Thesis (M. Phil.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 82-89).

Carpenter, Argyrozona argyrozona (Valenciennes, 1830), is an endemic South African sparid fish. They form an important component of the commercial linefishery on the South African east coast, where they are the third most important species landed. Recent investigations revealed that the catch per unit effort (cpue) of this species has declined markedly since the early 1900’s. Despite these declines and the importance of this resource, remarkably little biological information on this species exists for providing management advice. This thesis investigates the life history of carpenter, particularly those aspects that are used for management. This includes an investigation into the stock distribution and identification of nursery areas, and an assessment of age, growth, reproduction and movement patterns. Age and growth was assessed using methods based on both otoliths and mark-recapture. Transverse sagittal sections from the Tsitsikamma National Park showed clear opaque and translucent growth increments. Marginal growth zone analysis and mark-recapture of chemically tagged fish (Oxytetracycline) revealed that these were deposited on an annual basis: opaque in summer and translucent in winter. A. argyrozona were found to be long lived (up to 27 years) and slow growing. Within reader (between counts) and between readers average percent error (APE) was 5.3 and 1.8, respectively, showing that readability of carpenter otoliths is high. Comparison between whole and sectioned otoliths showed that the former significantly under-estimated the age of fish older than 10 years (p<0.01). A large proportion (68%) of the individual growth rates derived from mark-recapture data were below those predicted by the otolith based von Bertalanffy growth model (p<0.01). This was attributed to the negative influence of external tags, as hydroids, frequently occurring on the tags of recaptured fish, were observed to cause severe lesions and in some cases, extensive fin damage. This brings into question the use of mark-recapture studies to calculate growth of some species. The effects of sampling design and sample size on age and growth estimation were assessed. The minimum sample size required to accurately estimate growth and mortality, and the effects of using either random or stratified sampling procedures were tested. Decimal and integer ageing both produced similar estimates of von Bertalanffy growth parameters, growth curves, spawner biomass-per-recruit (SB/R) and fishing mortality (F) estimates. Sampling monthly throughout the year and collecting data in a single large sample provided similar growth curves, von Bertalanffy, F and SB/R estimates. The data showed that estimates based on less than 300 random samples were unreliable. However, accurate growth parameter estimates were achievable with less than 200 samples if the sample was stratified with 10 or more samples per 2 cm size class. An investigation into the reproductive biology of A. argyrozona within the Tsitsikamma National Park revealed that they were serial spawning late gonochorists. The size at 50% maturity (L₅₀) was estimated at 292 and 297 mm FL for females and males, respectively. Both monthly gonadosomatic indices and macroscopically determined ovarian stages strongly suggest that A. argyrozona within the Tsitsikamma National Park spawn in the austral summer between November and April. The presence of post-ovulatory follicles (POF's) confirmed the six month spawning season, while monthly proportions of early (0-6 hour old) POF's showed that spawning frequency was highest (once every 1-2 days) from December to March. Although spawning season was more highly correlated to photoperiod (r = 0.859) than temperature (r = -0.161), the daily proportion of spawning fish was strongly correlated (r = 0.93) to ambient temperature over the range 9-22⁰C. Both spawning frequency and season increased with fish length. As a result of the allometric relationship between annual fecundity and fish mass a 3 kg fish was calculated to produce 5 fold more eggs per kilogram of body weight than a fish of 1 kg. In addition to producing more eggs per unit weight each year, larger fish also produce significantly larger eggs. Adult emigration and larval dispersal of A. argyrozona from the Tsitsikamma National Park (TNP), South Africa, were investigated using mark-recapture data and Acoustic Doppler Current Profiler measurements of currents. Tagging data showed that adult carpenter were mainly resident, with a small proportion (7%) leaving the TNP in both easterly and westerly directions. No relationship was found between fish movement patterns and fish size or time-at-liberty. Current patterns suggest that eggs and larvae spawned within the TNP are mainly transported eastwards towards established nursery grounds; the median estimated distance moved was 299 km (range 42-561 km) in 30 days (time to flexion). Given this pattern of ichthyoplankton dispersal together with the fact that adult carpenter within the TNP display a high degree of residency and that they are much more abundant than in adjacent fishing grounds (cpue = 23 times greater), it appears that the TNP protects a viable carpenter spawner population capable of seeding adjacent fishing grounds. Fishery independent biomass surveys and commercial linefish catch returns were used to elucidate the spatial patterns of A. argyrozona distributed along the South African continental shelf. Two distinct areas of abundance were determined, one on the central and the other on the eastern Agulhas Bank. Tagging studies revealed little exchange between them. Two distinct nursery areas were identified. These data suggest that in each area juvenile A. argyrozona settle and move inshore, and then move offshore as they grow. Otolith readability and growth rates varied between regions, with fish from the Eastern Cape having the lowest average percentage error and the slowest growth rates, readability decreased westward. L₅₀ varied between the central and eastern Agulhas Bank as did mass at length. Based on the distribution of carpenter, variability in otolith readability, mass at length, variation in growth and size at maturity, it is concluded that carpenter exist as two separate stocks, one on the central Agulhas Bank and the other on the eastern Agulhas Bank. SB/R, fecundity-per-recruit (Egg/R) and yield-per-recruit (Y/R) models were used to model both South African carpenter stocks. Owing to the allometric relationship between annual fecundity and individual size, Egg/R ratios were between 40 and 74% of SB/R at equivalent F. Egg/R ratios account for allometric increases in fecundity with size/age, and are therefore regarded as more accurate estimates of reproductive potential, and biological reference points for per-recruit analysis should wherever possible be based on this quantum. It is shown that the current length at first capture (lc) (250 mm TL) and F (at M = 0.1) will reduce Egg/R to 6.41% of the pristine value in the Eastern Cape and between 6.06 and 14.15% on the central Agulhas Bank, indicating that both stocks are heavily over exploited. An increase in lc from 250 to 350 mm TL and a 70% reduction in commercial fishing effort is recommended to attain a target reference point of 40% Egg/RF=0. Bag frequency analysis indicates that a reduction in daily bag limit from 10 to 4 fish.person¹.day⁻¹ would effect an equivalent reduction in recreational F. The trawl bycatch of carpenter is only 3% of the reported line catch, consequently restrictions to this fishery are not recommended.

