Dissertations / Theses on the topic 'Fishes – Malawi'

In Malawi, fish contribute about 60-80% to the country's animal protein supply. The greater proportion (> 50%) comes from Lake Malawi. Bathyclarias nyasensis and other clariid catfish contribute up to > 20% of the total catches. Catches of Bathyclarias nyasensis in the inshore area of the south-east arm of Lake Malawi are declining and a management plan for the fishery is essentially lacking. There is paucity of biological data that precludes the use of any option to manage the species. The principal aim of the thesis was to define the ecological role B. nyasensis, the most abundant and common of the Bathyclarias species. By examining life history characteristics within a food web context, it was hypothesized that the study would provide an insight into the interrelationships between species, and, hence form the basis for the development of a rational exploitation strategy for the species. The study was undertaken in the south-east arm of Lake Malawi (9° 30'S, 14° 30'S). The principal objectives of the study were to investigate the feeding ecology of B. nyasensis by examining morphological characters and structures associated with feeding, diet of B. nyasensis, food assimilated in the species using carbon (∂¹³C) isotope analysis, daily food consumption rate for B. nyasensis; and to relate the feeding ecology to life history traits such as age, growth, and some aspects of the reproductive biology of B. nyasensis. The suitability of sectioned pectoral spines and sagittal otoliths to age B. nyasensis was assessed. Due to reabsorption of growth zones with increasing spine lumen diameter with fish size, and the relatively low number of spines that could be aged reliably, only otoliths were used. The maximum age for B. nyasensis was estimated at 14 vears. Growth was best was described by the four parameter Schnute mc: lt ={42+(81¹·⁸ - 42¹·⁸)x1-e⁻°·°⁵⁽t⁻¹⁾}¹/¹·⁸ over 1-e⁻⁽⁻°·°⁵⁾⁽¹¹⁾ for female, lt={41+(98¹·² - 41¹·²)x 1-e⁻°·°²⁽t⁻¹⁾}¹/¹·² over 1-e⁻⁽⁻°·°²⁾⁽¹³⁾ and for male fish. Age-at-50% maturity for females and males were estimated at 7 years and 4 years, respectively. Typically, fish grew rapidly in the first year, but slower during subsequent years. Smaller fish were found inshore while larger fish were found in offshore regions. It was hypothesised that the rapid growth in the first year and slower growth later is a consequence of change in diet from high quality and abundant food source to a more dilute food and that this may be associated with a shift in habitat. Morphological characters associated with feeding were used to predict the food and feeding behaviour of B. nyasensis. The size of premaxillary, vomerine, pharyngeal dental and palatine teeth and premaxillary and vomerine tooth plates suggested the capability of B. nyasensis to handle both large and small prey, with a propensity towards smaller prey in composition to C. gariepinus. The molariform teeth on the vomerine tooth plate suggested that molluscs form part of the diet. The relative gut length (1.27±0.24) suggested omnivory, with an ability to switch between planktivory and piscivory. Buccal cavity volume and filtering area changed with fish size at 500-600 mm TL upon which it was hypothesised that the fish diet changed to planktivory at this size. Detailed diet analysis provided information upon which the above hypotheses could be accepted. Percent Index of Relative Importance (%IRI) and a multi-way contingency table analysis based on log-linear models were used to analyse diet data. Results showed that B. nyasensis is omnivorous, but with a distinct ontogenetic dietary shift from piscivory to zooplanktivory at 500 - 600 mm TL. The increased buccal cavity volume at the same fish size therefore, suggests that B. nyasensis is well adapted to filter the dilute zooplankton resource. Increased foraging costs of feeding on zooplankton explained the slower growth of larger fish. The dietary shift was finally corroborated by results of the ∂¹³C isotope analysis. A polynomial equation described the change in carbon ratios with fish size: ∂¹³C = - 33.188 + 0.4997L - 0.0045 (total length)² (r² = 0.598, n = 12, p=0.022). The ontogenetic shift in diet was synchronised with a habitat shift postulated in life history studies. In the inshore region, B. nyasensis were predominantly piscivorous (apex predators), and were zooplanktivorous in the offshore region, thereby forming part of the pelagic food web in the latter region. After examining "bottom-up" and trophic cascade theories, it was postulated that perturbations of the B. nyasensis stock would be discernible both at the top and lower trophic levels. As a piscivore and therefore apex predator, effects of overfishing B. nyasensis in the inshore region could cascade to unpredictable ecological changes in inshore areas and, due to the ontogenetic