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Search Results: 1 - 10 of 6128 matches for " fish reproduction "
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Reproductive seasonality of fishes from a lotic stretch of the Grande River, high Paraná river basin, Brazil
Andrade, P. M.;Braga, F. M. S.;
Brazilian Journal of Biology , 2005, DOI: 10.1590/S1519-69842005000300003
Abstract: we searched for correlations between water level, rainfall, temperature, and reproductive activity of fishes in a lotic stretch of the grande river below the volta grande dam. gillnets were used to catch the fish on six field journeys made bimonthly between april 1998 and february 1999. fish gonads were classified according to maturation grade and the amount of mature or spent gonads was correlated with rainfall and air temperature. most fish species showed seasonal reproduction (between october and february). the relative frequency of fully mature and spent gonads significantly correlated with rainfall (spearman r = 0.94, p = 0.005) and air temperature (r = 0.84, p = 0.036), showing the importance of these factors in regulating the reproductive cycle of fishes in this location. nevertheless, dam operation resulted in minimal water level variation that did not significantly correlate with reproductive activity (r = -0.43, p = 0.396).
Biologia reprodutiva do peixe-rei Odontesthes argentinensis (Valenciennes) (Atherinopsidae) da regi?o marinha costeira do sul do Brasil
Moresco, Alex;Bemvenuti, Marlise de A.;
Revista Brasileira de Zoologia , 2006, DOI: 10.1590/S0101-81752006000400025
Abstract: the silverside odontesthes argentinensis (valenciennes, 1835) is distributed in the coastal region of the south atlantic since the south of brazil until argentina. this species presents two populations, a population resident in the patos lagoon estuary and another one in the coastal sea region. this work had as objective to determine the reproductive biology of the populations of coastal sea region. the sex ratio indicated predominance of females. the size of first maturation (l50) was estimated in 13.8 cm lt for the males and 16.1 cm lt for the females and the length where all were apt to spawn (l100) was estimated in 16.3 and 19.3cm lt for males and females, respectively. the gonadossomatic relation indicated reproductive period between ends of august and beginning of december, period where the temperature of the water is below 20oc. the factors of total condition (kt) and somatic (ks) had presented great variations during the cycle. a fall in the values of k coincided with the beginning of the spawning, establishing a relation this fall of k represented the energy that was directed for the development of the gonads. in the analysis of the diameter of the oocytes evidence was found allowing state that the spawning don't occur at once. the total fecundity (tf) and the lot fecundity (lf) are proportional to the total length. the average of oocytes was of 10,014 for ft and 3,651 for fl.
Estrutura populacional e época de reprodu??o de Astyanax fasciatus (Cuvier) (Characidae, Tetragonopterinae) do Rio Ceará Mirim, Po?o Branco, Rio Grande do Norte, Brasil
Gurgel, Hélio de Castro Bezerra;
Revista Brasileira de Zoologia , 2004, DOI: 10.1590/S0101-81752004000100022
Abstract: the aim of this study was to evaluate 209 samples (100 females and 109 males) of astyanax fasciatus (cuvier, 1819) collected from the ceará mirim river, rio grande do norte state, (5°37's e 35°39'w), between february 1996 and april 1997. the sex ratio was 1:1 and the the total length varied from 3.0 to 9.0cm, with most classes between 4.0-5.0 cm and 7.0-8.0 cm. the estimated value for the parameter (q = 2,59) suggests that this specie has an alometric growing pattern. the igs value started to increase in november-december-january, following the rainfall while the condition factor values showed.
Ciclo reproductivo de Lactophrys quadricornis (Pisces: Ostraciidae) de la costa nororiental de Venezuela
Ruiz,Lilia J.; Figueroa M.,Rogelia; Prieto A.,Antulio;
Revista de Biología Tropical , 1999,
Abstract: reproductive biology was studied in lactophrys quadricornis, from samples collected monthly from may 1990 to april 1991 in the east coast of venezuela. sex ratio was 1:1; half the population matured at total lenght of 198 mm for males and 222 mm for females. minimal sizes for maturity was 160 and 170 mm of l.t in males and females, respectively. the gonadosomatic index (ig) and gonadal maturity stages sugest year around reproduction with two peaks: from june through september, and from january through february. weight, ovary lenght and frequency of females in stages iv and v, are the evidence. asynchronous development of the ovocytes with diameters between 0.399 to 0.930 mm, indicates that spawning is fractionate. mean fecundity was 112 536 ± 57 047.97 eggs, and increases with lenght and weight of the fish and weight and length of the ovaries.
Progress in studies of fish reproductive development regulation
Ji Chen,Wei Hu,ZuoYan Zhu
Chinese Science Bulletin , 2013, DOI: 10.1007/s11434-012-5577-1
Abstract: Mechanisms of the animal reproductive development are an important research field in life sciences. The study of the reproductive development and regulatory mechanisms in fishes is important for elucidating the mechanisms of animal reproduction. This paper summarizes recent advances in the mechanisms of fish sex determination and differentiation, of fish gonad development and maturation, and of fish germ cell development, as well as the according regulating strategies. Fishes comprise an evolutionary stage that links invertebrates and higher vertebrates. They include diversiform species, and almost all vertebrate types of reproduction have been found in fishes. All these will lead to important advances in the regulatory mechanisms of animal reproduction by using fishes as model organisms. It will also enable novel fish breeding techniques when new controllable on-off strategies of reproduction and/or sex in fishes have been developed.
