebral ratios through the site sequences suggests that these patterns are related to both location and processing techniques. Chapter Six reviews the ecology of the Langebaan Lagoon, the identification of fish assemblages from three open midden stations; Stotbergfontein on the shores of the lagoon and Paternoster and Duiker Eiland which are located on the Vredenberg peninsula. Chapter Seven gives a short overview of the modern fishing situation at False Bay and discusses the fish assemblages from Smitswinkelbaai Cave and Rooiels Cave in the False Bay area. Chapter Eight deals with the archaeological evidence for fishing equipment and the depiction of fishing scenes in the rock art of South Africa and addresses the historical evidence for indigenous fishing in the south-western Cape. Chapter Nine gives an overview of the historical fishing at the Cape, the use of outposts near Langebaan Lagoon and Muizenberg in False Bay by the Dutch to supply the Cape settlement with provisions. In Chapter Ten the relevant evidence from each of the chapters is summarised and the conclusions for the three areas are presented.
6

A retrospective analysis of shark catches made by pelagic longliners off the east coast of South Africa and biology and life history of shortfin mako shark, Isurus oxyrinchus.

Foulis, Alan. 13 November 2013 (has links)
Oceanic pelagic shark species are under threat worldwide as fishing effort increases and they are taken as both targeted and bycatch. It is widely recognized that the life history characteristics of sharks make them inherently susceptible to overexploitation and as a result many shark-directed fisheries have collapsed. It is therefore essential that good-quality data are collected and analyzed in order to provide fisheries managers with the right information to manage these species sustainably. South Africa has a pelagic longline fishery which includes tuna-, swordfish-, and shark-directed vessels. This study analyzed logbook (1998 – 2010) and observer data (2002 – 2010) provided by the Department of Agriculture, Forestry and Fisheries in order to assess the catch composition and standardized catch-per-unit-effort (CPUE) of sharks captured as both targeted catch and bycatch. The study area consisted of four zones moving east of the 20°E meridian: the Agulhas Bank (20°E – 24°E), South Coast (25°E – 29°E), East Coast 1 (30°E – 32.8°E), and East Coast 2 (32.9°E – 36.5°E). The majority of fishing effort targeted at tuna was focused on the Agulhas Bank and consisted of foreign vessels which operated over the winter months, whereas local vessels targeted swordfish with consistent year-round effort along the upper east coast. Sharks made up 13% of total catches according to logbook data and catch composition was dominated by blue shark (Prionace glauca) and shortfin mako shark (Isurus oxyrinchus). Observer data identified a larger number of shark species than shown by logbooks, and notably, the crocodile shark (Pseudocarcharias kamoharai) made up 22.5% of shark bycatch on swordfish-directed vessels operating along the upper east coast. In addition, the observer data showed that although blue and mako shark dominated catches in the Agulhas Bank and South coast zones, carcharhinid sharks were more prevalent further east. Generalized linear models explained 54% of the variation in CPUE of shark bycatch, with year and target species being the two most important explanatory variables. The standardized CPUE index based on logbook data suggested a slightly increasing shark abundance trend between 1998 and 2010, but conversely, the index based on observer data suggested a decline between 2002 and 2010. Assuming that the observer data best reflected the actual CPUE trend (i.e. a declining trend), the increasing trend shown by logbooks over the same period most likely stems from initial under-reporting of shark capture events by skippers, followed by improved reporting in later years, thus masking the declining trend. Catch by target species revealed that swordfish vessels caught significantly more sharks per 1000 hooks than tuna vessels. The shortfin mako shark was one of the most common bycatch species, and also the primary target species of the shark-directed fishery. Generalized linear models of shortfin mako shark CPUE using the delta method produced similar trends than models of total shark bycatch; i.e. trends based on logbook data appeared stable but observer data showed a declining trend over time. Shortfin mako sharks were more abundant in the Agulhas Bank and South coast zones than along the East coast. A total of 817 shortfin mako shark samples were collected onboard a South African shark-directed pelagic longline vessel operating out of Cape Town and by the KwaZulu-Natal Sharks Board bather protection nets, set close inshore. Sharks collected inshore (from nets) were significantly larger than those collected offshore. More males than females were collected from the nets (2.3 males : 1 female), whereas the ratio for offshore samples was 1.1 : 1. Age and growth parameters were estimated from 89 sectioned vertebral samples consisting of 43 females and 46 males ranging in size from 90 cm to 299.4 cm fork length (FL). Annual band-pair deposition was assumed and growth was analyzed by fitting 3-parameter von Bertalanffy and Gompertz growth models. Parameter estimates for the Gompertz model were: K = 0.152 year¯¹ for males and 0.127 yearˉ¹ for females; L0 = 85 cm; L∞ = 295 cm for males and 315 cm for females; and longevity was 17 and 21 years for males and females respectively. Estimates for the von Bertalanffy model were: K = 0.08 yearˉ¹ for both sexes; L0 = 85 cm; L∞ = 354 cm for males and 321 cm for females; and longevity was 34 and 31 years for males and females respectively. Using these data, age and length at 50% maturity were calculated at 7 years and 199.1 cm FL for males, and 14 years and 252.8 cm for females. Litter size was in agreement with previous studies (9 to 14 pups). The gestation period was not estimated but parturition may be in late winter to spring. The stomach contents of 817 sharks showed that shortfin mako sharks are opportunistic feeders; elasmobranchs dominated in stomachs collected from sharks caught in nets near the shore (%F = 63.54%) whereas shark stomachs collected from the offshore contained mainly teleosts (70%). Length-frequency analyses revealed that large and reproductively active shortfin mako sharks were more common along the upper east coast and in the inshore environment, whereas juveniles and subadults preferred the oceanic environment, particularly over the Agulhas Bank and South Coast zones. The findings from the present study are a significant step forward towards developing a management strategy for protecting shortfin mako sharks in the South West Indian Ocean region. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2013.
7

