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

The reproductive biology of two commercially important species of threadfin bream, Nemipterus virgatus and N. japonicus

劉柏輝, Lau, Pak-fai. January 1999 (has links)
published_or_final_version / Ecology and Biodiversity / Master / Master of Philosophy
2

Spawning and parental care in the pink convict variety of Cichlasoma nigrofasciatum (Gunther)

Lundin, Francis C. January 1979 (has links)
Spawning and parental care in the pink variety of Cichlasoma nigrofasciatum (Gunther) was studied from September 1970 to May 1971. The objectives of the study were to determine: (1) the spawning behavior of C. nigrofasciatum when isolated as pairs; (2) the spawning behavior of a pair when sharing an aquarium with other cichlid species. The study was conducted in two parts.In Part 1 three aquaria were set up, each containing a pair of sexually mature pink convicts. Twelve different pairs were observed over a period of 120 days. Pre-spawning and post-spawning activities were noted. These were recorded in a pictograph form developed by the author. Eight of these activities were observed in the pre-spawning period and 46 were observed during the days following spawning. The interactions between the members of any one pair differed very little from the interactions of any other pair.One spawning was observed from start to finish and every egg placement was recorded. The eggs appeared to be deposited in an irregular pattern, but form a relatively compact mass when the spawning is completed. When a pair is isolated the female cares for both the eggs and the wigglers. The male takes an active role in the care of the fry when they are just starting to swim. The male becomes the more ardent parent once the fry are free swimming and spends much of his time keeping the female in close proximity to the young.In Part 2 the presence of other fishes in the aquarium changed the male's behavior appreciably. He became much more involved in the early post-spawning stages, actively involved in the defense of the eggs and wigglers. These changes were not limited to the male; the female's behavior also changed. She was a much more conscientious parent in the later stages of fry care. The male spent very little time driving the female toward the fry. Both parents became more attentive in Part 2.Six aquaria were used in Part 2. This section placed the pink convicts in aquaria with six other species. The interspecific activity was the prime observation. All of the species observed acted alike. The spawning of several of the species was observed, as was the activity of caring for the young of a different species. The most notable observation here was the similarity of behavior of the cichlids representing three different genera.In both parts all pairs spawned in or on a flowerpot provided. The egg and fry care was almost the same for all of the fishes. The interspecific interactions were as intense as most of the intraspecific. The level of intensity observed declined in the following order: (1) same sex same species; (2) same sex related species; (3) different sex same species; and (4) different sex different species.All of the species in Part 2 that spawned used the same behavioral displays used by the convicts in Part 1. All display with lateral weaving, erected fins, flared opercula, and lowered branchiostegals. All of the spawning pairs attempted to occupy a large territory, but none insisted on more than 5t of their spawning tank. Generally the pairs observed in this study established pair bonds and spawned within two weeks of their introduction to the aquarium.The pink convict lends itself well to this kind of behavioral study because it is a hardy, easy to spawn species large enough to observe easily. They tolerate laboratory conditions very well. The pink variety of C. nigrofasciatum is much less aggressive and more attractive than the native variety.
3

The effect of methyl testosterone on secondary sex characters and reproductive behaviour of gonadectomized sticklebacks (Gasterosteus aculeatus L.)

Wai, Evelyn January 1962 (has links)
Treatment of gonadectomized adult male and female sticklebacks as well as normal juvenile, with methyl testosterone, either by immersion in a hormone solution or by implanting hormone pellets, induces the kidney cells to develop into granular and mucous cells, accompanied by an increase in cell height. Increase in cell height, up to a limit, is a function of the length of hormone treatment. Prespawning aggressiveness and territoriality is induced in gonadectomized fish of both sexes by maintaining them under long photoperiod for four to five weeks. Short photoperiod has no effect. Administration of methyl testosterone to the already aggressive fish showed no definite effect on this behaviour. The combined effect of long photoperiod and methyl testosterone treatment induces the nest-building behaviour in gonadectomized males and females with a much higher percentage in the former than in the latter. The component elements of the nest-building movement in the treated gonadectomized male is similar qualitatively and quantitatively to that of the normal reproducing male. Treated gonadectomized females show deviations from the normal male in their nest-building movements. Sexual behaviour is the same in castrates treated with methyl testosterone as in the normal reproducing male, but completely absent in the similarly treated gonadectomized females. / Science, Faculty of / Zoology, Department of / Graduate
4

