236 leaves : ill., photos, tables, graphs ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Zoology, 1978

Thesis (Ph.D.) -- University of Adelaide, Department of Zoology, 1978.

The available literature on abalone nutrition was synthesised and the prospects for developing a complete pelleted dry feed for Haliotis midae evaluated. The similar body compositions, digestive structures, enzyme activity, acceptance of a wide variety of feed ingredients and comparable growth performance on formulated diets of various abalone species suggests that they have similar nutritional requirements. Abalone also appear to be similar to other farmed monogastric animals in that digestion is primarily extracelluar and they possess a large, muscular crop and stomach. Abalone energy metabolism is carbohydrate based. They are capable of digesting high levels of dietary protein but their ability to utilise fat is limited. Abalone have been shown to consume predictable amounts of dry feed which is efficiently converted into body weight. Efficiency indices of utilisation of formulated feeds, such as feed conversion ratio, protein efficiency ratio, net protein utilisation and apparent digestibility have been successfully applied to abalone. It was concluded that the prospects for developing complete diets for H. midae using a conventional animal feed science model were good. The ability of H. midae to utilise a range of proteins which had potential for inclusion in practical diets was investigated. Five protein rich ingredients, namely, casein, fishmeal, soya oil cake, Spirulina, and torula yeast, were fed to H. midae in semi-purified diets. Two algal diets, fresh Plocamium corallorhiza and dried Ecklonia maxima were fed as controls. Abalone fed on fishmeal and Spirulina based diets displayed significantly higher growth rates than diets containing soya oil cake, torula yeast, casein and E. maxima. Growth rates of abalone fed with P. corallorhiza were significantly lower than all other diets. All artificial diets yield lower feed conversion ratios (0.7-1.8) and higher protein efficiency ratios (3.3-6.5) ratios than the seaweed control diets (FCR = 2.8-3.4; PER = 2.2-3.0). The results indicated that fishmeal and Spirulina were the most suitable proteins for inclusion in practical diets for H. midae. The effect of protein level on growth rate and nutritional indices was evaluated by feeding starch bound, fishmeal based diets containing 27, 32, 37, 42 and 47% protein to juvenile H. midae. Weight gain was positively related to the level of dietary protein, increasing by 18% between 27% and 47% protein. Protein efficiency ratio declining from 3.2 to 2.3 with an increasing dietary protein content. Feed consumption rate was approximately 1% of body weight per day for all diets. Post-weaning abalone (ca. lOmm shell length, 0.2g) differed from larger juveniles (ca. 35mm, 8g) in their response to varying proportions of dietary protein and energy. The smaller animals appeared to have a lower protein requirement and poorer ability to utilise lipid than the larger juveniles. Proximate analyses revealed that the levels of protein, lipid and carbohydrate in abalone soft tissue increased with increasing dietary levels of these nutrients. Larger juveniles contained significantly higher levels of protein and carbohydrate, but lower levels of lipid, ash and moisture, than the smaller post-weaning abalone. The assimilation efficiency of [U-¹⁴C]-arginine by H. midae fed diets enriched with [U-¹⁴C]-arginine was only 0.45%. Furthennore, supplementation of diets with graded levels of crystalline arginine did not have any effect on growth rates. It was concluded that the prospects for defining the quantitative amino acid requirements of H. midae using crystalline amino acids are not promising. Rates of gastric evacuation and enzyme secretion were monitored in juvenile H. midae fed an extruded, fishmeal based dry feed. Gut fullness peaked 6h after feed was offered and the bulk of feed consumed was digested within 24 h. Enzyme secretion appeared to begin with the onset of feeding and continued for at least 6h after peak gut fullness was attained. Protease activity increased significantly following ingestion but amylase activity was maintained at a more or less constant level. A low level of lipase activity was observed suggesting that the ability of H. midae to digest fat is limited. The growth rate of H. midae fed an extruded, fishmeal based feed increased with increasing temperature between 12°C and 20°C. Between 20°C and 24°C a marked decline in growth rate accompanied by a deterioration in feed conversion and increased mortality was observed. Consumption of a dry pelleted feed was shown to be a function of body size and temperature. Based on these data a model which predicts a daily ration for H. midae was developed. The present study showed that H. midae efficiently utilises extruded dry feeds containing conventional feed ingredients. Although technical difficulties were encountered in measuring apparent digestibility, it was concluded that the prospects for developing practical diets according to established nutritional principles are promising.

