Data extracted from historic records have been used together with information collected during a survey of major fishing centres in the west and southwest Cape, from Port Nolloth to Struis Bay, to document the development of the handline fishery, with special reference to the fishery for hottentot Pachymetopon blochii (Val.). The fishing communities are described and social conditions are compared with those reported in earlier surveys. Changes in the fishing vessels and tackle used in the handline fishery are described and the economic status of the fishery evaluated. The distribution and availability of P. blochii are assessed in relation to the various tackle types and catch methods in different areas and the contribution by this species to the total annual linefish catch is estimated. Total fishing effort expended in the commercial linefishery is used to calculate catch-per-unit-effort indices for the hottentot fishery and the seasonal and long-term trends in these indices are evaluated in relation to past and present constraints on the marketing of this species.

Monthly zooplankton samples were collected as part of the Cape Egg and Larva Survey from August 1977 - 1978. A line of stations from the coast to approximately 90 Kilometres offshore at Lambert's Bay was selected for intensive study because of its location in the middle of the recruitment area of South African anchovy and pilchard. Examination of physical features showed perennial moderate upwelling, with slight seasonal variation in frequency and intensity. Chlorophyll "a" levels were generally high. Zooplankton standing stock was surprisingly low considering the abundant phytoplankton, and this was attributed to intense predation resulting in high production/biomass ratios. Among the zooplankton, copepods were singled out for special attention because of their importance as food for larval fish. Only six species comprised 83% of the copepod community. These species displayed different spatial and temporal distribution, which appeared to be partly the result of size-determined life histories with indications of time/space niche partitioning. In comparison to the more intense seasonal upwelling area off the Cape Peninsula, there was a trend toward fewer species, larger animals, and more carnivores. This trend was related to changes in the physical and biotic environment.

Includes abstract. / Includes bibliographical references. / Wild dog Lacaon pictus are obligate cooperative breeders with nulliparous helpers contributing to the rearing of a dominant pair's young through pup-provisioning and defence agianst predators. Despite the importance of allo-parental care to the survival of pups and the persistance of packs, few studies have addressed the group or individual level factors that influence helping in wild dogs. In this study we use data collected as part of a long-term project in the Kruger National Park (KNP) to provide the first detailed analysis on the relative contribution to pup rearing of dogs both within and between packs in the KNP.

Bibliography: leaves 77-96. / Larval and juvenile Cape anchovy (Engraulis encrasicolus) of the particularly strong 1999/2000 year-class were collected during two consecutive surveys in March and May 2000 in the southern Bengueia region off South Africa. Otoliths from sub-samples were examined to calculate hatchdate distributions and growth rates to estimate the main apparent spawning peaks of the 2000 year-class from both surveys, and to look for possible correlations between spawning, survival and growth of anchovy on die one hand. and the prevailing environmental conditions on the other. Sub-samples were chosen proportional to the length-frequency distributions at each stratum or station at each survey. Otoliths of 193 specimens (14-70 mm standard length, SL) from the March survey and 80 specimens (52-114 mm SL) from the May survey were successfully prepared for light microscopy and electron microscopy respectively. Daily increments were counted and otolith radii were measured. The age-structure of the anchovy population at the time of each survey was calculated from length-frequency distributions using age-length-keys. Mortality rates, hatch date distributions and growth rates were estimated. Instantaneous mortality rates calculated from the catch curves were 0.0353 day-1 for larvae caught in March 2000 and 0.0202 day-1 for juveniles caught in May 2000. These compared with previous laboratory studies and mathematical models in the literature and were, thus, used to back-calculate hatchdate distributions. Resulting hatchdate distributions of larvae and pre-recruits caught in March 2000 showed two apparent hatching peaks, late September - late October 1999 and late December - early January 2000. Thus. either 1) spawning peaked in those two periods or 2) continuous spawning took place between August 1999 and March 2000, but survival of eggs and young larvae peaked in September/October and January/February. The hatchdate distribution of juveniles caught in May 2000, showed peaks in early September - October and late November - December. Therefore, apparent hatching peaks were dissimilar between the two samples of the same year-class, taken three months apart. Thus, higher age-selective mortality of larvae younger than 75 days old in March 2000 (hatched after 17 December 1999) is likely to have taken place in 2000. Large areas of > 19 °C sea surface temperatures (SST) throughout the period from August to March indicated that spawning is likely to have been continuous. Conditions, especially in December-January, when upwelling was reduced because of a cessation in south-easterly winds, may have been conducive to survival of eggs and yolk-sac larvae, due to reduced offshore losses. The period of weak upwelling was subsequently followed by a period of strong upwelling from March to May 2000. This is likely to have increased availability of planktonic food for post-larvae and juveniles. On the other hand, upwelling may have caused offshore dispersal of food patches needed by younger larvae, which could lead to age-selective mortality caused by starvation. The critical period (Hjort 1914) thus seemed to be at a later stage than the first-feeding stage. Mean larval growth rates were estimated between 0.33 and 0.36 mm SL.day-1 using three different growth functions (linear r2 = 0.90, Laird-Gompertz r2= 0.90, and von Bertalanffy r2 = 0.89 growth functions). Juvenile growth rates were estimated at 0.22-0.24 mm SL.day-1l (r2= 0.45, 0.48. 0.47 for the three functions respectively). These rates were slower than previously reported rates, possibly due to the high density of larvae present and hence less per capita food availability. However, reduced food availability did not affect survival in 2000 and, therefore, does not support the Growth-mortality hypothesis (Ware 1925).

