Morphological and histological studies of imposex has been studied in the oyster drills, Thais clavigera and T. rufotincta. The sex ratios of the collected samples were close to 1:1 among sites of Shunsun, Taishi, Budai, Chiku and Donkang. The relative penis sizes (RPS values) of T. clavigera were higher than T. rufotincta, indicating a high imposex degree in T. clavigera. The RPS values of T. clavigera showed seasonal variations, because the penis length of males and females were longer in the reproductive season, but the trends were inconsistent among the sampling sites. The RPS values in Shunsun and Taishi were higher in March (reproductive season) and lower in August (non-reproductive season), but Budai and Chiku were in a contrary way. It is suggested that the inconsistent patterns may result from temporal and spacial variations of tributyltin (TBT) and triphenyltin (TPT) concentrations among sites. For imposex females, they all developed penis and vas deferens. In the heaviest affected female T. clavigera, aborted egg capsules within the capsule gland that renders the female sterile has been observed. The percentage of capsule gland blockage in Shunsun, Taishi, Budai and Chiku were 7.7%, 9.7%, 50% and 0%, respectively. Other accessory sex organs, i.e. the lengths of capsule gland and prostate glands were all longer in reproductive season, and the difference among sampling sites were also significant. In histological studies of T. clavigera and T. rufotincta, the male testis tissue from all sampling sites contained all developing stages sperm cells in March; as females from March, the ovary tissues were full with mature oocytes. However, in Shunsun and Budai, there were many hemocytes found in the ovary tissues of T. clavigera that might result from imposex. In lab-experiments, T. clavigera were treated with TBT and TPT for 44 days, there was no difference in female penis length between control and TBT or TPT treated groups. The ovary and testis tissues were all developed normally. In general, there is no obvious abnormality in imposexd T. rufotincta. On the contrary, in T. clavigera, the female opening (vulva) occluded by overgrowing vas deferens which might prevent the spawning of egg capsules. In addition, some hemocytes were found in the ovary tissues in T. clavigera and the phenomenon of sex change was not observed. Meanwhile, no obvious abnormality was observed in the testis tissues of T. clavigera.

Made available in DSpace on 2014-06-11T19:22:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-09-22Bitstream added on 2014-06-13T20:48:50Z : No. of bitstreams: 1 takahashi_elh_me_jabo.pdf: 1262645 bytes, checksum: 7dd065f23c1f6fb1a08fe2fc4ebc4fb4 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O ciclo reprodutivo da Tabarana, Salminus hilarii (VALENCIENNES, 1849) foi estudado no rio Sorocaba, estado de São Paulo. Entre abril de 2004 até março de 2006 foram realizadas coletas mensais totalizando 109 exemplares coletados. O período reprodutivo ocorreu entre os meses de novembro e dezembro e foi determinado pela analise do índice Gonadossomático (IGS) e pela determinação dos estádios gonadais em cada bimestre. A desova do tipo total foi constatada pela da análise microscópica dos ovários e distribuição da freqüência do diâmetro dos ovócitos de ovários maduros. A fecundidade foi estimada em 54.157 (DP ± 19.991) ovócitos com os diâmetros não alcançando não mais que 1428 m. Nos ovários foram observados seis tipos de ovócitos: Cromatina-nucléolo, Perinucleolar, Alvéolo-cortical, Vitelogênico, Maduro e Atrésico. Uma escala de maturidade foi construída baseando-se em observações morfológicas tanto macroscópicas quanto microscópicas e também pelo IGS em quatro estádios distintos: Repouso, Maturação, Maduro e Desovado. Nos testículos foram observados cinco tipos de células: Espermatogônia primária, Espermatogônia secundária, Espermatócito, Espermátide e Espermatozóide. A partir de observações macroscópicas e microscópicas foram identificados testículos em estádio de Maturação, Maduro e Esgotado. / Tabarana´s reproductive cycle, Salminus hilarii (VALENCIENNES, 1849) was studied in Sorocaba River, São Paulo state, Brazil. Between april 2004 until march 2006 collections were carried out monthly and 109 specimens were captured. Spawning period occured between november and dezember and was given by gonadossomatic index (GSI) analysis and through determination of the gonadal stages in each two months. Total spawning was noticied by microscopic analysis of the ovaries and oocyte distribution by size-diameter class from mature ovaries. Fecundity was valued in 54.157 (SD ± 19.991) oocytes, with largest diameter reaching no more than 1428 m. Six types of oocytes were observed in ovaries: Choromatin-nucleolus, Perinucleolar, Alveolus-cortical, Vitellogenic, Ripe and Atresic. A maturity scale has been made based in morphological observations as macroscopic as microscopic an either thorugh GSI in four distinct phases: Recovering, Mature, Ripe and Spawned. In the testis were observed five kinds of cells: primary and secondary spermatogonias, spermatocytes, spermatides and spermatozoa. Mature, Ripe and Empty stages were identificated by macroscoy and microscopy analysis.