published_or_final_version / Zoology / Master / Master of Philosophy

This study investigated the movement behaviour of three inshore South African sparids – blacktail (Diplodus sargus capensis), zebra (Diplodus cervinus hottentotus) and white musselcracker (Sparodon durbanensis), popular inshore fishery species caught in appreciable numbers along much of the South African coast. The first study component examined movements of juveniles in a rocky intertidal nursery area at Schoenmakerskop near Port Elizabeth. Juveniles in a single gully were tagged with Visible Implant Elastomer (VIE) and resighted at the study site on snorkelling gear over a seven-month period. Tagged zebra and musselcracker displayed limited movement between potential low tide refuges, being observed repeatedly in the same gully over the full duration of the study. However, blacktail displayed greater movements and were seen infrequently in the later period of the study, probably having undergone an ontogenetic habitat shift to subtidal areas. There was evidence that blacktail maintain use of their intertidal nursery over high tide, during which the other two species moved into shallower areas adjacent to their low tide refuge. The results of three national tagging programs were analysed to determine the movement patterns of adolescent and adult fishes. The coast-wide ORI-WWF National Voluntary Tagging Program and two dedicated research programs in marine protected areas (MPAs) at De Hoop MPA and Tsitsikamma National Park (TNP) recorded few large-scale movements of tagged adult blacktail, zebra and juvenile musselcracker. High spatial-resolution data from the TNP suggested movements were usually on scales far smaller than one km. Together with long periods at liberty for many recaptured individuals, this suggests these fishes are longterm residents of small home range areas. However, tagged musselcracker over 600 mm forklength (adults) were observed to make large-scale movements, including some in excess of 800 km from Eastern Cape to KwaZulu-Natal waters. Predominantly eastward movements of adults recaptured during the spawning season indicate seasonal spawning migrations that occur in different regions of the coast. These enable the use of prevailing oceanographic currents to disperse eggs and larvae to suitable rocky nursery habitat. The third component of this study made use of high-resolution data on the temporal and spatial distribution of catches by scientific angling in the TNP to examine the daily activity patterns of the study species in relation to diel and tidal cycles, and habitat use. Blacktail capture probability was correlated with the diurnal light cycle, with peaks close to twilight suggesting elevated crepuscular foraging activity. Catches of blacktail, zebra and small musselcracker were correlated with the tidal cycle, foraging peaking over high tide periods. All three species used shallow inshore habitats extensively for foraging, blacktail showing a preference for sandy areas, while zebra and small musselcracker preferred shallow reef. Capture probability of larger musselcracker, however, was unrelated to habitat, possibly evidence of increasing area and habitat use with an ontogenetic change in diet. The lifetime movement patterns of these three species are discussed in relation to conservation measures and their management in South African fisheries. Restricted movement throughout post-settlement life for blacktail and zebra, and during the juvenile phase for musselcracker, makes local populations vulnerable to overexploitation. At present, MPAs probably play an important role in protecting local blacktail and zebra populations from overexploitation, and limited post-settlement movements mean the degree of larval dispersal between protected and adjacent areas will likely determine the effectiveness of MPAs in enhancing fisheries for these species. By contrast, MPAs likely provide recruits to fisheries for musselcracker during ontogenetic movements and dispersal from MPAs during spawning migrations. MPAs only offer partial protection to adult musselcracker populations in the spawning season, but this could nevertheless be significant under high levels of exploitation.