The role of prostaglandins during sexual maturation, ovulation and spermiation in the goldfish, Carassius auratus

Bouffard, Maria Emilia Rachelle January 1979 (has links)
The objective of this study was to determine the involvement of prostaglandins in the sexual development of both male and female goldfish. Carassius auratus. A chromatographic method was developed to separate the different prostaglandin groups. To standardize the procedure, extraction and separation recoveries were measured using tritiated-prostaglandins. Radioimmunoassay was used to measure the PGB1, PGE1 and PGF2* in the plasma and gonad. Initially, a seasonal study was undertaken to assess the importance of prostaglandins during sexual maturation. Samples of plasma and gonad were assayed monthly for prostaglandins (from December to March) from two groups of fish, one held under natural photoperiod and the other under long photoperiod (16L:8D). Although monthly variations occurred in all three prostaglandins examined, these changes did not correlate with changes in gonadal maturationi Prostaglandins were then measured in serial plasma samples of non-gravid and ovulating female goldfish. Ovulation was induced in gravid fish by increasing the water temperature from 14° C to 20° C and by injecting human chorionic gonadotropin (HCG) . It was found that: 1) PGF2 increased over 14 fold, 12 hours after the onset of ovulation (from pre-injection levels of 300 pg/ml to more than 4,000 pg/ml); however, this increase appeared to commence immediately after ovulation. There was no change in plasma P1GF20< levels in non-gravid control fish. The concentration of PGF2^in the ovarian fluid was over 9,000 pg/ml. 2) PGE1 decreased almost three-fold between the time of HCG injection (an average of 10 hours before ovulation) and 24 hours later. The plasma PGE 1 levels in the non-gravid females were up to 20 times less than the gravid ovulating females. The concentration of PGE1 in the ovarian fluid was 630 pg/ml. 3) PGB1 levels decreased in the plasma of non-gravid and ovulating goldfish, following HCG injection. The ovarian fluid contained 300 pg/ml of PGB1. Parallel experiments were performed on male goldfish that were spermiating. There were no significant changes in plasma PGF20C within 24 hours of HCG injection, whereas PGB1 decreased slightly (as for the females), and PGE1 increased significantly 10 hours after HCG injection. The findings of this study suggest that PGF2 and PGE1 in the ovarian fluid are the agents controlling ovulation in the female goldfish and that corresponding levels in the blood contribute to other events associated with ovulation. The experiments on males indicate a possible role for PGE1 during spermiation; however, it is difficult to ascertain its precise involvement at present. / Science, Faculty of / Zoology, Department of / Unknown
5

The Influence of Somatic Investment on the Patterns of Reproduction in POECILIA LATIPINNA (Pisces: POECILIIDAE)