habitat shift, in the offshore regions. Examples of trophic cascade phenomena are provided. On the basis of the feeding study, it was possible to reconstruct the pelagic food web of Lake Malawi. Apart from the lakefly Chaoborus edulis, B. nyasensis is the other predator that preys heavily on zooplankton in the pelagic zone. Perturbations of the B. nyasensis stock could affect size composition of zooplankton which in tum, could affect production of C. edulis, a resource for the top predators in the food web. The findings of the present study contributed to the ongoing debate of introducing a zooplanktivore into the pelagic zone of Lake Malawi. Proponents for the introductions have argued that zooplankton predation by fish is inferior to that of C. edulis. Introduction of a clupeid zooplankton was proposed as a strategy to boost fish production in the lake. The zooplanktivore would either out-compete or prey on C. edulis to extinction. Opponents to this view argued that zooplankton biomass in the pelagic region was too low to support introductions and that the fish biomass in the pelagic region may have been underestimated. Results from the present study suggest that planktivorous fish (including B. nyasensis) might not be inferior to C. edulis in utilising the zooplankton resource; B. nyasensis is well adapted to utilise the dilute zooplankton resource, and by omitting B. nyasensis from previous studies, overall zooplankton predation by fish may have been underestimated by between 7 - 33%. On the basis of the theoretical migratory life history cycle of B. nyasensis, it is recommended that the current interest in increasing fishing effort in offshore areas should proceed with caution. Ecological changes that may have occurred in the inshore areas due to overfishing have probably not been noticed: as the offshore zone has never been fished. The latter zone may have acted as a stock refuge area. Higher fishing intensity in the offshore areas could lead to serious ecological imbalances and instability. The study has shown that life history characteristics studied in the context of the food web, and in the absence of other fisheries information and/or data, strongly advocates the precautionary principle to managing changes in exploitation patterns.

Behaviour and space utilisation of rock-dwelling cichlids were observed at Thumbi East Island, Lake Malawi. 1. Males of five species of the mbuna complex held long-term territories. Pseudotropheus elongatus "aggressive" vigorously defended a feeding area and sometimes a spawning site interspecifically, but did not feed in the peripheral part of their territory. Spawning sites of Pseudotropheus zebra, Pseudotropheus tropheops "orange chest", Labeotropheus fuelleborni, and Petrotilapia nigra were interspecifically-defended, while larger mating territories were defended against conspecific neighbours. Feeding areas were shared with many fish and often extended beyond the defended area. There was considerable variation in behaviour and space use within and between species and between times of day. 2. Non-territorial P. zebra used larger ranges than territorial conspecifics, and fed more on plankton, but individuals had preferred benthic feeding areas, often in conspecific territories. These 'floaters' were often aggressive. Both size and relative brightness independently predicted the outcome of aggressive interactions between floaters, and a site-specific dominance hierarchy was suggested, with some individuals appearing to be semi-territorial. 3. Males and females of 21 and 13 species respectively were found to establish temporary breeding territories. Overall breeding seasonality was bimodal, but reproductive timing and territory characteristics differed among species. Temporary territories had a considerable impact on the behaviour and habitat use of all resident mbuna species, even causing abandonment of territories. 4. Non-breeding Protomelas taeniolatus had limited home ranges, and showed little aggression. During the highly-synchronised reproductive season, males defended spawning sites and females fry-guarding territories. Most chases were directed towards the commonest fish, but predators were chased further and faster. Female behaviour changed over the guarding period. Females generally continued territorial defence after the brood had disappeared. Most broods contained fry of different sizes and species. Significant benefits were found for guarding females with clustered territories, but females did not appear to choose sites adjacent to conspecific parental females. 5. Territoriality in fish is taxonomically widespread and may serve several functions according to species, sex and developmental stage. It also varies according to genotype- and phenotype-limited strategies and short term costs and benefits. Territories may be simultaneously multifunctional.