Made available in DSpace on 2014-12-17T15:18:12Z (GMT). No. of bitstreams: 1 IngridVA_autorizado_ate_cap2.pdf: 705641 bytes, checksum: d9f1741d729cff0e052cd2778eb5ad9e (MD5) Previous issue date: 2007-02-27 / Cytogenetics analyses in fish are important because they compose a private group among the vertebrates, occupying a central position in the animal evolution. The Perciforms Order, dominant in the marine and freshwater environment, it constitutes a model potentially useful in the genetic evaluation of populations, as well as in the understanding of its evolutionary processes. In spite of this, cytogenetics studies in this great group is scarce, above all for the inhabitants of sandy bottom and pelagics habits. The present work proposed to contribute for the cytogenetic characterization of nine species of fish marine of sandy bottom of the coast of Rio Grande do Norte (Brazil), identifying the evolutionary patterns related to the karyotype in these species and the existence of filogenetics affinities between them and other Perciformes. The animals were collected in the beaches of the Redinha, Ponta Negra and B?zios (Coast of Rio Grande do Norte) and in Saint Peter and Saint Paul Archipelago. Later on they were submitted to the cytogenetics technical that consist of mitotic estimulation, obtaining of mitotics chromosomes, proceeded by techniques of conventional coloration (Giemsa) and chromosomic bands (Ag-RONs and C band). Diploid number and fundamental number equal to 48 were observed in most of the species: Menticirrhus americanus, Ophioscion punctatissimus, Pareques acuminatus (Sciaenidae); Chloroscombrus chrysurus (Carangidae); Echeneis sp. 2 (Echeneidae); Archosargus probatocephalus (Sparidae) and Orthopristis ruber (Haemulidae). Trachinotus goodei (NF=52) (Carangidae) and Echeneis sp. 1 (Echeneidae) (NF=54) presented variation in NF, staying constant a diploid number equal to 48. RONs was situated in pericentromeric position in whole the scianids, and in the species Echeneis sp. 2 (22? pair), O. ruber and A. probatocephalus (1? pair), coinciding with great heterocromatics blocks in M. americanus (1? pair), P. acuminatus (2? pairl) and O. ruber (1? pair). RONs was also located in the telomeric area of the short arm of the 5? and 11? acrocentrics pairs in T. goodei, 4? and 19? pairs of C. chrysurus, 1? pair (sm) of Echeneis sp. 1. The C band detected centromeric blocks in most of the chromosomes of the species of Sciaenidae, Carangidae and Echeneidae, with great blocks in A. probatocephalus (4? pair). Heterocromatic blocks in telomeric areas in submetacentrics of Echeneis sp. 1, and pericentromerics in M. americanus (1? and 8? pairs), O. punctatissimus (1? pair) and P. acuminatus (2? pair) were also observed. It is noticed a marked conservatism cromossomic in the species of the family Scianidae and Haemulidae in what says respect to the number of acrocentrics chromosomes and the location of RONs. Even so it is outstanding the presence of heterocromatinization events during the karyotypic evolution of this family. Already in the families Sparidae and Carangidae, the obtained results reaffirm examples of small variations structural resultants of inversion and translocation Robertsonian, as important mechanisms of diversification karyotipical, as well as a pattern numerical evolutionary conserved, also observed in representatives of Echeneidae of Atlantic in relation to Pacific. The presence of RONs multiple, observed in the species T. goodei and C. chrysurus seems to represent a character derived in the family Carangidae. The results for the species O. ruber and A. probatocephalus suggest the presence of possible geographical or climatic barriers among populations of NE of Brazil in relationship the one of the SE / An?lises citogen?ticas em peixes s?o importantes porque os mesmos comp?em um grupo particular entre os vertebrados, ocupando posi??o central na evolu??o animal. A Ordem Perciformes, dominante nos ambientes marinhos e dulc?colas, constitui um modelo potencialmente ?til na avalia??o gen?tica de popula??es, como tamb?m no entendimento de seus processos evolutivos. Apesar disto, ainda s?o escassos os estudos citogen?ticos neste grande grupo, sobretudo para os habitantes de fundo arenoso e h?bitos pel?gicos. O presente trabalho se prop?s a contribuir para a caracteriza??o citogen?tica de nove esp?cies de peixes marinhos litor?neos de fundo arenoso do litoral do Rio Grande do Norte (Brasil), identificando os padr?es evolutivos relacionados ao cari?tipo nestas esp?cies e a exist?ncia de afinidades filogen?ticas entre elas e outros Perciformes. Os animais foram coletados nas praias da Redinha, Ponta