Movement patterns and genetic stock delineation of an endemic South African sparid, the Poenskop, Cymatoceps nasutus (Castelnau, 1861) / Movement patterns and genetic stock delineation of an endemic South African sparid, the Poenskop, Cymatoceps nastus (Castelnau, 1861)

Murray, Taryn Sara January 2013 (has links)
Poenskop Cymatoceps nasutus (Pisces: Sparidae), an endemic South African sparid, is an important angling species being predominantly targeted by the recreational shore and skiboat sector. This species is slow-growing, long-lived, late-maturing and sex-changing, making poenskop acutely sensitive to over-exploitation. Despite interventions, such as the imposition of size and bag limits (currently 50 cm TL and one per licensed fisher per day) by authorities, catch-per-unit-effort trends reflect a severe and consistent stock decline over the last two decades. Poenskop has been identified as a priority species for research and conservation. Although the biology and population dynamics of this species have been well-documented, little is known about the movement behaviour of poenskop. Furthermore, there is a complete lack of information on its genetic stock structure. This thesis aimed to address the current knowledge gaps concerning movement behaviour and genetic stock structure of poenskop, making use of a range of methods and drawing on available information, including available fishery records as well as published and unpublished survey and research data, and data from long-term monitoring programmes. Analysis of available catch data (published and unpublished) revealed a decline in the number of poenskop caught as well as size of fish taken over the last two decades, ultimately reflecting the collapse of the stock (estimated to be at 20% of their pristine level). Improved catch-per-unit-effort data from the Tsitsikamma National Park Marine Protected Area (MPA), and larger poenskop being caught in the no-take areas than adjacent exploited areas of the Pondoland MPA confirmed that MPAs can be effective for the protection and management of poenskop. The current MPA network in South Africa is already wellestablished, and encompasses considerable reef areas, being preferable for poenskop habitation. Conventional dart tagging and recapture information from three ongoing, long-term fishtagging projects, conducted throughout the poenskop’s distribution, indicated high levels of residency at all life-history stages. Coastal region, seasonality and time at recapture did not appear to have a significant effect on the level of movement or distance moved. However, on examining the relationship among coastal movements and fish size and ages, larger and older fish (adults) moved greater distances, with juveniles and sub-adults showing high degrees of residency. An estimation of home-range size indicated smaller poenskop to hold smaller home-ranges, while larger poenskop hold larger home-ranges. Large easterly displacements of a number of adult poenskop is in accordance with previous findings that this species may undertake a unidirectional migration up the coastline of South Africa where they possibly settle in Transkei waters for the remainder of their lives. This high level of residency makes poenskop vulnerable to localised depletion, although they can be effectively protected by suitable MPAs. Despite considerable tagging effort along the South African coastline (2 704 poenskop tagged with 189 recaptures, between 1984 and 2010), there remains limited information on the connectivity of different regions along the South African coastline. This was addressed using mitochondrial DNA sequencing. The mitochondrial DNA control region was used due to its high substitution rate, haploid nature, maternal inheritance and absence of recombination. The mtDNA sequencing showed no evidence of major geographic barriers to gene flow in this species. Samples collected throughout the core distribution of poenskop showed high genetic diversity (h = 0.88, π = 0.01), low genetic differentiation among regions, no spatial structure (ɸST = 0.012, p = 0.208) and no evidence of isolation by distance. The collapsed stock status of poenskop as well as the fact that it is being actively targeted by recreational and commercial fishers suggests that this species requires improved management, with consideration given to its life-history style, residency and poor conservation status. Management recommendations for poenskop, combined with increasing South Africa’s existing MPA network, include the possibility of setting up a closed season (during known spawning periods) as well as the decommercialisation of this species. The techniques used and developed in this study can also be adopted for other overexploited linefish species.
8