Orientador: Laura Satiko Okada Nakaghi / Banca: Nelsy Fenerich Verani / Banca: Roberto Goitein / Resumo: O ciclo reprodutivo da Tabarana, Salminus hilarii (VALENCIENNES, 1849) foi estudado no rio Sorocaba, estado de São Paulo. Entre abril de 2004 até março de 2006 foram realizadas coletas mensais totalizando 109 exemplares coletados. O período reprodutivo ocorreu entre os meses de novembro e dezembro e foi determinado pela analise do índice Gonadossomático (IGS) e pela determinação dos estádios gonadais em cada bimestre. A desova do tipo total foi constatada pela da análise microscópica dos ovários e distribuição da freqüência do diâmetro dos ovócitos de ovários maduros. A fecundidade foi estimada em 54.157 (DP ± 19.991) ovócitos com os diâmetros não alcançando não mais que 1428 m. Nos ovários foram observados seis tipos de ovócitos: Cromatina-nucléolo, Perinucleolar, Alvéolo-cortical, Vitelogênico, Maduro e Atrésico. Uma escala de maturidade foi construída baseando-se em observações morfológicas tanto macroscópicas quanto microscópicas e também pelo IGS em quatro estádios distintos: Repouso, Maturação, Maduro e Desovado. Nos testículos foram observados cinco tipos de células: Espermatogônia primária, Espermatogônia secundária, Espermatócito, Espermátide e Espermatozóide. A partir de observações macroscópicas e microscópicas foram identificados testículos em estádio de Maturação, Maduro e Esgotado. / Abstract: Tabarana's reproductive cycle, Salminus hilarii (VALENCIENNES, 1849) was studied in Sorocaba River, São Paulo state, Brazil. Between april 2004 until march 2006 collections were carried out monthly and 109 specimens were captured. Spawning period occured between november and dezember and was given by gonadossomatic index (GSI) analysis and through determination of the gonadal stages in each two months. Total spawning was noticied by microscopic analysis of the ovaries and oocyte distribution by size-diameter class from mature ovaries. Fecundity was valued in 54.157 (SD ± 19.991) oocytes, with largest diameter reaching no more than 1428 m. Six types of oocytes were observed in ovaries: Choromatin-nucleolus, Perinucleolar, Alveolus-cortical, Vitellogenic, Ripe and Atresic. A maturity scale has been made based in morphological observations as macroscopic as microscopic an either thorugh GSI in four distinct phases: Recovering, Mature, Ripe and Spawned. In the testis were observed five kinds of cells: primary and secondary spermatogonias, spermatocytes, spermatides and spermatozoa. Mature, Ripe and Empty stages were identificated by macroscoy and microscopy analysis. / Mestre

The ability to manage a fish stock relies on an understanding of life history characteristics and basic biology of the species. Numerous age-growth studies are facilitated by the relative ease of ageing fishes through hard-part analyses. Determining reproductive parameters for fish populations is equally important for stock assessments and management, and histological examination of gonads provides the most accurate determination of fecundity and spawning periods. Coastal pelagic fishes are often targeted commercially and recreationally due to their easy access by private vessels. However, there are few studies researching the biology and reproduction of recreational fishes in the waters of Southeastern Florida that would lead to a better understanding for management practices. The objective of this study was to provide baseline reproductive data for two fishes particularly important to Florida fisheries: the coastal pelagic scombrids Blackfin Tuna Thunnus atlanticus and Little Tunny Euthynnus alletteratus. Archived gonad samples from 2010-2014 for these two species were evaluated, and GSI values and histological examination indicated one spawning season for both species. Little Tunny spawn April through August, and Blackfin Tuna spawn May through June. Additionally both species have asynchronous oocyte development, and are batch spawners. Postovulatory follicles were used to estimate spawning frequency; for Blackfin Tuna, mean spawning occurs once every 1.49 days, and for Little Tunny, mean spawning occurs once every 1.47 days. Comparison of otolith age data to these results indicates that Little Tunny mature at a smaller size and younger age than Blackfin Tuna. Size at 50% maturity for male Blackfin Tuna was 435.2 mm TL, for female Blackfin Tuna was 392.3 mm TL, and for male Little Tunny was 347.77 mm TL. Age at 50% majority for male Blackfin Tuna was 0.66 years, and for male Little Tunny was 0.50 years. In addition to providing important baseline data for fisheries management, this study collaborated with previous research to improve accuracy of reproductive age assessments. Finally, reproductive parameter studies of fishes in Florida and the Greater Caribbean area commercial and recreational fisheries provide information important for future ecosystem based management.

The most speciose group of fishes in the Gulf of Mexico is the dragonfishes (Family: Stomiidae). These fishes are dominant mesopelagic predators occurring throughout the world’s oceans, including the Antarctic seas. Little is known regarding their reproductive ecology, a consequence attributed to insufficient sample sizes of mature adults due to inadequacies of sampling gear; larger, sexually mature stomiid adults are more adept at net avoidance, thereby obfuscating synoptic reproductive biology studies. Between 2010-2011, the Offshore Nekton Sampling and Analysis Program was initiated in the northern Gulf of Mexico over all four seasons using a discrete-depth sampling system (MOCNESS) and a large, commercial-sized midwater trawl (Irish herring trawl). Gonads were dissected from 714 individuals belonging to 47 species of stomiids, of which the most 12 abundant species were subjected to detailed analysis. Female ovaries possessed an asynchronous oocyte development, suggesting that females are iteroparous. Males exhibited a similar pattern. Chauliodus sloani had an overall sex ratio that favored females, and was the only species in which the overall sex ratio significantly differed from the expected 1:1 ratio (male:female) (P < 0.05). Considering just mature specimens, Aristostomias xenostoma, Malacosteus niger, Eustomias fissibarbis, and Eustomias schmidti had sex ratios that favored males, and were the only species in which the sex ratio significantly differed from even (P < 0.05). Eustomias hypopsilus was the only species in which mean biomass significantly differed between sexes. Histological analysis and binomial regression indicated that females of the 12 most abundant species matured at larger lengths than males. Generally, only females were present in the larger size classes, suggesting that females also become larger than males. Size distribution plots by gear type to assess gear selectivity revealed two patterns: the MOCNESS caught fewer specimens per species than the Irish herring trawl, and the MOCNESS caught predominantly smaller specimens. These data are essential for ecosystem-based modeling of global deep-pelagic ecosystems, which contain the overwhelming majority of Earth’s fish biomass.