Negra e B?zios (Litoral do Rio Grande do Norte) e no Arquip?lago de S?o Pedro e S?o Paulo. Posteriormente foram submetidos ?s t?cnicas citogen?ticas que consistem em estimula??o mit?tica, obten??o de cromossomos mit?ticos, seguida por t?cnicas de colora??o convencional (Giemsa) e bandamentos cromoss?micos (Ag-RONs e bandamento C). N?mero dipl?ide e n?mero fundamental iguais a 48 foram observados na maioria das esp?cies: Menticirrhus americanus, Ophioscion punctatissimus, Pareques acuminatus (Sciaenidae); Chloroscombrus chrysurus (Carangidae); Echeneis sp. 2 (Echeneidae); Archosargus probatocephalus (Sparidae) e Orthopristis ruber (Haemulidae). Trachinotus goodei (NF=52) (Carangidae) e Echeneis sp. 1 (Echeneidae) (NF=54) apresentaram uma varia??o no NF, mantendo-se constante um n?mero dipl?ide igual a 48. As RONs estavam situadas em posi??o pericentrom?rica em todas os scian?deos, e nas esp?cies Echeneis sp. 2 (22? par), O. ruber e A. probatocephalus (1? par), coincidindo com grandes blocos heterocrom?ticos em M. americanus (1? par), P. acuminatus (2? par) e O. ruber (1? par). As RONs tamb?m foram localizadas na regi?o telom?rica do bra?o curto do 5? e 11? pares acroc?ntricos em T. goodei, 4? e 19? pares de C. chrysurus, 1? par (sm) de Echeneis sp. 1. O bandamento C detectou blocos centrom?ricos na maioria dos cromossomos das esp?cies de Sciaenidae, Carangidae e Echeneidae, com grandes blocos em A. probatocephalus (4? par). Blocos heterocrom?ticos em regi?es telom?ricas em submetac?ntricos de Echeneis sp. 1, e pericentrom?ricas em M. americanus (1? e 8? pares), O. punctatissimus (1? par) e P. acuminatus (2? par) tamb?m foram observados. Nota-se um marcante conservadorismo cromoss?mico nas esp?cies da fam?lia Scianidae e Haemulidae no que diz respeito ao n?mero de cromossomos acroc?ntricos e a localiza??o das RONs. Por?m ? destacada a presen?a de eventos de heterocromatiniza??o durante a evolu??o cariot?pica desta fam?lia. J? nas fam?lias Sparidae e Carangidae, os resultados obtidos reafirmam exemplos de pequenas varia??es estruturais resultantes de invers?es e transloca??es Robertsonianas, como principais mecanismos de diversifica??o cariot?pica, bem como um padr?o evolutivo mais conservado numericamente, tamb?m observado em representantes de Echeneidae do Atl?ntico em rela??o ao Pac?fico. A presen?a de RONs m?ltiplas, observadas nas esp?cies T. goodei e C. chrysurus parecem representar um car?ter derivado na fam?lia Carangidae. Os resultados para as esp?cies O. ruber e A. probatocephalus sugerem a presen?a de poss?veis barreiras geogr?ficas ou clim?ticas entre suas popula??es no NE do Brasil, quando comparada com a regi?o SE

by Lo Ka-Man. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 175-197). / Chapter I --- Title page --- p.i / Chapter II --- Thesis committee --- p.ii / Chapter II --- Acknowledgment --- p.iii-iv / Chapter III --- Abstract --- p.v-vi / Chapter IV --- Table of content --- p.vii-xiv / Chapter V --- List of figures --- p.xv-xviii / Chapter VI --- List of tables --- p.xix-xx / Forewords: / Overall objectives --- p.1 / Introduction on the fish used in this research study --- p.2 / Chapter Chapter 1: --- Literature Review on Biomarkers of Stress in Teleosts --- p.5 / Chapter 1.1 --- Definition of stress --- p.7 / Chapter 1.2 --- Classification of stress indicators --- p.8 / Chapter 1.2.1 --- Primary stress indicators --- p.8 / Chapter 1.2.1.1 --- Molecular stress indicators --- p.8 / Chapter 1.2.1.2 --- Hormonal stress indicators --- p.9 / Chapter (I) --- Corticosteroid --- p.9 / Chapter (II) --- Catecholamines --- p.11 / Chapter 1.2.2 --- Secondary stress indicators --- p.12 / Chapter 1.2.2.1 --- Metabolic changes --- p.12 / Chapter (I) --- Glucose metabolism --- p.13 / Chapter (II) --- Lactic acid --- p.14 / Chapter 1.2.2.2 --- Osmoregulatory changes --- p.15 / Chapter 1.2.2.3 --- Haematological changes --- p.16 / Chapter 1.2.2.4 --- Reproductive changes --- p.17 / Chapter 1.2.3 --- Tertiary stress indicators --- p.18 / Chapter 1.2.3.1 --- Histopathological indicators --- p.18 / Chapter 1.2.3.2 --- Ecological indicators --- p.19 / Chapter 1.3 --- Recent trends on the study of biomarkers --- p.20 / Chapter 1.3.1 --- Use of detoxification enzymes for specific indication of toxic pollutants in aquatic environment --- p.20 / Chapter 1.3.1.1 --- Metallothioneins (MTs) --- p.20 / Chapter 1.3.1.2 --- Cytochrome P450 monoxygenase (CYP450) --- p.21 / Chapter 1.3.2 --- Use of HSP 70 as a biomarker in teleost --- p.22 / Chapter 1.4 --- Future perspectives on the study of biomarkers in fish --- p.24 / Chapter Chapter 2: --- Literature Review on Heat Shock Proteins (HSPs) --- p.28 / Chapter 2.1 --- General