Empirical studies of fish movement behaviour and their application in spatially explicit models for marine conservation

Kerwath, Sven Ebo January 2006 (has links)
This thesis investigates the movement behaviour of South African two coastal fish species and evaluates the effectiveness of marine protected areas (MPAs) in their protection and management. Its primary focus is on resolving the movement patterns of roman Chrysoblephus laticeps (Sparidae) in and around the Goukamma and Castle Rock MPAs in the Western Cape province of South Africa. A pilot study of the methodology investigated the movement behaviour of spotted grunter Pomadasys commersonnii (Haemulidae) in the sheltered East Kleinmonde Estuary in the Eastern Cape province. The application of different tagging methods was tested in a controlled tank experiment. Tagged roman were monitored over a 198-day period. Barbed dart, t-bar anchor and Visible Implanted Fluorescent Elastomer (VIFE) tags were compared. Application techniques and underwater visibility of VIFE tags were tested on roman and on fransmadam Boobsoidia inornata in a pilot study. Needles of gauge 25 were found to be optimal for VIFE tag application. Whereas VIFE tagging caused fin rot in fransmadam, it had no negative effect on roman. VIFE tagged fish could be identified by divers from a distance of three metres under ambient light in an observation tank in five metres water depth. There was no significant difference in growth rate between groups of roman with different tags and controls after 198 days. High tag loss rates were experienced for barbed dart and t-bar anchor tags, although barbed dart tags performed better than t-bar anchor tags. Although some of the VIFE marks had deteriorated, all VIFE tagged fish were individually recognised at the end of the study. Conventional dart and VIFE tags are feasible methods to tag roman. However, the high tag loss rate of conventional tags must be taken into account in the design of a tagging study. Previous mark and recapture studies on roman are beset with a number of problems. Poor experimental design and low precision of capture positions resulted in equivocal results of limited value. A tagging experiment was designed to eliminate ambiguity in data interpretation and to produce a dataset that could be used to model roman residency and dispersal. A combination of conventional barbed dart tags and Visible Implanted Fluorescent Elastomer tags was used to tag roman in the Goukamma Marine Protected Area (GMPA) on the temperate South African south coast. Sixty one percent of roman were recaptured within 50 m of the tagging position. A small proportion moved considerable distances of up to four kilometres. The extent of these movements was not dependent on fish size or sex. Data from this experiment and from a previous tagging study in the Tsitsikamma National Park (TNP) were used to model the resident behaviour of roman. The model suggests a probability of 91% (GMPA) and 94% (TNP) of residency within a 10000 m² cell. This result suggests that individual roman will benefit from protection in small MPAs. A different experimental approach was required to investigate the exact home range of this species. Firstly the feasibility of using acoustic telemetry to study the movement of coastal fish in South Africa was investigated. The telemetry equipment comprised two VEMCO V8 transmitters and a VEMCO VR60 receiver linked to a directional hydrophone. A tank experiment was conducted to examine the effects of the transmitter implantation. A tracking experiment was conducted on spotted grunter Pomadasys commersonnii in the East Kleinmonde Estuary. Operated fish recovered quickly and, with respect to swimming behaviour and growth rates, no differences were found between fish with implants and controls. The maximum detection range in the estuary was 400 m. Interference between different transmitter frequencies was negligible. Transmitter location recordings were found to be accurate within five metres. Two fish were tracked over a seven-day period. The fish preferred the lower reaches of the estuary where they made repeated and prolonged use of specific areas. The success of the initial experiments allowed this method to be used to investigate the spatial utilisation and activity patterns of roman Chrysoblephus laticeps. Surgically implanted VEMCO V8, V13 and V16 transmitters were used to track 13 roman inside the Castle Rock MPA in False Bay. Transmitters implanted into C. laticeps in tanks had no apparent effects on growth and physiology. Manual boatand diver-based tracking experiments covered a 17-month period. A VEMCO VRAP radio acoustic positioning system was used over two one-month periods during and after the spawning season of roman. Analysis of data using a 95% fixed kernel algorithm suggests that roman are resident throughout their adult life, occupying home ranges between 1000 and 3000 m². Activity was lower at night. During periods of cold-water upwelling, fish retreated into caves. During the spawning season, females extended their home ranges, possibly to mate with different males. These results confirm that this species is well suited for protection and management with small MPAs. The effect of two MPAs on the South African south coast on the population of C. laticeps was simulated with a spatially explicit individual based model (IBM). Life history parameters determined in recent studies and the effect of fishing on the size of sex change was taken into account. Fish densities and size frequencies were based on recent underwater visual census. The distribution of suitable habitat in the study areas was also incorporated. The results show a rapid recovery of the fish size frequency spectrum and sex ratio to pre-exploitation levels inside both MPAs. Little 'spillover' of fish into the fished areas occurred resulting in negligible improvement of catches. The results suggest that for resident species like roman, even small MPAs offer sufficient protection.
9