Wetherington, Jeffrey D. 01 July 1982 (has links) (PDF)
In Poecilia latipinna size-specific reproductive and survivorship patterns were correlated with changes in habitat availability. Of the numerous physical, chemical, and biological parameters associated with a reduction in available habitat, probably the most important was reduced food availability. Large (old) females, theoretically with a low reproductive value, allocated energy to reproduction regardless of habitat and, presumably, food availability. When reproductive activities were initiated in March, habitat availability was modest. In association with a severe reduction in available habitat in April, large females were subject to a substantial loss of body weight during the yolk-loading phase of the reproductive cycle. This loss, primarily of somatic tissue, was very costly and heavy mortality ensued. Habitat availability increased during late May and June and survivorship increased. By August the somatic condition of large females had improved significantly. As in April, yolk-leading resulted in a loss of body weight; however, the loss consisted of approximately 70% lipid. Although the cost was lower than April, the necessity of subsidizing reproduction with somatic tissue may account for the slight reduction in survivorship observed in September. Smaller (younger) females, theoretically with a higher reproductive value, allocated energy to reproduction in response to increases in habitat, and presumably food availability. This response was in the form of an increased number of small reproducing females and was not evident until the month following the increase in available habitat. In contrast to large females, reproductive activities among small females were initiated in April. In association with a severe reduction in habitat availability, small females were subject to a loss of dry weight during yolk-loading, which consisted of approximately 44% lipid. The cost of reproduction was reduced and survivorship improved relative to the large females. Despite an increase in available habitat in June, small females curtailed reproduction in favor of survival and increased fecundity afforded by a greater body size. By early August an increase in reproductive activities was evident among small females. The somatic condition of these females was significantly improved in comparison to April females. In contrast to large August females, small females did not subsidize reproduction with somatic tissue. The change in body weight was attributable to a loss of lipid. By early September the available habitat had increased dramatically. In comparison to August, the high number of small reproducing females suggested the response to improved conditions may be rapid. Changes in food availability and, thus the total energy budget (lower in spring, higher in the summer and fall) and the associated cost of reproduction (higher in spring, lower in fall) from April to September were not reflected by changes in fecundity. It appeared that under the conditions that prevailed during this study, a female that made a commitment to reproduction produced a size-specific brood of a fixed quality regardless of food availability and reproduction cost. If a female was able to assimilate excess energy during the gestation period, that energy was allocated in maintenance (i.e. repaying any somatic debt) and growth.
6

Studies on the reproductive biology of Oreochromis niloticus L

Srisakultiew, Penpun January 1993 (has links)
This study investigated the reproductive biology of Oreochromis niloticus broodstock of known age structure and spawning history with the aim of synchronising and controlling their spawning for mass fry production. Hatchery reared stock was subjected to a constant photoperiod of 12L:12D and maintained at 27 ± 1°C. All stock was fed on commercial trout pellets. The feeding frequency and protein content of the diet varied depending on fish size. Oocyte development was classified into 6 stages including that of atresia based on histology. In order to quantify ovarian maturity, three stereological methods were compared. The ovarian volume fractions of different oocyte stages estimated by the mass, graphical and intersection methods showed homogeneous results. The intersection method required less time (2.6 mins/sample) whereas the others needed 11-12 mins/sample. In addition, the numerical density technique employing the intersection method was used and yielded similar oocyte estimates to those derived from the Gilson's fluid method. Onset of sexual differentiation was influenced by the stocking densities. At 10 and 20 fry/l, 30 and 45% of those fry, respectively, were sexually differentiated by day 11 post-hatch, whereas those held at 2 fry/l were not. Gonadal development was monitored in fish of known age. Fry were randomly sampled after hatching at two week intervals until 24 weeks. Total body length and weight were recorded and gonads were fixed for maturity determination. Serum samples were analyzed for total calcium (Ca2+), testosterone (T) and oestradiol-17ß (E2). The males grew faster than the females of the same age and showed secondary sexual characteristics and attained maturity with significantly (P<0.05) higher T levels by 16 and 22 weeks, respectively. Females in comparison showed a significant (P<0.05) increase in GSI during 18-24 weeks (0.5-3.6%). The volume fraction of stage 6 oocytes, which were positively correlated to GSIs (r2=0.84; P<O.05), increased from 46.7% (20 weeks) to 71.8% by 22 weeks and then declined to 67.5% by 24 weeks. These results coincided with the mean levels of E2 whereas the Ca2+ and T levels showed high average levels through 24 weeks. These trials suggested that the females attained sexual maturity by 22 weeks. Ovarian recrudescence and average levels of Ca2+, T and E2 over 2 to 3 spawning cycles were studied. Within each spawning cycle the volume fraction of stage 6 oocytes increased from 0-15% (at day 1) to 65-72% by day 10 after spawning, which coincided with the high levels of Ca2+ and T whereas E2 levels peaked at day 5 and then decreased at day 10 after spawning. Females at day 10 post-spawning had, therefore, completed vitellogenesis and spawning occurred at the median time of 13 days. In addition, average hormonal levels, egg quality and quantity over 2 to 3 spawning cycles were monitored in eight individual females. Females were bled twice a week after their first spawning. The median of spawning cycles of these females for the first and second cycles were 13 (short cycle) and 28 days (long cycle), respectively, and their overall median spawning cycle was 15 days (short cycle). Levels of E2 were significantly (P<0.05; r2=0.79) correlated to the volume fractions of stage 6 oocytes and their peak levels were significantly correlated (P<0.05; r2=0.49) to fertilisation rates of eggs in subsequent spawns. Fecundity and fertilisation rates of eggs from those females in the second and third spawning were higher than the first spawning which indicated that the females that had spawned previously tend to ovulate more eggs than those that had spawned for the first time. The spawning history showed no effect on their fertilisation rates. The females which were selected by their external characteristics were either injected (10 to 300μg D-Ala6-Gly10-LHRH + 0.1mg pimozide/kg body weight) or implanted (fast or slow release pellets containing LHRH; 100μg/kg) with the hormones. Neither the injections nor LHRH pellets were effective in inducing the females to spawn. At day 10 after each spawning, a mixture of 100μg LHRH + 0.1mg pimozide/kg body weight was injected into the females kept under two spawning conditions. Females were held in either separated compartments (limited contact) or under normal communal spawning conditions (unlimited contact). Spawning environment affected the success of induced spawning. The females which were held in the separated compartments spawned within 2 to 6 days post-injection whereas the sham controls spawned in 7 to 8 days postinjection. In contrast, the females in the communal spawning environment did not respond to hormone induction. The timing at day ten post-spawning and the conditions of spawning were found to be the important factors affecting exogenous hormonal administration in this fish species.
7