The cichlid fishes inhabiting Lakes Malawi, Tanganyika and Victoria have undergone explosive speciation, and are now unparalleled as a system in which to study large scale rapid speciation in vertebrates. Current theories on the origin and diversification of these cichlid faunas were critically reviewed. Sexual selection by female choice was concluded to be the most likely mechanism behind the phenomenal explosion in species numbers. Sexual selection by female choice was investigated in Copadichromis thinos, a bower-building cichlid. A significant relationship was found between the asymmetry of an extended phenotypic trait (sand bowers), and male parasite load (not previously demonstrated in any taxa). Males which spawned were found to have a significantly lower total parasite load than those which did not spawn, never before demonstrated in a lekking fish. Further, males which spawned were found to have significantly higher eviscerated gonadosomatic indices than unsuccessful males. Significant correlations were also found between hepatosomatic index and some measures of reproductive success. This may indicate females are choosing to mate with males in better condition. A morphological study of the sand-dwelling species of the genus Aulonocara showed that differently coloured males represented distinct morphospecies, rather than colour 'morphs' of a single or few species. Twelve new species were subsequently described, along with preliminary descriptions of three further species. Preliminary laboratory studies of three sympatric species of the Pseudotropheus zebra species complex from Nkhata Bay demonstrated that females were able to distinguish between conspecific and heterospecific males using visual cues only. Further, no significant differences were found in female choice between males using visual cues only and visual and olfactory cues.

Diplotaxodon limnothrissa Turner (1995) is a widely distributed species occurring throughout Lake Malawi, extending from the surface to a depth of at least 220m. It is probably the most abundant cichlid in the lake with biomass estimates of around 87 000 tonnes in the pelagic zone alone. The species is exploited commercially in the southern part of the lake but since its inception the fishery has never been assessed. As such this study investigates some aspects of age and growth of the species besides applying a yield-per-recruit analysis to assess the status of the fishery. Analysis of sectioned sagittal otoliths revealed that D. limnothrissa is fast growing and relatively long-lived species, attaining ages in excess of 10 years. Growth in length was rapid in immature fish, with fish attaining almost half of their maximum size within their first year. Le ngth-at-age was described by the von Bertalanffy growth model with combined-sex growth described as Lt = 211.21(1-exp(- 0.24(t+1.36))) mm TL. Total, natural and fishing mortalities were estimated at 0.76 yr⁻¹, 0.31 yr⁻¹ and 0.45 yr⁻¹ respectively. Per-recruit analysis indicated that the D. limnothrissa stock in the southeast arm of the lake is fully exploited as indicated by the current spawner biomass-per-recruit ratios of 31-55% (SB/R)F=0. Modelling indicated that the current age-at-capture (2.67 years) is lower than the age at which yield is optimised (> 5 years) based on the F₀·₁ harvesting strategy. It is, therefore, recommended that the age-at-capture should be increased from 2.67 to 5 years to optimise yield.

More than twenty years ago, over twenty species of the rock-dwelling cichlid species (Mbuna) were translocated from the northern Lake Malawi, where they are endemic, to Thumbi West Island, Lake Malawi National Park, in the southern part of Lake Malawi. Among these species, Cynotilapia afra, Pseudotropheus callainos and Pseudotropheus tropheops 'red cheek' are strongly territorial, and have increased substantially in number and are widely distributed, particularly in the three to seven metre depth band of the rocky habitats at the Island of Thumbi West. It is feared that the increase in population density of translocated species (hereafter referred to as introduced species) may be at the expense of ecologically equivalent native species which could be eliminated. In this thesis the following key hypotheses have been tested: (i) that the introduced species having originated from a region of Lake Malawi which is generally poor in nutrients and introduced in an area which is richer in nutrients, would cope better than the native species during periods of nutrient scarcity which occur frequently, often seasonally in oligotrophic lakes, such as Lake Malawi; (ii) that the introduced species are fitter than their ecologically equivalent native species in the acquisition of territorial space in which they breed, feed and seek shelter, and (iii) that introduced and native species coexist by utilizing different microhabitats. Results show that: 1. the introduced species, P. callainos and P. tropheops 'red cheek' may have responded positively to enhanced nutrient availability, as they were found to have better condition factors and fecundity indices at Thumbi West Island than at sites of their origin, in the northern lake Malawi. Cynotilapia afra, P. callainos and P. tropheops 'red cheek' also maximise their life-span fecundity by starting to reproduce at relatively smaller size than the native species