Includes bibliographical references / Marine capture fisheries around the world are widely perceived to be in a state of crisis, with growing recognition that conventional resource-centred management strategies are insufficient to counter ongoing problems of overexploitation. This is considered particularly true in the small‐scale sector, which employs the overwhelming majority of the world’s fishers but has historically been overlooked. To manage marine resources more sustainably, new approaches to fisheries governance have been sought that recognise the complex nature of fisheries systems, paying attention to the social dimensions of fisheries management in addition to important ecological processes. In South Africa, many of these new approaches have been embraced in a recently adopted policy for the small-scale sector. Attempts to reform marine fisheries have been ongoing in the country since the end of apartheid (a system of legalised racial segregation and white supremacy that ruled for almost 50 years) but have largely failed to bring meaningful change to impoverished fishing communities. Frustration at ineffective reform has contributed to widespread non-compliance – most notably in the abalone fishery, which has collapsed in the face of rampant poaching, driven by a lucrative, illegal export market to the Far East. Although the new small-scale fisheries (SSF) policy has been hailed as a progressive shift in thinking, questions remain about how it is to be implemented. One major challenge will be dealing with illegal fishing. The purpose of this study, was to profile the human dimensions of abalone poaching in the Cape Town fishing community of Hangberg and to draw lessons for implementing the new SSF policy. A qualitative multi-method research approach, based mainly on unstructured interviews and participant observation, was used to access the clandestine fishery and investigate its historical development, current structure, scale and methods of operation and main socio-economic drivers and impacts. It was found that abalone poaching has become deeply embedded in Hangberg, having evolved into a highly organized boat-based fishery in a period of less than 15 years. At least five local poaching groups – representing some 250 individuals in total – currently used dedicated high-powered vessels to access reefs around the Cape Peninsula. Profits earned from poaching are substantial but vary, with poachers operating according to a loose hierarchy and performing a range of different tasks in the fishery. This variation notwithstanding, the illegal fishery appears to have become a mainstay of the impoverished local economy, funding poachers’ expensive lifestyles, in addition to contributing more meaningfully to the livelihoods of an estimated 1000 residents.

Includes bibliographical references. / The energy balance components of a laboratory population of juvenile Ostrea edulis, fed on Tetraselmis seucica at 15°C and 35%, were investigated. The results show that filtration rate is a power function of body size and is dependent on food concentration. The relationship between food concentration and filtration rate closely approximated a theoretical model proposed for copepods, which was therefore adapted to suit bivalves. Filtration rate showed no selection of particles on the basis of size. However, oysters are probably able to recognise algae on a chemosensory basis and reject undesirable particles. Routine metabolism was found to be proportional to the 1,09 power of body mass. This agrees with expected values of the mass exponent predicted in the literature for animals of this size. No evidence of energy loss as dissolved organic carbon was recorded.