Characteristics of HSPs --- p.29 / Chapter 2.1.1 --- HSP90 family --- p.30 / Chapter 2.1.2 --- HSP70 family --- p.31 / Chapter 2.1.3 --- HSP60 family (Chaperonin-60) --- p.32 / Chapter 2.1.4 --- Low-molecular weight HSPs (HSP20) --- p.33 / Chapter 2.2 --- Structure of HSP70 encoding gene --- p.33 / Chapter 2.2.1 --- General characteristics of HSP70-encoding gene --- p.33 / Chapter 2.2.2 --- Heat shock transcription factor (HSF) --- p.35 / Chapter 2.2.3 --- Heat shock elements (HSE) --- p.35 / Chapter 2.3 --- Stress-mediated control of HSP70 transcription --- p.36 / Chapter 2.4 --- Characterization of HSP70 expression in teleost --- p.38 / Chapter 2.4.1 --- Tissues-specific expression of HSP70 in teleost --- p.39 / Chapter 2.4.2 --- Inter-relationship of HSP70 expression with seasonal variation and thermotolerance of teleost --- p.40 / Chapter 2.4.3 --- Induction of HSP70 in teleost upon acute thermal stress --- p.41 / Chapter 2.4.4 --- Induction of HSP70 in teleost by non-thermal stressors --- p.43 / Chapter 2.4.4.1 --- Heavy metal-induced HSP70 expression --- p.43 / Chapter 2.4.4.2 --- Handling stress-induced HSP70 expression --- p.43 / Chapter Chapter 3: --- "Induction of HSP70 in blood cells of seabream, Sparus sarba subjected to in vivo and in vitro thermal stress" --- p.48 / Chapter 3.1 --- Introduction --- p.49 / Chapter 3.2 --- Materials and Methods --- p.52 / Chapter 3.2.1 --- Overall experimental design --- p.52 / Chapter 3.2.2 --- Fish --- p.53 / Chapter 3.2.3 --- Blood sampling --- p.53 / Chapter 3.2.4 --- Preparation of blood cells --- p.54 / Chapter 3.2.5 --- Thermal stress regimes --- p.54 / Chapter 3.2.5.1 --- Time couse of HSP70 induction profile in blood cells after in vitro exposure to thermal stress --- p.54 / Chapter 3.2.5.2 --- HSP70 synthesis in blood cells taken from fish subjected to in vivo hyper- thermic stress --- p.55 / Chapter 3.2.5.3 --- Transcriptional inhibitory effect of actinomycin D on the synthesis of HSP70 in blood cells subjected to in vitro thermal stress --- p.55 / Chapter 3.2.6 --- Protein analysis --- p.56 / Chapter 3.2.7 --- Gel electrophoresis --- p.57 / Chapter 3.2.8 --- Immunoblotting (Western blot analysis) --- p.57 / Chapter 3.2.9 --- Autroradiography --- p.58 / Chapter 3.3 --- Results --- p.59 / Chapter 3.3.1 --- Time course of HSP70 induction profile in blood cells subjected to in vitro thermal treatments --- p.59 / Chapter 3.3.1.1 --- Results of immunoblotting from blood cells of fish acclimated to 26°C --- p.59 / Chapter 3.3.1.2 --- Results of immunoblotting in blood cells from 18°C-acclimated fish --- p.60 / Chapter 3.3.1.3 --- Results of immunoblotting in blood cells from fish acclimated to 20°C --- p.60 / Chapter 3.3.1.4 --- 35S-methionine labelling of de novo protein synthesis in blood cells of fish acclimated to 15 and 20°C --- p.61 / Chapter 3.3.2 --- Blood cell HSP70 levels in 20°C-acclimated fish subjected to in vivo hyperthermic stress --- p.61 / Chapter 3.3.3 --- Transcriptional inhibitory effect of actinomycin D on HSP70 induction in blood cells subjected to in vitro thermal stress --- p.62 / Chapter 3.4 --- Discussions --- p.60 / Chapter 3.4.1 --- Characteristics of HSP70 induction in blood cells of seabream subjected to in vitro temperature stress --- p.72 / Chapter 3.4.1.1 --- Induction profile of HSP70 in blood cells --- p.72 / Chapter 3.4.1.2 --- Time course ofHSP70 induction in blood cells --- p.75 / Chapter 3.4.1.3 --- Effect of acclimation temperature of fish on the induction of HSP70 --- p.76 / Chapter 3.4.2 --- Comparison of HSP70 induction in in vitro and in vivo thermal treatment on blood cells --- p.78 / Chapter 3.4.3 --- "Effect of transcriptional inhibitor, actinomycin D, on the de novo synthesis of HSP70" --- p.80 / Chapter 3.5 --- Conclusions --- p.70 / Chapter Chapter 4: --- "Effects of seasonal variation and transportation stress on level of HSP70, serum glucose and serum Cortisol in seabream, Sparus sarba" --- p.86 / Chapter 4.1 --- Introduction --- p.87 / Chapter 4.2 --- Materials and methods --- p.90 / Chapter 4.2.1 --- Overall experimental design --- p.90 / Chapter 4.2.2 --- Fish and blood sampling --- p.91 / Chapter 4.2.3 --- Preparation of blood samples --- p.92 / Chapter 4.2.4 --- Determination of HSP70 levels in blood cells sampled from seabream upon different seasons --- p.92 / Chapter 4.2.5 --- Immunoblotting analysis --- p.92 / Chapter 4.2.6 --- Enzyme-linked Immnosorbent Assay (ELISA) --- p.93 / Chapter 4.2.7 --- Measurement of serum parameter in seabream --- p.95 / Chapter 4.2.7.1 --- Serum glucose --- p.95 / Chapter 4.2.7.2 --- Serum Cortisol --- p.96 / Chapter 4.3 --- Results --- p.96 / Chapter 4.3.1 --- Determination of HSP70 levels in blood cells sampled from seabream in different seasons --- p.96 / Chapter 4.3.1.1 --- Immunoblotting analysis --- p.96 / Chapter 4.3.1.2 --- Enzyme-linked immunosorbent assay (ELISA) --- p.96 / Chapter 4.3.2 --- Serum analysis of seabream sampled from fish farm in different seasons --- p.98 / Chapter 4.3.2.1 --- Serum glucose --- p.98 / Chapter 4.3.2.2 --- Serum Cortisol --- p.99 / Chapter 4.4 --- Discussions --- p.117 / Chapter 4.4.1 --- Characterization of HSP70 expression in blood cells of seabream --- p.117 / Chapter 4.4.2 --- Dynamicity of HSP70 content and thermo- tolerance of fish in different seasons --- p.118 / Chapter 4.4.3 --- Effect of transportation stress on HSP70 induction in blood cells of seabream --- p.121 / Chapter 4.4.4 --- Dynamicity of serum glucose level in seabream subjected to seasonal variations --- p.123 / Chapter 4.4.5 --- Effect of transportation stress on the serum glucose level of seabream in different seasons --- p.124 / Chapter 4.4.6 --- Dynamicity of senam Cortisol level in seabream subjected to seasonal variations --- p.125 / Chapter 4.4.7 --- Effect of transportation stress on the serum Cortisol level of seabream in different seasons --- p.126 / Chapter 4.4.8 --- "Comments on the use of HSP70, serum Cortisol and serum glucose as biomarkersin environmental supervision" --- p.126 / Chapter 4.5 --- Conclusions --- p.129 / Chapter Chapter 5: --- "In vitro and in vivo effects of Cortisol, dexamethasone and adrenaline on the induction of HSP70 in seabream, Sparus sarba" --- p.131 / Chapter 5.1 --- Introduction --- p.132 / Chapter 5.2 --- Materials and methods --- p.133 / Chapter 5.2.1 --- Overall experimental design --- p.133 / Chapter 5.2.2 --- Acclimation of fish and regimes of treatment --- p.133 / Chapter 5.2.3 --- Serum Cortisol and adrenaline analysis --- p.135 / Chapter 5.2.4 --- "Protein analysis, gel electrophoresis, immuno- blotting and ELISA analysis" --- p.136 / Chapter 5.3 --- Results --- p.137 / Chapter 5.3.1 --- "HSP70 level in blood cells treated with Cortisol, dexamethasone and adrenaline in vitro" --- p.137 / Chapter 5.3.2 --- "Serum hormones and HSP70 level in tissues of fish injected with Cortisol, adrenaline and dexamethasone invivo" --- p.137 / Chapter 5.3.2.1 --- Serum Cortisol and adrenaline level of fish after hormone injections --- p.137 / Chapter 5.3.2.2 --- "HSP70 level in blood cells, brain and liver tissue of fish after hormone injections" --- p.138 / Chapter (I) --- Level of HSP70 in blood cells of fish after hormone injections --- p.138 / Chapter 5.4 --- Discussions --- p.156 / Chapter 5.4.1 --- In vitro and in vivo study of the hormonal effect on HSP70 level in blood cells of seabream --- p.156 / Chapter 5.4.2 --- Hypothetical mechanism of hormone-receptor mediated HSP70 regulation --- p.158 / Chapter 5.4.3 --- In vivo study of the hormonal effect on HSP70 level in blood cells of seabream --- p.160 / Chapter 5.4.4 --- In vivo study on the hormonal effect of HSP70 synthesis in liver of seabream --- p.163 / Chapter 5.4.5 --- In vivo study on the hormonal effect of HSP70 synthesis in brain tissue of seabream --- p.165 / Chapter 5.4.6 --- HSP70 level in different tissues of fish in relation to the induction and sensitivity against stress --- p.166 / Chapter 5.5 --- Conclusions --- p.169 / Chapter Chapter 6: --- Summary --- p.171 / References --- p.175

Η μεταμόρφωση (metamorphosis), το πέρασμα δηλαδή των ψαριών από το στάδιο της ιχθυονύμφης στο στάδιο του ιχθυδίου (juvenile), συνδέεται με αλλαγές στη μορφολογία, την αύξηση, τη συμπεριφορά και το ενδιαίτημα, οι οποίες είναι καθοριστικές για την επιβίωση των ατόμων και συνεπώς για τη δομή και τη δυναμική του πληθυσμού στον οποίο πρόκειται να ενσωματωθούν. Στην παρούσα εργασία μελετήθηκε η φάση της μεταμόρφωσης σε τέσσερα είδη της οικογένειας Sparidae με την ταυτόχρονη εξέταση της μορφομετρίας και της μορφολογίας συγκεκριμένων χαρακτήρων. Τα είδη που εξετάστηκαν ήταν τα Oblada melanura (μελανούρι), Diplodus puntazzo (μυτάκι), Diplodus vulgaris (σαργόπαπας ή κακαρέλος) και Diplodus sargus (σαργός). Τα αποτελέσματα της μελέτης, έδειξαν πως με τη μεθοδολογία που ακολουθήθηκε, η φάση της μεταμόρφωσης μπορεί να προσδιοριστεί ικανοποιητικά και να οριστεί ένα μέσο μήκος μεταμόρφωσης. Αποκαλύφθηκαν επίσης διαφορές και ομοιότητες στην αλλομετρική αύξηση των ειδών που εξετάστηκαν, καθώς και ισχυρή συσχέτιση της αλλομετρικής αύξησης με την πρόσφατη θερμοκρασιακή ιστορία του περιβάλλοντος ανάπτυξής για το στάδιο πριν το εκτιμηθέν μέσο μήκος μεταμόρφωσης του κάθε είδους. Τα αποτελέσματα, συζητούνται σε σχέση με τις οικολογικές απαιτήσεις των ψαριών κατά τη μετάβαση από την πελαγική στη