with which they overlap in microhabitat requirements. Similarly, their breeding peaks precede the breeding peaks of the native species with which they overlap in microhabitat requirements. Consequently, due to priority residence effects, the offspring of introduced species may have a competitive edge in the use of essential resources, e.g., refuge over the offspring of the native species whose peak-recruitment occurs later in the year. 2. There is an overlap between the introduced and native species in their microhabitat requirements. Consequently, interference competition between them for territorial sites occurs. The choice of optimal territory sites is constrained by the fact that females preferentially mate with males that defend significantly smaller holes, or crevices among the rocks, probably as a means of minimizing egg predation during spawning. 3. The population of territorial males of introduced species seems to grow exponentially, depending on the availability of suitable microhabitats, and an equilibrium between them and males of the native species may be reached. Competition for optimal territory sites seems to intensify, once the carrying capacity in a particular area has been reached, and it is at this stage that some territorial males of the introduced and native species with similar microhabitat requirements, e.g., C. afra and P. zebra, or P. tropheops 'red cheek' and its sibling native species, P. tropheops 'orange chest' displace each other. However, it seems unlikely that any of the native species which were compared with the introduced species would be driven to extinction because: (a) there is a considerable interspecific territory turn-over between the introduced and native species that overlap in microhabitat requirements. (b) Even in situations where some of the native species occur in microhabitats that are not of their preference, they occupy patches of suitable sites and are capable of breeding. (c) It has been suggested that since introduced and native species breed throughout the year and are polygamous and have intraspecifically shared paternity, they are capable of fertilizing many gravid females of their own species. Therefore, the population of native species may not be detrimentally limited by the presence of introduced species. (d) The introduced and native Mbuna species that prefer small rocks coexist in the same microhabitats, partly by feeding at different sites with different intensity and they also feed at different heights in the water column. 4. The following studies have been recommended before any management intervention, such as culling is adopted: (i). interaction between the introduced and native species in the shallow and deep rocky habitats; (ii) space utilization and survivorship of juveniles of the introduced and native species; (iii) laboratory studies to confirm the role of different nutrient regimes on the fecundity of Mbuna; (iv) the possibility of hybridization between the introduced and native species; (v) monitoring of population growth and distribution of the introduced species around Thumbi West Island should continue in order to detect their long-term effects on the native species.

The aim of the study was to investigate local community contributions to the existing Malawi College of Fisheries curriculum with a focus on Chambo fishery. Chambo fish (Oreochromis species) is the most favoured fish in Lake Malawi. Chambo catches have declined over the years. Responding to the declining catches, the Fisheries Department is engaged in a number of management options to address the issues. Most of these management options are governed by scientific recommendations and do not consider the socio-economic situation of the people who are dependent on fishery. This approach to fishery has influenced the Malawi College of Fisheries curriculum. The existing curriculum is product-centred, developed by a consultant. During the development of the curriculum, there was little consultation with the lecturers and no consultation with the local communities who are using the resource. The fishing communities have been fishing for a long time and have acquired knowledge, skills and experience worth investigating for its potential role in improving the existing curriculum. Through the use of interviews, focus group discussions and workshops with local communities local knowledge was identified for inclusion into the curriculum. A review of the existing curriculum revealed that it has primarily technical focus, grounded in the protection, control and management of the fish stocks, while the local knowledge has a practical focus based on existing practices and requiring an understanding of the sources of the issues. There is also more emphasis on a historical perspective and the context in which fishing practices take place at the moment. It was evident from the study that local communities have much of knowledge, skills and experience gained over the years of fishing , and if properly utilised, it can improve the MCF curriculum. I therefore recommend in this study that the curriculum be reviewed in order to integrate and draw on the local knowledge through a deliberative and participatory process between the local communities and the government so that it addresses the needs of the local communities and improves the training of the extension workers.