Ciência Animal Brasileira , 2011,
Abstract: This study aimed to describe the seasonal variation of condition factor (K) correlated with gonadossomatic (GSI) and hepatossomatic index (HSI) of Leporinus obtusidens (Valenciennes, 1837), collected downstream of the Hidroelectric Power Station of Funil, state of Minas Gerais, Brazil, and to evaluate if these indices can indicate the reproductive period of this species. The animals were captured between September/2006 and August/2007 and grouped seasonally. The length and the weight of 110 individuals were measured to calculate K, the weight of the liver was determined to calculate HSI and the weight of the gonad to calculate GSI. The K of females and malesgrouped and of males alone were significantly lower (p<0.05) in the summer. As for the females alone, no significant variation of the K was observed throughout the year. The values of HSI were significantly greater during the spring and summer for both sexes, whereas the GSI of males and females was superior (p<0.05) in the summer. In the correlation tests, K was not related with the GSI andHSI factors; however, strong correlation between GSI and HSI was found. K is not an index of the reproductive period of Leporinus obtusidens (Valenciennes, 1837), whereas GSI and HIS can be used for indicating reproduction.
Características do sêmen de tambaqui (Colossoma macropomum) em latitude equatorial
Vieira,M.J.A.F.; Carvalho,M.A.M.; Salmito-Vanderley,C.S.B.; Salgueiro,C.C. de M.; Viveiros,A.T.M.; Moura,A.A.A.N.; Nunes,J.F.;
Archivos de Zootecnia , 2011,
Abstract: the amazonian fish known as tambaqui (colossoma macropomum cuvier, 1818) is a osseous fish and has high commercial value because of its meat quality and for recreational fishing. tambaqui is one of the major species in the amazon basin and found in most rivers and surroundings of manaus city (silva et al., 1984). the present study was carried out to evaluate sperm parameters from tambaqui, subjected or not to hormone treatment for a period of 12 months. we used 26 males with three years of age, raised at the aquaculture research center of the national department for drought control (dnocs). animals were identified with magnetic chips and divided into two groups: controls (ni) and hormone-treated (i), which received 2 mg of carp pituitary extract (cpekg-1) of body weight (via intra celomic). semen was collected 14 hours after hormonal induction and the following parameters evaluated: volume, ph, osmolarity and sperm concentration. fishes had body weight of 5410 g, with total length and standard length of 68 cm and 59.17 cm, respectively. in the case of hormone-treated and control animals, we found the following criteria, respectively: semen volume of 5.05 ml and 0.55 ml (p<0.05); ph of 8.21 and 8.09; osmolarity of 320.51 and 323 mosm/kg; sperm concentration of 22.93 x 109 and 40.46 x 109 sptz/ml (p<0,05). total sperm productions were quantified as 115.79 x 109 sperm/ml in treated fishes and 22.25 x 109 sperm/ml in the controls. we conclude that treatment of adult tambaqui with carp pituitary extract increase semen volume but reduces sperm concentration while had no effect on sperm osmolarity and ph.
Factores fisicoquímicos que regulan la motilidad espermática en peces: aspectos básicos y aplicados. Una revisión
Valdebenito,I; Fletcher,C; Vera,V; Fernández,J;
Archivos de medicina veterinaria , 2009, DOI: 10.4067/S0301-732X2009000200002
Abstract: in most teleost fish with external fertilization, the spermatozoids are immobile in the seminal fluid and they are activated only after making contact with an aqueous medium. the time of flagellar movement is short in most species. furthermore, the factors that trigger this process are different for each one. however, almost for all species, factors such as osmolarity, temperature, ph and ionic composition have a key role in activating or modulating the flagellar activity. the present review examines the factors involved in the activation of sperm and its regulation in fish with external fertilization. additionally, an analysis is conducted regarding the management of commercially farmed fish semen, with emphasis on salmonid species.
Terapias hormonales utilizadas en el control artificial de la madurez sexual en peces de cultivo: una revisión
Archivos de medicina veterinaria , 2008, DOI: 10.4067/S0301-732X2008000200002
Abstract: the present literature review analyzes the current state of artificial control of sexual maturity in fish culture using hormone therapy, evaluating the advantages and disadvantages of different technological strategies available. the discussion covers from the first successful attempt conducted by houssay (1930), argentina, up to the most recent and more effective techniques of slow release and the use of dopamine inhibitors. in addition, the evaluation of the use of non traumatic methodologies that up until now have not been entirely effective is covered.
Reproductive biology of Steindachnerina insculpta (Fernandez-Yépez) (Teleostei, Curimatidae) in Furnas reservoir, Minas Gerais, Brazil
Ribeiro, Vinicius M. A.;Santos, Gilmar B.;Bazzoli, Nilo;
Revista Brasileira de Zoologia , 2007, DOI: 10.1590/S0101-81752007000100009
Abstract: the 'saguiru' steindachnerina insculpta, a small teleost detritivorous fish species in furnas reservoir, upper rio paraná basin, minas gerais, brazil, has a prolonged period of reproductive activity that extends from september to march, with fractionated spawning. during gonadal maturation, the females showed a low hepatosomatic index, suggesting that hepatic substances are possibly transferred from liver to ovaries. during the reproductive period, this fish had lower stomach repletion and coelomic fat indexes, indicating that the species eat less and consume more fat reserves. the weight of the ovaries influenced positively the condition factor (k1), since the lowest k2 values (without the gonads weight), were obtained during maturation, confirming the influence of the weight of the ovaries upon the physiological condition of the females.
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