Magister Scientiae - MSc (Biodiversity and Conservation Biology / Beach-cast kelp (the most widely used feed for commercially grown South African abalone) is plentiful during winter months when periodic storms cause kelp to wash ashore. During summer, however, this resource is not always readily available and farmed abalone are often starved for short periods. The aim of this research was to assess how periodic kelp starvation influences growth of the commercially grown abalone, Haliotis midae Linnaeus. / South Africa

The principle aim of this study was to isolate a chemical for the "safe anaesthesia" of abalone under commercial farming conditions. "Safe anaesthesia" implied that the anaesthetic had no immediate detrimental or long term sublethal effect on the abalone, that it was safe for the farmer, the consumer and the environment. Four chemicals, magnesium sulphate (MgS0₄), ethylenediamine tetra-acetic acid (EDTA), 2-phenoxyethanol and procaine hydrochloride were shown to effectively inhibit the in vitro contraction of isolated tarsal muscle of Haliotis midae. This identified them as potential anaesthetics for abalone. Since abalone, like any other aquaculture species, would be subject to frequent size-sorting during the grow-out period, size related dosage tables were developed for the four chemicals at a temperature of 18⁰C. Dosage tables were also developed for benzocaine and carbon dioxide (C0₂), Three size classes (5-15, 20-50 and 60-90 mm shell length (SL)) of abalone were considered. Only three of the six chemicals, viz. MgS0₄, 2-phenoxyethanol and CO₂, met the criteria of an effective abalone anaesthetic in that they effected rapid and mortality-free anaesthesia. The other three chemicals caused mortalities and were considered to be unsuitable for commercial scale anaesthesia. Temperature related dosage tables were then developed for MgS0₄ and CO₂, MgS0₄ concentrations and CO₂ flow rates for effective anaesthesia in abalone were found to be inversely related to temperature. The three size classes of H. midae were intermittently exposed to MgS0₄ and 2-phenoxyethanol anaesthesia for an eight month period to determine the effect of the anaesthetics on growth rate. Because of an increased resistance to the efficacy of 2-phenoxyethanol and high monthly mortalities it was concluded that this chemical was unsafe and unsuitable for commercial use. MgS0₄, on the other hand, had no effect on growth of abalone and no significant effect on the rate of mortality. MgS0₄ also had no measurable effect on H. midae muscle ultrastructure and, by implication had no effect on flesh texture. The use of MgS0₄ as an anaesthetic would, therefore, not affect marketability. Moreover, no magnesium residues were found in H. midae muscle tissue after short term or intermittent long term exposure to MgS0₄ anaesthesia. It was found that the three size classes of H. midae used in this study could be safely exposed to the recommended MgS0₄ concentrations for up to 40 minutes without any mortalities. This is more than adequate for routine farming procedures. Medium size abalone (20-50 mm SL) were also safely exposed to 14 g.100 ml⁻¹ MgS0₄ for up to 6 hours without any mortalities. The results have shown that MgS0₄ was undoubtedly the best chemical that was evaluated for anaesthesia of H. midae in this study. It fulfils the requirements set forth by the U.S.A. Food and Drug Administration (FDA) in that it is safe for the abalone, the farmer, the consumer and the environment.

A physiological study was carried out to determine the effects of temperature, quantity of food fed, feeding activity and size class on the oxygen consumption and ammonia production of the South African abalone Haliotis midae L.. A set of intermittent flow respirometer chambers were used in a recirculating system to measure the oxygen consumption rates of fed (postprandial) and unfed (postabsorptive) abalone for three different size classes (15, 30, and 50mm) at three different temperatures (16°, 20° and 23°C) over a 24 hour period. Ammonia production rates and food consumption rates were simultaneously determined. Oxygen consumption and Ammonia production rates per gram abalone were linear functions of abalone size, temperature, and mass of food consumed. Oxygen consumption and ammonia production rates were found to increase proportionally to temperature and in inverse proportion to abalone size. These rates were significantly higher for fed as opposed to unfed abalone. Equations were derived to predict oxygen consumption and ammonia production for fed and unfed animals for a range of temperatures and size classes of abalone. A 96h LC50 lethal toxicity test for exposure to ammonia established 1.08mg.1⁻¹ of unionised ammonia as the lethal limit. A test on the long term effects on growth of acute exposure (12h) to various sublethal concentrations of ammonia showed no significant effects on growth for concentrations below 0.88 mg.1⁻¹. A safe chronic exposure level of 0.02 mg.1¹ NH₃-N was used to predict optimal flow rates required per kilogram of abalone in a rearing tank over a range of size classes and temperatures. The physiological and biological requirements of H. midae and the implications of this knowledge for rearing tank management and optimal design are discussed.