Philosophiae Doctor - PhD
Cichlids are one of the most diverse groups of fishes in the world. The highest concentration of cichlids is found in Lake Malawi, where over 1500 species are recorded to occur, which are dominated by the haplochromine tribe. Several authors proposed that sexual selection has been a major contributor in the high rate of speciation of haplochromine cichlids. However, sexual selection alone may not be sufficient to fully explain high speciation rates among cichlids. Many closely related cichlids in Lake Malawi differ only in coloration, yet occur in sympatry. It is still not fully understood how they remain reproductively isolated. Previous studies suggest that visual cues are primarily used for reproductive isolation and species recognition. In the current study, visual, chemical and acoustic cues were investigated to observe how they may potentially influence species recognition and reproductive isolation between two closely related species, Metriaclima estherae and M. callainos, as well as between alternate colour morphs of M. estherae.

The potential role of sanctuary areas for biological control of Schistosomiasis and development of sustainable fisheries was investigated at Cape Maclear, Lake Malawi National Park (LMNP). There has been a recent increase in the incidence of schistosomiasis infection which is a threat to the local community as well as the tourism industry which is the major source of income to LMNP as well as Chembe Village. At the same place there is increasing fishing pressure due to growing human population and declining fish resource. The increase in the incidence of schistosomiasis transmission was attributed in part to over-fishing of the molluscivorous fish which are believed to control the vector snails for schistosomiasis. Four molluscivorous fish species, Trematocranus placodon; Trematocranus microstoma; Mylochromis sphaerodon and Mylochromis anaphyrmus were reported to account for more than 90% of the fishes (by numerical abundance) which feed on the gastropods above 15 metre depth. The gastropod numbers was reported to be highest at 1.5 to 4.5 metre depth. Of the four molluscivores, T. placodon was proposed as a biological control agent for schistosomiasis based upon the previous observations of its feeding habits in artificial conditions. Captive propagation of T. placodon for reintroduction at Cape Maclear in Lake Malawi has been proposed. The present study aimed at providing baseline data required to test the hypotheses that: 1) Over-fishing of the molluscivorous fish has resulted to the increased incidence of schistosomiasis at Cape Maclear. A sub hypothesis to this was that an extension of the LMNP can act as a sanctuary area for the biological control of schistosomiasis by protecting molluscivorous fish which could control schistosomiasis vector snails. 2) A park initially designed to protect the colourful rock dwelling fish and for promotion of tourism may not effectively protect the food fish. To test the first hypothesis, the biology and ecology of T. placodon were investigated with a view to evaluating the effect this species could have on the schistosomiasis vector snail population and hence the control of bilharzia in the lake. The proportions of various gastropod species at Cape Maclear was compared with those found in T. placodon guts. Comparisons of T. placodon abundance and demographic structure inside and outside LMNP were made. To test the second hypothesis, this study investigated the food fish species that use LMNP 100 m protected zone and some basic ecological factors to appreciate the extent to which the adjacent fishery might benefit from their use of the park waters. T. placodon numerical abundance (number of individuals per unit area) ranged from 5.7 to 40.5 /200 m² and it significantly (P< 0.05) varied between sampling sites. Otter Point and Mitande which are inside the park had the lowest abundance as compared to the other three sites; Nguli inside the park; Fisheries and Nchenga outside the park. Two sites in the park, Otter Point and Mitande, had a greater proportion of mature T. placodon individuals than all other sites. The abundance of T. placodon fluctuated significantly from month to month at Nchenga, Nguli and Fisheries (X² test, P<0.0001 for all the three sites) and insignificantly (P>0.05) at Otter Point and Mitande (X² test). T. placodon densities found in the present study corresponded to the peak density of 30 individuals / 200 m² reported in 1986 but did not correspond to that of 1.0 / 200 m² for 1994. There was no evidence to support the previous reports that T. placodon abundance had decreased tremendously from 1986. The reason suggested to account for the discrepancies of T. placodon abundance reported in the present study and other studies was inadequate sampling in the previous studies which did not take into account spatial and temporal variability in T. placodon abundance. The findings reported in this thesis show that there is no need for captive propagation of T. placodon to be reintroduced into the lake at Cape Maclear and that it may prove to be unsuccessful. However, since juvenile T. placodon dominated in abundance at the three sites along the major beach which is outside the park boundaries, it is suggested that the park boundaries be extended to this area so that T. placodon should be protected to allow individuals to grow to bigger size which would be more effective for gastropod control. T. placodon between 60 mm and 80 mm TL fed on benthic insects, phytoplankton and from detritus material. Individuals between 80 mm and 100 mm fed on a mixture of benthic insects, fish scales and small gastropods and at sizes greater than 100 mm individuals specialized feeding on gastropods. Gastropods of five genera were taken and they were: Melanoides , Bulinus, Gabiella, Lanistes and Bellamya. Of these genera Melanoides fonned the greatest part of T. placodon diet. Bulinus was the second most abundant genus but compared to Melanoides its proportion was very small. Of the three Bulinus species taken by T. placodon, B. globosus, is a confirmed vector for Schistosoma haematobium which is prevalent at Cape Maclear. This species was eaten in the least quantities. A comparison ofthe