An assessment of impacts of illegal subsistence fishing on riverine biodiversity on selected areas of the Eastern Cape Province, South Africa / The impact of illegal fishing on Eastern Cape Province River and marine biodiversity

Mbanjwa, Sibonelo Thanda 06 1900 (has links)
Subsistence fishing is impacting on freshwater and marine biodiversity to the extent of extinction of some fish species. These illegal subsistence fishermen have created a huge impact on marine biodiversity, irrespective of marine and riverine laws that are put in place and practiced. There have been attempt to provide subsistence fishing extension officer services to facilitate in bringing subsistence fishermen fully into the management system, in an orderly and equitable manner, by facilitating the granting of formal subsistence fishing right, providing permits via policy management and effective rules via permit applications. However the follow up process as to whether these policies and rules administered is effective or not has not been measured. This investigation attempts to identify potential fishing that should be considered as suitable for subsistence fisheries in selected highly exploitable areas. Though it cannot be confirmed from previous studies that some relevant organizations are not fully taking their responsibilities, the study will further enable exploration of options and challenges associated with future management of subsistence fisheries and provide recommendations to enable proper implementation of the policies and legislations. / Environmental Sciences / M. Env. Sc. (Agriculture and Environmental Affairs)
10

Women and the management of household food security in Paternoster

Swartz, Eleanor 12 1900 (has links)
Thesis (MA)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: This study focuses on the gendered social relations that are attached to food, through an exploration of women’s management of food and food security in poor households in Paternoster, a small fishing community on the west coast of the Western Cape Province of South Africa. My study explores how women navigate the everyday provision, management and distribution of food within a context of limited resources, with food understood both in terms of sustenance and as implicated in processes whereby gender norms and larger concerns with ‘respectability’ (ordentlikheid) are established and maintained under difficult economic conditions. One of the important strategies employed to ensure food security within households in Paternoster is the establishment and maintenance by and among women of foodways in and between households. An exploration of foodways between households sheds light on the various social networks that exist in Paternoster and the important role of women within these networks. Paternoster is a space where the navigation of these issues is informed by the long history of subsistence fishing in the area and the symbolism attached to fish and fishing in the ways in which the local fishing community engages with the challenges of food security. Of particular interest is how women manage individual and/or household food security in Paternoster in the light of existing gender dynamics involved in the production, collection and consumption of food. The sharp division of labour historically has meant that women have traditionally been involved in the pre- and post-harvest sector, rather than in the actual catching of fish. This study is also driven by concerns around the impacts of the changing fishing environment on food security and social relations in this small village. One of the major consequences of these changes is the feeling of impending food insecurity experienced by many households. The increase in