Reproductive strategies and social organization in damselfishes

MacDonald, Craig D (Craig Dixon) January 1981 (has links)
Typescript. / Bibliography: leaves 212-226. / Photocopy. / xv, 226 leaves, bound ill. 29 cm
8

The reproductive physiology of triploid Pacific salmonids

Benfey, Tillmann J. January 1988 (has links)
Triploidy was induced in rainbow trout, Salmo gairdneri Richardson, by heat shock (10 min at 26, 28 or 30°C, applied 1 min after fertilization at 10°C) and in pink salmon, Oncorhynchus gorbuscha Walbaum, and coho salmon, 0. kisutch Walb., by hydrostatic pressure shock (1, 2, 3 or 4 min at 69,000 kPa, applied 15 min after fertilization at 10.5°C). Triploid individuals were identified by the flow cytometric measurement of DNA content of erythrocytes stained with propidium iodide. Gonadosomatic index was reduced to a much greater extent in triploid females than males. Triploid ovaries remained very small, and contained virtually no oocytes. Triploid testes became quite large, but few cells developed beyond the spermatocyte stage. Triploid male rainbow trout had significantly lower spermatocrits than diploids, and their spermatozoa were aneuploid. Growth rates were the same for diploid and triploid rainbow trout, but triploid female pink salmon were smaller than maturing diploid females and diploid and triploid males of the same age. Triploid males of both species developed typical secondary sexual characteristics and had normal endocrine profiles for plasma sex steroids and plasma and pituitary gonadotropin, but their cycle was delayed by about one month. Triploid females developed no secondary sexual characteristics and showed no endocrine signs of maturation, even at the level of the pituitary. Vitellogenin synthesis was induced in immature diploid and triploid coho salmon by the weekly injection of 17β-estradiol. Plasma vitellogenin and pituitary gonadotropin levels were significantly elevated over levels of sham-injected fish, whereas plasma gonadotropin levels were slightly depressed. There was no significant difference between diploids and triploids for any of these results, indicating that normal vitellogenesis is not impaired by triploidy per se. It is concluded that triploids of both sexes are genetically sterile, but that only triploid females do not undergo physiological maturation. Triploid testes develop sufficiently for their steroidogenic cells to become active, which is not the case for triploid ovaries. The occasional cells that pass through the normal meiotic block develop to full maturity in triploid males but not in triploid females, probably due to the absence of the appropriate stimulus to initiate and maintain vitellogenesis. Although triploids of both sexes should make valuable tools for basic research on reproductive physiology, only the females will be useful for practical fish culture to avoid the economically detrimental effects of maturation in fish destined for human consumption. / Science, Faculty of / Zoology, Department of / Graduate
9