βενθική διαβίωση. / During metamorphosis, fish undergo major changes in morphology and growth followed by shifts in behavior and habitat use. In this study, metamorphosis was examined on the early life stages of four Sparidae species, by analyzing their allometric growth patterns concurrently with the evolution of specific morphological characters. The species examined were Oblada melanura (saddled seabream), Diplodus puntazzo (sharpsnout seabream), Diplodus vulgaris (common two-banded seabream) και Diplodus sargus (white seabream). Our results showed that metamorphosis can be adequately defined and an average length at metamorphosis can be estimated, with the use of the methodology proposed. Moreover, specific patterns of allometric growth were detected within each species, as well as, a strong correlation of allometric growth with recent environment temperature, for the stage before the estimated average metamorphosis length. Results are discussed in terms of the ecological demands of fish during their transition from the pelagic to the benthic/coastal existence.

This study provides information on the biology, stock status and the management of C. puniceus, a key linefish resource in southern Mozambique. This is regionally endemic to Mozambique and KwaZulu-Natal. Fairly resident species, is found on the continental shelf ranging north to Zavora and south to KwaZulu-Natal and Transkei, and inhabits rocky seabeds, ranging between 20 and l00m. In Mozambique is manly exploited by semi-industrial fleet, and exported to South Africa. The reproductive biology, assessed through gonad somatic index as well as microscopic and macroscopic assessment, indicates that spawning extends over the spring months from August to November, peaking in September. It is a protogynous hermaphrodite, relatively slow growing and long lived species. The length-weight relationships for male and female C. puniceus show to be different, and the overall length frequency distribution shows clear difference in size between male and female C. puniceus, with male length frequency distribution restricted to the larger size classes. The monthly length frequency distribution of female C. puniceus is unimodal and peak at 300 mm FL, male shows unclear year classes. Age determination was carried out using otoliths and growth was estimated using the model developed by Punt et al (1993) for protogynous hermaphrodites reproductive styles. Validation of annuli was done by examining the outer margin of otolith, and also through mark and recapture information. Validation following the first method indicated that the opaque band is laid down twice a year, but the mark recapture results were inconsistent. This contradicts previously published information on C. puniceus, and thus; both single and double scenarios were modelled. The Von Bertalanffy growth parameters found for C. puniceus suggest relatively slow-growth, with the number of rings found from reading the sectioned otolith ranging from 2 to 18. Reproducibility of age estimates was evaluated using the average percentage error (APE) technique, and was equal to 22%. The age at full recruitment was found to be 2.5 and 5 years for bi-annual and annual banding, respectively. The analysis of the age-at-50% maturity, based on double band scenario, suggests that C. puniceus mature at 1.5 year-old, which corresponds to a mean FL of 240mm. A preliminary yield per recruit assessment revealed that at the current fishing mortality, C. puniceus fishery is moderately overfished, with the spawning biomass-per-recruit at 35.43% and 36.57%, for one and two bands, respectively, of its unexploited level. Fishing mortality was equal to 0.2 year-1 and 0.41 year-1, for single and double band, respectively. YPR analysis shows that the single band scenario is less conservative than the double band assessment, which has a bearing on the management approach. It is suggested as the preliminary management strategy a reduction of the number of boats. Indeed the average number of crew per boat, needs to be evaluated in terms of overall effort. To complement this management measures, there is a strong and urgent need to establish marine reserves in order to protect spawning stock, and also, to develop an overall linefish management plan, which will help in the management of the whole linefish resource in Mozambique. Furthermore, an age and growth study for C. puniceus over a larger geographical area needs to be done as a mean to overcome the differences between previous study and this study, once C. puniceus is being shared between the two countries (Mozambique and KwaZulu-Natal). / Thesis (M.Sc.)-University of Natal, Durban, 2001.