In the late 1980's abalone culturalists noticed reduced growth rate and shell deformities in some abalone stocks. These problems were the result of infestations by a shell boring polychaete, Terebrasabella heterouncinata. Under intensive abalone culture conditions the level of infestation can reach epidemic proportions and there are often severe consequences for the host abalone. Heavy sabellid infestation levels have placed the economic viability of several South African farms under threat. This study formed part of an ongoing project that is aimed at investigating the basic biology of Terebrasabella heterouncinata. The majority of abalone farmers in South Africa feed their abalone either naturally occurring kelp (Ecklonia maxima) or the formulated abalone feed, Abfeed. Farmers have suggested that the use of Abfeed is associated with higher sabellid infestation levels and changing the abalone diet from Abfeed to kelp helps reduce sabellid infestation. Speculation has arisen indicating that older, slower growing abalone are more susceptible to sabellid infestation. The effect of host abalone diet history and their growth on sabellid settlement success, morphometries and reproduction was quantified. To better understand the plasticity of the expression of life history traits the variability of morphometric and reproductive characteristics was compared between different farm environments. And more...

The abalone Haliotis laevigata Donovan is commercially exploited in southern Australia; Haliotis scalaris Leach is a smaller, noncommercial species. This thesis describes the early life history of both species and other aspects of the fishery biology of H. Iaevigata required for fishery management. Both abalone species recruit onto a crustose coralline substratum variously from spring to winter. After settlement the growth rate of both species Is linear for a number of years (1 .7mm/month for H. Iaevigata and 1.1mm/month for H. scalaris) . Crustose coralline algae are the main food during the first year of life but thereafter the diet switches largely to drift algae and seagrass. Survival of newly-settled cohorts differed between years and between species. Overall, it appeared to be density Independent at low densities but density-dependent at high densities, Recruitment strength (measured at 2-1/2 - 3 years of age) and natural mortality of adults in a closed population was measured over 17 years at West I. There were sequences of strong and weak recruitments, but no relationship with presumed spawning stock size was apparent. Adult natural mortality rates ranged from 0.02 to 0.86 and were strongly density dependent. Stingrays were a major, and octopuses a minor, cause of mortality. The fecundity of H. Iaevigata was investigated at a number of sites and was adequately described by linear regressions of fecundity on total weight. Fecundity ratios and growth rate differed between sites and fecundity appears subject to phenotyplc and genotypic variation. The short and long term movement of H. laevigata was also examined, !n short term studies sexually mature Individuals aggregate during the spawning season but disperse randomly at other times of the year. In the longer term the amount of movement depends on availability of crevice space and size. Movement is also directional and, at one site, was toward that of the approaching swell. A method is described for estimating density of abalone by using a free-range search technique and adjusting for individual variation in power and efficiency of different divers and in differing degrees of habitat heterogeneity. The method is useful for estimating recruitment strength and density of abalone in surveys of abalone stocks.

Thesis (M. Sc. (Ichthyology))--Rhodes University, 2003.