five gastropod proportions in T. placodon diet and in the habitats they occupy showed that Melanoides were taken in proportionately more quantities than Bulinus at most sites. These findings contrasted the previous reports that T. placodon preferred Bulinus to Melanoides. By applying the optimal foraging theory which predicts that an animal species searching for food will go for the type of prey with the highest profitability, it is concluded that the Bulinus cannot be eliminated completely by molluscivores because if their population size falls below a certain level, the fish will switch to other gastropod types. It is concluded that the increase in schistosomiasis may not be necessarily due to overfishing the molluscivorous fish but could be due to the fact that there has been an increase in the proportion of the B. globosus albeit in small numbers which are infected with schistosomiasis parasites. An integrated approach to schistosomiasis control at Cape Maclear comprising vector control, improved water supply, sanitation and health education is suggested since no method can be effective in isolation. Few food fish species were observed to use the park at various times, varying from one species to another with regards to duration, life history stages and abundance. Only a few fish species taken by the adjacent artisanal and commercial fisheries were represented among those observed in the park. This was attributed to the limited diversity of habitat types covered. Only small population size of some species visited the protected area and only part of the life cycle of some species were observed in the park. The use of the park area was seasonal for some species and the protected zone boundaries can be crossed more than once within a day because 100 m distance is just a few minutes swim by fish. Under such circumstances the park cannot function as an effective sanctuary for food fish. An increase of the park size may be a better option to effectively protect the food fish.

This research investigates the livelihoods of artisanal fishing families at Lake Malawi. The key research question that it addresses is how artisanal fishers adapt their behaviour to cope with fluctuations in fish availability that occur naturally, i. e. that do not occur primarily as the outcome of human fishing behaviour. In Lake Malawi two such fish species, usipa and utaka, exhibit considerable spatial, seasonal, and interannual variability. These species are also by far the most important for the artisanal fishery. Fluctuating fisheries pose special challenges for livelihoods and fisheries management. For livelihoods they imply big seasonal variations in the ability of families to rely on fishing as a primary livelihood component, and they make fishing-based livelihoods insecure and risky. For fisheries management, they pose the problem that the true status of the resource is almost impossible to measure, with apparent risks in both directions: that overly restrictive management will result in an unexploited resource that could have made a greater contribution to the livelihoods of poor people and to the nutritional status of the population of Malawi more generally; or that overly lax management will result in a depletion of the resource beyond its sustainable yield. The research shows that fishers adapt to the fluctuating fish stocks in two main ways. One way is to specialise mainly in fishing but to emphasise mobility, so that short and medium term movements around the lake are made in pursuit of the resource. The other way is to maintain diverse livelihoods, combining fishing with farming and other non-farm income generating activities. There are, of course, also intermediate cases between these two opposing poles. The research demonstrates that migration for fishing purposes brings benefits both to migrants and resident communities. While for the migrants it is important to be allowed to settle for varying periods at different lakeshore beaches and villages; for residents the presence of the mobile fishers brings an increase of cash into circulation, the arrival of fish traders, the ability to open shops and bars to service this increased activity, and more buoyant markets for locally produced commodities. There are thus important income and employment benefits for resident communities that result from the behaviour of fishing migrants. At Lake Malawi, migrant fishermen tend to be from the Tonga ethnic group from the north of the country, and they generally differ in ethnicity from the resident communities where they take up temporary settlement. Fisheries policy in Malawi has been moving away from a top-down regulation by the Fisheries Department towards the idea of community management of fisheries. The argument is that if fishing communities are given their own powers to enforce regulations, within a participatory framework, then community self-interest will ensure that regulations are properly policed. This idea involves establishing territoriality over areas of the lake, so that "beach village committees" (BVCs) have regulatory powers over the lake areasa djacentt o villages. The researchd emonstratesth at there are many flaws in this concept in the case of Lake Malawi: BVCs are dominated by part-time fishing or non-fishing residents, migrants are excluded, territoriality is nonsensical for a mobile resource, and previously successful reciprocal relationships and other complex adaptive strategies are weakened and disrupted. The artisanal fishery in Malawi is opportunistic; it adapts to fluctuations either by ceasing to fish or by moving to other fishing grounds. It is argued that this sort of fishing requires minimal management, in which mobility and diversity are recognised and encouraged. If indeed there is a threat to the resource, it is rather the large scale commercial sector comprising a few trawlers of immense capacity relative to the yield potential of the Lake that pose that threat. There is an unequivocal need to monitor and regulate the catch volumes of this sector. For the artisanal fishery, however, a low key, flexible and resilient management approach is suggested; one that builds on the strengths of existing patterns of behaviour rather than seeking to change and undermine them.