Acanthopagrus berda is an estuarine-dependent fish species which is widespread in the tropical Indo-Pacific. In South Africa, it is particularly abundant in the three large northern KwaZulu-Natal estuarine systems, namely Kosi Bay, St Lucia and Richards Bay. In these systems, A. berda is harvested by a variety of methods, including traditional fish traps, gillnets and hook and line. The importance of A. berda to the different fisheries was evaluated by analysing all the available monitoring data specific to catches in these three systems. A. berda was found to be one of the five most important species taken in both the gill net and recreational fisheries at Kosi Bay and St Lucia. It was less important in the marine-dominated Richards Bay system. Catches were generally seasonal, with trends in catch per unit effort (cpue) for A. berda related to annual spawning migrations. The long-term trend in cpue for this species in the Kosi recreational fishery showed a disturbing downward trend. Ages of A. berda specimens caught in northern KwaZulu-Natal estuaries were determined by examining whole otoliths. Age estimates were validated by marginal zone analysis and oxytetracycline labelling, which indicated that opaque deposition occurs primarily from September to November each year. The reproducibility of age estimates was described by a coefficient of variation of 10%. The special von Bertalanffy growth curve was found to best describe the growth of A. berda. The parameters of the von Bertalanffy growth curve indicated that A. berda in northern KwaZulu-Natal is slow growing, attaining at least 16 years of age. The age and growth parameters and mortality estimates from catch curves were used to complete a per-recruit stock assessment of the species. The results of the spawning biomass per-recruit model using different ages of first capture indicate that A. berda is at 47% to 55% of its unfished level. Although these results may indicate that A. berda in northern KwaZulu-Natal is not at present overexploited, longevity coupled with late maturation, sex change, estuarine dependency, increasing catches of A. berda and poor monitoring give cause for concern for the continued sustainable use of this species in northern KwaZulu-Natal. / Thesis (M.Sc.)-University of Natal, Durban, 2001.

This study investigated aspects of the biology of Sarpa salpa, such as reproduction, age and growth, and mortality, which are necessary for an assessment of the status of this species off the KwaZulu-Natal (KZN) Coast. The importance of S. salpa to the shore-based fishery in KZN was evaluated using Natal Parks Board shore patrol data. These data were validated by analysing preliminary results of an independent shore-angling survey along the KZN Coast. Despite differences in the catch composition and catch rates between the two analyses, both data sources highlighted the importance of S. salpa to the shore-based fishery in KZN. Shore-based catches were markedly seasonal coinciding with the breeding season of the species. The species in KZN is targeted primarily to provide a supplementary source of animal protein. An investigation of the reproductive biology of S. salpa indicated a protracted spawning period for the species. Size at 50 percent maturity for combined sexes was attained at 145 mm fork length. The sex ratio in shore-based catches was 1:1.6 in favour of males. A frequency distribution by size indicated that males dominated the smaller size classes while females dominated the larger size classes. Detailed histological examination of gonadal development showed that S. salpa has the potential for protandrous sex change. An age and growth study based on the examination of whole otoliths indicated that S. salpa was relatively fast-growing and a maximum age of six years was recorded for the species. One opaque band was laid down per year. This was validated by marginal increment analysis and by an oxytetracycline labelling experiment using captive fish. Growth in S. salpa was described by a Von Bertalanffy growth function: Lage (mm FL) = 224mm(1 -e-o.55 year-1(age+o.51years)) The natural mortality rate (M = 0.6 year-1) was derived using Pauly's equation and the current fishing mortality (F) rate was estimated at 0.8 year-1. The current status of S. salpa in the shore-based fishery was assessed by determining the effects of F and age-at-capture on the yield- and spawner biomass-per-recruit. Current levels of fishing pressure on S. salpa appeared to be appropriate for utilisation of the stock off the KZN South Coast. In terms of management, S. salpa appears to be in no need of any restrictive measures at present. / Thesis (M.Sc.)-University of Natal, Durban, 1995.