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The South African abalone, Haliotis midae, commonly known as perlemoen, is an economically important gastropod mollusc. Historically, this species maintained a lucrative fisheries sector; however with increasingly lower landings there has now been a shift to aquaculture. Efforts to conserve natural populations and to improve abalone aquaculture production are thus running in parallel. Previous studies reported significant disparities in parental contributions in aquaculture populations that could explain the rapid divergence of commercial stocks from wild populations. Furthermore, subtle, but significant, population differentiation has also been reported for wild populations on the west-, south-, and east coast of the South African coastline. This study therefore aimed to investigate the evolutionary forces, in particularly selection, facilitating population divergence in wild and cultured H. midae populations using a population genomics approach. By using both microsatellite- and single nucleotide polymorphism (SNP) markers it was found that approximately 10% to 27% of the H. midae genome may be influenced by selection. When incorporating these loci into analyses of population differentiation (e.g. AMOVA, factorial correspondence analysis and estimates of genetic distance) there was a marked increase in genetic divergence between wild and cultured populations (especially when using microsatellite loci) and amongst populations from different geographic regions (particularly supported by the SNP loci). The differences in population clustering as highlighted by microsatellite- and SNP markers can most likely be attributed to the genomic distribution of the respective loci: The SNP markers were developed from EST sequences and therefore mostly represents protein structural variation; whereas the microsatellite markers, found to be putatively under selection, were mainly located in regulatory motifs. The results of this study therefore confirmed previous observations of divergence amongst wild- and cultured populations, but more importantly demonstrated that selection is an important factor driving this divergence. In wild populations selection probably facilitates adaptation to local environmental conditions, whilst amongst aquaculture population adaptation to captivity, husbandry practices and artificial selection may be important determinants. There is evidence for population bottlenecks in wild- and cultured populations; nonetheless long-term effective population sizes seem to be large. Amongst the wild populations, however, short-term population sizes appear to be small most likely due to differential spawning rates amongst reproductively active animals leading to temporal fluctuation in genetic diversity. The results indicate that contact between wild and cultured abalone should be minimised to prevent any adverse effects due to outbreeding depression. With regards to conservation, an emphasis on maintaining adaptive diversity of the wild stocks might be warranted. Continued genetic monitoring is advisable for both wild and cultured abalone populations as to optimally manage the abalone resource for both conservation and commercial viability and sustainability. / AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse perlemoen, Haliotis midae, is 'n ekonomies belangrike buikpotige weekdier. Histories het hierdie spesie 'n winsgewende vissery gehandhaaf, maar met steeds dalende vangste is daar nou 'n verskuiwing na akwakultuur. Pogings om natuurlike populasies te bewaar en perlemoen te verbeter vir verhoogde akwakultuur produksie loop dus in parallel. Vorige studies het bevind dat beduidende verskille in ouerlike bydraes tot die nageslag, in akwakultuur populasies, kan verduidelik hoekom die populasies so vinnig divergeer van die wilde voorouers. Verder, is subtiele, maar betekenisvolle genetiese differensiasie tussen wilde populasies aan die wes-, suid-en ooskus van die land gevind. Hierdie studie is dus daarop gemik om ondersoek in te stel na die mate waartoe verskeie evolusionêre prosesse, in besonder seleksie, die populasie divergensie in beide wilde en gekweekte H. midae teweegbring deur gebruik te maak van ‘n populasie genomika benadering. Deur gebruik te maak van beide mikrosatelliet- en enkel nukleotied polimorfisme (ENP) merkers is dit bevind dat ongeveer 10% tot 27% van die H. midae genoom moontlik beïnvloed word deur seleksie. Met die gebruik van loki onder seleksie tydens die ontleding van populasie differensiasie (bv. AMOVA, faktoriaal korrespondensie analise en genetiese afstand ramings) was daar 'n merkbare toename in genetiese divergensie tussen wilde- en gekweekte populasies (veral wanneer mikrosatelliet loki gebruik is) en onder die populasies vanuit verskillende geografiese gebiede (veral ondersteun deur die ENP loki). Die verskille in die populasie groeperings soos uitgelig deur die mikrosatelliet- en ENP-merkers kan waarskynlik toegeskryf word aan die genomiese verspreiding van die onderskeie loki: Die ENP-merkers is ontwikkel vanaf uitgedrukte volgorde merker (UVM) volgordes en daarom verteenwoordig dit meestal proteïen strukturele veranderinge, terwyl mikrosatelliet merkers eerder in regulatoriese motiewe geleë is. Die resultate van hierdie studie steun dus vorige waarnemings, maar meer belangrik, het dit getoon dat seleksie ‘n betekenisvolle faktor in populasie divergensie in beide wilde en gekweekte populasies is. In wilde populasies fasiliteer seleksie waarskynlik die aanpassing tot plaaslike omgewingstoestande terwyl seleksie onder die gekweekte populasies teweeggebring kan word as gevolg van aanpassing tot aanhouding, boerdery praktyke en kunsmatige seleksie. Daar is bewyse vir populasie bottelnekke in wilde- en gekweekte populasies; tog blyk langtermyn effektiewe populasiegroottes om redelik groot te wees. Onder die wilde populasies is egter gevind dat kort-termyn populasiegroottes klein kan wees, waarskynlik as gevolg van differensiële broeikoerse onder reproduktiewe diere. Dit het tot gevolg dat daar beduidende fluktuasies is in temporale genetiese diversiteit. Die resultate dui daarop dat kontak tussen wilde en gekweekte perlemoen tot 'n minimum beperk moet word om enige nadelige effekte weens uitteling depressie te voorkom. Verder, met betrekking tot bewaring, is ‘n klem op die handhawing van aangepaste genetiese diversitiet dalk geregverdig. Voortgesette genetiese monitering word aanbeveel vir beide wilde- en gekweekte perlemoen populasies ter wille van die optimale bestuur van die perlemoen hulpbron vir beide bewaring en kommersiële lewensvatbaarheid en volhoubaarheid. / International Foundation for Science / National Research Foundation of South Africa / Stellenbosch University