This study investigates and expands learning associated with the co-management of fisheries resources to inform extension and training in the fisheries sector in two case study sites in Malawi. The study was located in the field of environmental education with a specific focus on community learning, agency and sustainability practices in co-management of fisheries resources. It focuses on how fisheries stakeholder learning can be mediated through expansive social learning processes to inform extension and training in the Malawi fisheries sector and aims at understanding learning as an emergent, agency centred process of change through social learning models that are said to have power to mobilise community agency for change. The empirical research for the study was conducted in two Malawian fishing communities: in Lake Malombe and the south-east arm of Lake Malawi using qualitative case study research design. The two sites were selected because they were the first sites in Malawi to implement fisheries co-management programmes following the failure of centralised management of fisheries resources. Data was generated through interviews, focus group discussions, document analysis, observations and change laboratory workshops in both sites. The two sites fall under one administrative office based in Mangochi where the two important institutions of the sector – the Fisheries Research Unit of the Department of Fisheries and the Fisheries College (a government institution responsible for the training of extension services) are also based. Both sites have implemented new governance structures named Beach Village Committees which are community-based organisational structures that function in parallel with traditional authorities to manage the fishery. Contextual and literature review work showed that extension services and programmes over the past hundred years, as observed in the fisheries sector in Malawi and in extension services elsewhere, have co-evolved with approaches to natural resources management. Early approaches to natural resources management involved traditional management (associated extension services and programmes were community based); later fisheries governance practices changed to centralised management and associated extension approaches were mainly top-down involving command and control or technology transfer. These early approaches have been problematic as resource users were pushed away from their own resources and were viewed as poachers. This resulted in loss of ownership among resources users. Recently in Malawi, after the change of government to democracy in 1994, fisheries management policy focused on co-management and/or adaptive co-management approaches, an approach that has also been adopted in other African water bodies. This has implications for extension service programmes in the fisheries sector that are not yet well defined. The study’s literature review revealed that co-management approaches assume collaborative learning, or co-learning, also termed social learning, or approaches that promote the engagement of different actors who are working on shared practice. They also assume a new form of agency among co-management stakeholders and extension workers. However, the theoretical foundations for establishing co-learning or social learning approaches in support of co-management policies are not well established in the fisheries co-management sector in Malawi, nor are the practices of how to support co-learning amongst diverse stakeholders in the fisheries co-management in the Lake Malawi context. This study sought to address this gap in knowledge and practice.