Includes bibliographical references. / Ardeola ibis (.L.) is a small white heron, generally considered to be one of the most terrestrial members of its semi-aquatic family. It is a highly successful species, both in terms of numbers and of geographic range. Apart from man and his commensals, it is probably the commonest of the six terrestrial vertebrates with cosmopolitan breeding ranges, the other five all being bird species too (Voous 1960). A. ibis is gregarious, roosting and nesting in very large numbers, so one aim of this study is to investigate advantages of and adaptations to a social way of life, and to see whether the species' success is in any way a result of its gregariousness. Several taxonomic reviews, notably those of Lorenz (1941) and Johnsgard (1961) on Anatidae, have been based on behavioural characters, because many behaviour patterns are as conservative and species-constant as structural features are. For this reason, and because adequate behavioural studies have to date been carried out on only about 7 of the 64 Ardeid species, the work was extended to include two other species, Egretta garzetta and E. intermedia. The present study is also designed to provide material for a projected review of the Ardeidae (Curry-Lindahl pers. comm.).

Population patterns of the alien mussel Mytilus galloprovincialis were investigated at two locations on the west coast of South Africa: Camps Bay and Groenrivier. Specifically, wave exposure and zonation were examined for their effect on mussel cover and total density, mussel size and recruit intensity. Two areas were compared at Camps Bay; the first was a prominent rock experiencing heavy wave action, and the second was a sheltered bay. Three areas were selected at Groenrivier, the third experiencing an intermediate gradient of wave action. A number of interesting patterns emerged, although not all were statistically significant. At both Camps Bay and Groenrivier mussel cover increased with increasing wave exposure and decreased with increasing tidal height. The exception to this zonational trend was exhibited in the very sheltered bay at Groenrivier, where mussel cover increased upshore, from 2% to 6%. Total mussel density and recruit intensity declined with a reduction in wave action at both locations. An unexpected zonational pattern occurred at both Camps Bay and Groenrivier - total densities tended to be greater upshore, a pattern which closely followed recruit densities. The maximum size achieved by mussels is greatest at more exposed areas, but the difference between sheltered and exposed regions at Camps Bay was not notable. Maximum shell size tended to decrease with increasing tidal height in all areas but the sheltered bay at Groenrivier, where little variation in maximum size occurred. Multivariate comparisons of population demography between all of the sites revealed that the sheltered site at Camps Bay was most similar to the semi-exposed site at Groenrivier, which points to similar environmental conditions in these areas. This pattern was repeated for total densities, a result which supports the previous suggestion. The sheltered bay at Groenrivier was most dissimilar in both demographic structure and density to all other sites. Bibliography: leave 89-99.

Bibliography: pages 110-125. / 1. A flow-through aquarium facility, for testing the toxicity of the water-soluble fraction (WSF) of crude oil is described. 2. The 24 hour median lethal concentration (LC50) of WSF of crude oil for 2 to 3 year old (30 - 45 mm cephalothorax length) juvenile Jasus lalandii ranged from 3,7 to 5,9 mg l⁻¹. 3. Behavioural experiments appear to provide a quick and convenient approach for estimating the relative toxicity of the WSF of crude oil. 4. The major effect of the WSF of crude oil on Jasus heart beat rate was bradycardia. Furthermore, the greater the initial exposure concentration the sooner the heart beat frequency decreased. 5. Exposure of Jasus muscle fibres to the WSF of crude oil resulted in a shift of the resting membrane potential of those fibres in a hyperpolarising direction. Preliminary investigations into the level of excitability of decapod neurons after exposure to the WSF, indicated a rapid increase, followed by a decrease in excitability, to a level below that of unexposed tissue. 6. Recommendations are made as to how the findings of this study could be applied to enhance the sensitivity of toxicity bioassays.

Includes bibliographical references (pages 68-73). / In this paper, the morphological differences among the three common species of Ephestia have been confirmed by the present author, so that they may be easily identified. The life history of E. cautella has also been worked out, as well as some aspects of the life history of E. elutelle. and E. kuhniella. These three species have been found to differ at certain points of their life histories. Finally, the results of other authors have been compared with the findings of the present author.