The ontogeny and morphology of the upper pharyngeal pad of Oreochromis mossambicus (Peters) and its possible role in the rearing of young

01 September 2015 (has links)
Ph.D. / The declining marine fish catches and the increasing demand for farmed fresh water fishes are motivation for research and development of improved strains and techniques for the production of gynogenetic and triploid offspring of popular fresh water fishes ...
10

Caracterização espermáticas na subfamília Cichlinae (Perciformes : Chlidae) e suas implicações filogenéticas

Ortiz, Rinaldo José [UNESP] 05 March 2012 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:30:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-03-05Bitstream added on 2014-06-13T20:40:51Z : No. of bitstreams: 1 ortiz_rj_dr_botib.pdf: 1128298 bytes, checksum: a9ab81176a4785a3d69e016af013af18 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Cichlidae é a maior família de peixes não-Ostariophysi de água doce, e uma das maiores famílias de vertebrados. De ampla distribuição mundial, os gêneros neotropicais atualmente foram elevados a status de subfamília, Cichlinae. As hipóteses existentes para as relações de parentesco em Cichlinae, tendo por base características osteológicas e de partes moles e mais recentemente dados moleculares, não são congruentes entre si. Sabe-se que as características espermáticas contem informações filogenéticas e podem ser úteis no estudo do relacionamento entre as espécies. Neste estudo, descreveu-se a espermiogênese e os caracteres ultraestruturais dos espermatozóides de membros da subfamília Cichlinae e da subfamília Pseudocrenilabrinae. Os dados resultantes foram utilizados numa análise filogenética, que comparada as proposta pré-existentes, recupera alguns dos grupos mais proximamente relacionados, caso dos gêneros Retroculus e Cichla. Estes gêneros são reconhecidos como basais dentro da subfamília. Outro grupo que se mantém, é o formado por Andinoacara rivulatus, Cichlasoma portalegrense e Aequidens tetramerus, membros da tribo Cichlasomatini. Além disso, a tribo Cichlasomatini ocupa posição derivada no cladograma, como em hipóteses anteriores / Cichlidae is the largest family of non-Ostariophysi freshwater fish and one of the largest family of vertebrates. With a worldwide distribution, the Neotropical genera have been now elevated to a subfamily status, Cichlinae. The existing hypotheses for the phylogenetic relationships in Cichlinae, based on osteological features and soft tissue and more recently on molecular data, are not congruent. It is known that the spermatics characteristics contains phylogenetic information and can be useful in the studies of the relationship between species. Then, this study described the spermiogenesis and sperm ultrastructural characterics from some members of the Neotropical subfamily Cichlinae and from the African, Pseudocrenilabrinae. The data was used in a phylogenetic analysis, that when compared to pre-existing proposals, recovers some of the most closely related genera, for example, Cichla and Retroculus. These genera are recognized as basal within the subfamily Cichlinae. Another group that remains, it is that formed by Andinoacara rivulatus, Cichlasoma portalegrense and Aequidens tetramerus, members of the tribe Cichlasomatini. The tribe Cichlasomatini occupies a derivative position in the cladograma

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