Aggression is ubiquitous in the animal kingdom and a major field of investigation within the area of behavioural ecology. The haplochromine cichlid fish have been used extensively in studies relating not only to the behavioural ecology of aggression but also with respect to how aggression may play a role in the spectacular diversity found within the African Great Lakes. In the first half of this thesis, I investigate the nature of aggression within the rock dwelling fish of Lake Malawi. Aggression biases within polymorphic populations are initially investigated with field work determining the consequences of rare morph advantage. This is followed by experiments determining which cues males and females may use; lastly a pair of recently diverged allopatric species is studied to determine what may happen should secondary contact occur. The second half of this thesis focuses on the behaviorual ecology of female aggression. Females exhibiting the ancestral condition of post brood care are compared to a species with the more derived condition of no post release care. Non-maternal aggression is investigated with comparisons of the type of behavior used by males and females. When and why females are aggressive is also investigated. The results of this thesis suggest that overall a common morph bias may exist in some populations and the consequences are manifested in a rare morph advantage. Colour is important in aggression biases but potentially not limited to the dorsal region. Females and males use different kinds of aggressive behaviors and brooding females are able to vary levels of aggression towards different types of threat.

Lernaea spp. was identified as a widespread problem in West Malaysia and various aspects of the parasite were studied. A survey of the distribution of Lernaea spp. in West Malaysia revealed its presence in all the 8 government owned fish breeding stations, 104 privately owned farms and 4 out of 5 consignments of imported fingerlings. The Lernaea spp. present in these ponds were identified as L. piscinae and L. cyprinacea "Asian" form (=b.elegans) and its morpha forms, L. ctenopharyngodonis and L.guadrinucifera. The life cycles of L. cyprinacea and L. piscinae were determined under laboratory conditions. Infection of ~. auratus with the offspring of L. cyprinacea "Asian" form produced adult females similar to the maternal form and another form identified as b. ctenopharyngodonis. A. nobilis, infected with L. cyprinacea "Asian" form and L. piscinae produced only species identical to the maternal form. A high degree of polymorphism was revealed and was further investigated. Morphometric studies on the larval stages and adult female parasites were investigated and reliable characteristics for the identification of Lernaea is discussed. The distribution frequency of b. cyprinacea on 3 host species and L. piscinae on A. nobilis in aquarium tanks was goodness of tested for/fit with the theoretical negative binomial distribution. The bases of fins were found to be the preferred site of infection for both species. studies on growth performance of A. nobilis infected with L. piscinae in ponds, revealed a significant reduction in Specific Growth Rates. Infected fish had a higher mortality than uninfected fish. A decrease in parasite infection on the body surface after 3 months was associated with its appearance in the eye. A challenge infection did not establish and the fish were suspected of being immune. Histopathological studies showed a typical inflammatory response with the formation of a granuloma. Eosinophilic granular cells, lymphocytes, and club cells which were identified in the hosts immune to the infection, were believed to play an important role in the rejection of parasites.

Fishing, and artisanal fishing in particular, plays a key role in the provision of rural employment and more importantly, household food security in the developing nations. The importance of artisanal fishery is shown in Malawi where artisanal fishery produces between 85-95% of the total fish production, and about 70% of the animal protein in human consumption comes from fish. About 43,000 people are employed directly in artisanal fisheries and approximately 100,000150,000 are indirectly employed within the artisanal fishery. Owing to increasing human population in the developing countries coupled with the common property, open-access nature of the fish resource, the resource has not been able to cope with the ever-increasing socio-economic demand placed on it. The resource is so degraded that it is has started to decline beyond capacity to sustain itself. This study was an attempt to examine and understand the artisanal fishery as it contributes to the socio-economic well being of the rural population particularly, the enclave communities of Lake Malawi National Park. The present study used structured interviews, focus group interviews, key informant interviews and personal observation to collect socio-economic information of the fishery. These research tools revealed that among the enclave communities income levels are low and unsustainable due to declining productivity of fishing. The decline may be a result of increasing human population, weak community-based institutions, limited agriculture, poor infrastructure with regard to processing and marketing of fish, limited supplementary and alternatives economic activities, and the fishing methods. Documentary information was used to contextualize artisanal fishery, to examine and understand the common-property and open-access nature of the fish resource as it relates to the exploitation Of fish among the enclave communities. Integrated development that brings together conservation and socio-economic development is the only option that will increase the income of the enclave communities to sustainable levels and achieve the Park's conservation objectives. The socio-economic intervention options should include provision of basic social facilities such as education, health, safe water etc, increase the economic power of the enclave communities through irrigation, adding more value to the fishery, engaging in aquarium trade, community-based eco-tourism and beekeeping. These options would lead to socio-economic sustainability among the enclave communities and would bring about the conservation objectives of the Park.
Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998.