mechanization in marine resource use activities, drastic changes in fishing policies and the process of fisheries rights allocations as well as diminishing fish stocks are systematically impacting on the social systems and lived experiences of the people who were, and still are, heavily dependent on the fishing industry in Paternoster for their livelihoods.. Paternoster has seen the development of new sources of employment as a result of the growth of tourism, which has presented women in particular with new work opportunities, including working in guest houses and restaurants. However, this is on the low wage end. In this context the management of food security within the household and between households through maintaining foodways and established food networks is predominantly the responsibility of women. / AFRIKAANSE OPSOMMING: Hierdie studie fokus op sosiale verhoudings van gender wat verband hou met voedsel, deur‘n verkenning van vroue se bestuur van voedsel en voedselsekerheid in arm huishoudings in Paternoster, ‘n klein vissersgemeenskap aan die weskus van die Wes-Kaap Provinsie van Suid-Afrika. My studie verken hoe vroue die daaglikse voorsiening, bestuur en verspreiding van voedsel navigeer in ‘n konteks van beperkte hulpbronne, met ‘n begrip van voedsel as lewensmiddele sowel as geïmpliseer in prosesse waarin gender-norme en ‘n gerigtheid op 'ordentlikheid' onder moeilike ekonomiese omstandighede gevestig en onderhou word. Een van die belangrike strategieë wat deur en tussen vroue in huishoudings in Paternoster onderneem word om voedselsekerheid te verseker is die vestiging en onderhouding van voedselnetwerke (foodways) in en tussen huishoudings. ‘n Verkenning van voedselnetwerke tussen huishoudings werp lig op die verskeidenheid sosiale netwerke wat in Paternoster bestaan en die belangrike rol van vroue in hierdie netwerke. Paternoster is ‘n plek waar die navigasie van hierdie kwessies ingelig word deur die lang geskiedenis van bestaansvissery in die gebied sowel as die simboliek wat aan vis en visvang geheg word in die wyses waarop die plaaslike gemeenskap met die uitdagings van voedselsekerheid handel. Wat van besondere belang is, is hoe vroue individuele en huishoudelike voedselsekerheid in Paternoster bestuur in die lig van die bestaande gender-dinamika met betrekking tot die produksie, versameling en gebruik van voedsel. Die skerp historiese geslagsverdeling van arbeid het beteken dat vroue tradisioneel betrokke was in die voor- en na-oes proses, eerder as in die werklike vang van vis. Hierdie studie word ook gemotiveer deur kommer oor die impak wat die veranderende vissery-omgewing op voedselsekerheid en sosiale verhoudings in hierdie dorpie het. Een van die belangrikste gevolge van hierdie veranderinge is die gevoel van dreigende voedselonsekerheid wat deur talle huishoudings ondervind word. Die toename in meganisering in die aktiwiteite rondom die gebruik van mariene hulpbronne, die drastiese veranderinge in visserybeleid en die toekenningsproses van visregte asook die afname in visbronne impakteer sistemies op die sosiale sisteme en ervaring van die mense wat sterk afhanklik was van die visindustrie in Paternoster vir hul leeftog afhanklik was en nog steeds is. Paternoster het die ontwikkeling van nuwe bronne van werk ervaar as gevolg van die groei van toerisme. Dit het aan vroue veral nuwe werksgeleenthede gebied, insluitend werk in gastehuise en restourante. Hierdie werk was egter op die lae loonvlak. In hierdie konteks is die bestuur van voedselsekerheid binne die huishouding en tussen huishoudings, deur die handhawing van foodways en gevestigde voedselnetwerke hoofsaaklik die verantwoordelikheid van vroue.

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